Articles de revues : « Lean burn aero-engine combustor »

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Li, J., X. Sun, Y. Liu et V. Sethi. « Preliminary aerodynamic design methodology for aero engine lean direct injection combustors ». Aeronautical Journal 121, n^o 1242 (21 juin 2017) : 1087–108. http://dx.doi.org/10.1017/aer.2017.47.

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ABSTRACTThe Lean Direct Injection (LDI) combustor is one of the low-emissions combustors with great potential in aero-engine applications, especially those with high overall pressure ratio. A preliminary design tool providing basic combustor sizing information and qualitative assessment of performance and emission characteristics of the LDI combustor within a short period of time will be of great value to designers. In this research, the methodology of preliminary aerodynamic design for a second-generation LDI (LDI-2) combustor was explored. A computer code was developed based on this method covering the design of air distribution, combustor sizing, diffuser, dilution holes and swirlers. The NASA correlations for NOxemissions are also embedded in the program in order to estimate the NOx production of the designed LDI combustor. A case study was carried out through the design of an LDI-2 combustor named as CULDI2015 and the comparison with an existing rich-burn, quick-quench, lean-burn combustor operating at identical conditions. It is discovered that the LDI combustor could potentially achieve a reduction in liner length and NOxemissions by 18% and 67%, respectively. A sensitivity study on parameters such as equivalence ratio, dome and passage velocity and fuel staging is performed to investigate the effect of design uncertainties on both preliminary design results and NOxproduction. A summary on the variation of design parameters and their impact is presented. The developed tool is proved to be valuable to preliminarily evaluate the LDI combustor performance and NOxemission at the early design stage.

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Antoshkiv, O., Th Poojitganont, L. Jehring et C. Berkholz. « Main aspects of kerosene and gaseous fuel ignition in aero-engine ». Aeronautical Journal 121, n^o 1246 (décembre 2017) : 1779–94. http://dx.doi.org/10.1017/aer.2017.113.

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ABSTRACTVarious liquid and gaseous alternative fuels have been proposed to replace the kerosene as aircraft fuel. Furthermore, new combustion technologies were developed to reduce the emissions of aero-engine. A staged fuel injection arrangement for a lean burn combustion system was applied to improve the operability of an aero-engine by achieving high flame stability at reduced combustion emissions. Originally, both circuits (pilot and main) are fuelled by kerosene; moreover, the pilot injector is operating at low power (engine idle and approach) and the pilot flame is anchored in an airflow recirculation zone. In the case of the performed research, the pilot injector was modified to allow the use of gaseous fuels. Thus, the burner model allows a flexible balancing of the mass flows for gaseous and liquid fuel. The present paper describes the investigation of ignitability for the proposed staged combustor model fuelled by gaseous and liquid fuels. A short overview on physical properties of used fuels is given. To investigate atomisation and ignition, different measurements systems were used. The effectiveness of two ignitor types (spark plug and laser ignitor) was analysed. The ignition performance of the combustor operating on various fuels was compared and discussed in detail.

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Innocenti, Alessandro, Antonio Andreini, Bruno Facchini et Antonio Peschiulli. « Numerical analysis of the dynamic flame response of a spray flame for aero-engine applications ». International Journal of Spray and Combustion Dynamics 9, n^o 4 (16 mai 2017) : 310–29. http://dx.doi.org/10.1177/1756827717703577.

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Incoming standards on NO x emissions are motivating many aero-engine manufacturers to adopt the lean burn combustion concept. One of the most critical issues affecting this kind of technology is the occurrence of thermo-acoustic instabilities that may compromise combustor life and integrity. Therefore the prediction of the thermo-acoustic behaviour of the system becomes of primary importance. In this paper, the complex interaction between the system acoustics and a turbulent spray flame for aero-engine applications is numerically studied. The dynamic flame response is computed exploiting reactive URANS simulations and system identification techniques. Great attention has been devoted to the impact of liquid fuel evolution and droplet dynamics. For this purpose, the GE Avio PERM (partially evaporating and rapid mixing) lean injection system has been analysed, focussing attention on the effect of several modelling parameters on the combustion and on the predicted flame response. A frequency analysis has also been set up and exploited to obtain even more insight on the dynamic flame response of the spray flame. The application is one of the few in the literature where the dynamic flame response of spray flames is numerically investigated, providing a description in terms of flame transfer function and detailed information on the physical phenomena.

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Notaristefano, Andrea, et Paolo Gaetani. « Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation ». International Journal of Turbomachinery, Propulsion and Power 5, n^o 4 (19 octobre 2020) : 27. http://dx.doi.org/10.3390/ijtpp5040027.

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Modern aero-engine combustion chambers burn a lean and premixed mixture, generating a turbulent flame which involves large heat-release fluctuations, thus producing unsteady temperature phenomena commonly referred to as entropy waves (EWs). Furthermore, to enhance the fuel air mixing, combustion air is swirled, leading to vorticity disturbances. These instabilities represent one of the biggest challenges in gas turbine design. In this paper, the design and testing of a novel entropy wave generator (EWG) equipped with a swirler generator (SG) are described. The novel EWG will be used in future works on the high-speed test rig at Politecnico di Milano to study the combustor–turbine interaction. The paper shows the process of the EWG geometry and layout. The EWG is able to produce an engine-representative EW, the extreme condition is at the maximum frequency of 110 Hz, a peak-to-valley temperature value of 20 °C and swirling angles of ±25° are measured. By virtue of these results, the proposed system outperforms other EWG devices documented in the literature. Furthermore, the addition of a swirling generator makes this device one of a kind.

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Huang, Shengfang, Zhibo Zhang, Huimin Song, Yun Wu et Yinghong Li. « A Novel Way to Enhance the Spark Plasma-Assisted Ignition for an Aero-Engine Under Low Pressure ». Applied Sciences 8, n^o 9 (1 septembre 2018) : 1533. http://dx.doi.org/10.3390/app8091533.

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Finding a new ignition strategy for ignition enhancement in a lean-burn combustor has always been the biggest challenge for high-altitude, long-endurance unmanned aerial vehicles (UAVs). It is of great importance for the development of high-altitude, long-endurance aircraft to improve the secondary ignition ability of the aero-engine at high altitude where the ignition capability of the aero-engine igniter rapidly declines. An innovative ignition mode is therefore urgently needed. A novel plasma-assisted ignition method based on a multichannel discharge jet-enhanced spark (MDJS) was proposed in this study. Compared to the conventional spark igniter (SI), the arc discharge energy of the MDJS was increased by 13.6% at 0.12 bar and by 14.7% at 0.26 bar. Furthermore, the spark plasma penetration depth of the MDJS was increased by 49% and 103% at 0.12 bar and 0.26 bar, respectively. The CH* radicals showed that the MDJS obtained a larger initial spark kernel and reached a higher spark plasma penetration depth, which helped accelerate the burning velocity. Ignition tests in a model swirl combustor showed that the lean ignition limit was extended 24% from 0.034 to 0.026 at 25 m/s with 20 °C kerosene and 17% from 0.075 to 0.062 at 12 m/s with −30 °C kerosene maximally. The MDJS was a unique plasma-assisted ignition method, activated by the custom ignition power supply instead of a special power supply with an extra gas source. The objective of this study was to provide a novel multichannel discharge jet-enhanced spark ignition strategy which would help to increase the arc discharge energy, the spark plasma penetration depth and the activated area without changing the power supply system and to improve the safety and performance of aero-engines.

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Hendricks, R. C., D. T. Shouse, W. M. Roquemore, D. L. Burrus, B. S. Duncan, R. C. Ryder, A. Brankovic, N. S. Liu, J. R. Gallagher et J. A. Hendricks. « Experimental and Computational Study of Trapped Vortex Combustor Sector Rig with High-Speed Diffuser Flow ». International Journal of Rotating Machinery 7, n^o 6 (2001) : 375–85. http://dx.doi.org/10.1155/s1023621x0100032x.

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The Trapped Vortex Combustor (TVC) potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO) performance. Computational fluid dynamics (CFD) simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

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Smith, Lance L., Hasan Karim, Marco J. Castaldi, Shahrokh Etemad, William C. Pfefferle, Vivek Khanna et Kenneth O. Smith. « Rich-Catalytic Lean-Burn Combustion for Low-Single-Digit NOx Gas Turbines ». Journal of Engineering for Gas Turbines and Power 127, n^o 1 (1 janvier 2005) : 27–35. http://dx.doi.org/10.1115/1.1787510.

