Dissertationen: „Fuel injectors“

1

Wang, Hongjuan. „Simulation of fuel injectors excited by synthetic microjets“. Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/11862.

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2

Ahmed, Aqeel. „LES of atomization and cavitation for fuel injectors“. Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR048/document.

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Cette thèse présente la Simulation des Grandes Echelles (LES) de l’injection, de la pulvérisation et de la cavitation dans un injecteur pour les applications liées aux moteurs à combustion interne. Pour la modélisation de l’atomisation, on utilise le modèle ELSA (Eulerian Lagrangian Spray Atomization). Le modèle résout la fraction volumique du combustible liquide ainsi que la densité de surface d’interface liquide-gaz pour décrire le processus complet d’atomisation. Dans cette thèse, l’écoulement à l’intérieur de l’injecteur est également pris en compte pour une étude ultérieure de l’atomisation. L’étude présente l’application du modèle ELSA à un injecteur Diesel typique, à la fois dans le contexte de RANS et de LES.Le modèle est validé à l’aide de données expérimentales disponibles dans Engine Combustion Network (ECN). Le modèle ELSA, qui est normalement conçu pour les interfaces diffuses (non résolues), lorsque l’emplacement exact de l’interface liquide-gaz n’est pas pris en compte, est étendu pour fonctionner avec une formulation de type Volume of Fluid (VOF) de flux à deux phases, où l’interface est explicitement résolu. Le couplage est réalisé à l’aide de critères IRQ (Interface Resolution Quality), qui prennent en compte à la fois la courbure de l’interface et la quantité modélisée de la surface de l’interface. Le modèle ELSA est développé en premier lieu en considérant les deux phases comme incompressibles. L’extension à la phase compressible est également brièvement étudiée dans cette thèse. Il en résulte une formulation ELSA compressible qui prend en compte la densité variable de chaque phase. En collaboration avec l’Imperial College de Londres, la formulation de la fonction de densité de probabilité (PDF) avec les champs stochastiques est également explorée afin d’étudier l’atomisation. Dans les systèmes d’injection de carburant modernes, la pression locale à l’intérieur de l’injecteur tombe souvent en dessous de la pression de saturation en vapeur du carburant, ce qui entraîne une cavitation. La cavitation affecte le flux externe et la formulation du spray. Ainsi, une procédure est nécessaire pour étudier le changement de phase ainsi que la formulation du jet en utilisant une configuration numérique unique et cohérente. Une méthode qui couple le changement de phase à l’intérieur de l’injecteur à la pulvérisation externe du jet est développée dans cette thèse. Ceci est réalisé en utilisant le volume de formulation de fluide où l’interface est considérée entre le liquide et le gaz; le gaz est composé à la fois de vapeur et d’airambiant non condensable
This thesis presents Large Eddy Simulation (LES) of fuel injection, atomization and cavitation inside the fuel injector for applications related to internal combustion engines. For atomization modeling, Eulerian Lagrangian Spray Atomization (ELSA) model is used. The model solves for volume fraction of liquid fuel as well as liquid-gas interface surface density to describe the complete atomization process. In this thesis, flow inside the injector is also considered for subsequent study of atomization. The study presents the application of ELSA model to a typical diesel injector, both in the context of RANS and LES. The model is validated with the help of experimental data available from Engine Combustion Network (ECN). The ELSA model which is normally designed for diffused (unresolved) interfaces, where the exact location of the liquid-gas interface is not considered, is extended to work with Volume of Fluid (VOF) type formulation of two phase flow, where interface is explicitly resolved. The coupling is achieved with the help of Interface Resolution Quality (IRQ) criteria, that takes into account both the interface curvature and modeled amount of interface surface. ELSA model is developed first considering both phases as incompressible, the extension to compressible phase is also briefly studied in this thesis, resulting in compressible ELSA formulation that takes into account varying density in each phase. In collaboration with Imperial College London, the Probability Density Function (PDF) formulation with Stochastic Fields is also explored to study atomization. In modern fuel injection systems, quite oftenthe local pressure inside the injector falls below the vapor saturation pressure of the fuel, resulting in cavitation. Cavitation effects the external flow and spray formulation. Thus, a procedure is required to study the phase change as well as jet formulation using a single and consistent numerical setup. A method is developed in this thesis that couples the phase change inside the injector to the external jet atomization. This is achieved using the volume of fluid formulation where the interface is considered between liquid and gas; gas consists of both the vapor and non condensible ambient air

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3

Savic, Sasha. „Liquid fuel spray characteristics“. Thesis, University of Brighton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324470.

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4

Tran, Xuan-Thien Mechanical &amp Manufacturing Engineering Faculty of Engineering UNSW. „Modelling and simulation of electronically controlled diesel injectors“. Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2003. http://handle.unsw.edu.au/1959.4/19278.

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The study presents a one-dimensional, transient and compressible flow models of a commercial Common Rail Injector (CRI) and a prototype of a single-fuel Hydraulically actuated Electrically controlled Unit Injector (HEUI) developed at the University of New South Wales (UNSW) in conjunction with local industry. The unique feature of the UNSW HEUI is the fact that it uses diesel fuel as the driver for pressure amplification within the unit injector. The work undertaken is part of a wider study aimed at optimization of the design of diesel injectors for dual-fuel systems to reduce green house gas emissions. The contribution of this thesis is the development of the model of the UNSW HEUI injector, which can be used to investigate possible modifications of the injector for its use in dual-fuel injection systems. The developed models include electrical, mechanical and hydraulic subsystems present in the injectors. They are based on Kirchhoff??s laws, on the mass and momentum conservation equations and on the equilibrium of forces. The models were implemented in MATLAB/SIMULINK graphical software environment, which provides a high degree of flexibility and allows simulation of both linear and nonlinear elements. The models were used to perform sensitivity analysis of both injectors. The sensitivity analysis has revealed that the temperature of the solenoid coil is one of the critical parameters affecting the timing and the quantity of the fuel injection of both injectors. Additional critical parameters were found to be the dimensions of the piston of the CRI, the stiffness of the needle spring of the HEUI and the dimensions of the intensifier of the HEUI. The models also revealed that in the case of pilot injections the speed of the solenoid is the major limiting factor of the performance. The developed models provide better understanding of the issues and limitations of the injectors. They give detailed insight into their working principles. The investigations of the models permit making quantitative analysis of the timing of the HEUI solenoid and to evaluate the proposed change of the direction of the pressure acting on the HEUI solenoid plunger.

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5

Chen, Rui. „Fluidic devices as fuel injectors for natural gas engines“. Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/13566.

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A novel, fast switching, reliable, and economical fluidic gaseous fuel injector system designed for natural gas engines has been developed in this research. The system consists mainly of no-moving-part fluidic devices and piezo-electric controlling interfaces. The geometric parameters of a fluidic device seriously affect its performance. Traditionally, these parameters can only be optimised through "trial and error" exercise. In this research, a computer simulation model for the jet steady state attachment and dynamic switching has been developed. The good agreements between predicted results and experimental ones show that the model can not only explain the jet attaching and switching mechanism, but also optimise the design of geometric parameters of a fluidic device. The steady state and dynamic characteristics of the system were tested on a laboratory experimental rig. The results show that the system can handle the large gas volume flow rate required by natural gas engines and is capable of operating via pulse width modulation. A few typical commercial solenoid type gas injectors were also tested and the results were compared with those from the fluidic system. It was found that the fluidic gaseous fuel injector system has faster switching responses and smaller injection cycle-to-cycle variations.

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6

Martynov, Sergey. „Numerical simulation of the cavitation process in diesel fuel injectors“. Thesis, University of Brighton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418575.

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7

VanDerWege, Brad A. (Brad Alan). „The effects of fuel volatility and operating conditions on sprays from pressure-swirl fuel injectors“. Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9427.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.
"June 1999."
Includes bibliographical references (p. 205-208).
Optimal design of modern direct injection gasoline engines depends heavily on the fuel spray. Most of the studies published regarding these fuel sprays involve cold bench tests or motored optical engines, neglecting the roles of the fuel volatility and temperature. This study, therefore, was designed to describe changes in the spray properties due to fuel volatility and operating conditions using a firing optically-accessible engine. Planar laser-induced fluorescence and planar Mie scattering imaging experiments were performed to show changes in the spray structure, including its radial and axial penetration. Phase-Doppler particle analysis experiments were included to track the droplet diameter and velocity at various points throughout the spray. A computational fluid dynamics model was also used to study the physics leading to the observed changes. The results show that the spray structure changes with not only ambient gas density, which is often measured, but also fuel temperature and volatility. The mean droplet diameter was found to decrease substantially with increasing fuel temperature and decreasing ambient density. Under conditions of low potential for vaporization, the observed trends agree with published correlations for pressure-swirl atomizers. As ambient density decreases and fuel temperature increases, the volatile ends of multi-component fuels evaporate quickly, producing a vapor core along the axis of the spray. Beyond a certain point, evaporation is violent enough to cause additional breakup of the droplets. A fit to this volatility-induced breakup data provides an additional correlation for determining the mean diameter of volatile sprays. Coincident with the volatility-induced breakup trend is an increase in the initial cone angle of the spray. However, the reduced droplet diameter and rapid vapor generation under these superheated conditions result in a narrow spray with increased axial penetration. In the process of performing these experiments, insights were found regarding the operation of these diagnostics in high-density sprays.
by Brad A. VanDerWege.
Ph.D.

