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1
Johnson, A. B. "The aerodynamic effects of nozzle guide vane shock wave and wake on a transonic turbine rotor." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329958.
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2
Plewacki, Nicholas. "Modeling High Temperature Deposition in Gas Turbines." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587714424017527.
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3
Templalexis, I. K. "Gas turbine performance with distorted inlet flow." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427101.
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4
Batt, J. J. M. "Three-dimensional unsteady gas turbine flow measurement." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:3302ca8f-0618-4440-9e23-3bf99bc3705d.
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The high pressure turbine stage can be considered the most important component for the efficiency and longevity of a modern gas turbine. The flow field within this stage is highly complex and is both unsteady and three-dimensional. Understanding this flow field is essential if improvements are to be made to future engine designs. Increasingly designers are placing more emphasis on the use of Computational Fluid Dynamics (CFD) rather than experimental results. CFD methods can be more flexible and cost effective. However before these predictions can be used they must be validated against experimental data at engine conditions. The hostile environment and complexity of flows within a gas turbine engine mean that collection of experimental data is extremely challenging. This thesis describes the development of an instrumentation technique for unsteady gas turbine flow measurement capable of resolving unsteady three-dimensional flow. The technique is based on an aerodynamic probe constructed with miniature semiconductor pressure transducers manufactured by Kulite Semiconductor Inc. Measurements recorded using this instrumentation technique from the Oxford Rotor experiment are presented to illustrate its use, and these in turn are compared with a CFD prediction of the rotor flow-field. This work was funded by the Engineering and Physical Sciences Research Council and Kulite Semiconductor Inc. The Oxford Rotor project is jointly funded by the Engineering and Physical Sciences Research Council (EPSRC), and Rolls-Royce Plc.
5
Palafox, Pepe. "Gas turbine tip leakage flow and heat transfer." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427699.
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6
Stitzel, Sarah M. "Flow Field Computations of Combustor-Turbine Interactions in a Gas Turbine Engine." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/30992.
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The current demands for higher performance in gas turbine engines can be reached by raising combustion temperatures to increase thermal efficiency. Hot combustion temperatures create a harsh environment which leads to the consideration of the durability of the combustor and turbine sections. Improvements in durability can be achieved through understanding the interactions between the combustor and turbine. The flow field at a combustor exit shows non-uniformities in pressure, temperature, and velocity in the pitch and radial directions. This inlet profile to the turbine can have a considerable effect on the development of the secondary flows through the vane passage.
This thesis presents a computational study of the flow field generated in a non-reacting gas turbine combustor and how that flow field convects through the downstream stator vane. Specifically, the effect that the combustor flow field had on the secondary flow pattern in the turbine was studied. Data from a modern gas turbine engine manufacturer was used to design a realistic, low speed, large scale combustor test section. This thesis presents the results of computational simulations done in parallel with experimental simulations of the combustor flow field.
In comparisons of computational predictions with experimental data, reasonable agreement of the mean flow and general trends were found for the case without dilution jets. The computational predictions of the combustor flow with dilution jets indicated that the turbulence models under-predicted jet mixing. The combustor exit profiles showed non-uniformities both radially and circumferentially, which were strongly dependent on dilution and cooling slot injection. The development of the secondary flow field in the turbine was highly dependent on the incoming total pressure profile. For a case with a uniform inlet pressure in the near-wall region no leading edge vortex was formed. The endwall heat transfer was found to also depend strongly on the secondary flow field, and therefore on the incoming pressure profile from the combustor.<br>Master of Science
7
Hollis, David. "Particle image velocimetry in gas turbine combustor flow fields." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/7640.
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Current and future legislation demands ever decreasing levels of pollution from gas turbine engines, and with combustor performance playing a critical role in resultant emissions, a need exists to develop a greater appreciation of the fundamental causes of unsteadiness. Particle Image Velocimetry (PIV) provides a platform to enable such investigations. This thesis presents the development of PIV measurement methodologies for highly turbulent flows. An appraisal of these techniques applied to gas turbine combustors is then given, finally allowing a description of the increased understanding of the underlying fluid dynamic processes within combustors to be provided. Through the development of best practice optimisation procedures and correction techniques for the effects of sub-grid filtering, high quality PN data has been obtained. Time average statistical data at high spatial resolution has been collected and presented for generic and actual combustor geometry providing detailed validation of the turbulence correction methods developed, validation data for computational studies, and increased understanding of flow mechanisms. These data include information not previously available such as turbulent length scales. Methodologies developed for the analysis of instantaneous PIV data have also allowed the identification of transient flow structures not seen previously because they are invisible in the time average. Application of a new `PDF conditioning' technique has aided the explanation of calculated correlation functions: for example, bimodal primary zone recirculation behaviour and jet misalignments were explained using these techniques. Decomposition of the velocity fields has also identified structures present such as jet shear layer vortices, and through-port swirling motion. All of these phenomena are potentially degrading to combustor performance and may result in flame instability, incomplete combustion, increased noise and increased emissions.
8
Alhajeri, Hamad. "Heat removal in axial flow high pressure gas turbine." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/11465.
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The demand for high power in aircraft gas turbine engines as well as
industrial gas turbine prime mover promotes increasing the turbine entry
temperature, the mass flow rate and the overall pressure ratio. High
turbine entry temperature is however the most convenient way to increase
the thrust without requiring a large change in the engine size.
This research is focused on improving the internal cooling of high pressure
turbine blade by investigating a range of solutions that can contribute to
the more effective removal of heat when compared with existing
configuration. The role played by the shape of the internal blade passages
is investigated with numerical methods. In addition, the application of mist
air as a means of enhanced heat removal is studied.
The research covers three main area of investigation. The first one is
concerned with the supply of mist on to the coolant flow as a mean to
enhancing heat transfer. The second area of investigation is the
manipulation of the secondary flow through cross-section variation as a
means to augment heat transfer. Lastly a combination of a number of
geometrical features in the passage is investigated.
A promising technique to significantly improve heat transfer is to inject
liquid droplets into the coolant flow. The droplets which will evaporate after
travelling a certain distance, act as a cooling sink which consequently
promote added heat removal. Due to the promising results of mist cooling
in the literature, this research investigated its effect on a roughened
cooling passage with five levels of mist mass percentages.
In order to validate the numerical model, two stages were carried out.
First, one single-phase flow case was validated against experimental
results available in the open literature. Analysing the effect of the rotational
force, on both flow physics and heat transfer, on the ribbed channel was
the main concern of this investigation. Furthermore, the computational results using mist injection were also validated against the experimental
results available in the literature.
Injection of mist in the coolant flow helped achieve up to a 300% increase
in the average flow temperature of the stream, therefore in extracting
significantly more heat from the wall. The Nusselt number increased by
97% for the rotating leading edge at 5% mist injection.
In the case of air only, the heat transfers decrease in the second passage,
while in the mist case, the heat transfer tends to increase in the second
passage. Heat transfer increases quasi linearly with the increase of the
mist percentage when there is no rotation. However, in the presence of
rotation, the heat transfers increase with an increase in mist content up to
4%, thereafter the heat transfer whilst still rising does so more gradually.