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A new rich-catalytic lean-burn combustion concept (trademarked by PCI as RCL) was tested at industrial gas turbine conditions, in Solar Turbines’ high-pressure (17 atm) combustion rig and in a modified Solar Turbines engine, demonstrating ultralow emissions of NOx<2 ppm and CO<10 ppm for natural gas fuel. For the single-injector rig tests, an RCL catalytic reactor replaced a single swirler/injector. NOx<3 ppm and CO<10 ppm were achieved over a 110°C operating range in flame temperature, including NOx<1 ppm at about 1350°C flame temperature. Combustion noise was less than 0.15% peak to peak. Four RCL catalytic reactors were then installed in a modified (single can combustor) engine. NOx emissions averaged 2.1 ppm over the allowable operating range for this modified engine, with CO<10 ppm and without combustion noise (less than 0.15% peak to peak).

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Li, Y. G., et R. L. Hales. « Steady and Dynamic Performance and Emissions of a Variable Geometry Combustor in a Gas Turbine Engine ». Journal of Engineering for Gas Turbines and Power 125, n^o 4 (1 octobre 2003) : 961–71. http://dx.doi.org/10.1115/1.1615253.

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One of the remedies to reduce the major emissions production of nitric oxide NOx, carbon monoxide (CO), and unburned hydrocarbon (UHC) from conventional gas turbine engine combustors at both high and low operating conditions without losing performance and stability is to use variable geometry combustors. This type of combustor configuration provides the possibility of dynamically controlling the airflow distribution of the combustor based on its operating conditions and therefore controlling the combustion in certain lean burn conditions. Two control schemes are described and analyzed in this paper: Both are based on airflow control with variable geometry, the second including fuel staging. A model two-spool turbofan engine is chosen in this study to test the effectiveness of the variable geometry combustor and control schemes. The steady and dynamic performance of the turbofan engine is simulated and analyzed using an engine transient performance analysis code implemented with the variable geometry combustor. Empirical correlations for NOx, CO, and UHC are used for the estimation of emissions. Some conclusions are obtained from this study: (1) with variable geometry combustors significant reduction of NOx emissions at high operating conditions and CO and UHC at low operating condition is possible; (2) combustion efficiency and stability can be improved at low operating conditions, which is symbolized by the higher flame temperature in the variable geometry combustor; (3) the introduced correlation between nondimensional fuel flow rate and air flow ratio to the primary zone is effective and simple in the control of flame temperature; (4) circumferential fuel staging can reduce the range of air splitter movement in most of the operating conditions from idle to maximum power and have the great potential to reduce the inlet distortion to the combustor and improve the combustion efficiency; and (5) during transient processes, the maximum moving rate of the hydraulic driven system may delay the air splitter movement but this effect on engine combustor performance is not significant.

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McGuirk, J. J. « The aerodynamic challenges of aeroengine gas-turbine combustion systems ». Aeronautical Journal 118, n^o 1204 (juin 2014) : 557–99. http://dx.doi.org/10.1017/s0001924000009386.

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Abstract The components of an aeroengine gas-turbine combustor have to perform multiple tasks – control of external and internal air distribution, fuel injector feed, fuel/air atomisation, evaporation, and mixing, flame stabilisation, wall cooling, etc. The ‘rich-burn’ concept has achieved great success in optimising combustion efficiency, combustor life, and operational stability over the whole engine cycle. This paper first illustrates the crucial role of aerodynamic processes in achieving these performance goals. Next, the extra aerodynamic challenges of the ‘lean-burn’ injectors required to meet the ever more stringent NO x emissions regulations are introduced, demonstrating that a new multi-disciplinary and ‘whole system’ approach is required. For example, high swirl causes complex unsteady injector aerodynamics; the threat of thermo-acoustic instabilities means both aerodynamic and aeroacoustic characteristics of injectors and other air admission features must be considered; and high injector mass flow means potentially strong compressor/combustor and combustor/turbine coupling. The paper illustrates how research at Loughborough University, based on complementary use of advanced experimental and computational methods, and applied to both isolated sub-components and fully annular combustion systems, has improved understanding and identified novel ideas for combustion system design.

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Andreini, Antonio, Bruno Facchini, Andrea Giusti et Fabio Turrini. « Assessment of Flame Transfer Function Formulations for the Thermoacoustic Analysis of Lean Burn Aero-engine Combustors ». Energy Procedia 45 (2014) : 1422–31. http://dx.doi.org/10.1016/j.egypro.2014.01.149.

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Corbett, N. C., et N. P. Lines. « Control Requirements for the RB 211 Low-Emission Combustion System ». Journal of Engineering for Gas Turbines and Power 116, n^o 3 (1 juillet 1994) : 527–33. http://dx.doi.org/10.1115/1.2906851.

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The RB 211 DLE series staged, premix, lean burn combustor demands total integration of control system and combustion hardware. The controls design process is described from the conception of the Engine Management System (EMS), which provides protection and control in separate environments, through to implementation of engine development testing. The process of devising an acceptable fueling strategy to each combustion stage is discussed. This identified the requirements for the computation of complex routines in order to control combustion zone temperatures. The sensitivity of the control design to external conditions of humidity, ambient temperature, and fuel composition is explored. Extensive simulation was used to determine necessary instrumentation accuracies. The paper concludes with a review of the development testing and the final control system configuration.

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Leong, M. Y., C. S. Smugeresky, V. G. McDonell et G. S. Samuelsen. « Rapid Liquid Fuel Mixing for Lean-Burning Combustors : Low-Power Performance ». Journal of Engineering for Gas Turbines and Power 123, n^o 3 (1 janvier 2001) : 574–79. http://dx.doi.org/10.1115/1.1362318.

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Designers of advanced gas turbine combustors are considering lean direct injection strategies to achieve low NOx emission levels. In the present study, the performance of a multipoint radial airblast fuel injector Lean Burn injector (LBI) is explored for various conditions that target low-power gas turbine engine operation. Reacting tests were conducted in a model can combustor at 4 and 6.6 atm, and at a dome air preheat temperature of 533 K, using Jet-A as the liquid fuel. Emissions measurements were made at equivalence ratios between 0.37 and 0.65. The pressure drop across the airblast injector holes was maintained at 3 and 7–8 percent. The results indicate that the LBI performance for the conditions considered is not sufficiently predicted by existing emissions correlations. In addition, NOx performance is impacted by atomizing air flows, suggesting that droplet size is critical even at the expense of penetration to the wall opposite the injector. The results provide a baseline from which to optimize the performance of the LBI for low-power operation.

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Lefebvre, A. H. « The Role of Fuel Preparation in Low-Emission Combustion ». Journal of Engineering for Gas Turbines and Power 117, n^o 4 (1 octobre 1995) : 617–54. http://dx.doi.org/10.1115/1.2815449.

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The attainment of very low pollutant emissions, in particular oxides of nitrogen (NOx), from gas turbines is not only of considerable environmental concern but has also become an area of increasing competitiveness between the different engine manufacturers. For stationary engines, the attainment of ultralow NOx has become the foremost marketing issue. This paper is devoted primarily to current and emerging technologies in the development of ultralow emissions combustors for application to aircraft and stationary engines. Short descriptions of the basic design features of conventional gas turbine combustors and the methods of fuel injection now in widespread use are followed by a review of fuel spray characteristics and recent developments in the measurement and modeling of these characteristics. The main gas-turbine-generated pollutants and their mechanisms of formation are described, along with related environmental risks and various issues concerning emissions regulations and recently enacted legislation for limiting the pollutant levels emitted by both aircraft and stationary engines. The impacts of these emissions regulations on combustor and engine design are discussed first in relation to conventional combustors and then in the context of variable-geometry and staged combustors. Both these concepts are founded on emissions reduction by control of flame temperature. Basic approaches to the design of “dry” low-NOx and ultralow-NOx combustors are reviewed. At the present time lean, premix, prevaporize combustion appears to be the only technology available for achieving ultralow NOx emissions from practical combustors. This concept is discussed in some detail, along with its inherent problems of autoignition, flashback, and acoustic resonance. Attention is also given to alternative methods of achieving ultralow NOx emissions, notably the rich-burn, quick-quench, lean-burn, and catalytic combustors. These concepts are now being actively developed, despite the formidable problems they present in terms of mixing and durability. The final section reviews the various correlations now being used to predict the exhaust gas concentrations of the main gaseous pollutant emissions from gas turbine engines. Comprehensive numerical methods have not yet completely displaced these semi-empirical correlations but are nevertheless providing useful insight into the interactions of swirling and recirculating flows with fuel sprays, as well as guidance to the combustion engineer during the design and development stages. Throughout the paper emphasis is placed on the important and sometimes pivotal role played by the fuel preparation process in the reduction of pollutant emissions from gas turbines.