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8

Kolokotronis, Dimitrios. „Experimental investigation of the internal flow field of model fuel injectors“. Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507950.

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9

Senousy, Youssef Mohamed Salah. „Experimental investigation and theoretical modeling of piezoelectric actuators used in fuel injectors“. Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/15230.

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Piezoelectric stack actuators are increasingly used in micropositioning applications due to their precision and responsiveness. Advanced automotive fuel injectors have recently been developed that utilize multilayer piezoelectric actuators. Since these injectors must operate under high dynamical excitations at high temperatures, understanding their thermo-electro-mechanical performance under such operating conditions is crucial to their proper design. In this thesis, the effect on soft Lead Zirconate Titanate (PZT) piezoelectric actuators of different controlling parameters relevant to fuel injection is studied experimentally. These parameters include electric-field magnitude and frequency, driving-field rise time, DC offset, duty-cycle percentage, and ambient temperature. Soft PZT actuators generate a significant amount of heat when driven under high electric-field magnitudes and/or high frequency, both of which occur in fuel injectors. They also exhibit hysteretic nonlinear behavior when driven under high electric-field magnitudes. Self-heating and hysteretic nonlinearity are interconnected, and both are undesirable in applications that require precise positioning, such as fuel injection. Self-heating in PZT stacks is considered to be caused by ferroelectric hysteretic nonlinearity, originating from domain-switching. Theoretical studies of self-heating and domain-switching in PZT materials are developed in this thesis. An analytical self-heating model based on the first law of thermodynamics is presented that accounts for different parameters such as geometry, magnitude and frequency of applied electric field, duty-cycle percentage, and surrounding properties. It also directly relates self-heating in PZT actuators to displacement-electric field loss (displacement hysteresis), which is found to increase linearly with increased temperature. The model shows reasonable agreement with experimental results at low and high electric-field magnitudes. A novel domain-switching model for PZT materials is developed. The model is based on changes in potential energy, and accounts for the temperature effect on domain switching. It also accounts for full thermo-electro-mechanical coupling. Additionally, different energy levels are assumed for different domain-switching types. It is assumed that 180° switching is a two-step process caused by two 90° switching events. A finite element implementation of a thermo-piezoelectric continuum, based on the proposed switching model, is presented. The model shows good agreement with experimental results at different temperatures and loading conditions.

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10

Kumar, A. „Investigation of in-nozzle flow characteristics of fuel injectors of IC engines“. Thesis, City, University of London, 2017. http://openaccess.city.ac.uk/17583/.

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Almost all automotive fuel injection systems are experiencing some form of cavitation within their nozzle under different operating conditions. In-nozzle cavitation initiates in various forms and directly influences the emerging spray. Experimental studies have shown that cavitation in diesel injectors leads to smaller droplet formation, especially by the on-going trend towards higher injection pressures, which enhances fuel evaporation but also creates undesirable consequences due to transient nature of cavitation such as spray instabilities, erosion on internal surfaces, and hydraulic flip. Thus, the understanding of the internal flow of automotive fuel injectors is critical for injector design. On the other hand, biodiesel has emerged as one of the potential alternative fuel which can also be carbon neutral because it uptakes CO2 during cultivation of its feedstock and can be used in existing diesel engines with little or no modifications. Therefore, the present study is focused on assessing and outlining cost-effective methods to analyse internal flow in fuel injectors for diesel and biodiesel fuel applications. In the present study, RANS-based (Reynolds-averaged Navier–Stokes) CFD (Computational fluid dynamics) approach has been chosen to simulate quasi-steady flows in the steady state test rigs of fuel injectors of IC engines. The RANS approach is selected over computationally expensive SAS (Scale Adaptive Simulations), DES (Detached Eddy Simulations) and LES (Large Eddy Simulations) because it was considered that these quasi-steady simulations could be performed within hours and with less computing resources using RANS rather using SAS, DES and LES which may require orders more time and computing resources. Cavitation models and RANSbased turbulence models have been evaluated for single-hole and multi-hole injectors operating on steady state test rigs. Furthermore, influences of liquid and vapour compressibility were also investigated. Influences of biodiesel properties such as higher viscosity and density on cavitation were also assessed. In the first part of the study, single-phase simulations have been carried out in the mini-sac type multi-hole (6) injector. Several two-equation turbulence and near wall models were assessed, amongst most appropriate for the application were identified. Predicted mean velocity and RMS velocity were compared with measurements and showed good agreements. Flow field analysis showed predictions of different types of vortices in the injector. Two main types of vortex structures were predicted: ‘Hole-to-hole’ connecting vortex and double ‘counterrotating’ vortices emerging from the needle wall and entering the injector hole facing it. The latter create a complex 3D flow inside the injector hole when it interacts with the recirculation region at the entrance of the injector hole. Cavitation simulations inside a single-hole injector were next performed. Simulations were assessed by comparing predicted vapour volume fraction with measurements. Influences of liquid and vapour compressibility were also checked. The compressibility of vapour was modelled using ideal gas law and liquid compressibility was modelled using the Tait equation. Vapour compressibility resulted in an increase of vapour volume fraction at the low-pressure region and predictions were also in better agreements with experimental data. The liquid compressibility made no impact on the simulation results. The local sonic speed in the liquid-vapour mixture was computed using Wallis model which predicted a very low local sonic speed in the liquid-vapour mixture. Therefore, the local flow in liquid-vapour mixture became supersonic. A normal shock wave was predicted just downstream of the cavitation bubble cloud as local flow velocity was reduced from supersonic to subsonic. Finally, the cavitation simulations were performed in the enlarged mini-sac type multi-hole injector. Established turbulence, cavitation and compressibility models from above studies were used. Reasonable quantitative agreements with experimental data were obtained for the mean axial velocity and RMS velocity. Reasonable qualitative agreements were also achieved when predicted cavitation results were compared with high-speed digital images. Henceforth a parametric study to assess the influence of biodiesel fuel properties such as an increase in viscosity and density on the cavitation was performed. Viscosity and density of both phases in the fluid were parametrically increased by 20%. Results showed that cavitation was suppressed when the viscosity was increased because it increased the flow resistance, thus reduced the velocity. This caused a reduction in the size of recirculation region at the entrance of the injector hole and hence a smaller saturation pressure region was predicted. Cavitation was further suppressed when density was increased causing the reduction in the velocity at the same mass flow rate, which further reduced the recirculation region, therefore, reduced the saturation pressure region and consequently cavitation.

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11

Birger, Nicholas Joseph. „Flow characteristics of gas-blast fuel injectors for direct-injection compression-ignition engines“. Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/25752.

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Natural gas has a high auto-ignition temperature, therefore natural gas engines use an ignition source to promote combustion. The high-pressure direction-injection (HPDI) systems available use small diesel injections prior to the main gas injection. A new series of HPDI injectors have been developed that inject diesel and gas simultaneously through the same holes. In order to understand and control injection and combustion behavior in an engine, it is essential to understand how injection mass is related to the diesel/gas ratio and injection command parameters. Three prototype injectors are examined. “Prototype B” most closely resembles a standard J36 HPDI injector, but has a modified diesel needle that injects diesel internally into a common diesel/gas reservoir. Prototypes “CS & CSX” have the diesel needle eliminated and replaced with a flow restrictor. The pressure difference between the diesel and the gas controls the quantity of diesel injected. A single pulse width (GPW) for the gas needle controls the fuel quantities. An injection visualization chamber (IVC) was developed for flow measurements and optical characterization of injections into a chamber at pressures up to 80 bar. Diesel and natural gas are replaced by VISCOR® and nitrogen to study non-reacting flows. A novel feature of the IVC is a retracting shroud that allows the injector to reach steady-state prior to imaging. For low commanded injection duration (GPW less than 0.60 ms), the relation between GPW and injected mass is non-linear, for all injectors tested. For gas pulse widths greater than 0.65 ms the Co-injectors exhibit approximately linear behavior with higher diesel fuelling quantities lowering gas flow quantities. All Co-injectors are compared to baseline gas flow quantities of a standard J36 to show design difference effects on flow quantities. The sensitivity of gas flow to diesel in injection quantities, as well as the discharge coefficient are computed and theoretically modeled for each prototype. Results suggest differing diesel/gas distributions, dependent on method of diesel introduction and actuator response. Imaging indicates the mechanical delay of the injectors is independent of chamber backpressure but dependent on fuel supply pressure. However, gas injection quantities are increased by higher chamber backpressure. Changes in the gas/liquid ratio are reflected in different jet image characteristics. These results are compared to theory using an AMESim model developed for an existing production injector.

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12

Bilger, Camille. „Numerical investigation of liquid film dynamics and atomisation in jet engine fuel injectors“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274203.