The second part of this research studies the effect of non-uniform cross-
section on the secondary flow and heat transfer in order to identify a
preferential design for the blade cooling internal passage. Four different
cross-sections were investigated. All cases start with square cross-section
which then change all the way until it reaches the 180 degree turn before it
changes back to square cross-section at the outlet. All cases were
simulated at four different speeds. At low speeds the rectangle and
trapezoidal cross-section achieved high heat transfer. At high speed the
pentagonal and rectangular cross-sections achieved high heat transfer.
Pressure loss is accounted for while making use of the thermal
performance factor parameter which accounts for both heat transfer and
pressure loss. The pentagonal cross-section showed high potential in
terms of the thermal performance factor with a value over 0.8 and higher
by 33% when compared to the rectangular case.
In the final section multiple enhancement techniques are combined in the
sudden expansion case, such as, ribs, slots and ribbed slot. The maximum
heat enhancement is achieved once all previous techniques are used
together. Under these circumstances the Nusselt number increased by
60% in the proposed new design.
9
Janakiraman, S. V. "Fluid flow and heat transfer in transonic turbine cascades." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06112009-063614/.
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10
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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11
Blackburn, Robert John. "Maximising the thermal efficiency of a pressure gain combustion gas turbine." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709490.
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12
Vidlák, David. "Využití absorpčních systémů v teplárenství." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378742.
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Main goal of this work is familiarization with basic features of absorption heat pumps and it’s growing importance on the market. In the first part of the work there is a research for clarifying facts associated with such pumps. In the introduction there are descriptions of basic information from the field of heating industry and its connections to our systems. Next there is a brief analysis of price changes in electricity and heat in the last five years. Main part of the analytical section is a description of the used absorption system. Second part of the work is focused on the calculation of the absorption system itself. First there is calculated internal and external part of the device according to the parameters from GE Power s.r.o. After this step there are parametric studies based on changes of key parameters of the default device for a demonstration of the behavior of a heating pump. In the end of the work there is a integration of the unit into the heating cycle for variations including flue gas condenser and using a cooling water from the turbine condenser.
13
Storer, John Andrew. "Tip clearance flow in axial compressors." Thesis, University of Cambridge, 1991. https://www.repository.cam.ac.uk/handle/1810/251503.
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14
Forsyth, Peter. "High temperature particle deposition with gas turbine applications." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:61556237-feed-43cb-9f4a-d0aed00ca3f8.
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This thesis describes validated improvements in the modelling of micron-sized particle deposition within gas turbine engine secondary air systems. The initial aim of the research was to employ appropriate models of instantaneous turbulent flow behaviour to RANS CFD simulations, allowing the trajectory of solid particulates in the flow to be accurately predicted. Following critical assessment of turbophoretic models, the continuous random walk (CRW) model was chosen to predict instantaneous fluid fluctuating velocities. Particle flow, characterised by non-dimensional deposition velocity and particle relaxation time, was observed to match published experimental vertical pipe flow data. This was possible due to redefining the integration time step in terms of Kolmagorov and Lagrangian time scales, reducing the disparity between simulations and experimental data by an order of magnitude. As no high temperature validation data for the CRW model were available, an experimental rig was developed to conduct horizontal pipe flow experiments under engine realistic conditions. Both the experimental rig, and a new particulate concentration measurement technique, based on post test aqueous solution electrical conductivity, were qualified at ambient conditions. These new experimental data compare well to published data at non-dimensional particle relaxation times below 7. Above, a tail off in the deposition rate is observed, potentially caused by a bounce or shear removal mechanism at higher particle kinetic energy. At elevated temperatures and isothermal conditions, similar behaviour is observed to the ambient data. Under engine representative thermophoretic conditions, a negative gas to wall temperature gradient is seen to increase deposition by up to 4.8 times, the reverse decreasing deposition by a factor of up to 560 relative to the isothermal data. Numerical simulations using the CRW model under-predict isothermal deposition, though capturing relative thermophoretic effects well. By applying an anisotropic Lagrangian time scale, and cross trajectory effects of the external gravitational force, good agreement was observed, the first inclusion of the effect within the CRW model. A dynamic mesh morphing method was then developed, enabling the effect of large scale particle deposition to be included in simulations, without continual remeshing of the fluid domain. Simulation of an impingement jet array showed deposition of characteristic mounds up to 30% of the hole diameter in height. Simulation of a passage with film-cooling hole off-takes generated hole blockage of up to 40%. These cases confirmed that the use of the CRW generated deposition locations in line with scant available experimental data, but widespread airline fleet experience. Changing rates of deposition were observed with the evolution of the deposits in both cases, highlighting the importance of capturing changing passage geometry through dynamic mesh morphing. The level of deposition observed, was however, greater than expected in a real engine environment and identifies a need to further refine bounce-stick and erosion modelling to complement the improved prediction of impact location identified in this thesis.
15
Tzannatos, E. "Stability of split flow fans." Thesis, Cranfield University, 1986. http://dspace.lib.cranfield.ac.uk/handle/1826/10520.
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The
performance requirements of turbofan engines demands a
stability and transient capability beyond that associated with
the
past generations of gas turbine engines. The axial flow fan
unit is most vulnerable to
loading limitations due to the
primary problems associated with the compression process, its
sensitivity to inlet distortion and the
difficulty to design
for an overall
optimum blade duty in a machine of wide
radial
blade
loading distribution. The development of mathematical
models with some
capability of predicting the stable operating
range of an axial flow fan has to overcome the
difficulties
associated with the
modelling of the radially distinct
flow
regions and their dynamic interaction. '
The current
investigation combined the available knowledge of
one-dimensional models (based on the
principles of conservation
of mass, linear momentum and
energy) with the assumptions of the
parallel compressor theory, in order to develop a linearized
system of equations for stability analysis (surge prediction).
The
stability conditions which emerged from this approach were
applied on the experimentally derived characteristics of a low
hub to
tip ratio split flow fan in a manner which involved the
modelling of the dynamic interaction of the inner and outer flow
region of the fan.
The
development of the governing equations was achieved by
applying one-dimensional flow analysis to the inner and outer
section of the fan. Their interaction was modelled on the
experimentally obtained radial movement of the splitter
streamline and the
discharge ,static pressure 'radial
distribution. The inner and outer region were treated as a
lumped volume element search operating on a local masflow
averaged total pressure rise characteristic and alternatively
acting in conjunction with a common nozzle and separate nozzles.
The experimental investigation was carried out on a low hub
totipratio two-stage split flow fan(with the facility of
independent bypass and core throttles)in order to examine the
localised and overall performance of such a fan(and the
staling processes involved)and to enable the application of
the stability analysis. The influence of reducing the distance
between the fan flow spliter and the last bladerowasal so
investigated,
«The mathematical mode1s predicted the point of dynamic
instability within 4.52 of the experimental observed mas flow
rate and pressure is value.
16
Biesinger, Thomas Ernst. "Secondary flow reduction techniques in linear turbine cascades." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5626/.