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Bell, R. C., T. W. Prete et J. T. Stewart. « Specification, Development, and Testing of the FT8-2 Dry Low NOx Control System ». Journal of Engineering for Gas Turbines and Power 118, n^o 3 (1 juillet 1996) : 547–52. http://dx.doi.org/10.1115/1.2816682.

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This paper describes the specification, development, and testing of the FT8-2 Dry Low NOx control system, and how the lean burn process requires an integration of the control system and combustion hardware. The FT8-2 digital fuel control system was developed to achieve the precise multizone fuel metering of both gas and liquid fuels, the calculation of combustor air flow necessary to achieve Dry Low NOx and the traditional governing/limiting control loops necessary for safe, stable engine operation. The system design goals were accomplished by the concurrent development of software-based fuel metering algorithms and fuel metering hardware. The fuel metering hardware utilizes an all-electronic valve positioner, employing a combination of feedback and software to achieve closed-loop control of actual fuel flow. Extensive testing under actual gas flow conditions and closed-loop bench testing using a real time engine model and fuel system model was conducted to prove system operation and develop system transient response prior to installation on the test engine. The setup and results of the flow testing and closed-loop testing are described. The paper describes the control scheme used to apportion the gas fuel between combustion zones and how external conditions such as ambient temperature and fuel gas composition affect the apportionment. The paper concludes with a description of the control system installation in the engine test cell and a review of engine test results.

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Karim, H., K. Lyle, S. Etemad, L. L. Smith, W. C. Pfefferle, P. Dutta et K. Smith. « Advanced Catalytic Pilot for Low NOx Industrial Gas Turbines ». Journal of Engineering for Gas Turbines and Power 125, n^o 4 (1 octobre 2003) : 879–84. http://dx.doi.org/10.1115/1.1586313.

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This paper describes the design and testing of a catalytically stabilized pilot burner for current and advanced Dry Low NOx (DLN) gas turbine combustors. In this paper, application of the catalytic pilot technology to industrial engines is described using Solar Turbines’ Taurus 70 engine. The objective of the work described is to develop the catalytic pilot technology and document the emission benefits of catalytic pilot technology when compared to higher, NOx producing pilots. The catalytic pilot was designed to replace the existing pilot in the existing DLN injector without major modification to the injector. During high-pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over wide range of combustion temperatures. The catalytic reactor lit off at a temperature of approximately 598 K (325°C/617°F) and operated at simulated 100% and 50% load conditions without a preburner. At high pressure, the maximum catalyst surface temperature was similar to that observed during atmospheric pressure testing and considerably lower than the surface temperature expected in lean-burn catalytic devices. In single-injector rig testing, the integrated assembly of the catalytic pilot and Taurus 70 injector demonstrated NOx and CO emission less than 5 ppm @ 15% O2 for 100% and 50% load conditions along with low acoustics. The results demonstrate that a catalytic pilot burner replacing a diffusion flame or partially premixed pilot in an otherwise DLN combustor can enable operation at conditions with substantially reduced NOx emissions.

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Mills, Andrew Robert, et Visakan Kadirkamanathan. « Sensing for aerospace combustor health monitoring ». Aircraft Engineering and Aerospace Technology 92, n^o 1 (6 janvier 2020) : 37–46. http://dx.doi.org/10.1108/aeat-11-2018-0283.

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Purpose This paper proposes new methods of fault detection for fuel systems in order to improve system availability. Novel fault systems are required for environmentally friendly lean burn combustion, but can carry high risk failure modes particularly through their control valves. The purpose of the developed technology is the rapid detection of these failure modes, such as valve sticking or impending sticking, and therefore to reduce this risk. However, sensing valve state is challenging due to hot environmental temperatures, which results in a low reliability for conventional position sensing. Design/methodology/approach Starting with the business needs elicited from stakeholders, a quality functional deployment process is performed to derive sensing system requirements. The process acknowledges the difference between test-bed and in-service aerospace needs through weightings on requirements and maps these customer requirements to systems performance metrics. The design of the system must therefore optimise the sensor suite, on- and off-board signal processing and acquisition strategy. Findings Against this systems engineering process, two sensing strategies are outlined which illustrate the span of solutions, from conventional gas path sensing with advanced signal processing to novel non-invasive sensing concepts. While conventional sensing may be feasible within a test cell, the constraints of aerospace in-service operation may necessitate more novel alternatives. Acoustic emission (detecting very high frequency surface vibration waves) sensing technology is evaluated to provide a non-invasive, remote and high temperature tolerant solution. Through this comparison, the considerations for the end-to-end system design are highlighted to be critical to sensor deployment success in-service. Practical implications The paper provides insight into different means of addressing the important problem of monitoring faults in combustor systems in gas turbines. By casting of the complex design problem within a systems engineering framework, the outline of a toolset for solution evaluation is provided. Originality/value The paper provides three areas of significant contributions: a diversity of methods to diagnosing fuel system malfunctions by measuring changes fuel flow distributions, through novel means, and the combustor exit temperature profiles (cause and effect); the use of analytical methods to support the selection (types and quantities) and placement of sensors to ensure adequate state awareness while minimising their impact on the engine system cost and weight; and an end-to-end data processing approach to provide optimised information for the engine maintainers allowing informed decision-making.

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Meyers, D. P., et J. T. Kubesh. « The Hybrid Rich-Burn/Lean-Burn Engine ». Journal of Engineering for Gas Turbines and Power 119, n^o 1 (1 janvier 1997) : 243–49. http://dx.doi.org/10.1115/1.2815555.

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This paper describes a new low-emissions engine concept called the hybrid rich-burn/lean-burn (HRBLB) engine. In this concept a portion of the cylinders of a multicylinder engine are fueled with a very rich natural gas-air mixture. The remaining cylinders are operated with a lean mixture of natural gas and air and supplemented with the rich combustion exhaust. The goal of this unique concept is the production of extremely low NOx (e.g., 5 ppm when corrected to 15 percent exhaust oxygen content). This is accomplished by operating outside the combustion limits where NOx is produced. In rich combustion an abundance of hydrogen and carbon monoxide is produced. Catalyst treatment of the rich exhaust can be employed to increase the hydrogen concentration and decrease the carbon monoxide concentration simultaneously. The hydrogen-enriched exhaust is used to supplement the lean mixture cylinders to extend the lean limit of combustion, and thus produces ultralow levels of NOx. Results to date have shown NOx levels as low as 8 ppm at 15 percent oxygen can be achieved with good combustion stability and thermal efficiency.

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Wang, Tianyu, Jinlu Yu, Bingbing Zhao, Weida Cheng, Lei Zhang et Yongkun Sun. « Study on plasma combustion process in aero engine combustor ». Journal of Physics : Conference Series 2228, n^o 1 (1 mars 2022) : 012034. http://dx.doi.org/10.1088/1742-6596/2228/1/012034.

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Abstract In order to explore the effect of plasma combustion on the performance of aeroengine combustion chamber, a simplified 9-Step plasma reaction mechanism was added to the 16 component 25 step reaction mechanism of aviation kerosene, and a kerosene combustion chemical reaction process model considering the excited state relaxation reaction of plasma electron collision reaction and the chemical reaction involved in excited state was established, The numerical calculation of combustion process in combustion chamber was carried out, and the numerical calculation results of combustion process with and without plasma combustion support were compared and analyzed. The results showed that after adding plasma in the combustion chamber, the active particles produced by plasma reaction made kerosene burn more fully in the main combustion zone. Under the appropriate chemical ratio, the average temperature of the outlet section of the combustion chamber increases from 2208.5K to 2543.5K, and the combustion efficiency increases by 11% to 95.6% on the basis of 84.6%; The outlet temperature field was more uniform, and the temperature distribution coefficient (OTDF) was reduced from 0.131 to 0.111, which improved the performance of the combustion chamber.

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Stone, C. R., K. J. S. Mentis et M. Daragheh. « Measurements and Modelling of a Lean Burn Gas Engine ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 210, n^o 6 (décembre 1996) : 449–62. http://dx.doi.org/10.1243/pime_proc_1996_210_072_02.