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Today’s aerospace industry continues to exploit liquid hydrocarbon fossil fuels. Motivated by operational considerations, continued availability and cost, this is likely to be the case for many years, despite the obvious environmental concerns. The interplay of liquid atomisation, spray vaporisation and the combustion process are intricately linked. However, the physical process of fuel injection and its atomisation into tiny droplets prior to combustion remains poorly understood. Because atomisation governs the size of the fuel droplets, and therefore their subsequent evaporation rate, adjusting the injection sequence is of paramount importance and will have far-reaching repercussions on many aspects of the combustion process, for example pollutant formation. In the context of jet engines, kerosene is usually injected in its liquid form via an airblast-type fuel injector. A coflowing high-speed airstream destabilises the liquid fuel, which is thus sprayed into fine droplets into the combustion chamber. The prediction of this phenomenon for various operating conditions relevant to the aeronautical industry requires a deeper understanding of the mechanisms involved in the interaction of the two fluids. A key element in predicting the complex behaviour of spray formation and evolution in jet engines is accurate modelling of fuel atomisation. Atomisation represents one of the key challenges that remains to be undertaken to make predictive computational simulations possible. However, the inherent multi-physics and multi-scale nature of this process limits numerical investigations. Thanks to the steady progress in computer power and Computational Fluid Dynamics (CFD) methods, computational modelling of injection systems emerges as a promising tool that can drive the design of future devices. This research project sets out to investigate the atomisation process in detail, in particular in providing physical insight into the fundamental physics of the phenomenon, in conjunction with an analysis on wetting behaviours and liquid droplet tracking. High-fidelity numerical simulations are performed using a novel in-house state-of-the-art multiphase flow modelling capability, RCLSFoam. The performance of the numerical scheme is demonstrated on typical two-dimensional and three-dimensional benchmark test cases relevant to both multiphase flow modelling and atomisation, and validated against other computational methods. An informed and systematic qualitative assessment of the topological variations of the phase interface during primary atomisation of a liquid film is made through dynamical analysis, while investigating an extensive domain of operating conditions at ambient and aero-engine injection conditions relevant to industry. This analysis demonstrated the influence of shear-driven instabilities on the atomisation process. The shear stress and difference in inertia between liquid and gas are observed to play a significant role in the atomisation process. In addition, the key physical mechanisms and their competing effects have been mapped out in order to predict the evolution of the process according to the operating conditions of the injection system. The proposed cartography gathers four different atomisation mechanisms. In particular, for sufficiently high liquid injection speeds, three-dimensional wave modes were observed to co-exist (the “3-D wave mode” regime). For very low liquid flow rates, accumulated liquid at the atomising edge undergoes deformation by which droplets are generated (the “accumulation” regime). For an increasing gas injection speed and a fixed liquid velocity, the effects of surface tension were observed to result in the generation of streamwise ligaments only, which tend to pair up (the “ligament-merging” regime). Finally, “vortex action” is another observed mechanism by which the liquid film is fragmented. Overall, this research project culminated in (i) the study of dynamic wetting behaviours, with the implementation and validation against experimental data of the Kistler dynamic contact model; and (ii) the demonstration of an algorithm for droplet capture and subsequent post-processing analysis of the droplet characteristics.

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13

Hofmann, Oliver [Verfasser]. „Modeling, Identification and Control of Aging Effects in Common Rail Fuel Injectors / Oliver Hofmann“. München : Verlag Dr. Hut, 2019. http://d-nb.info/1194289193/34.

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14

Rees, Simon John. „Hydrodynamic instability of confined jets & wakes & implications for gas turbine fuel injectors“. Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609152.

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15

Pelteret, Jean-Paul. „A CFD investigation of cavitation and associated deposit formation in modern diesel fuel injectors“. Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5487.

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Includes bibliographical references (leaves 78-81).
Reducing the pollution of new vehicles has become a priority to vehicle manufacturers, particularly given the fact that emissions requirements that must be achieved by diesel vehicles are becoming more stringent. Modem fuel injectors on common-rail diesel vehicles use very high rail pressures to aid atomisation and increase combustion efficiency. However, associated with the high injections pressures is the issue of nozzle cavitation. Cavitation leads to pockets of diesel vapour forming in the nozzle and it is hypothesised that this causes the formation of deposits in the nozzle. It is also suggested that the collapse of the cavitation vapour space results in extremely high temperatures within the nozzle, resulting in thermal cracking of the fuel and eventually the formation of carbon deposits. A two-dimensional axisymmetric CFD model with dimensions representative of an injector nozzle was constructed using a fully structured grid.

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16

Torab, Babak. „The adaptation of solenoid-actuated injectors for use with dimethyl ether fuel in diesel engines“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ43663.pdf.

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17

Alexander, Derrick. „Hypersonic fuel/air mixing enhancement by cantilevered ramp injectors in the presence of wavy walls“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62886.pdf.

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18

Cheng, Liangta. „Combined PIV/PLIF measurements in a high-swirl fuel injector flowfield“. Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/11936.

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Current lean-premixed fuel injector designs have shown great potential in terms of reducing emissions of pollutants, but such designs are susceptible to combustion instabilities in which aerodynamic instability plays a major role and also has an effect on mixing of air and fuel. In comparison to prototype testing with combustors running in operating conditions, computational approaches such as Large Eddy Simulations (LES) offer a much more cost-effective alternative in the design stage. However, computational models employed by LES require validation by experimental data. This is one of the main motivations behind the present experimental study. Combined particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) instrumentation allowed simultaneous measurements of velocity vector and a conserved scalar introduced into the fuel stream. The results show that the inner swirl shear layer features two pairs of vortices, which draw high concentration fuel mixture from the central jet into the swirl stream and causes it to rotate in their wakes. Such periodic entrainment also occurs with the characteristic frequencies of the vortices. This has clear implications for temporal variations in fuel/air ratio in a combusting flow; these bursts of mixing, and hence heat release, could be a possible cause of mixing-induced pressure oscillation in combusting tests. For the first time in such a flow, all 3 components of the turbulent scalar flux were available for validation of LES-based predictions. A careful assessment of experimental errors, particularly the error associated with spatial filtering, was carried out. Comparison of LES predictions with experimental data showed very good agreement for both 1st and 2nd moment statistics, as well as spectra and scalar pdfs. It is particularly noteworthy that comparison between LES computed and measured scalar fluxes was very good; this represents successful validation of the simple (constant Schmidt number) SGS model used for this complex and practically important fuel injector flow. In addition to providing benchmark data for the validation of LES predictions, a new experimental technique has been developed that is capable of providing spatially resolved residence time data. Residence times of combustors have commonly been used to help understand NOx emissions and can also contribute to combustion instabilities. Both the time mean velocity and turbulence fields are important to the residence time, but determining the residence time via analysis of a measured velocity field is difficult due to the inherent unsteadiness and the three dimensional nature of a high-Re swirling flow. A more direct approach to measure residence time is reported here that examines the dynamic response of fuel concentration to a sudden cutoff in the fuel injection. Residence time measurement was mainly taken using a time-resolved PLIF technique, but a second camera for PIV was added to check that the step change does not alter the velocity field and the spectral content of the coherent structures. Characteristic timescales evaluated from the measurements are referred to as convection and half-life times: The former describes the time delay from a fuel injector exit reference point to a downstream point of interest, and the latter describes the rate of decay once the effect of the reduced scalar concentration at the injection source has been transported to the point of interest. Residence time is often defined as the time taken for a conserved scalar to reduce to half its initial value after injection is stopped: this is equivalent to the sum of the convection time and the half-life values. The technique was applied to a high-swirl fuel injector typical of that found in combustor applications. Two test cases have been studied: with central jet (with-jet) and without central jet (no-jet). It was found that the relatively unstable central recirculation zone of the no-jet case resulted in increased transport of fuel into the central region that is dominated by a precessing vortex core, where long half-life times are also found. Based on this, it was inferred that the no-jet case may be more prone to NOx production. The technique is described here for a single-phase isothermal flow field, but with consideration, it could be extended to studying reacting flows to provide more insight into important mixing phenomena and relevant timescales.

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19

Midgley, Kristofer. „An isothermal experimental study of the unsteady fluid mechanics of gas turbine fuel injector flowfields“. Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/10755.