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This thesis investigates a novel secondary flow reduction method. The inlet boundary layer to a linear turbine cascade is skewed by injection of air through an upstream slot to oppose regular generated negative stream wise vorticity. Other methods from the pertinent literature are reviewed on a broad basis. Detailed measurements of the flowfield in the Durham Linear Cascade facility have shown that substantial reductions in secondary flows and losses are possible. If the kinetic energy required for the blowing is taken into account by means of an availability analysis, no net gain in loss is achieved. Tests are performed at two different angles, of which the higher is typical for film cooling applications, and at a wide range of injection ratios. Calculation of the mixed-out losses show the tangential rather than spanwise momentum of the injected air is more effective in countering the generation of secondary flows. Computations using a state-of-the-art Navier-Stokes solver indicated shortcomings in modelling a flow governed by complex vortex dynamics. Improvements in the turbulence model and injection geometry could remedy this. The evaluation of turbulent and laminar production rates obtained without injection helps to explain total pressure loss generation mechanisms. The comparison of calculated and experimental eddy viscosities reveals the inadequacy of the Boussinesq assumption for high turning flows. The results obtained in this work are relevant to endwall film cooling applications. The tangential injection of air in front of the leading edge provides coolant in an optimum manner whilst possibly reducing secondary losses to a large extent. Disc cooling air, present in a real engine to prevent the ingestion of hot air from the mainstream, could be used to supply the injection.
17
Wilson, Alexander George. "Stall and surge in axial flow compressors." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/10432.
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The objective of the work described in this thesis is twofold; to elucidate the nature of
stall and
surge in an axial flow aeroengine compressor, and to improve on current
computational stall modelling techniques. Particular attention is paid to
the initial stages of the stall/surge transient, and to the possibility of using active control
techniques to prevent or delay the onset of stall/surge.
A detailed
analysis is presented of measurements of the stalling behaviour of a Rolls-
Royce VIPER jet engine, showing a wide variety of stall inception and post-stall
behaviour. Stall transients are traced from disturbances through to stable
rotating stall or axisymmetic surge. The stall inception pattern at nearly all speeds is
shown to conform to the short circumferential length scale pattern described by Day
[1993a].
A multiple compressors in parallel stall model is developed using conventional stall
modelling techniques, but extended to include the
effects of the jet engine environment
The model is shown to
give a good representation of the overall stalling behaviour of
the
engine, although the details of the stall inception period are not accurately
predicted. A system identification technique is applied to the results of the model in
order to
develop a method of active control of stall/surge.
A new stall model is introduced and
developed, based on a time-accurate three
dimensional (but pitchwise averaged) solution of the viscous flow equations, with
bladerow performance represented by body forces. The flow in the annulus boundary
layers is calculated directly, and hence this new method is sufficiently complex to
model the initial localised disturbances that lead to
stall/surge. At the same time the
computational power required is compatible with application to long multistage
compressors.
18
Wang, Liang. "Experimental and Computational Investigation of Thermal-Flow Characteristics of Gas Turbine Reverse-Flow Combustor." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1212.
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Reverse-flow combustors have been used in heavy land-based gas turbines for many decades. A sheath is typically installed to provide cooling at an expense of large pressure losses, through small jet impingement cooling and strong forced convention channel flow. With the modern advancement in metallurgy and thermal-barrier coating technologies, it may become possible to remove this sheath to recover the pressure losses without melting the combustor chamber. However, without the sheath, the flow inside the dump diffuser may exert nonuniform cooling on the combustion chamber. Therefore, the objective of this project is to investigate the flow pattern, pressure drop, and heat transfer in the dump-diffuser reverse-flow combustor with and without sheath to determine if the sheath could be removed. The investigation was conducted through both experimental and computational simulation. The results show that 3.3% pressure losses could be recovered and the highest wall temperature will increase 18% without the sheath.
19
Dale, Adrian Peter. "Radial, vaneless, turbocharger turbine performance." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/11363.
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20
Schulte, Volker Benno. "Unsteady separated boundary layers in axial-flow turbomachinery." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/252035.
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21
Griffiths, Julian P. "Measurements of the flow field in a modern gas turbine combustor." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/12714.
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A detailed investigation into the aerodynamics of a modern gas turbine combustor is reported in this thesis. The main objectives of this work were to examine the interactions between the various features of the internal flow field, and between the external and internal aerodynamics, and to obtain sufficient flow field data for validation of CFD codes. A new experimental facility was developed to allow optical access for high quality internal and external measurements of the isothermal flow field in a three sector segment of an annular gas turbine combustor whose geometry is typical of the combustors in use in current turbofan engines. A specialised traverse system was designed to enable measurements of the flow field by a three component Laser Doppler Anemometry (LDA) system, and a considerable effort was made to maximise the accuracy of the LDA system. Measurements of three orthogonal mean velocity components and all six Reynolds stresses were obtained throughout a burner sector of the combustor. A set of data has been obtained that is sufficiently extensive for use as a benchmark data set for CFD validation. Measurements in the feed annuli showed that the behaviour of the flow was as expected. Internal measurements revealed a strong coupling between the flow in the feed annuli and the flow entering the flame tube through primary and secondary ports. Differences in the geometries and flow splits in the inner and outer annuli caused significant differences between the opposed jets inside the flame tube. The initial pitch angle and axial and radial momentum components of the jets were found to be strongly dependent on the ports' feed conditions. Differences between the opposed jets, due to differences in their feed conditions, affected the location of their impingement and the trajectory of the jet fluid after impingement. The impingement process was also found to be unstable. The centre primary jets, which are downstream of the fuel injector, displayed a dramatically increased sensitivity to their feed conditions, caused by the low pressure in the recirculation induced by the swirler. This caused the jets to be deflected in opposite directions, with no impingement. The flow field in the primary zone was thus substantially altered, with serious implications for the performance of the combustor. These results also demonstrate the importance of coupling the internal and external flows in all experimental and computational models.
22
Daud, Harbi Ahmed. "Numerical and experimental study of flow in a gas turbine chamber." Thesis, Sheffield Hallam University, 2012. http://shura.shu.ac.uk/19535/.
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This thesis examines the cooling performance and the flow on a gas turbine blade. Numerical and experimental methods are described and implemented to assess the influence of film cooling effectiveness. A modem gas turbine blade geometry has been used. The blade is considered as a solid body with the blade cross section from hub to shroud varying with a degree of skewness. Computational Fluid Dynamics (CFD) is employed to assess blade film cooling effectiveness via simulation of the effect of varying blowing ratios (BR=1, 1.5 and 2), varying coolant fluid temperature (Tc=153 K and Tc=287.5 K), various angles of injection (35°,45° and 60°), increasing the number of cooling holes (32 and 42) and increasing the cooling holes diameter (D= 0.5 mm and 1mm). A full three-dimensional finite-volume method has been utilized in this study via the FLUENT 6.3 code with a k-epsilon (RNG) turbulence model. Results of the CFD models were carefully validated by studying aerodynamic flow and heat transfer in turbine blade film cooling performance. A two-dimensional channel and NACA 0012 airfoil were selected to investigate turbulence effects. The solution accuracy is assessed by carrying out a sensitivity analysis of mesh type and quality effects with enhancement wall treatment and standard wall function effects also addressed for turbulent boundary layers. In this study, four different turbulence models were utilized (S-A, mu-epsilon, (RNG), and (SST) mu-o). The computations were compared with available Direct Numerical Simulation (DNS) and experimental data. Good correlation was observed when using the RNG turbulence model in comparison with other turbulence models. Film cooling effectiveness and heat transfer along a flat plate has been analyzed for four different plate materials, namely steel, carbon steel, copper and aluminum, with 30° angle of injection. The cooling holes arrangement was simulated for a hole diameter of D=1 mm and different sections of the blade showing cooling effectiveness and heat transfer characteristic variation with increasing (BR = 0.5, 1). Furthermore a symmetrical single hole at 35° angle of injection was studied both the solid and shell plate cases. Cooling effectiveness numerical results were compared with available experimental data and the effect of material thermal properties for the solid plate on cooling performance evaluated. Numerical modeling has clearly identified that there is no benefit in reducing the number of holes as this decreases film cooling effectiveness. The experimental investigation showed the effect of increasing volumetric flow rate V°=1000, 800 and 600 cm3/min, as a term of the blowing ratio (BR) and angle of injection (35°,45° and 60°) for a modem gas turbine blade specimen using Thermal Paint Technology (TPT) and a Thermal Wind Tunnel (TWT). Both methods confirmed that the blade specimen with angle of injection of 45°, blowing ratio of BR=2 (which corresponds to 1000cm[3]/min), cooling holes diameter D=lmm and 42 holes developed a better film cooling effectiveness compared with the 35° and 60° cases. In addition TPT is a sufficient and relatively easy method for evaluating temperature distributions in experimental studies.