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Natural gas is an alternative fuel that has potential for low emissions and a high efficiency. This paper presents the experimental results and predictions from a computer simulation of a fast burn high compression ratio (FBHCR) combustion system intended for use in a lean burn natural gas engine. Comparisons are made between the FBHCR combustion system at two compression ratios, predictions made by a two-zone combustion model and measurements from the original combustion system, for the brake efficiency, brake mean effective pressure, maximum cylinder pressure and the brake specific NOx emissions. Experimental measurements of the unburnt hydrocarbon emissions, the burn duration and the cycle-by-cycle variations in combustion are also discussed from the original and fast burn combustion systems. The results show how the conflicting aims of low emissions and low fuel consumption can be satisfied using a lean burn combustion system. The computer predictions are shown to be reliable, and thus suitable for estimating the performance of other engine builds.

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Costa, Roberto B. R., Carlos A. J. Gomes, Fabricio J. P. Pujatti, Ramon Molina Valle et José E. M. Barros. « Ethanol Lean Combustion Characteristics of a GDI Engine ». Applied Mechanics and Materials 798 (octobre 2015) : 219–23. http://dx.doi.org/10.4028/www.scientific.net/amm.798.219.

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In the present study, ethanol combustion analysis was carried in a wall guided type GDI engine, to achieve combustion stability under lean burn operation and to expand the flammability limit for increasing engine efficiency. Tests were performed at constant engine speed, load and injection pressure (1000 rpm, NIMEP = 3 bar, 100 bar), for a wide range of injection, ignition and mixture formation parameters. NISFC, combustion stability, PMEP and burn duration were evaluated at each excess air ratio. An improvement on fuel economy and, consequently, increased engine efficiency was achieved for excess air ratios of λ = 1.1 and λ = 1.2.

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Mendis, K. J. S., C. R. Stone, N. Ladommatos et M. Daragheh. « A Lean Burn Low Emissions Gas Engine for Co-Generation ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 210, n^o 3 (juin 1996) : 203–11. http://dx.doi.org/10.1243/pime_proc_1996_210_033_02.

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This paper presents the rationale behind a fast burn high compression ratio (FBHCR) combustion system intended for use in a lean burn natural gas engine. Comparisons are made between the FBHCR combustion system, predictions made by a two-zone combustion model and measurements from the original combustion system, for the brake efficiency, brake mean effective pressure and the brake specific NOx emissions. Experimental measurements of the unburnt hydrocarbon emissions, the burn duration and the cycle-by-cycle variations in combustion are also discussed from the two combustion systems. The results show how the conflicting aims of low emissions and low fuel consumption can be satisfied by using a lean burn combustion system. A comparison is also made between the following ways of expressing the exhaust emissions: volumetric, brake specific, mass per megajoule of fuel and gravimetric referenced to a specified oxygen level.

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Shahzad, Raja, P. Naveenchandran, A. Rashid et Amir Aziz. « Characteristics of Lean and Stoichiometric Combustion of Compressed Natural Gas in a Direct Injection Engine ». Applied Mechanics and Materials 110-116 (octobre 2011) : 357–69. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.357.

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This paper discusses the combustion characteristics of CNG under lean and stochiometric conditions in a direct injection engine. The experiments were carried out on a dedicated CNG-Direct Injection engine with 14:1 compression ratio. Combustion characteristics of CNG have been investigated on various injection timings. Injection timing of the fuel injection timing had significant effects on the engine performance, combustion and emissions. The effects became more significant when injection timing was retarded. Injection timing was set after the closing of intake valve and experiments are conducted at 0% and 50% load conditions. Lean stratified operation experiences faster combustion compared to that of stochiometric. In lean stratified operation, there were fast burn rates at the initial stage and slower burning at the later stage. Whereas in stochiometric conditions there is a slightly slower burn at the initial stage and a moderately faster burn at the later stage. The faster initial combustion in lean stratified operation might be due to rapid burn of the initial mixture due to higher turbulence, while a slower burn in the later stage due to diffusion. In contrary to that in stochiometric operations the initial burn is slightly slower, due to moderately strong turbulence and a faster burn due to moderately proceeding mixture. Thus the main effect of fuel injection timing can be explained by the fuel air mixing and the turbulence produced.

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Wang, Jia Jun, Jun Wei Tao, Hong Da Zhang et Jin Bo Guo. « Research on Control System of Quasi-Homogeneous Lean-Burn Engine ». Applied Mechanics and Materials 496-500 (janvier 2014) : 1248–51. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.1248.

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Quasi-homogeneous lean mixture combustion technology can take full advantages of lean-combustion, and help reduce the engine fuel consumption and emissions. Quasi-Homogeneous Lean-burn engine Control System, combined virtual instruments with engine electronic control technology, can precisely control air-fuel ratio injection, timing, fuel injection pulse and ignite on timing, which provides a reliable and convenient platform for the engine lean-burning performance tests..

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Khandelwal, B., A. Karakurt, V. Sethi, R. Singh et Z. Quan. « Preliminary design and performance analysis of a low emission aero-derived gas turbine combustor ». Aeronautical Journal 117, n^o 1198 (décembre 2013) : 1249–71. http://dx.doi.org/10.1017/s0001924000008848.

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Abstract Modern gas turbine combustor design is a complex task which includes both experimental and empirical knowledge. Numerous parameters have to be considered for combustor designs which include combustor size, combustion efficiency, emissions and so on. Several empirical correlations and experienced approaches have been developed and summarised in literature for designing conventional combustors. A large number of advanced technologies have been successfully employed to reduce emissions significantly in the last few decades. There is no literature in the public domain for providing detailed design methodologies of triple annular combustors. The objective of this study is to provide a detailed method designing a triple annular dry low emission industrial combustor and evaluate its performance, based on the operating conditions of an industrial engine. The design methodology employs semi-empirical and empirical models for designing different components of gas turbine combustors. Meanwhile, advanced DLE methods such as lean fuel combustion, premixed methods, staged combustion, triple annular, multi-passage diffusers, machined cooling rings, DACRS and heat shields are employed to cut down emissions. The design process is shown step by step for design and performance evaluation of the combustor. The performance of this combustor is predicted, it shows that NO x emissions could be reduced by 60%-90% as compared with conventional single annular combustors.

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Wang, Li, Wei Yu Zhang et Yi Qiang Pei. « Fuzzy Auto-Tuning Techniques Applied to Air-Fuel Ratio Control on a Lean Burn Engine ». Applied Mechanics and Materials 127 (octobre 2011) : 434–38. http://dx.doi.org/10.4028/www.scientific.net/amm.127.434.

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Lean burn technology shows great potential in meeting the more strict emission regulation and realizing high efficiency and clean combustion. In this paper, a feedforward-feedback control system of the air-fuel ratio controlling for lean burn engine is presented. A fuzzy parameter self-tuning PID control scheme is used as feedback to balance the control accuracy and system complexity. Some lean burn engine air-fuel ratio control experiments are given to show the efficiency of the proposed method. With the proposed control system, the the actual engine air-fuel ratio can quickly track the desired air-fuel ratio when the engine load changes suddenly regardless of whether the target air-fuel ratio is 20 or 14.6. So, the fuzzy parameter self-tuning PID controller has excellent control performance under transient condition of lean burn engine.

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Yu, Meiqi, Hongliang LUO, Chang Zhai, Yanzhao An et Keiya Nishida. « Combustion Performance of Hydrogen Direct Injection under Lean-burn Conditions for Power Generation ». Journal of Advanced Thermal Science Research 9 (28 décembre 2022) : 84–94. http://dx.doi.org/10.15377/2409-5826.2022.09.7.

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This paper studies the combustion phenomenon of hydrogen (H2) direct injection (DI) in a modified spark ignition (SI) engine. As we known, ignition timing strongly correlates with combustion performance, especially for power output and efficiency. Therefore, different ignition timing varying among -20, -15, -10, -5, 0, 5, 10, 15, and 20 deg top dead center (TDC) are tested in this research. Besides, different H2 injection timings and injection pressures are also compared in this study. Moreover, as H2 usually favors lean-burn combustion, λ at 3, 3.5, and 4 are tested to find the lean-burn limitation. In order to obtain the engine speed influences on power output, finally 1500, 2000, and 2500 revolutions per minute (rpm) are evaluated in this study. Finally, thermal brake efficiency (BTE) and power output are analyzed. Results showed that power output and efficiency increase with the delay of ignition timing from -20 to 5 deg TDC and then decrease with delaying timing from 5 to 20 deg TDC. However, injection timing has less effect on the H2 combustion phenomenon. H2 lean-burn limitation is found that when λ is larger than 3, the efficiency decreases sharply. Moreover, both power output and efficiency firstly increase then decrease with higher engine speed and 2000 rpm is the best option for this small engine. Finally, by evaluating the contribution index, ignition timing and engine speed should be optimized first to achieve higher efficiency.