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Low-emissions combustor design is crucially important to gas turbine engine manufacturers. Unfortunately, many designs are susceptible to unsteady oscillations that can result in structural fatigue and increased noise. Computational approaches that resolve flow unsteadiness, for example Large Eddy Simulation (LES), are being explored as one avenue to help understand such phenomena. However, in order to quantifY the accuracy of LES predictions, benchmark validation data in suitably chosen test cases are required. Comprehensive experimental data covering both time-averaged and timeresolved features are currently scarce. It was the aim of this thesis, therefore, to provide such data .in a configuration representing the near-field of a typical gas turbine fuel injector. It was decided to focus on the fuel injector since many unsteady events are believed to originate because of the transient interactions between the fuel injector flow and the main combustor flow. A radial fed two-stream fuel injector, based on a preexisting industrial gas-turbine Turbomeca design was used, since this geometry was known to be susceptible to unsteadiness. The fuel injector was investigated under isothermal conditions to place emphasis on the fluid mechanical behaviour of the fuel injector, including detailed capture of any unsteady phenomena present. Light Sheet Imaging (LSI) systems were used as the primary experimental technique to provide high quality spatially and temporally resolved instantaneous velocity and scalar field information in 2D planes (using ParticieImage Velocimetry (PIV) and Planar LaserInduced Fluorescence (PUF) techniques). Several methods were employed to extract information quantifYing the flow unsteadiness and improve visualisation of timedependent large-scale turbulent structures. Proper Orthogonal Decomposition (POD) analysis enabled clear identification of the dominant modes of energy containing structures. The results indicated that periodic high-energy containing vortex structures occurred in the swirl stream shear layer, emerging from the fuel injector. These formed a two-strong two-weak rotating vortex pattern which propagated down the main duct flow path. The formation of these vortices was found to be a function of the swirl number and originated due to an interaction between the forward moving swirl flow and the furthest upstream penetration point ofthe recirculation zone present in the main duct flow. Dependent on the magnitude of the swirl number (influencing the swirl stream cone angle) and the geometry of the fuel injector, the vortex formation point was sometimes found inside the fuel injector itself. If the vortices originated inside the fuel injector they appeared much more coherent in space and time and of higher energy. A second unsteady high energy containing phenomenon was also identified, namely a Precessing Vortex Core (PVC), which was damped out if the fuel injector contained a central jet. The dynamics of the PVC interacted with the dynamics of the swirl stream shear layer vortices to reduce there strength. Transient scalar measurements indicated that there was a clear connection between the unsteady vortex pattern and the rate of mixing, resulting in bursts of high heat release and is therefore identified as one source of combustor oscillations. Future fuel injector designs need to pay close attention to these unsteady features in selecting swirl number and internal geometry parameters.

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Slator, Duncan. „Fuel injector spray diagnostic development“. Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/17488.

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New technologies are constantly developing towards the goal of increasing the performance of gas turbine engines while reducing pollutant emissions. The design of the combustion system is vital in the drive to reduce pollutants in order to meet legislative targets. As part of this, the fuel injector is crucial in preparing the fuel for combustion through atomization and correct mixing with the air flow. Thus, it is desirable to develop techniques to allow the analysis of performance in these key criteria and improve the understanding of both fuel injector aerodynamics and fuel atomisation. Particle Image Velocimetry (PIV) allows for spatially resolved velocity data of flow fields to be recorded and therefore enables the inspection of flow behaviour.

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Dufva, Johannes, und Andreas Lindgren. „Machine Learning Models for Fueling Inaccuracy Detection using Gas Exchange Signals in Heavy-duty Vehicle Engines“. Thesis, Uppsala universitet, Avdelningen för systemteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-447180.

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Heavy-duty trucks are important links in the logistic chains of transport. Critical components in trucks include fuel injectors in which inaccuracies can lead to severe financial damage and higher emissions. Intelligent and efficient ways to detect such scenarios are thus of high importance. This thesis applies machine learning algorithms to measured or estimated engine data, focused on gas exchange signals, to detect inaccuracies in fueling quantities. The fueling inaccuracies considered were of low deviations from the nominal curve, with magnitudes not covered by the currently used fueling diagnostics. The data used for the models was generated from Scania test cell engines where different setups of injectors were deliberately set to over- or underfuel. Seven different machine learning models were used on the data and evaluated on how well they could detect deviations from nominal fueling. The tests were mainly done with a pure data-driven approach but also improved through different data selection techniques and using domain knowledge. An investigation to connect the findings within the thesis to real customer data was initiated in order to make the results useful for e.g. predictive maintenance. The complications connected to why this was not ultimately achieved were discussed.

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Giannadakis, Emmanouil. „Modelling of cavitation in automotive fuel injector nozzles“. Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420301.

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23

Bajaj, Siddhant, und Erik Günther-Hanssen. „Preliminary study of the fuel injector assembly capacity“. Thesis, KTH, Industriell produktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259578.

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In the near future the demand of the XPI fuel injectors of Scania Cummins JV assembled in Södertälje is predicted to increase. To meet this new demand the assembly line needs to increase its capacity. This paper is a preliminary study of how this capacity increment could be carried out to meet a future demand of 50% higher than today. The assembly line is semi-automated and consists of eight stations in which 100 operators are working in two shifts. The study includes situational analysis, VSM, cycle time analysis, flow analysis, line balancing and optimisation. Each station has been studied separately including all circumstances that can hinder the production of the line. The study shows how a step-by-step ramp up could be carried out for increasing the capacity of the fuel injectors. The suggestions include structural change, layout change, automation, optimisation and program logic changes.
Inom en snar framtid förutsägs efterfrågan på XPI-bränsleinsprutningsmunstycken från Scania Cummins JV monterade i Södertälje öka. För att möta denna nya efterfrågan måste monteringslinan öka sin kapacitet. Detta dokument är en preliminär studie av hur denna kapacitetsökning kan genomföras för att möta en framtida efterfrågan som är 50 % högre än idag. Monteringslinan är halvautomatisk och består av åtta stationer där 100 operatörer arbetar i två skift. Studien inkluderar lägesanalys, VSM, cykeltidsanalys, flödesanalys, linbalansering och optimering. Varje station har studerats separat inkluderande alla scenarier som kan hindra produktionen på linan. Studien visar hur en steg-för-steg upptrappning skulle kunna genomföras för att öka produktionen av bränsleinsprutningsmunstycken. Förslagen inkluderar strukturförändringar, layoutändring, automatisering, optimering och programlogikändringar.

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24

Bergstrand, David. „Investigation of Internal Diesel Injector Deposits on fuel injector performance for proposal of injector test rig test method“. Thesis, Uppsala universitet, Elektricitetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417012.

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With increasing demands for lowering emissions from diesel engines, bio fuel has been introduced to the fuel mixture. This fuel is based on vegetable oil with a much smaller carbon footprint than fossil fuel. The chemical composition of bio fuel has lead to deposits forming inside the fuel injector in diesel engines, these deposits are usually denoted as Internal Diesel Injector Deposits (IDID). At Scania CV AB an injector test rig is designed with the goal of creating and investigating IDID. This project has made a theoretical investigation of how IDID are formed and how this affects the mechanics inside the injector. It has also analysed injector components from a worst case scenario perspective in order to find a testing method for creating IDID in the test rig. By analysing performance changes from a build-up perspective, where IDID decreases the tolerances inside the injector, as well as friction, formed when deposits cause injector mechanics to stick together, it has been found that injector performance does hardly change from build-up and that performance changes only occur when friction is introduced. From the injector component analysis it is found that the limiting factors in rig testing come from fuel system components rather than the injector itself. This is the base for a rig running test method presented.

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Mandokhot, Mohit Atul. „Development of Predictive Gasoline Direct Fuel Injector Model for Improved In-cylinder Combustion Characterization“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534517269503352.

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26

Morris, David Wyn. „Temporal characterisation of various G-DI fuel injector concepts“. Thesis, Cardiff University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440615.

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27

Ghulam, Mohamad. „Characterization of Swirling Flow in a Gas Turbine Fuel Injector“. University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563877023803877.

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28

MEICENHEIMER, HEIDI L. „INDEPENDENT STAGE CONTROL OF A CASCADE INJECTOR“. University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155655108.

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29

Petropoulou, Stamatina. „Adjoint-based geometry optimisation with applications to automotive fuel injector nozzles“. Thesis, City University London, 2006. http://openaccess.city.ac.uk/8492/.

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Methods of Computational Fluid Dynamics (CFD) have matured, over the last 30 years, to a stage where it is possible to gain substantial insight into fluid flow processes of engineering relevance. However, the motives of fluid dynamic engineers typically go well beyond the level of improved understanding, to the pragmatic aim of improving the performance of the engineering systems in consideration. It is in recognition of these circumstances that the present thesis investigates the use of automated design optimisation methodologies in order to extend the power of CFD as an engineering design tool. Optimum design problems require the merit or performance of designs to be measured explicitly in terms of an objective function. At the same time, it may be required that one or more constraints should be satisfied. To describe allowable variations in design, shape parameterisation using basic geometric entities such as straight lines and arcs is employed. Taking advantage of previous experience in the research group concerning cavitating flows, a fully automated method for nozzle design/optimisation was developed. The optimisation is performed by means of discharge coefficient (Cd) maximisation. The objective is to design nozzle hole shapes that maximise the nozzle Cd for a given basic nozzle geometry (i.e. needle and sac profile) and reduce or even eliminate the negative pressure region formed at the entry of the injection hole. The deterministic optimisation model was developed and implemented in the in-house RANS CFD code to provide nozzle shapes with pre-defined flow/performance characteristics. The required gradients are calculated using the continuous adjoint technique. A parameterisation scheme, suitable for nozzle design, was developed. The localised region around the hole inlet, where cavitation inception appears, is parameterised and modified during the optimisation procedure, while the rest of the nozzle remains unaffected. The parameters modifying the geometry are the radius of curvature and the diameter of the hole inlet or exit as well as the relative needle seat angle. The steepest descent method has been used to drive the calculated gradients to zero and update the design parameters. For the validation of the model two representative inverse design cases have been selected. Studies showing the behaviour of the model according to different numerical and optimisation parameters are also presented. For the purpose of optimising the geometries, a cost function intended to maximise the discharge coefficient was defined. At the same time it serves the purpose of restructuring geometries which have controlled or eliminated cavitation inception in the hole entrance. This is identified in the steady-state mode by reduction of the volume of negative relative pressure appearing in the hole entrance. Results of cavitation control on some representative nozzle geometries show significant benefits gained by the use of the developed method. This is mainly because the developed model performs optimisation on numerous parametric combinations automatically. Results showed that, by using the proposed method, geometries with larger Cd values can be achieved and the cavitation inception can, in some cases, be completely eliminated. Cases where all the parameters were combined for redesign the geometry required less modification to predict larger Cd values than cases where each parameter was modified individually. This is an important result since manufacturers are seeking improvement in the performance of products resulting from the least geometry modifications.