23
Rice, Matthew Jason. "Simulation of Isothermal Combustion in Gas Turbines." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9723.
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Current improvements in gas turbine engine performance have arisen primarily due to increases in turbine inlet temperature and compressor pressure ratios. However, a maximum possible turbine inlet temperature exits in the form of the adiabatic combustion temperature of the fuel. In addition, thermal limits of turbine blade materials also places an upper bound on turbine inlet temperatures. Thus, the current strategy for improving gas turbine efficiency is inherently limited. Introduction of a new gas turbine, based on an alternative work cycle utilizing isothermal combustion (i.e. combustion within the turbine) affords significant opportunities for improving engine output and/or efficiency. However, implementation of such a scheme presents a number of technological challenges such as holding a flame in high-speed flow. The current research is aimed at determining whether such a combustion scheme is feasible using computational methods. The geometry, a simple 2-D cascade utilizes surface injection within the stator or rotor boundary layers (including the rotor pressure side recirculation zone (a natural flame holder).
Computational methods utilized both steady and time accurate calculations with transitional flow as well as laminar and turbulent combustion and species transport. It has been determined that burning within a turbine is possible given a variety of injection schemes using "typical" foil geometries under "typical" operating conditions. Specifically, results indicate that combustion is self-igniting and, hence, self-sustaining given the high temperatures and pressures within a high pressure turbine passage. Deterioration of aerodynamic performance is not pronounced regardless of injection scheme. However, increased thermal loading in the form of higher adiabatic surface temperatures or heat transfer is significant given the injection and burning of the fuel within the boundary layer. This increase in thermal loading is, however, minimized when injection takes place in or near a recirculation zone. The effect of injection location on pattern factors indicates that suction side injection minimizes temperature variation downstream of the injection surface (for rotor injection only). In addition, the most uniform temperature profile (in the flow direction) is achieved by injection fuel and combustion nearest to the source of work extraction. Namely, injection at the rotor produces the most "isothermal" temperature distribution. Finally, a pseudo direct simulation of an isothermal machine is conducted by combining simulation data and assumed processes. The results indicate that isothermal combustion results in an increase in turbine specific work and efficiency over the equivalent Brayton cycle.<br>Master of Science
24
Abou-Haidar, Nabil Ibrahim. "Compressible flow pressure losses in branched ducts." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330238.
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25
Jayasinghe, Prabodha. "Development of a tool for simulating performance of sub systems of a combined cycle power plant." Thesis, KTH, Energiteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99164.
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Abstract In Sri Lanka, around 50% of the electrical energy generation is done using thermal energy, and hence maintaining generation efficiencies of thermal power plants at an acceptable level is very important from a socio-economic perspective for the economic development of the country. Efficiency monitoring also plays a vital role as it lays the foundation for maintaining and improving of generation efficiency. Heat rate, which is the reciprocal of the efficiency, is used to measure the performance of thermal power plants. In combined cycle power plants, heat rate depends on ambient conditions and efficiencies of subsystems such as the gas turbine, Heat Recovery Steam Generator (HRSG), steam turbine, condenser, cooling tower etc. The heat rate provides only a macroscopic picture of the power plant, and hence it is required to analyse the efficiency of each subsystem in order to get a microscopic picture. Computer modelling is an efficient method which can be used to analyse the each subsystem of a combined cycle power plant. Objective of this research is to develop a computer based tool which simulates the performance of subsystems of a combined cycle power plant in Sri Lanka. At the inception of the research, only heat rate was measured, and performances of subsystem were unknown. During the analysis, plant is divided into main systems, in order to study them macroscopically. Then, these main systems are divided into subsystems in order to have a microscopic view. Engineering equation solver (EES) was used to develop the tool, and the final computer model was linked with Microsoft excel package for data handling. Final computer model is executed using both present and past operating data in order to compare present and past performance of the power plant. In combined cycle power plants steam is injected into the gas turbine to reduce the NOx generation and this steam flow is known as NOx flow. According to the result it was evident that turbine efficiency drops by 0.1% and power output increase by 1MW when NOx flow increases from 4.8 to 6.2kg/s. Further it was possible to conclude that gas turbine efficiency drop by 0.1% when ambient temperature increased by 3 C; and gas turbine power output decrease by 2MW when ambient temperature increases from 27 to 31 degrees. Regarding the steam cycle efficiency it was found that steam turbine power output drops by 0.5MW when ambient temperature increases from 27 to 31 degrees; and steam cycle efficiency increases by 1% when NOx flow increases from 4.8 to 6.2kg/s. Further, steam turbine power output decreases by 0.25MW When NOx flow increases from 4.8 to 6.2kg/s Heat rate, which is the most important performance index of the power plant, increases by 10units (kJ/kWh) when ambient temperature increases by 3 C. Heat rate also increases with raising NOx flow which was 6.2kg/s in 2007 and 4.2kg/s in 2011. Hence, heat rate of the power plant has improved (decreased) by 10units (kJ/kWh) from 2007 to 2011. Other than above, following conclusions were also revealed during the study. 1) HRSG efficiency has not change during past 4 years 2) Significant waste heat recovery potential exists in the gas turbine ventilation system in the form of thermal energy
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Farrall, Mark. "Numerical modelling of two-phase flow in a simplified bearing chamber." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367991.
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Vick, Michael J. "High efficiency recuperated ceramic gas turbine engines for small unmanned air vehicle propulsion." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/10970.