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Pan, Shiyi, Jinhua Wang, Bin Liang, Hao Duan et Zuohua Huang. « Experimental Study on the Effects of Hydrogen Injection Strategy on the Combustion and Emissions of a Hydrogen/Gasoline Dual Fuel SI Engine under Lean Burn Condition ». Applied Sciences 12, n^o 20 (19 octobre 2022) : 10549. http://dx.doi.org/10.3390/app122010549.

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Hydrogen addition can improve the performance and extend the lean burn limit of gasoline engines. Different hydrogen injection strategies lead to different types of hydrogen mixture distribution (HMD), which affects the engine performance. Therefore, the present study experimentally investigated the effects of hydrogen injection strategy on the combustion and emissions of a hydrogen/gasoline dual-fuel port-injection engine under lean-burn conditions. Four different hydrogen injection strategies were explored: hydrogen direct injection (HDI), forming a stratified hydrogen mixture distribution (SHMD); hydrogen intake port injection, forming a premixed hydrogen mixture distribution (PHMD); split hydrogen direct injection (SHDI), forming a partially premixed hydrogen mixture distribution (PPHMD); and no hydrogen addition (NHMD). The results showed that 20% hydrogen addition could extend the lean burn limit from 1.5 to 2.8. With the increase in the excess air ratio, the optimum HMD changed from PPHMD to SHMD. The maximum brake thermal efficiency was obtained with an excess air ratio of 1.5 with PPHMD. The coefficient of variation (COV) with NHMD was higher than that with hydrogen addition, since the hydrogen enhanced the stability of ignition and combustion. The engine presented the lowest emissions with PHMD. There were almost no carbon monoxide (CO) and nitrogen oxides (NOx) emissions when the excess air ratio was, respectively, more than 1.4 and 2.0.

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Mou, Jiang Feng, Rui Qing Chen et Yi Wei Lu. « The Research of Lean Combustion Characteristic of Compound Injection System of Direct Injection Engine ». Applied Mechanics and Materials 532 (février 2014) : 362–66. http://dx.doi.org/10.4028/www.scientific.net/amm.532.362.

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This paper studies the lean burn limit characteristic of the compound injection system of the direct-injection gasoline engine. The low pressure nozzle on the intake manifold can achieve quality homogeneous lean mixture, and the direct injection in the cylinder can realized the dense mixture gas near the spark plug. By adjusting the two injection timing and injection quantity, and a strong intake tumble flow with special shaped combustion chamber, it can produces the reverse tumble to form different hierarchical levels of mixed gas in the cylinder. Experimental results show: the compound combustion system to the original direct-injection engine lean burn limit raise 1.8-2.5 AFR unit.

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Zhou, You, Wei Hong, Ye Yang, Xiaoping Li, Fangxi Xie et Yan Su. « Experimental Investigation of Diluents Components on Performance and Emissions of a High Compression Ratio Methanol SI Engine ». Energies 12, n^o 17 (1 septembre 2019) : 3366. http://dx.doi.org/10.3390/en12173366.

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Increasing compression ratio and using lean burn are two effective techniques for improving engine performance. Methanol has a wide range of sources and is a kind of suitable fuel for a high-compression ratio spark-ignition lean burn engine. Lean burn mainly has a dilution effect, thermal effect and chemical effect. To clarify the influences of different effects and provide guidance for improving composition of dilution gases and applications of this technology, this paper chose Ar, N2 and CO2 as diluents. A spark-ignition methanol engine modified from a diesel engine with a compression ratio of 17.5 was used for the experiments. The results obtained by using methanol spark ignition combustion indicated that at engine speed of 1400 rpm and 25% load, NOx dropped by up to 77.5%, 100% and 100% by Ar, CO2 and N2. Gases with higher specific heat ratio and lower heat capacity represented by Ar exhibited the least adverse effect on combustion and showed a downward break-specific fuel consumption (BSFC) trend. Gas with high specific heat capacity represented by CO2 can decrease NOx and total hydro carbons (THC) emissions at the same time, but the BSFC of CO2 showed the worst trend, followed by N2. Gas affecting the combustion process like CO2 had chemical effect.

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Li, Le, Jianqin Suo, Han Yu et Longxi Zhang. « Optimal Design and Application of Gas Analysis System ». Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, n^o 1 (février 2020) : 104–13. http://dx.doi.org/10.1051/jnwpu/20203810104.

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To accurately measure the performance parameters of an aero-engine combustor under high-temperature and high-pressure environment, such as outlet temperature, combustion efficiency and pollutant emission, the optimal design of the existing gas sampling and analysis system was carried out, the data post-processing method was corrected, and the full-component enthalpy conservation method suitable for calculating combustor outlet temperature was established. A lean direct injection and low-pollution combustor was used to evaluate the performance and application of its gas analysis system and its data post-processing method. The investigation results indicate that the optimized gas analysis system meets the International Civil Aviation Organization's pollutant emission measurement requirements and that it has a fast response and a high data quality. The comparison of the measurement results of the gas analysis system with those of the traditional measurement methods shows that the gas analysis system has a more accurate measurement, a wider condition range and a better stability, thus accurately evaluating the outlet temperature, combustion efficiency and emission characteristics of a gas turbine combustor.

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Song, Chang Qing, Jun Li, Da Wei Qu et Qi Jie Liu. « Simulation Study on Different Composition Fuels in Lean-Burn CNG Engine ». Applied Mechanics and Materials 448-453 (octobre 2013) : 3430–33. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.3430.

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The Paper has Established a Combustion Model of Lean-Burn CNG Engine by Three-Dimensional Simulation Software AVL FRIE. Based on Test Validation in the Model, the Combustion Processes of Seven CNG Samples were Simulated and Compared from the Intake Valve Closed to the Exhaust Valve Opening. the Effects on Different Composition Fuels for CNG Engine were Researched. the Results Showed that: the Maximum Average Pressure within the Cylinder , the Highest Average Temperature, the Maximum Heat Release Rate, the Initial Mass Fraction of Fuels, CO and NO Formation Increased with the Hydrocarbon Fuel Ratio C/H, the Composition of Heavy Paraffin in CNG Directly Affected the Performance and Service Life of the Engine.

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Wang, Li-Yuan, Li-Ping Yang, En-Zhe Song, Chong Yao et Xiu-Zhen Ma. « Effect of Port Gas Injection on the Combustion Instabilities in a Spark-Ignition Lean-Burn Natural Gas Engine ». International Journal of Bifurcation and Chaos 28, n^o 10 (septembre 2018) : 1850124. http://dx.doi.org/10.1142/s0218127418501249.

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The combustion instabilities in a lean-burn natural gas engine have been studied. Using statistical analysis, phase-space reconstruction, and wavelet transforms, the effect of port gas injection on the dynamics of the indicated mean effective pressure (IMEP) fluctuations have been examined at a speed of 800[Formula: see text]rpm and engine load rates of 25% and 50%. The excessive air coefficient is 1.6 for each engine load, and the port gas injection timing (PGIT) ranges from 1 to 120 degrees of crankshaft angle ([Formula: see text]CA) after top dead center (ATDC) of the intake process. The results show that the PGIT has a significant effect on cyclic combustion fluctuations and the dynamics of the combustion system for all studied engine loads. An unreasonable PGIT leads to increased combustion fluctuations, and loosened and bifurcated structures of combustion system attractors. Furthermore, for both low and medium engine loads, the IMEP time series at earlier gas injections ([Formula: see text]CA and [Formula: see text]CA ATDC) undergoes low-frequency fluctuation together with high-frequency fluctuations in an intermittent fashion. For other PGITs, high-frequency intermittent fluctuations become persistent combined with weak low-frequency oscillations. Our results can be used to understand the oscillation characteristics and the complex dynamics of combustion system in a lean-burn natural gas engine. In addition, they may also be beneficial to the development of more sophisticated engine control strategies.

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WEIßNER, Michael, Frank BEGER, Martin SCHÜTTENHELM et Gunesh TALLU. « Lean-burn CNG engine with ignition chamber : from the idea to a running engine ». Combustion Engines 176, n^o 1 (1 février 2019) : 3–9. http://dx.doi.org/10.19206/ce-2019-101.