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30

Rock, Christopher. „Experimental Studies of Injector Array Configurations for Circular Scramjet Combustors“. Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77208.

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A flush-wall injector model and a strut injector model representative of state of the art scramjet engine combustion chambers were experimentally studied in a cold-flow (non-combusting) environment to determine their fuel-air mixing behavior under different operating conditions. The experiments were run at nominal freestream Mach numbers of 2 and 4, which simulates combustor conditions for nominal flight Mach numbers of 5 and 10. The flush-wall injector model consists of sixteen inclined, round, sonic injectors distributed around the wall of a circular duct. The strut injector model has sixteen inclined, round, sonic injectors distributed across four struts within a circular duct. The struts are slender, inclined at a low angle to minimize drag, and have two injectors on each side. The experiments investigated the effects of injectant molecular weight, freestream Mach number, and jet-to-freestream momentum flux ratio on the fuel-air mixing process. Helium, methane, and air injectants were studied to vary the injectant molecular weight over the range of 4-29. All of these experiments were performed to support the needs of an integrated experimental and computational research program, which has the goal of upgrading the turbulence models that are used for Computational Fluid Dynamics predictions of the flow inside a scramjet combustor. The primary goals of this study were to use injector models that represent state of the art scramjet engine combustion chambers to provide validation data to support the development of turbulence model upgrades and to add to the sparse database of mixing results in such configurations. The main experimental results showed that higher molecular weight injectants had approximately the same amount of penetration in the far field as lower molecular weight injectants at the same jet-to-freestream momentum flux ratio. Higher molecular weight injectants also demonstrated a mixing rate that was the same as or slower than lower molecular weight injectants depending on the flow conditions. A comparison of the experimental results for the two different injector models revealed that the flush-wall injector mixed significantly faster than the strut injector in all of the experimental cases.
Ph. D.

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31

Meeboon, Non. „Design and Development of a Porous Injector for Gaseous Fuels Injection in Gas Turbine Combustor“. University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1427813298.

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32

Rydalch, Andrew J. „Ignition delay properties of alternative fuels with Navy-relevant diesel injectors“. Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42715.

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Approved for public release; distribution is unlimited
In support of the Navy’s Green Fleet Initiative, this thesis researched the ignition characteristics for diesel replacement fuels used with Navy-relevant fuel injectors. A constant-volume combustion chamber was used to simulate Top-Dead-Center conditions of a diesel engine using an ethylene-air preburn with appropriate make-up oxygen. The injection conditions ranged from temperatures of 1,000 K to 1,300 K and densities has high as 14.8 kg/m3. Hydrotreated renewable diesel (HRD) and direct sugar-to-hydrocarbon (DSH) fuels were injected into the combustion chamber using a Sturman research injector, a Yanmar injector, and an Electro Motive Diesel (EMD) injector. The primary means of data collection was optical emission imaging of laser induced fluorescence of the fuel and broadband emission of the combustion event. The ignition delay was determined using high speed imaging at 50 kHz to determine the time delay between start of injection and start of combustion. The results of the study show that the ignition delay characteristics for the F-76/HRD 50/50 blend are compatible with those of conventional F-76 diesel fuel for both the Yanmar and EMD injectors at the conditions tested. The ignition delay characteristics of the F-76/DSH 50/50 blend fuel for the Yanmar injector were also compatible with those of F-76.

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33

Kushari, Abhijit. „Study of an internally mixed liquid injector for active control of atomization process“. Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15928.

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34

Turcu, Viorel. „Combustion of the fuel/air mixture in the vicinity of a cantilevered ramp fuel injector in a hypervelocity flow“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58732.pdf.

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35

Königsson, Fredrik. „Advancing the Limits of Dual Fuel Combustion“. Licentiate thesis, KTH, Förbränningsmotorteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96945.

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There is a growing interest in alternative transport fuels. There are two underlying reasons for this interest; the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors the Diesel Dual Fuel, DDF, engine is an attractive concept. The primary fuel of the DDF engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste; commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. The DDF engine is from a combustion point of view a hybrid between the diesel and the otto engine and it shares characteristics with both. This work identifies the main challenges of DDF operation and suggests methods to overcome them. Injector tip temperature and pre-ignitions have been found to limit performance in addition to the restrictions known from literature such as knock and emissions of NOx and HC. HC emissions are especially challenging at light load where throttling is required to promote flame propagation. For this reason it is desired to increase the lean limit in the light load range in order to reduce pumping losses and increase efficiency. It is shown that the best results in this area are achieved by using early diesel injection to achieve HCCI/RCCI combustion where combustion phasing is controlled by the ratio between diesel and methane. However, even without committing to HCCI/RCCI combustion and the difficult control issues associated with it, substantial gains are accomplished by splitting the diesel injection into two and allocating most of the diesel fuel to the early injection. HCCI/RCCI and PPCI combustion can be used with great effect to reduce the emissions of unburned hydrocarbons at light load. At high load, the challenges that need to be overcome are mostly related to heat. Injector tip temperatures need to be observed since the cooling effect of diesel flow through the nozzle is largely removed. Through investigation and modeling it is shown that the cooling effect of the diesel fuel occurs as the fuel resides injector between injections and not during the actual injection event. For this reason; fuel residing close to the tip absorbs more heat and as a result the dependence of tip temperature on diesel substitution rate is highly non-linear. The problem can be reduced greatly by improved cooling around the diesel injector. Knock and preignitions are limiting the performance of the engine and the behavior of each and how they are affected by gas quality needs to be determined. Based on experiences from this project where pure methane has been used as fuel; preignitions impose a stricter limit on engine operation than knock.
QC 20120626
Diesel Dual Fuel

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36

Anderson, Cody Dean. „Development and Testing of an Integrated Liquid-Fuel-Injector/Plasma-Igniter for Scramjets“. Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31416.

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A newly designed liquid fuel (kerosene) aeroramp injector/plasma igniter was tested in cold flow using the Virginia Tech supersonic wind tunnel at Mach 2.4. The liquid fuel (kerosene) injector is flush wall mounted and consists of a 2 hole aeroramp array of impinging jets that are oriented in a manner to improve mixing and atomization of the liquid jets. The two jets are angled downstream at 40 degrees and have a toe-in angle of 60 degrees. The plasma torch used nitrogen and air as feedstocks and was placed downstream of the injector as an ignition aid. First, schlieren and shadowgraph photographs were taken of the injector flow to study the behavior of the jets, shape of the plume, and penetration of the liquid jet. The liquid fuel aeroramp was found to have better penetration than a single, round jet at 40 degrees. However, the liquid fuel aeroramp does not penetrate as well as an upstream/downstream impinging jet in a plane aligned with the flow. Next, the Sauter mean droplet diameter distribution was measured downstream of the injector. The droplet diameter was found to vary from 21 to 37 microns and the atomization of the injector does not appear to improve beyond 90 effective jet diameters from the liquid fuel aeroramp. These results were then used to decide on an initial location for the plasma torch. The combined liquid injector/plasma torch system was tested in an unheated (300 K) Mach 2.4 flow with a total pressure of 345 kPa. The liquid fuel (kerosene) volumetric flow rate was varied from 0.66 lpm to 1.22 lpm for the combined liquid injector/plasma torch system. During this testing the plasma torch was operated from 1000 to 5000 watts with 25 slpm of nitrogen and air as feedstocks. The interaction between the spray plume and the plasma torch was observed with direct photographs, videos, and photographs through an OH filter. It is difficult to say that any combustion is present from these photographs. Of course, it would be surprising if much combustion did occur under these cold-flow, low-pressure conditions. Differences between the interaction of the spray plume and the plasma torch with nitrogen and air as feedstocks were documented. According to the OH wavelength filtered photographs the liquid fuel flow rate does appear to have an effect on the height and width of the bright plume. As the liquid fuel flow rate increases the bright plume increases in height by 30% and increases in width slightly (2%). While, a decrease in liquid fuel flow rate resulted in an increase in height by 9% and an increase in width by 10%. Thus, as the liquid fuel flow rate varies the width and height of the bright plume appear to always increase. This can be explained by noticing that the shape of the bright plume changes as the liquid fuel flow rate varies and perhaps anode erosion during testing also plays a part in this variation of the bright plume. From the OH wavelength filtered photographs it was also shown that the bright plume appears to decrease in width by 9% and increase in height by 22% when the plasma torch is set at a lower power setting. When air is used as the torch feedstock, instead of nitrogen, the penetration of the bright plume can increase by as much as 19% in width and 17% in height. It was also found that the height and width of the bright plume decreased slightly (2%) as the fuel flow rate increased when using air as the torch feedstock. Testing in a hot-flow facility is planned.
Master of Science

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37

Pierson, S. R. „Application of commercial CFD to improve gasoline port fuel injector design and targeting“. Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/11426.