Full textAbstract:
To perform long missions, small unmanned air vehicles (UAVs) need efficient, lightweight propulsion systems that can operate on energy dense fuels. Gas turbines offer better reliability, life, fuel flexibility, noise, and vibration than internal combustion (IC) engines, but they are uncompetitive due to fuel efficiencies around 6%. At this scale, conventional efficiency improvement approaches such as high pressure ratios and cooled metal turbines are impractical. Ceramic turbines could withstand high temperatures without cooling, but their life and reliability have been inadequate. This work explores the hypothesis that a low pressure ratio, highly recuperated ceramic engine design could overcome these problems. First, an accepted water vapor erosion model is extended to correctly account for the effects of recuperation, fuel type, and atmospheric humidity on the burned gas water vapor content. The results show that ceramic turbines without environmental barrier coatings can last 10,000 hours or more in highly recuperated engines, even at temperatures exceeding 1200[degrees]C. Next, a new design for a small recuperated ceramic engine is developed and analyzed, in which blade speeds are limited to 270 m/s – about half the typical value. A CARES slow crack growth analysis indicates this will lead to vastly improved life and reliability. The literature on foreign object damage and production costs suggests likely improvements in those areas, as well. Finally, an original ceramic recuperator is developed to fit the proposed engine design. Tradeoffs between fabrication constraints, weight, volume, effectiveness, pressure losses, and other considerations are explored through analysis, simulations, and experiments. For one design, these predict a thermal effectiveness in the 84-87% range at a specific weight of 44 grams per gram/second of airflow, surpassing the current state of the art by a factor of 1.25-1.5. A prototype designed for 1100[degrees]C operation was tested at 675[degrees]C exhaust inlet temperature. It did not crack or leak, and the performance roughly matched analytical predictions. With a heat exchanger of this type, a small, low pressure ratio turboshaft engine could achieve an efficiency of 23%, making it highly competitive with other state of the art propulsion systems by almost all performance metrics. In sum, this work contributes a novel ceramic recuperator that can enable low pressure ratio gas turbines to achieve high fuel efficiencies, and provides a significant extension of ceramic turbine life and reliability theory that shows such engines could achieve long service lives.
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Alexiou, A. "Flow and heat transfer in gas turbine H.P. compressor internal air systems." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402026.
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Ieronymidis, Ioannis. "Flow and heat transfer measurements in a gas turbine wall cooling passage." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670199.
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Mehdi, Ahad. "Effect of swirl distortion on gas turbine operability." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/12129.
Full textAbstract:
The aerodynamic integration of an aero-engine intake system with the airframe
can pose some notable challenges. This is particularly so for many military air-
craft and is likely to become a more pressing issue for both new military systems
with highly embedded engines as well as for novel civil aircraft configurations.
During the late 1960s with the advent of turbo-fan engines, industry became in-
creasingly aware of issues which arise due to inlet total pressure distortion. Since
then, inlet-engine compatibility assessments have become a key aspect of any new
development. In addition to total temperature and total pressure distortions, flow
angularity and the associated swirl distortion are also known to be of notable con-
cern. The importance of developing a rigorous methodology to understand the
effects of swirl distortion on turbo-machinery has also become one of the major
concerns of current design programmes.
The goal of this doctoral research was to further the current knowledge on
swirl distortion, and its adverse effects on engine performance, focusing on the
turbo-machinery components (i.e. fans or compressors). This was achieved by
looking into appropriate swirl flow descriptors and by correlating them against the
compressor performance parameters (e.g loss in stability pressure ratios). To that
end, a number of high-fidelity three-dimensional Computational Fluid Dynamics
(CFD) models have been developed using two sets of transonic rotors (i.e. NASA
Rotor 67 and 37), and a stator (NASA Stator 67B). For the numerical purpose,
a boundary condition methodology for the definition of swirl distortion patterns
at the inlet has been developed. Various swirl distortion numerical parametric
studies have been performed using the modelled rotor configurations. Two types of swirl distortion pattern were investigated in the research, i.e. the pure bulk
swirl and the tightly-wound vortex.
Numerical simulations suggested that the vortex core location, polarity, size
and strength greatly affect the compressor performance. The bulk swirl simula-
tions also showed the dependency on swirl strength and polarity. This empha-
sized the importance of quantifying these swirl components in the flow distortion
descriptors. For this, a methodology have been developed for the inlet-engine
compatibility assessment using different types of flow descriptors. A number of
correlations have been proposed for the two types of swirl distortion investigated
in the study.
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Hilditch, Mary Anne. "Unsteady heat transfer measurements in a rotating gas turbine stage." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:2d3e6d7a-1f55-4536-b863-e9ccc9a281eb.
Full textAbstract:
As the performance required of high pressure turbines continues to increase, there is a need to investigate many details of the flow which occur in a gas turbine stage that were previously overlooked. These include the effects of rotation and three-dimensional flow as well as unsteady effects due to the relative motion of the blade rows. In order to obtain a better understanding of the turbine flowfield a new transient facility has been commissioned in which aerodynamic and heat transfer measurements can be undertaken in a full stage turbine at engine representative conditions. The previously used technique of measuring the heat transfer rate by mounting thin film gauges on models manufactured from machineable glass ceramic was not suitable for use on the rotor blade because of the high stress levels involved. An alternative technique has been developed in which a metal turbine blade is coated with an insulating layer of enamel and thin film gauges painted on top. The developments in signal processing and calibrations which were necessary for the use of this type of thin film gauge are discussed in detail. Signal conditioning electronics have been developed which permit amplification of the thin film gauge output to a higher level within the rotating frame before transmission through a slipring. Extensive tests have been undertaken, in a purpose built spinning rig, to establish the effects of rotation on the performance and mechanical integrity of the instrumentation and associated electronics. The heat transfer measurements recorded in the rotor facility to date are presented and compared with data from a previous two-dimensional simulation of wake passing flow on the mid-height section of the same blade.
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Pretorius, Johannes Jacobus. "A network approach for the prediction of flow and flow splits within a gas turbine combustor." Diss., University of Pretoria, 2005. http://hdl.handle.net/2263/26712.
Full textAbstract:
The modern gas turbine engine industry needs a simpler and faster method to facilitate the design of gas turbine combustors due to the enormous costs of experimental test rigging and detailed computational fluid dynamics (CFD) simulations. Therefore, in the initial design phase, a couple of preliminary designs are conducted to establish initial values for combustor performance and geometric characteristics. In these preliminary designs, various one-dimensional models using analytical and empirical formulations may be used. One of the disadvantages of existing models is that they are typically geometric dependant, i.e. they apply only to the geometry they are derived for. Therefore the need for a more versatile design tool exists. In this work, which constitutes the first step in the development of such a versatile design tool, a single equation-set network simulation model to describe both steady state compressible and incompressible isothermal flow is developed. The continuity and momentum equations are solved through a hybrid type network model analogy which makes use of the SIMPLE pressure correction methodology. The code has the capability to efficiently compute flow through elements where the loss factor K is highly flow dependant and accurately describes variable area duct flow in the case of incompressible flow. The latter includes ducts with discontinuously varying flow sectional areas. Proper treatment of flow related non-linearities, such as flow friction, is facilitated in a natural manner in the proposed methodology. The proposed network method is implemented into a Windows based simulation package with a user interface. The ability of the proposed method to accurately model both compressible and incompressible flow is demonstrated through the analyses of a number of benchmark problems. It will be shown that the proposed methodology yields similar or improved results as compared to other’s work. The proposed method is applied to a research combustor to solve for isothermal flows and flow splits. The predicted flows were in relatively close agreement with measured data as well as detailed CFD analysis.<br>Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2005.<br>Mechanical and Aeronautical Engineering<br>unrestricted
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Slater, J. T. D. "Three-dimensional aerodynamic studies of a turbine stage in a transient flow facility." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358729.
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Cleak, James Gilbert Edwin. "Validation of viscous, three-dimensional flow calculations in an axial turbine cascade." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6429/.