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Current and further developing CO2- and emission regulations worldwide and the competition to full electric mobility deliver a chal-lenge for internal combustion engines in general. A state of the art solution is the use of natural gas mainly contending methane to reduce CO2 significantly and to offer lowest emission levels. The EU-funded project GasOn developed engine concepts to fully exploit the advantages of CNG. This article describes the development of an innovative, monovalent engine dedicated to Compressed Natural Gas (CNG) and characterised by the lean burn concept and the innovative pre-chamber combustion.

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Kaiser, Sascha, Markus Nickl, Christina Salpingidou, Zinon Vlahostergios, Stefan Donnerhack et Hermann Klingels. « Investigations of the synergy of Composite Cycle and intercooled recuperation ». Aeronautical Journal 122, n^o 1252 (15 mai 2018) : 869–88. http://dx.doi.org/10.1017/aer.2018.46.

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ABSTRACTThe synergistic combination of two promising engine architectures for future aero engines is presented. The first is the Composite Cycle Engine, which introduces a piston system in the high pressure part of the core engine, to utilise closed volume combustion and high temperature capability due to instationary operation. The second is the Intercooled Recuperated engine that employs recuperators to utilise waste heat from the core engine exhaust and intercooler to improve temperature levels for recuperation and to reduce compression work. Combinations of both architectures are presented and investigated for improvement potential with respect to specific fuel consumption, engine weight and fuel burn against a turbofan. The Composite Cycle alone provides a 15.6% fuel burn reduction against a turbofan. Options for adding intercooler were screened, and a benefit of up to 1.9% fuel burn could be shown for installation in front of a piston system through a significant, efficiency-neutral weight decrease. Waste heat can be utilised by means of classic recuperation to the entire core mass flow before the combustor, or alternatively on the turbine cooling bleed or a piston engine bypass flow that is mixed again with the main flow before the combustor. As further permutation, waste heat can be recovered either after the low pressure turbine – with or without sequential combustion – or between the high pressure and low pressure turbine. Waste heat recovery after the low pressure turbine was found to be not easily feasible or tied to high fuel burn penalties due to unfavourable temperature levels, even when using sequential combustion or intercooling. Feasible temperature levels could be obtained with inter-turbine waste heat recovery but always resulted in at least 0.3% higher fuel burn compared to the non-recuperated baseline under the given assumptions. Consequently, only the application of an intercooler appears to provide a considerable benefit for the examined thermodynamic conditions in the low fidelity analyses of various engine architecture combinations with the specific heat exchanger design. Since the obtained drawbacks of some waste heat utilisation concepts are small, innovative waste heat management concepts coupled with the further extension of the design space and the inclusion of higher fidelity models may achieve a benefit and motivate future investigations.

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Takeuchi, Kazuo, Pawel Luszcz et Philipp Adomeit. « Homogeneous Lean Burn Engine Combustion System Development - Concept Study ». MTZ worldwide 80, n^o 3 (8 février 2019) : 18–25. http://dx.doi.org/10.1007/s38313-018-0155-9.

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Polcar, Adam, Vojtěch Kumbár et Jiří Čupera. « Alcohol Fuel in Passenger Car ». Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 64, n^o 3 (2016) : 863–69. http://dx.doi.org/10.11118/actaun201664030863.

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The present article studies the effects of combustion of high-percentage mixture of bioethanol and gasoline on the output parameters of a passenger car engine. The car engine has not been structurally modified for the combustion of fuels with higher ethanol content. The mixture used consisted of E85 summer blend and Natural 95 gasoline in a ratio of 50:50. The parameters monitored during the experiment included the air-fuel ratio in exhaust gasses, the power output and torque of the engine and also the specific energy consumption and efficiency of the engine. As is apparent from the results, E85+N95 (50:50) mixture combustion results in lean-burn (λ > 1) due to the presence of oxygen in bioethanol. The lean-burn led to a slight decrease in torque and power output of the engine. However, due to the positive physicochemical properties of bioethanol, the decrease has not been as significant as would normally be expected from the measured air-fuel ratio. These findings are further confirmed by the calculated energy required to produce 1 kWh of energy, and by the higher efficiency of the engine during the combustion of a 50% bioethanol mixture.

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Bureshaid, Khalifa, Dengquan Feng, Hua Zhao et Mike Bunce. « Combustion and emissions of gasoline, anhydrous ethanol, and wet ethanol in an optical engine with a turbulent jet ignition system ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 233, n^o 13 (8 février 2019) : 3528–37. http://dx.doi.org/10.1177/0954407019825999.

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Turbulent jet ignition is a pre-chamber ignition system for an otherwise standard gasoline spark ignition engine. Turbulent jet ignition works by injecting chemical active turbulent jets to initiate combustion in a premixed fuel/air mixture. The main advantage of turbulent jet ignition is its ability to ignite and burn completely very lean fuel/air mixtures in the main chamber charge. This occurs with a very fast burn rate due to the widely distributed ignition sites that consume the main charge rapidly. Rapid combustion of lean mixtures leads to lower exhaust emissions due to more complete combustion at lower combustion temperature. The purpose of the paper is to study the combustion characteristics of gasoline, ethanol, and wet ethanol when operated with the pre-chamber combustion system and the ability of the pre-chamber ignition to extend the lean-burn limits of such fuels. The combustion and heat release process was analyzed and exhaust emissions measured. Results show that the effect of turbulent jet ignition system on the lean-burn limit and exhaust emissions varied with fuels. The lean limit was extended by using fueled pre-chamber furthest, to λ = 1.71 with gasoline, followed by λ = 1.77 with wet ethanol and λ = 1.9 with ethanol. NOx emissions were significantly reduced with increased lambda for each fuel under stable combustion conditions. For ethanol, at maximum lean limit lambda 1.9, the NOx emissions were almost negligible due to lower combustion temperature.

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Fu, Xue-Qing, Bang-Quan He, Si-Peng Xu, Tao Chen, Hua Zhao, Yan Zhang, Yufeng Li et Honglin Bai. « Multi-point micro-flame ignited hybrid lean-burn combustion of gasoline with direct injection dimethyl ether ». International Journal of Engine Research 22, n^o 1 (8 avril 2019) : 140–51. http://dx.doi.org/10.1177/1468087419840469.

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Lean-burn combustion is effective in reducing fuel consumption of gasoline engines because of the higher specific heat ratio of the fuel lean mixture and reduced heat loss from lower combustion temperature. However, its application to real engines is hampered by the unstable ignition, high cyclic variability, and partial-burn due to slower combustion, as well as the restricted maximum lean-burn air/fuel ratio limit and the insufficiently low nitrogen oxides emission. Multi-point micro-flame-ignited hybrid combustion has been proposed and applied to extend the lean burn limit of premixed gasoline and air mixture. To achieve micro-flame-ignited combustion in premixed lean gasoline mixture formed by port fuel injection, a small amount of dimethyl ether is injected directly into the cylinder of a four-stroke gasoline engine to control and accelerate the ignition and combustion process so that the engine could be operated with the overall excess air coefficient (Lambda) of 1.9. The results show that heat release processes can be grouped into three forms, that is, ramp type, double-peak type, and trapezoid type. Regardless of single or split injections, direct injection timing of dimethyl ether dominates the features of heat release. The ramp type occurs at early injection timing while the double-peak type takes place at late injection timing. Trapezoid type appears between the above two types. Dimethyl ether injection timing controls the ignition timing and has less effect on combustion duration. Single injection of dimethyl ether leads to much earlier ignition timing and slightly longer combustion duration, forming higher nitrogen oxides emissions than the split injections. Ultra-low nitrogen oxides emissions and higher thermal efficiency are achieved in the ramp type combustion compared to the other two types of combustion in both injection approaches.

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Mavinahally, N. S., D. N. Assanis, K. R. Govinda Mallan et K. V. Gopalakrishnan. « Torch Ignition : Ideal for Lean Burn Premixed-Charge Engines ». Journal of Engineering for Gas Turbines and Power 116, n^o 4 (1 octobre 1994) : 793–98. http://dx.doi.org/10.1115/1.2906887.

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Sluggish flame initiation and propagation, and even potential misfiring, become major problems with lean-fueled, premixed-charge, spark-ignited engines. This work studies torch ignition as a means for improving combustion, fuel economy, and emissions of a retrofitted, large combustion chamber with nonideal spark plug location. A number of alternative configurations, employing different torch chamber designs, spark-plug locations, and materials, were tested under full-load and part-load conditions. Results indicate a considerable extension of the lean operating limit of the engine, especially under part-load conditions. In addition, torch ignition can lead to substantial thermal efficiency gains for either leaner or richer air-fuel ratios than the optimum for the conventional ignition system. On the richer side, in particular, the torch-ignited engine is capable of operating at maximum brake torque spark timings, rather than compromised, knock-limited spark timings used with conventional ignition. This translates into thermal efficiency improvements as high as 8 percent at an air-fuel ratio of 20:1 and full load.