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The need to meet ever more stringent emission regulations and the desire to improve fuel economy has led to the significant development of the gasoline spark ignition combustion engine in recent years. One area of development has been mixture preparation, and PH (Port Fuel Injection) has been introduced to increase engine responsiveness whilst meeting emission regulations. Successful PH designs however depend upon good targeting of the fuel spray onto the back of the intake valve. Geometric predictions based on injector axis and spray bone angles have been used in the past, but require development to account for the momentum exchange between the spray and the charge air. Alternatively CFD (Computational Fluid Dynamics) can be used. In this study a validated methodology has been successfully developed using the commercial CFD code Fluent5.5, to simulate the spray behaviour from a multi-hole port fuel injector. The approach taken ignored the primary and secondary atomisation phases, and instead droplets were injected at the injector tip position. The droplets velocity and size were then tuned until the predicted spray profile matched the measurement data at 60rnm and 90mm downstream of the injector tip. Having developed a tuned injector model, CFD simulations assessing the injector targeting performance of the Jaguar AJV8 engine were then undertaken. Based upon these assessments some suggestions to improve the engine's injector targeting performance were made. Before this methodology could be developed, a series' of experiments were necessary to characterise a state of the art port fuel injector. A combination of Planar Mie and PDA laser techniques, were used to measure how the spray behaved under different operating and atmospheric conditions. As well as providing spray boundary and validation data, an in depth understanding of the spray structure was gained for both pulsed and continuous injector operations.

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38

Hoag, Matthew W. „Effects of fuel rail design and fuel injector durability on the starting performance of a liquid LPG fuelled PFI engine“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62221.pdf.

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39

Negro, Sergio <1971&gt. „The prediction of flash evaporation in superheated fuel injections for automotive applications“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3294/.

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In gasoline Port Fuel Injection (PFI) and Direct Injection (GDI) internal combustion engines, the liquid fuel might be injected into a gaseous ambient in a superheated state, resulting in flash boiling of the fuel. The importance to investigate and predict such a process is due to the influence it has on the liquid fuel atomization and vaporization and thus on combustion, with direct implications on engine performances and exhaust gas emissions. The topic of the present PhD research involves the numerical analysis of the behaviour of the superheated fuel during the injection process, in high pressure injection systems like the ones equipping GDI engines. Particular emphasis is on the investigation of the effects of the fuel superheating degree on atomization dynamics and spray characteristics. The present work is a look at the flash evaporation and flash boiling modeling, from an engineering point of view, addressed to keep the complex physics involved as simple as possible, however capturing the main characteristics of a superheated fuel injection.

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40

Schumacher, Jurgen. „Numerical simulation of cantilevered ramp injector flow fields for hypervelocity fuel/air mixing enhancement“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0021/NQ53652.pdf.

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41

Homitz, Joseph. „A Lean-Premixed Hydrogen Injector with Vane Driven Swirl for Application in Gas Turbines“. Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/36334.

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Hydrogen, as an alternative to conventional aviation fuels, has the potential to increase the efficiency of a gas turbine as well as reduce emissions of greenhouse gases. In addition to significantly reducing the number of pollutants due to the absence of carbon, burning hydrogen at low equivalence ratios can significantly reduce emissions of oxides of nitrogen (NOx). Because hydrogen has a wide range of flammability limits, fuel lean combustion can take place at lower equivalence ratios than those with typical hydrocarbon fuels.

Numerous efforts have been made to develop gas turbine fuel injectors that premix methane/natural gas and air in fuel lean proportions prior to the reaction zone. Application of this technique to hydrogen combustion has been limited due to hydrogen's high flame rate and the concern of the reaction zone propagating into the premixing injector, commonly referred to as flashback. In this investigation, a lean-premixing hydrogen injector has been developed for application in small gas turbines. The performance of this injector was characterized and predictions about the injector's performance operating under combustor inlet conditions of a PT6-20 Turboprop have been made.
Master of Science

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42

Henkel, Sebastian. „Effects of fuel properties, injector conditions and impingement on the sprays of direct injection engines“. Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/58209.

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The concept of gasoline direct injection engines is at the forefront of modern research. Two major concerns with the design are the incomplete evaporation of the injected fuel that leads to increased engine-out emissions and the process of injector fouling caused by the direct exposure of the injector to the flame. The latter also reduces the lifetime of this component and also increases emissions at the same time. These are critical issues for OEMs as emissions legislations around the world demand increasingly stricter thresholds. The research presented is split into two separate parts, to tackle both concerns. First, a series of fuel blends and operating conditions and their effect towards spray shape, droplet size and velocity as well as wall wetting will be investigated in a dedicated injection chamber. In order to quantify the amount of fuel that forms a liquid deposit on the surface a novel measurement technique is presented. The data gathered in these measurements is then used to show trends between the blends investigated and to give suggestions for potential improvements of future engine designs and modified engine operating conditions to reduce the amount of particulate emissions. In the second part of the research a series of injectors that were previously fouled are investigated. The fouling caused a significant increase of particulate emissions in test engines and the focus here is to provide possible explanations for this drift. Additionally, some of the injectors were treated with a detergent fuel which reverted the change in emissions. A comparison of these injectors shall provide information about potential applications of such blends and how they would benefit the longevity of modern engines.

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43

Grossman, Peter Michael. „Experimental Investigation of a Flush-Walled, Diamond-Shaped Fuel Injector for High Mach Number Scramjets“. Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/30974.

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An experimental investigation of a flush-wall, diamond-shaped injector was conducted in the Virginia Tech supersonic wind tunnel. The diamond injector was elongated in the streamwise direction and is aimed downstream angled up at 60° from the wall. Test conditions involved sonic injection of helium heated to approximately 313 K into a nominal Mach 4.0 crossstream airflow. These conditions are typical of a scramjet engine for a Mach 10 flight, and heated helium was used to safely simulate hydrogen fuel. The injector was tested at two different injectant conditions. First, it was investigated at a baseline mass flow rate of 3.4 g/s corresponding to an effective radius of 3.54 mm and a jet-to-freestream momentum flux ratio of 1.04. Second, a lower mass flow rate of 1.5 g/s corresponding to an effective ratio of 2.35 mm and a jet-to-freestream momentum flux ratio of 0.49 was studied. The diamond injector was tested both aligned with the freestream and at a 15° yaw angle for the baseline mass flow rate and aligned with the freestream at the lower mass flow rate. For comparison, round injectors angled up at 30° from the wall were also examined at both flow rates. A smaller round injector was used at the lower mass flow rate such that the jet-to-freestream momentum flux ratio was 1.75 for both cases. A concentration sampling probe and gas analyzer were used to determine the local helium concentration, while Pitot, cone-static and total temperature probes were used to determine the flow properties.

The results of the investigation can be summarized as follows. For the baseline case, the aligned diamond injector penetrated 44% higher into the crossflow than did the round injector. The addition of yaw angle increased the crossflow penetration to 53% higher than the round injector. The aligned diamond injector produced a 34% wider jet than the round injector, while the addition of yaw angle somewhat reduced this widening effect to 26% wider than the round injector. The aligned and yawed diamond injectors exhibited 10% and 15% lower mixing efficiency than the round injector, respectively. The total pressure loss parameter of the aligned diamond was 22% lower than the round injector, while the addition of yaw angle improved the total pressure loss parameter to 34% lower than the round injector. For the lower mass flow (and momentum flux ratio) case, the diamond injector demonstrated 52% higher penetration and a 39% wider plume than the round injector. The mixing efficiency was nearly identical between the two injectors with just a 4% lower mixing efficiency for the diamond injector. The total pressure loss parameter of the diamond injector was 32% lower than round injector. These results confirm the conclusions of earlier, lower free stream Mach number and higher molecular weight injectant, studies that a slender diamond injector provides significant benefits for crossflow penetration and lower total pressure losses.
Master of Science

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Reid, Benjamin A. „An optical investigation of cavitation phenomena in true-scale high-pressure diesel fuel injector nozzles“. Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6358.