Full textAbstract:
This thesis presents a detailed investigation of the capability of a modern three-dimensional Navier-Stokes solver to predict the secondary flows and losses in a linear cascade of high turning turbine rotor blades. Three codes were initially tested, to permit selection of the best of the available numerical solvers for this case. This program was then tested in more detail. Results showed that although very accurate prediction of the effects of inviscid fluid mechanics is now possible, the Reynolds stress modelling can have profound effects upon the quality of the solutions obtained. Solutions using two different calculation meshes, have shown that the results are not significantly grid dependent. The flowfield of the cascade was traversed with hot-wires to obtain measurements of the turbulent Reynolds stresses. A turbulence generating grid was placed upstream of the cascade, to produce a more realistic inlet turbulence intensity. Results showed that regions of high turbulent kinetic energy are associated with regions of high total pressure loss. Calculation of eddy viscosities from the Reynolds stresses showed that downstream of the -cascade the eddy viscosity is fairly isotropic. Evaluation of terms in the kinetic energy equation, also indicated that both the normal and shear Reynolds stresses are important as loss producing mechanisms in the downstream flow. The experimental Reynolds stresses have been compared with those calculated from the eddy viscosity and velocity fields of Navier-Stokes predictions using a mixing length turbulence model, a one equation model, and K - ϵ model. It was found that in the separated, shear flows, agreement was poor, although the K - ϵ model performed best. Further experimental work is suggested to obtain data with which to determine the accuracy of the models within the blade and endwall boundary layers.
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Green, T. "Effect of external flow on the sealing performance of rotor-stator rim seals." Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358187.
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Rahman, Faisal. "Numerical modelling of heat transfer and thermal stresses in gas turbine guide vanes." Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-05302005-103404/.
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Miniscloux, Glenn. "Investigation of a Fluidic Device for Cooling Flow Modulation in Gas Turbine Engines." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505903.
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Luff, John K. "Numerical prediction of flow, thermal and stress fields in gas turbine combustor components." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/15458.
Full textAbstract:
In this work an integrated set of numerical methods is developed for the analysis of gas turbine combustors, which can predict the flow, temperature and stress fields in modern geometrically complex combustor walls. A key problem for accurate flow and temperature field prediction is the wide range of geometric length scales within modern combustor components. These components typically contain multiple small-scale cooling features such as pedestals and effusion cooling holes, which cannot be resolved by a computational mesh without incurring huge penalties in terms of computer processor and memory requirements. In this work a sub-grid-scale model is developed, which accounts for the effects of small-scale features such as pedestals without resolving them in the computational mesh. Validation of this model using experimental results from the literature shows that the pressure drop, turbulence generation and heat transfer effects of pedestal arrays can be successfully modelled using this approach. Another difficulty in the analysis of combustors is coupling the interdependent temperature field predictions in the fluid and solid regions. This has led to a unified approach to conjugate heat transfer prediction being adopted in this work, whereby a structured finite volume solver is used to predict temperature fields throughout fluid and solid domains. A new conjugate heat transfer discretisation scheme is developed, which can cope with the demanding combination of strong temperature gradient discontinuities and highly skewed grids. Several test cases are presented which demonstrate the accuracy of this new scheme, as well as demonstrating the inadequacy of conventional treatment of the diffusive fluxes for the solution of conjugate problems. The assembled numerical methods are used to predict the flow, thermal and stress fields in a geometrically complex combustor heatshield/backplate assembly, typical of that found in modern engines. This calculation shows that a viable route to computational life prediction has been established.
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Carmack, Andrew Cardin. "Heat Transfer and Flow Measurements in Gas Turbine Engine Can and Annular Combustors." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32466.
Full textAbstract:
A comparison study between axial and radial swirler performance in a gas turbine can combustor was conducted by investigating the correlation between combustor flow field geometry and convective heat transfer at cold flow conditions for Reynolds numbers of 50,000 and 80,000. Flow velocities were measured using Particle Image Velocimetry (PIV) along the center axial plane and radial cross sections of the flow. It was observed that both swirlers produced a strong rotating flow with a reverse flow core. The axial swirler induced larger recirculation zones at both the backside wall and the central area as the flow exits the swirler, and created a much more uniform rotational velocity distribution. The radial swirler however, produced greater rotational velocity as well as a thicker and higher velocity reverse flow core. Wall heat transfer and temperature measurements were also taken. Peak heat transfer regions directly correspond to the location of the flow as it exits each swirler and impinges on the combustor liner wall.
Convective heat transfer was also measured along the liner wall of a gas turbine annular combustor fitted with radial swirlers for Reynolds numbers 210000, 420000, and 840000. The impingement location of the flow exiting from the radial swirler resulted in peak heat transfer regions along the concave wall of the annular combustor. The convex side showed peak heat transfer regions above and below the impingement area. This behavior is due to the recirculation zones caused by the interaction between the swirlers inside the annulus.<br>Master of Science
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Lyes, Peter A. "Low speed axial compressor design and evaluation : High speed representation and endwall flow control studies." Thesis, Cranfield University, 1999. http://hdl.handle.net/1826/4251.
Full textAbstract:
This Thesis reports the design, build and test of two sets of blading for the
Cranfield University low speed research compressor. The first of these was a datum low
speed design based on the fourth stage of the DERA high speed research compressor
C 147. The emphasis of this datum design was on the high-to-low speed transformation
process and the evaluation of such a process through comparing detailed flow
measurements from both compressors.
Area traverse measurements in both the stationary and rotating frame of reference
were taken at Cranfield along with overall performance, blade surface static pressure and
flow visualisation measurements. These compare favourably with traverse and
performance measurements taken on C147 before commencement of the PhD work.
They show that despite the compromises made during the transformation process, due to
both geometric and aerodynamic considerations, both the primary and secondary flow
features can be successfully reproduced in the low speed environment.
The aim of the second design was to improve on the performance of the datum
blading through the use of advanced '3D' design concepts such as lean and sweep. The
blading used nominally the same blade sections as the datum, and parametric studies
were conducted into various lean/sweep configurations to try to optimise the blade
performance. The final blade geometry also incorporated leading edge recambering
towards the fixed endwalls of both the rotor and stator. The '3D' blading demonstrated a
1.5% increase in efficiency (over the datum blading) at design flow rising to around 3%
at near stall along with an improvement in stall margin and pressure rise characteristic.
The design work was completed using the TRANSCode flow solver for both the
blade-to-blade solutions (used in the SI-S2 datum design calculation) and the fully 3D
solutions (for the advanced design and post datum design appraisal). The 3D solutions
gave a reasonable representation of the mid-span and main 3D flow features but failed to
model the corner and tip clearance flow accurately. An interesting feature of the low
speed flowfield was the circumferential variation in total pressure observed at exit from
all rotors for both designs. This was not present at high speed and represents one of the
main differences between the high and low speed flow. Unsteady modelling of mid-
height sections from the first stage indicate that part of this variation is due to the
potential interaction of the rotor with the downstream stator while the remainder is due
to the wake structure from the upstream stator convecting through the rotor passage.
Finally, the implications for a high speed design based on the success of the 3D low
speed design are considered.
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Almutlaq, Ahmed N. "Density-based unstructured simulations of gas-turbine combustor flows." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/13892.