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Jamrozik, Arkadiusz, et Wojciech Tutak. « A study of performance and emissions of SI engine with a two-stage combustion system ». Chemical and Process Engineering 32, n^o 4 (1 décembre 2011) : 453–71. http://dx.doi.org/10.2478/v10176-011-0036-0.

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A study of performance and emissions of SI engine with a two-stage combustion systemLean mixture burning leads to a decrease in the temperature of the combustion process and it is one of the methods of limiting nitric oxide emissions. It also increases engine efficiency. An effective method to correct lean mixture combustion can be a two-stage system of stratified mixture combustion in an engine with a prechamber. This article presents the results of laboratory research on an SI engine (spark ignition) with a two-stage combustion system with a cylinder powered by gasoline and a prechamber powered by propane-butane gas LPG (liquefied petroleum gas). The results were compared to the results of research on a conventional engine with a one-stage combustion process. The test engine fuel mixture stratification method, with a two-stage combustion system in the engine with a prechamber, allowed to burn a lean mixture with an average excess air factor equal to 2.0 and thus led to lower emissions of nitrogen oxides in the exhaust of the engine. The test engine with a conventional, single-stage combustion process allowed to properly burn air-fuel mixtures of excess air factors λ not exceeding 1.5. If the value λ > 1.5, the non-repeatability factorCOVLiincreases, and the engine efficiency decreases, which makes it virtually impossible for the engine to operate. The engine with a two-stage combustion process, working with λ = 2.0, theQin/Qtot= 2.5%, reduced the NOxcontent in the exhaust gases to a level of about 1.14 g/kWh. This value is significantly lower than the value obtained in a conventional engine, which worked at λ = 1.3 with comparable non-repeatability of successive cycles (about 3%) and a similar indicated efficiency (about 34%), was characterised by the emissions of NOxin the exhaust equal to 26.26 g/kWh.

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Wang, Xiaoyan, Tanqing Zhou, Quan Dong, Zhaolin Cheng et Xiyu Yang. « A Virtual Combustion Sensor Based on Ion Current for Lean-Burn Natural Gas Engine ». Sensors 22, n^o 13 (21 juin 2022) : 4660. http://dx.doi.org/10.3390/s22134660.

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In this study, an innovative sensor was designed to detect the key combustion parameters of the marine natural gas engine. Based on the ion current, any engine structurally modified was avoided and the real-time monitoring for the combustion process was realized. For the general applicability of the proposed sensor, the ion current generated by a high-energy ignition system was acquired in a wide operating range of the engine. It was found that engine load, excess air coefficient (λ) and ignition timing all generated great influence on both the chemical and thermal phases, which indicated that the ion current was highly correlated with the combustion process in the cylinder. Furthermore, the correlations between the 5 ion current-related parameters and the 10 combustion-related parameters were analyzed in detail. The results showed that most correlation coefficients were relatively high. Based on the aforementioned high correlation, the novel sensor used an on-line algorithm at the basis of neural network models. The models took the characteristic values extracted from the ion current as the inputs and the key combustion parameters as the outputs to realize the online combustion sensing. Four neural network models were established according to the existence of the thermal phase peak of the ion current and two different network structures (BP and RBF). Finally, the predicted values of the four models were compared with the experimental values. The results showed that the BP (with thermal) model had the highest prediction accuracy of phase parameters and amplitude parameters of combustion. Meanwhile, RBF (with thermal) model had the highest prediction accuracy of emission parameters. The mean absolute percentage errors (MAPE) were mostly lower than 0.25, which proved a high accuracy of the proposed ion current-based virtual sensor for detecting the key combustion parameters.

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Anggono, Willyanto, Soen Peter Stanley, Ferdinand Ronaldo, Gabriel J. Gotama, Bin Guo, Emir Yilmaz, Mitsuhisa Ichiyanagi et Takashi Suzuki. « Engine Performances of Lean Iso-Octane Mixtures in a Glow Plug Heated Sub-Chamber SI Engine ». Automotive Experiences 5, n^o 1 (25 novembre 2021) : 16–27. http://dx.doi.org/10.31603/ae.5118.

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Due to the difficulty to directly study ammonia, the present work investigated the engine performance of lean iso-octane/air mixture to approximate ammonia combustion behaviour. The study was conducted using a single cylinder modified diesel engine that features a spark plug and glow plug in the sub-chamber. The investigations varied the engine speeds (1000 and 1500 RPM), glow plug voltages (6 and 10 volts), excess air ratios (1.4 to 1.8), and ignition timings (-2 to -5 °BTDC). The results suggested improved engine performances with a lower excess ratio and higher glow plug voltage due to more complete and stable combustion. By increasing the engine speed, the lean burn limit was extended and improved the engine performances. Because of the sub-chamber feature, delaying the ignition timing improved the engine performances. A larger excess air ratio was found to increase the sensitivity of the engine performances with the ignition timing. The brake mean effective pressure for all conditions has a coefficient of variation of less than 7%, indicating stable combustion. The results suggested that the current setup can be used to investigate ammonia blended fuel and direct ammonia combustion in future works.

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Zhou, Dong Qing, Jun Li, Ying Gao, Da Wei Qu et Qi Jie Liu. « Research on LPG Dual-Spark Ignition Engine Combustion by CFD ». Advanced Materials Research 443-444 (janvier 2012) : 1032–38. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.1032.

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.To study the dual-spark ignition methods of combustion of LPG, numerical simulation is conducted on the lean burn LPG turbocharged engine by three-dimensional simulation software.Based on the model validation test of dual-spark ignition model engine, the effect of synchronization ignition and asynchronous ignition are discussed.The results obtained show that asynchronous dual spark ignition model can be helpful to reduce flame propagation distance, form the stronger swirl rapidly,accelerate the flame propagation speed significantly,improve the rapid lean-burning process of LPG engine. Meanwhile, the results will also offer theoretical guidance for combustion optimization.

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Arcoumanis, C., D. R. Hull et J. H. Whitelaw. « Optimizing local charge stratification in a lean-burn spark ignition engine ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 211, n^o 2 (1 février 1997) : 145–54. http://dx.doi.org/10.1243/0954407971526317.

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Gas pressure and local gas velocities have been measured in a single-cylinder spark ignition engine operating at low load and 1000 r/min and the results have characterized the extent to which combustion was enhanced by the injection of a small quantity of a mixture of propane vapour and air towards the spark plug in an otherwise quiescent chamber filled with a homogeneous lean propane/air charge. The effects of the locally generated mean flow/turbulence and equivalence ratio on combustion were examined separately by first injecting a mixture of equivalence ratio identical to that of the homogeneous charge and then a slightly rich mixture into homogeneous charges of lower equivalence ratios. The results show the advantageous effect of jet-induced local turbulence for overall air—fuel ratios between 17 and 24 with a maximum gain in peak pressure of 55 per cent at an air—fuel ratio of 20. The local injection of a rich mixture, in addition to increasing the gain in peak pressure from 30 to 50 per cent at an air—fuel ratio of 24, has extended the lean limit of the engine to 29. The timing of ignition relative to the end of injection, which varied as a function of the injection pressure, was found to have a strong effect on the peak combustion pressure so that, for example, a reduction of 8°(CA) in the time between the spark and the end of injection resulted in a 25 per cent reduction in combustion pressure at an air—fuel ratio of 22. The average flame speed was increased by local injection at all equivalence ratios; for example, a value of 7 m/s was obtained with local injection at an equivalence ratio of 0.7 which is equivalent to the flame speed measured with a homogeneous charge at the much higher equivalence ratio of 0.9.

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Chérel, Jérôme, Jean-Marc Zaccardi, Bernard Bouteiller et Alain Allimant. « Experimental assessment of new insulation coatings for lean burn spark-ignited engines ». Oil & ; Gas Science and Technology – Revue d’IFP Energies nouvelles 75 (2020) : 11. http://dx.doi.org/10.2516/ogst/2020006.