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Efforts to improve diesel fuel sprays have led to a significant increase in fuel injection pressures and a reduction in nozzle-hole diameters. Under these conditions, the likelihood for the internal nozzle flow to cavitate is increased, which potentially affects spray breakup and atomisation, but also increases the risk of causing cavitation damage to the injector. This thesis describes the study of cavitating flow phenomena in various single and multi-hole optical nozzle geometries. It includes the design and development of a high-pressure optical fuel injector test facility with which the cavitating flows were observed. Experiments were undertaken using real-scale optical diesel injector nozzles at fuel injection pressures up to 2050 bar, observing for the first time the characteristics of the internal nozzle-flow under realistic fuel injection conditions. High-speed video and high resolution photography, using laser illumination sources, were used to capture the cavitating flow in the nozzle-holes and sac volume of the optical nozzles, which contained holes ranging in size from 110 micrometers to 300 micrometers. Geometric cavitation in the nozzle-holes and string cavitation formation in the nozzle-holes and sac volume were both observed using transient and steady-state injection conditions; injecting into gaseous and liquid back pressures up to 150 bar. Results obtained have shown that cavitation strings observed at realistic fuel injection pressures exhibit the same physical characteristics as those observed at lower pressures. The formation of string cavitation was observed in the 300 micrometers multi-hole nozzle geometries, exhibiting a mutual dependence on nozzle flow-rate and the geometry of the nozzle-holes. Pressure changes, caused by localised turbulent perturbations in the sac volume and transient fuel injection characteristics, independently affected the geometric and string cavitation formation in each of the holes. String cavitation formation of was shown to occur when free-stream vapour was entrained into the low pressure core of a sufficiently intense coherent vortex. Hole diameters less than or equal to 160 micrometers were found to suppress string cavitation formation, with this effect a result of the reduced nozzle flow rate and vortex intensity. Using different hole spacing geometries, it was demonstrated that the formation of cavitation strings in a particular geometry became independent of fuel injection and back pressure once a threshold pressure drop across the nozzle had been reached.

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Vuokila, A. (Ari). „CFD modeling of auxiliary fuel injections in the blast furnace tuyere-raceway area“. Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526217703.

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Abstract The blast furnace process is the most common way throughout the world to produce pig iron. The primary fuel and reducing agent in a blast furnace is coke. Coke is a fossil fuel and the most expensive raw material in iron production. Blast furnace ironmaking is an energy-intensive process, which results in high energy costs. Auxiliary fuels are injected into the blast furnace to replace expensive coke. They provide energy for the blast furnace operation and act as a source of reduction agents for iron oxides. Coke replacement with high auxiliary fuel injection levels leads to permeability changes in a blast furnace shaft, because of the increased amount of unburnt coal. In this thesis, fuel injection with two different auxiliary fuels, heavy oil and pulverized coal, was studied using computational fluid dynamics (CFD) modeling. The aim was to improve the combustion of auxiliary fuels by increasing the understanding of the phenomena in the blast furnace tuyere-raceway area. The atomization model for modeling the heavy oil combustion was selected and validated using the results of an experimental rig from the literature. The atomization model was applied to study the effect of different nozzles on heavy oil mixing with the air blast. In addition, the model was used to study the effect of lance position on the combustion efficiency of heavy oil. A pulverized coal combustion model was developed and validated with experimental data from the literature. Pulverized coal combustion was modeled with different lance positions to evaluate its effect on combustion efficiency. Based on the results, heavy oil mixing in the air blast can to a great extent, be boosted by the nozzle design. Furthermore, the heavy oil combustion is more efficient when the lance position is farthest from the tuyere nose. But the increasing temperature inside the tuyere causes ablation of the tuyere walls, which creates a constraint for the lance position. The results from the pulverized coal combustion study show that the model works well for the tuyere-raceway area. In addition, the effect of lance position on the combustion efficiency of the pulverized coal is very small, and the lance should be positioned as close to the tuyere nose as possible to avoid fouling of the tuyere walls and the ignition inside the tuyere
Tiivistelmä Suurin osa maailman raakaraudasta valmistetaan masuuniprosessilla. Masuunin ensisijainen polttoaine ja rautaoksidien pelkistin on koksi. Koksi on fossiilinen polttoaine ja kallein raaka-aine masuunissa. Raudanvalmistus on erittäin energiaintensiivistä, joten valmistuksen energiakustannukset ovat korkeat. Lisäpolttoaineinjektiota käytetään masuunissa korvaamaan osa koksista sekä energian tuottajana että pelkistimenä. Injektiomäärät pyritään kasvattamaan mahdollisimman suuriksi, mutta injektiomäärien kasvaessa palamattoman kiinteän polttoaineen määrä kasvaa ja koksipatjan kaasunläpäisevyys heikkenee. Väitöskirjatutkimuksessa luotiin virtauslaskentamalli hormin ja palo-onkalon alueelle kahta lisäpolttoainetta (raskas polttoöljy, kivihiilipöly) varten. Sen avulla tutkittiin palamista hormin ja palo-onkalon alueella tavoitteena lisätä tietoa palamista rajoittavista tekijöistä. Pisaroitumismalli valittiin ja validoitiin kirjallisuusdatan perusteella raskaan polttoöljyn toimiessa lisäpolttoaineena. Mallia käytettiin tutkittaessa erilaisia suuttimia palamisilman ja polttoaineen sekoittumisen tehostamiseen. Lisäksi sitä käytettiin mallinnettaessa lanssin sijainnin vaikutusta raskaan polttoöljyn palamistehokkuuteen. Kivihiilipölylle luotiin palamismalli, joka validoitiin olemassa olevan kokeellisen datan perusteella. Tätä mallia hyödynnettiin tutkittaessa kaksoislanssin sijainnin vaikutusta palamistehokkuuteen. Tulosten perusteella voidaan todeta, että öljylanssin suuttimella on suuri vaikutus palamisilman ja polttoaineen sekoittumiseen. Lisäksi voidaan päätellä, että raskaan polttoöljyn palaminen tehostuu siirrettäessä lanssia syvemmälle hormiin, mutta syttyminen tapahtuu liian aikaisin ja kasvava lämpötila voi sulattaa hormin seinämät. Tämä aiheuttaa rajoituksen lanssin sijainnille hormissa. Kivihiilipölyn palamisen mallin todettiin toimivan erittäin hyvin hormin ja palo-onkalon alueilla. Tämän ohella havaittiin, että lanssin sijainnilla oli hyvin pieni vaikutus palamisasteeseen, jolloin lanssi kannattaa sijoittaa mahdollisimman lähelle hormin suuta, jotta vältetään hormiin kohdistuva ylimääräinen lämpökuorma ja hormin likaantuminen

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Carreres, Talens Marcos. „Thermal effects influence on the Diesel injector performance through a combined 1D modelling and experimental approach“. Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/73066.