Full textAbstract:
The goal of the present work was to identify and implement modifications to a density-based unstructured RANS CFD algorithm, as typically used in turbomachinery flows (represented here via the RoIIs-Royce 'Hydra' code), for application to Iow Mach number gas-turbine combustor flows. The basic algorithm was modified to make it suitable for combustor relevant problems. Fixed velocity and centreline boundary conditions were added using a characteristic based method. Conserved scalar mean and variance transport equations were introduced to predict scalar mixing in reacting flows. Finally, a flarnelet thermochemistry model for turbulent non-premixed combustion with an assumed shape pdf for turbulence-chemistry interaction was incorporated. A method was identified whereby the temperature/ density provided by the combustion model was coupled directly back into the momentum equations rather than from the energy equation. Three different test cases were used to validate the numerical capabilities of the modified code, for isothermal and reacting flows on different grid types. The first case was the jet in confined cross flow associated with combustor liner-dilution jetcore flow interaction. The second was the swirling flow through a multi-stream swirler. These cases represent the main aerodynamic features of combustor primary zones. The third case was a methane-fueled coaxial jet combustor to assess the combustion model implementation. This study revealed that, via appropriate modifications, an unstructured density-based approach can be utilised to simulate combustor flows. It also demonstrated that unstructured meshes employing nonhexahedral elements were inefficient at accurate capture of flow processes in regions combining rapid mixing and strong convection at angles to cell edges. The final version of the algorithm demonstrated that low Mach RANS reacting flow simulations, commonly performed using a pressure-based approach, can successfully be reproduced using a density-based approach.
42
McDougall, Neil Malcolm. "Stall inception in axial compressors." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237803.
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Gullia, Alessandro. "Thrust and Flow Prediction in Gas Turbine Engine Indoor Sea-Level Test Cell Facilities." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/7496.
Full textAbstract:
The principal aim of this research was to provide a detailed understanding of the
performance of gas turbine engines inside indoor sea-level test beds. In particular the
evaluation of both thrust correction factors and the estimation of the mass flow
entering the test cell were at the core of the research.
The project has been fully sponsored by Rolls-Royce pIc. Initially, their principal
objective was to assess the relevance and accuracy of CFD when applied to thrust
measurement inside indoor test beds with an intended outcome of minimising the use
of expensive experimental measurements.
The different system interfaces and accounting systems for in-flight conditions,
available in the open literature have been developed and adapted for indoor
environments. This has led to the definition of three different thrust correction
equations using alternative definitions of thrust correction factor. Aero-dynamic
principles have been applied for the derivation of one-dimensional relationships for
the calculation of each thrust correction factor using generic engine-cell performance
and dimensions.
A one-dimensional analytical model has been developed to represent the enginedetuner
ejector pump. This is able to characterise the engine-cell system performance
and is used as the main tool for providing a matching procedure capable of predicting
the cell entrainment ratio.
By processing experimental data relevant to different engine-cell configurations
through the ejector pump analytical model, a method for achieving the entrainment
ratio control inside the cell has been identified.
The CFD work has been concentrated into three main activities:
• A quantitative extrapolation of the thrust correction factors including, the
pre-entry force, the external and the total bellmouth force, the throat stream
force, the intake momentum drag and the base drag.
• The representation of the engine-detuner ejector performance for a
variety of engine-cell configurations.
• The modelling of the generic test cell components including the inlet
stack, the cascade elbow, the exhaust stack & the blast basket.
The outcomes of this research have been very successful in enhancing the validity of
the thrust correction equations developed .. In particular, the use of a one-dimensional
approach in their estimation has been shown to be fully justified. The work has also
emphasised the value of CFD in supporting the derivation of the matching procedure
for predicting and controlling cell entrainment ratio. Indeed, one of the strongest
outcomes of this work has been the conclusion that both the engine-cell characteristic
lines computed with the one-dimensional model and those computed with CFD for
different cell configurations are almost identical.
In addition, the use of CFD as a tool for the quantitative evaluation of the thrust
correction factors has been established. Finally, the CFD results have facilitated an
enhanced understanding of the complex flow structure inside indoor test cells
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Brouwer, Silke [Verfasser]. "Research on the Accuracy of Flow Simulation in Gas Turbine Exhaust Diffusers / Silke Brouwer." Aachen : Shaker, 2018. http://d-nb.info/1186590777/34.
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Abraham, Santosh. "Heat Transfer and Flow Measurements on a One-Scale Gas Turbine Can Combustor Model." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35177.
Full textAbstract:
Combustion designers have considered back-side impingement cooling as the solution for modern DLE combustors. The idea is to provide more cooling to the deserved local hot spots and reserve unnecessary coolant air from local cold spots. Therefore, if accurate heat load distribution on the liners can be obtained, then an intelligent cooling system can be designed to focus more on the localized hot spots. The goal of this study is to determine the heat transfer and pressure distribution inside a typical can-annular gas turbine combustor. This is one of the first efforts in the public domain to investigate the convective heat load to combustor liner due to swirling flow generated by swirler nozzles. An experimental combustor test model was designed and fitted with a swirler nozzle provided by Solar Turbines Inc. Heat transfer and pressure distribution measurements were carried out along the combustor wall to determine the thermo-fluid dynamic effects inside a combustor. The temperature and heat transfer profile along the length of the combustor liner were determined and a heat transfer peak region was established.
Constant-heat-flux boundary condition was established using two identical surface heaters, and the Infrared Thermal Imaging system was used to capture the real-time steady-state temperature distribution at the combustor liner wall. Analysis on the flow characteristics was also performed to compare the pressure distributions with the heat transfer results. The experiment was conducted at two different Reynolds numbers (Re 50,000 and Re 80,000), to investigate the effect of Reynolds Number on the heat transfer peak locations and pressure distributions. The results reveal that the heat transfer peak regions at both the Reynolds numbers occur at approximately the same location. The results from this study on a broader scale will help in understanding and predicting swirling flow effects on the local convective heat load to the combustor liner, thereby enabling the combustion engineer to design more effective cooling systems to improve combustor durability and performance.<br>Master of Science
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Petrov, Miroslav. "Biomass and Natural Gas Hybrid Combined Cycles." Licentiate thesis, KTH, Energy Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1660.