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Clean and highly efficient internal combustion engines will still be necessary in the future to meet the ambitious CO2 emissions reduction targets set for light-duty vehicles. The maximal efficiency of stoichiometric Spark-Ignited (SI) gasoline engines has been steadily increasing in recent years but remains limited by the important relative share of cooling losses. Low heat rejection engines using ceramic barrier coatings have been presented in the past but smart insulation coatings are gaining a renewed interest as a more promising way to further increase the engine maximal thermal efficiency. This article is highlighting some important effects of smart insulation coatings developed for lean-burn spark-ignited gasoline engines. Five different coatings with low heat conductivity and capacity are applied on aluminum engine parts with the atmospheric plasma spray technique and are tested with two different engines. The laser induced phosphorescence technique is firstly used in an optical single cylinder engine to quantify the thermal performance of these coatings in terms of temperature swing during combustion. A maximal increase in the piston surface temperature of around 100 °C is measured at low load, confirming thus the expected impact of the low heat conductivity and capacity, and suggesting thus a positive impact on fuel consumption. Thanks to the tests performed with a similar metal single cylinder engine, it is shown that the unburned hydrocarbon emissions can significantly increase by up to 25% if the open porosity on top of the coating is not properly sealed, while the surface roughness has no impact on these emissions. When applied on both the piston and the cylinder head, the optimized coating displays some distinct effects on the maximal heat release rate and NOx emissions, indicating that the thermal environment inside the combustion chamber is modified during combustion. Thanks to the temperature swing between cold and hot engine phases the volumetric efficiency can also be kept constant. However, no increase in efficiency can be measured with this optimized coating which suggests that the heat balance is not affected only by the reduction in the temperature differential between the walls and the gas.

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Cecere, Giovanni, Adrian Irimescu, Simona Silvia Merola, Luciano Rolando et Federico Millo. « Lean Burn Flame Kernel Characterization for Different Spark Plug Designs and Orientations in an Optical GDI Engine ». Energies 15, n^o 9 (6 mai 2022) : 3393. http://dx.doi.org/10.3390/en15093393.

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Lean burn spark ignition (SI) engines represent an effective solution for improving fuel economy and reducing exhaust emissions and can be implemented both in conventional and hybrid powertrains. On the other hand, lean operation increases cyclic variability with negative impact on power output, engine efficiency, roughness, and operating stability. Although this phenomenon has been widely investigated, the effects of flow field on the inception and development of flames in direct injection spark ignition (DISI) engines under lean burn conditions is not yet completely understood. In particular, the effect of spark plug geometry and electrode orientation with respect to tumble motion has been minimally investigated. For these reasons, two different spark-plug geometries (i.e., single- and double-ground electrode) and three different orientations (i.e., cross-, counter-, and uni-flow with respect to the direction of tumble motion) were investigated in an optically accessible DISI engine for understanding their influence on the initial phase of combustion. The relative air–fuel ratio (AFRrel) was changed from stoichiometric to lean burn (1.00 to 1.30) for different spark timings around the maximum brake torque setting at fixed engine speed (2000 rpm). An image processing procedure was developed for evaluating the morphological parameters of flame kernels and studying the effects of spark plug design on engine operating stability. With a focus on the correlation between the position where ignition occurs with the subsequent locations of the flame kernel during the first phases of the combustion process, the analysis allowed the gathering of a better understanding of the influence that the electrodes’ geometries and orientation can have on the first stages of combustion development.

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Zhang, Wen, Zhi Jun Li, Chun Qia Liu, Ming Li et Qing Chang. « A Study of Quasi-Homogeneous Lean Burn Gasoline Engine Performance Based on the Numerical Simulation ». Applied Mechanics and Materials 278-280 (janvier 2013) : 174–77. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.174.

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A CA3GA2 lean combustion gasoline engine one dimensional model was built by AVL BOOST software. The relationship between air-to-fuel ratio (A/F) and emission characteristic and fuel economy was simulated. Simulation shows that: (1) CO emission decreases as the A/F ratio increases; (2) HC emission reaches its lowest point at A/F=16~18; (3) NOX emission reaches its highest point at A/F=16~18; (4) the engine lean combustion limit is A/F=22, the brake specific fuel consumption (BSFC) decreases as the A/F ratio increases within the lean combustion limit.

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Liu, Jinlong, et Cosmin Emil Dumitrescu. « Optical analysis of flame inception and propagation in a lean-burn natural-gas spark-ignition engine with a bowl-in-piston geometry ». International Journal of Engine Research 21, n^o 9 (7 janvier 2019) : 1584–96. http://dx.doi.org/10.1177/1468087418822852.

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Heavy-duty diesel engines can convert to lean-burn natural-gas spark-ignition operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector to initiate and control combustion. However, the combustion phenomena in such converted engines usually consist of two distinct stages: a fast-burning stage inside the piston bowl followed by a slow-burning stage inside the squish area. This study used flame luminosity data and in-cylinder pressure measurements to analyze flame propagation inside a bowl-in-piston geometry. The experimental results showed a low coefficient of variation and standard deviation of peak cylinder pressure, moderate rate of pressure rise, and no knocking for the lean-burn (equivalence ratio 0.66), low-speed (900 r/min), and medium-load (6.6 bar IMEP) operating condition. Flame inception had a strong effect on the flame expansion velocity, which increased fast once the flame kernel established, but it reduced near the bowl edge and the entrance of the narrow squish region. However, the burn inside the bowl was very fast. In addition, the long duration of burn inside the squish indicated a much lower flame propagation speed for the outside-the-bowl combustion, which contributed to a long decreasing tail in the apparent heat release rate. Furthermore, cycles with fast flame inception and fast burn inside the bowl had a similar end of combustion with cycles with delayed flame inception and then a retarded burn inside the bowl, which indicated that the combustion inside the squish region determined the combustion duration. Overall, the results suggested that the spark event, the flame development inside the piston bowl, and the start of the second combustion stage affected the phasing and duration of the two combustion stages, which (subsequently) can affect engine efficiency and emissions of diesel engines converted to a lean-burn natural-gas spark-ignition operation.

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Teodosio, Luigi, Fabio Berni, Alfredo Lanotte et Enrica Malfi. « 1D/3D simulation procedure to investigate the potential of a lean burn hydrogen fuelled engine ». Journal of Physics : Conference Series 2385, n^o 1 (1 décembre 2022) : 012085. http://dx.doi.org/10.1088/1742-6596/2385/1/012085.

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Abstract In recent years hydrogen, especially the one generated by renewable energy, is gaining increasing attention as a clean fuel to support the future mobility towards efficient and low emission solutions for propulsion systems. In this scenario, the present work deals with the virtual conversion of a single-cylinder Diesel engine, conceived for marine applications, into a hydrogen Spark Ignition (SI) unit. A simulation methodology is adopted, combining 1D and 3D Computational Fluid Dynamics (CFD) methods. First, experiments are realized on the original Diesel engine mounted on a test bench, collecting main performance indicators and emissions. A complete 1D engine model (GT-Power™) is developed and validated against measurements. Then, a 3D model of the cylinder (STAR-CD) is set-up and the related combustion outcomes are compared both with 1D and experimental results, showing an overall good agreement. In the second stage, the Diesel unit is converted into a port-injected hydrogen SI engine; the 3D model is re-arranged and utilized to reproduce pre-mixed hydrogen combustions under ultra-lean air/fuel (A/F) mixtures. Also, the 1D model is partly modified and coupled to an advanced combustion sub-model integrated with fast tabulated chemical kinetics to predict the knock. In particular, 1D combustion evolution is calibrated against the results of 3D CFD hydrogen combustion simulation. Finally, the calibrated 1D model is applied to investigate the advantages of ultra-lean hydrogen combustion in terms of efficiency, NO, and unburned H2 formation at medium/high loads.

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Feng, Li Yan, Chun Huan Zhang et Chang Jun Xiong. « Numerical Simulation on the Working Process of a Lean Burn Natural Gas Engine ». Advanced Materials Research 664 (février 2013) : 916–22. http://dx.doi.org/10.4028/www.scientific.net/amr.664.916.

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The working process of a lean burn natural gas spark ignition engine was simulated with a 3-D CFD software package AVL-FIRE. Such simulations were made to analyze and understand the flow field, fuel/air mixture distribution, ignition and flame propagation. The simulations provide basis for the optimization of the combustion system of the engine. Two injection strategies for the pre-chamber enrichment were established and compared. The results indicate that with enrichment injection in the pre-chamber, the fuel/air equivalence ratio is precisely controlled in the range of 1.0 to 1.1, stable ignition in the pre-chamber is ensured, and fast initial flame propagation in main combustion chamber is realized.

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