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[EN] The injection system is one of the topics that has been paid most attention to by researchers in the field of direct injection diesel engines, due to its key role on fuel atomization, vaporization and air-fuel mixing process, which directly affect fuel consumption, noise irradiation and pollutant emissions. The increasing injection pressures in modern engines have propitiated the need of studying phenomena such as cavitation, compressible flow or the effect of changes in the fuel properties along the process, whose relative importance was lower in early stages of the reciprocating engines development. The small dimensions of the injector ducts, the high velocities achieved through them and the transient nature of the process hinder the direct observation of these facts. Computational tools have then provided invaluable help in the field. The objective of the present thesis is to analyse the influence of the thermal effects on the performance of a diesel injector. To this end, the fuel temperature variation through the injector restrictions must be estimated. The influence of these changes on the fuel thermophyisical properties relevant for the injection system also needs to be assessed, due to its impact on injector dynamics and the injection rate shape. In order to give answer to the previous objectives, both experimental and computational techniques have been employed. A dimensional and a hydraulic experimental characterization of a solenoid-actuated Bosch CRI 2.20 injector has been carried out, including rate of injection measurements at a wide range of operating conditions, with special attention to the fuel temperature control. A 1D computational model of the injector has been implemented in order to confirm and further extend the findings from the experiments. Local variations of fuel temperature and pressure are considered by the model thanks to the assumption of adiabatic flow, for which the experimental characterization of the fuel properties at high pressure also had to be performed. The limits of the validity of this assumption have been carefully assessed in the study. Results show a significant influence of the fuel temperature at the injector inlet on injection rate and duration, attributed to the effect of the variation of the fuel properties and to the fact that the injector remains in ballistic operation for most of its real operating conditions. Fuel temperature changes along the injector control orifices are able to importantly modify its dynamic behaviour. In addition, if the fuel at the injector inlet is at room temperature or above, the temperature at the nozzle outlet has not been proved to importantly change once steady-state conditions are achieved. However, a significant heating may take place for fuel temperatures at the injector inlet typical of cold-start conditions.
[ES] El sistema de inyección es uno de los elementos que más interés ha despertado en la investigación en el campo de los motores diésel de inyección directa, debido a su papel clave en la atomización y vaporización del combustible así como en el proceso de mezcla, que afectan directamente al consumo y la generación de ruido y emisiones contaminantes. Las crecientes presiones de inyección en motores modernos han propiciado la necesidad de estudiar fenómenos como la cavitación, flujo compresible o el efecto de los cambios de las propiedades del combustible a lo largo del proceso, cuya importancia relativa era menor en etapas tempranas del desarrollo de los motores alternativos. Las pequeñas dimensiones de los conductos del inyector, las altas velocidades a través de los mismos y la naturaleza transitoria del proceso dificultan la observación directa en estas cuestiones. Por ello, las herramientas computacionales han proporcionado una ayuda inestimable en el campo. El objetivo de la presente tesis es analizar la influencia de los efectos térmicos en el funcionamiento de un inyector diésel. Para tal fin, se debe estimar la variación de la temperatura del combustible a lo largo de las restricciones internas del inyector. La influencia de estos cambios en las propiedades termofísicas del combustible más relevantes en el sistema de inyección también debe ser evaluada, debido a su impacto en la dinámica del inyector y en la forma de la tasa de inyección. Para dar respuesta a estos objetivos, se han utilizado técnicas experimentales y computacionales. Se ha llevado a cabo una caracterización dimensional e hidráulica de un inyector Bosch CRI 2.20 actuado mediante solenoide, incluyendo medidas de tasa de inyección en un amplio rango de condiciones de operación, para lo que se ha prestado especial atención al control de la temperatura del combustible. Se ha implementado un modelo 1D del inyector para confirmar y extender las observaciones extra\'idas de los experimentos. El modelo considera variaciones locales de presión y temperatura del combustible gracias a la hipótesis de flujo adiabático, para lo cual también se ha tenido que llevar a cabo una caracterización experimental de las propiedades del combustible a alta presión. Los límites de la validez de esta hipótesis se han analizado cuidadosamente en el estudio. Los resultados muestran una influencia significativa de la temperatura del combustible a la entrada del inyector en la tasa y duración de inyección, atribuida al efecto de la variación de las propiedades del combustible y al hecho de que el inyector permanece en operación balística para la mayoría de sus condiciones de funcionamiento. Los cambios en temperatura del combustible a lo largo de los orificios de control del inyector son capaces de modificar su dinámica considerablemente. Además, si el combustible a la entrada del inyector se encuentra a temperatura ambiente o por encima, se ha observado que la temperatura a la salida de la tobera no varía de manera importante una vez se alcanzan condiciones estacionarias. No obstante, un calentamiento significativo puede tener lugar para temperaturas de entrada típicas de las condiciones de arranque en frío.
[CAT] El sistema d'injecció és un dels elements que més interés ha despertat en la investigació en el camp dels motors dièsel d'injecció directa, degut al seu paper clau en l'atomització i vaporització del combustible, així com en el procés de mescla, que afecten directament el consum i la generació de soroll i emissions contaminants. Les creixents pressions d'injecció en motors moderns han propiciat la necessitat d'estudiar fenòmens com la cavitació, flux compressible o l'efecte dels canvis de les propietats del combustible al llarg del procés, la importància relativa dels quals era menor en les primeres etapes del desenvolupament dels motors alternatius. Les menudes dimensions dels conductes de l'injector, les altes velocitats a través dels mateixos i la natura transitòria del procés dificulten l'observació directa en estes qüestions. Per això, les ferramentes computacionals han proporcionat una ajuda inestimable en el camp. L'objectiu de la present tesi és analitzar la influència dels efectes tèrmics en el funcionament d'un injector dièsel. Per a tal fi, es deu estimar la variació de la temperatura del combustible al llarg de les restriccions internes de l'injector. La influència d'estos canvis en les propietats termofísiques del combustible més relevants en el sistema d'injecció també ha de ser avaluada, degut al seu impacte en la dinàmica de l'injector i en la forma de la tasa d'injecció. Per tal de donar resposta a estos objectius, s'han utilitzat tècniques experimentals i computacionals. S'ha dut a terme una caracterització dimensional i hidràulica d'un injector Bosch CRI 2.20 actuat mitjançant solenoide, incloent mesures de tasa d'injecció en un ampli rang de condicions d'operació, per al que s'ha prestat especial atenció al control de la temperatura del combustible. S'ha implementat un model 1D de l'injector per tal de confirmar i estendre les observacions extretes dels experiments. El model considera variacions locals de pressió i temperatura del combustible gràcies a la hipòtesi de flux adiabàtic, per la qual cosa també s'ha hagut de dur a terme una caracterització experimental de les propietats del combustible a alta pressió. Els límits de la validesa d'esta hipòtesi s'han analitzat acuradament en l'estudi. Els resultats mostren una influència significativa de la temperatura del combustible a l'entrada de l'injector en la tasa i duració d'injecció, atribuïda a l'efecte de la variació de les propietats del combustible i al fet que l'injector roman en operació balística per a la majoria de les seues condicions de funcionament. Els canvis en temperatura del combustible al llarg dels orificis de control de l'injector són capaços de modificar la seua dinàmica considerablement. A més, si el combustible a l'entrada de l'injector es troba a temperatura ambient o per damunt, s'ha observat que la temperatura a l'eixida de la tobera no varia de manera important una vegada s'han assolit condicions estacionàries. No obstant això, un escalfament significatiu pot tenir lloc per a temperatures d'entrada típiques de les condicions d'arrancada en fred.
Carreres Talens, M. (2016). Thermal effects influence on the Diesel injector performance through a combined 1D modelling and experimental approach [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/73066
TESIS

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Mohamad, Taib Iskandar. „Development of a spark plug fuel injector for direct injection of natural ags in spark ignition engine“. Thesis, Cranfield University, 2006. http://hdl.handle.net/1826/4436.

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In the name of God, The Most Gracious, The Most Merciful. By His will, this thesis has been completed as another episode of knowledge seeking and contribution. The author wishes to express a greatest gratitude to the academic supervisor for this project, Dr. Matthew Harrison and Professor Douglas Greenhalgh for their warmth, continuous guidance and support, priceless knowledge and expertise, and kindly understanding. Secondly, author's deepest appreciation to Dr. Mark Jermy, the initial supervisor for this project, for his ideas, understanding, support, availability and generosity for providing assistance both in author's academic and private life. To my mother and father whose supplications and encouragements have given me strength to complete this work. To my family whose support during this course of studies has given me comfort. To my parents in-law and siblings in-law, thank you for your support. My dearest gratitude to the beloved wife, Ira for standing by my side and giving me continuous support throughout this course of study and the hardship of life due to it. Your sacrifice is priceless. To my children, Balgis, Naufal, Nadiyah and Safiyah, you are my source of inspirations. A special thank to Dr. Glenn Sherwood, Tim Lee, Brian Scully, Richard Kennewell, Alan Hutching, and all others for providing technical supports during the experiment works. To Andreas, Eudoxios, Anni, Edouard, Fatiha, Alessio, Andy and Adam, I thank you all for the friendship and helps during my studies.

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Anning, Grant Hugh Gary. „The Effect of Fuel Injector Geometry on the Flow Structure of a Swirl Stabilized Gas Turbine Burner“. University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1024672199.

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49

Alborzi, Ehsan. „An investigation into carbon deposition growth in jet engine injector feed arm due to fuel thermal degradation“. Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.700954.

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50

Mohamad, Taib Iskandar. „Development of a spark plug fuel injector for direct injection of natural gas in spark ignition engine“. Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/4436.

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The use of methane in spark ignition engines is mainly due to its cleaner emissions and relatively low price. However, when methane replaces gasoline in the externally mixing carburettor or port injection engine, power is reduced and upper speed is limited. These are because the burning velocity of methane is slower than of gasoline, and some air is displaced in the intake manifold in order to compensate the low density methane. The problem can be mitigated when fuel is directly injected into the combustion chamber after the intake valve closes. This results in an increased volumetric efficiency, a higher absolute heating value of mixture and a faster burning rate. The work presented in this thesis aims to develop a conversion system that enables methane to be directly injected into the combustion chamber of a spark ignition engine without modifying the original structure of the engine. The system, named as Spark Plug Fuel Injector (SPFI) combines a fuel injector with a spark plug. A fuel path is drawn along the periphery of the spark plug body to deliver the injected fuel to the combustion chamber. The system was installed and tested on a Ricardo E6 single cylinder engine with compression ratio of 10.5: 1. Cylinder pressures were taken as the main indicator of the engine performance and selected indicated performance were presented. A set of port injected data for the engine running on methane was also taken in order to provide a comparison of performance with SPFI direct injection. Results show that the indicated performance of the SPFI methane direct injection at the tested speed was lower than the optimised methane port injection operation. This was mainly due to the quality of air-fuel mixing, which is a result of spatial and temporal limitation of direct injection operation. Flow visualization using the PLIF method shows that even though sufficient gas jet penetration from SPFI injection nozzle was achieved, the cone angle was very narrow. The conclusion from imaging experiments implies poor mixing, hence the performance suffers drawback. However, with direct injection, volumetric efficiency is increased ands combustion duration is faster. These two factors are desirable for engine performance improvement. SPFI has proven to be a practical and low cost conversion to methane. Even though the performance is lower than port injection, its benefits are significant. As the SPFI design is simple and requires no modification to the original structure of the converted engine.

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