Full textAbstract:
<p>Biomass is one of the main natural resources in Sweden.Increased utilisation of biomass for energy purposes incombined heat and power (CHP) plants can help the country meetits nuclear phase-out commitment. The present low-CO2 emissioncharacteristics of the Swedish electricity production system(governed by hydropower and nuclear power) can be retained onlyby expansion of biofuels in the CHP sector. Domestic Swedishbiomass resources are vast and renewable, but not infinite.They should be utilised as efficiently as possible in order tomeet the conditions for sustainability in the future.Application of efficient power generation cycles at low cost isessential for meeting this challenge. This applies also tomunicipal solid waste (MSW) incineration with energyextraction, which is to be preferred to landfilling.</p><p>Modern gas turbines and internal combustion engines firedwith natural gas have comparatively low installation costs,good efficiency characteristics and show reliable performancein power applications. Environmental and source-of-supplyfactors place natural gas at a disadvantage as compared tobiofuels. However, from a rational perspective, the use ofnatural gas (being the least polluting fossil fuel) togetherwith biofuels contributes to a diverse and more secure resourcemix. The question then arises if both these fuels can beutilised more efficiently if they are employed at the samelocation, in one combined cycle unit.</p><p>The work presented herein concentrates on the hybriddual-fuel combined cycle concept in cold-condensing and CHPmode, with a biofuel-fired bottoming steam cycle and naturalgas fired topping gas turbine or engine. Higher electricalefficiency attributable to both fuels is sought, while keepingthe impact on environment at a low level and incorporating onlyproven technology with standard components. The study attemptsto perform a generalized and systematic evaluation of thethermodynamic advantages of various hybrid configurations withthe help of computer simulations, comparing the efficiencyresults to clearly defined reference values.</p><p>Results show that the electrical efficiency of hybridconfigurations rises with up to 3-5 %-points in cold-condensingmode (up to 3 %-points in CHP mode), compared to the sum of twosingle-fuel reference units at the relevant scales, dependingon type of arrangement and type of bottoming fuel. Electricalefficiency of utilisation of the bottoming fuel (biomass orMSW) within the overall hybrid configuration can increase withup to 8-10 %-points, if all benefits from the thermalintegration are assigned to the bottoming cycle and effects ofscale on the reference electrical efficiency are accounted for.All fully-fired (windbox) configurations show advantages of upto 4 %-points in total efficiency in CHP mode with districtheating output, when flue gas condensation is applied. Theadvantages of parallel-powered configurations in terms of totalefficiency in CHP mode are only marginal. Emissions offossil-based CO2 can be reduced with 20 to 40 kg CO2/MWhel incold-condensing mode and with 5-8 kg CO2 per MWh total outputin CHP mode at the optimum performance points.</p><p>Keywords: Biomass, Municipal Solid Waste (MSW), Natural Gas,Simulation, Hybrid, Combined Cycle, Gas Turbine, InternalCombustion Engine, Utilization, Electrical Efficiency, TotalEfficiency, CHP.</p>
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Carrotte, Jonathan F. "The mixing characteristics of dilution jets issuing into a confined cross-flow." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/32627.
Full textAbstract:
An experimental investigation has been carried out into the mixing of a row of jets injected into a confined cross-flow. Measurements were made on a fully annular test facility, the geometry of the rig simulating that found in the dilution zone of a gas turbine combustion chamber. A small temperature difference of 44°C between the cross-flow and dilution fluid allowed the mixing characteristics to be assessed, with hot jets being injected into a relatively cold cross-flow at a jet to cross-flow momentum flux ratio of 4.0. The investigation concentrated on differences in the mixing of individual dilution jets, as indicated by the regularity of the temperature patterns around the cross-flow annulus. Despite the uniform conditions approaching the dilution holes there were significant differences in the temperature patterns produced by the dilution jets around the annulus.
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Collin, Félix. "Modeling and numerical simulations of two-phase ignition in gas turbine." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0053.
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Afin de répondre aux nouvelles réglementations environnementales internationales tout en maintenant une forte compétitivité économique, des technologies innovantes de chambres de combustion aéronautiques sont développées. Ces technologies doivent garantir un rallumage rapide en cas d’extinction, qui est un des aspects les plus critiques et complexes de la conception moteur. La maîtrise de cette phase implique une compréhension approfondie des phénomènes physiques mis en jeu. Dans cette thèse la séquence d’allumage diphasique de moteur aéronautique a été étudiée dans son intégralité, du claquage de la bougie à la propagation de la flamme dans le moteur complet. Dans cet objectif, des Simulations aux Grandes Échelles (SGE) utilisant une description détaillée de la phase liquide (formalisme Euler-Lagrange) et du processus de combustion (Chimie Analytiquement Réduite) ont été réalisées. Les résultats ont également permis de développer un modèle simplifié pour la prédiction de carte de probabilité d’allumage, particulièrement utile pour le dimensionnement et la conception des chambres de combustion<br>In order to meet the new international environmental regulations while maintaining a strong economic competitiveness, innovative technologies of aeronautical combustion chambers are developed. These technologies must guarantee fast relight in case of extinction, which is one of the most critical and complex aspects of engine design. Control of this phase involves a thorough understanding of the physical phenomena involved. In this thesis the full two-phase ignition sequence of an aeronautical engine has been studied, from the breakdown of the spark plug to thepropagation of the flame in the complete engine. For this purpose, Large-Eddy Simulations (LES) using a detailed description of the liquid phase (Euler-Lagrange formalism) and of the combustion process (Analytically Reduced Chemistry) were performed. The results also led to the development of a simplified model for the prediction of ignition probability map, which is particularly useful for the design of combustion chambers
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Scrittore, Joseph. "Experimental Study of the Effect of Dilution Jets on Film Cooling Flow in a Gas Turbine Combustor." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28171.
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Cooling combustor chambers for gas turbine engines is challenging because of the complex flow fields inherent to this engine component. This complexity, in part, arises from the interaction of high momentum dilution jets required to mix the fuel with effusion film cooling jets that are intended to cool the combustor walls. The dilution and film cooling flow have different performance criteria, often resulting in conflicting flow mechanisms.
The purpose of this study is to evaluate the influence that the dilution jets have on the film cooling effectiveness and how the flow and thermal patterns in the cooling layer are affected by both the dilution flow and the closely spaced film cooling holes. This study also intends to characterize the development of the flow field created by effusion cooling injection without dilution injection. This work is unique because it allows insight into how the full-coverage discrete film cooling layer is interrupted by high momentum dilution jets and how the surface cooling is affected.
The film cooling flow was disrupted along the combustor walls in the vicinity of the high momentum dilution jets and the surface cooling effectiveness was reduced with increased dilution jet momentum. This was due to the secondary flows that were intensified by the increased jet momentum. High turbulence levels were generated at the dilution jet shear layer resulting in efficient mixing. The film cooling flow field was affected by the freestream turbulence and complex flow fields created by the combined dilution and effusion cooling flows both in the near dilution jet region as well as downstream of the jets. Effusion cooling holes inclined at 20Ë created lower coolant layer turbulence levels and higher surface cooling effectiveness than 30Ë cooling holes. Results showed an insensitivity of the coolant penetration height to the diameter and angle of the cooling hole in the region downstream of the dilution mixing jets.
When high momentum dilution jets were injected into crossflow, a localized region in the flow of high vorticity and high streamwise velocity was created. When film cooling air was injected the inlet flow field and the dilution jet wake were fundamentally changed and the vortex diminished significantly. The temperature field downstream of the dilution jet showed evidence of a hot region which was moderated appreciably by film cooling flow. Differences in the temperature fields were nominal compared to the large mass flow increase of the coolant.
A study of streamwise oriented effusion film cooling flow without dilution injection revealed unique and scaleable velocity profiles created by the closely spaced effusion holes. The effusion cooling considered in these tests resulted in streamwise velocity and turbulence level profiles that scaled well with blowing ratio which is a finding that allows the profile shape and magnitude to be readily determined at these test conditions. Results from a study of compound angle effusion cooling injection showed significant differences between the flow field created with and without crossflow. It was found from the angle of the flow field velocity vectors that the cooling film layer grew nearly linearly in the streamwise direction. The absence of crossflow resulted in higher turbulence levels because there was a larger shear stress due to a larger velocity difference between the coolant and crossflow. The penetration height of the coolant was relatively independent of the film cooling momentum flux ratio for both streamwise oriented and compound angle cooling jets.<br>Ph. D.
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Tse, David Gar Nile. "Flow and combustion characteristics of model annular and can-type combustors." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/8941.
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