Articles de revues : « Combustore »

1

Davidović, Nikola S., Nenad M. Kolarević, Miloš B. Stanković et Marko V. Miloš. « Research of expendable turbojet tubular combustion chamber ». Advances in Mechanical Engineering 14, n^o 5 (mai 2022) : 168781322210959. http://dx.doi.org/10.1177/16878132221095999.

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This paper presents research related to the tubular combustion chamber of an expendable turbojet. Although annular combustors are dominant at present, tubular combustors are still attractive because they are simpler to produce and require lower amounts of air flow for testing. The objective of this research was to assess the combustor’s primary zone configuration, and four configurations were tested to obtain experimental answers for use in future work. The configuration of the combustion chamber is a simple and classic design in line with its expendable purpose. The test methodology was to perform initial testing of the primary and secondary zones under atmospheric conditions using the four configurations, and then to subsequently complete the combustor using the best configuration. The complete combustor was then tested under both atmospheric conditions and working conditions. The results showed that the stability margin was wide enough to cover the combustor’s entire working area. The measured efficiency and pressure drop were in very good agreement with the corresponding designed values. The design and testing methodology proposed here could be used for similar scientific and engineering research applications.

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Hosseini, Seyed, Evan Owens, John Krohn et James Leylek. « Experimental Investigation into the Effects of Thermal Recuperation on the Combustion Characteristics of a Non-Premixed Meso-Scale Vortex Combustor ». Energies 11, n^o 12 (4 décembre 2018) : 3390. http://dx.doi.org/10.3390/en11123390.

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In small-scale combustors, the ratio of area to the combustor volume increases and hence heat loss from the combustor’s wall is significantly enhanced and flame quenching occurs. To solve this problem, non-premixed vortex flow is employed to stabilize flames in a meso-scale combustion chamber to generate small-scale power or thrust for propulsion systems. In this experimental investigation, the effects of thermal recuperation on the characteristics of asymmetric non-premixed vortex combustion are studied. The exhaust gases temperature, emissions and the combustor wall temperature are measured to evaluate thermal and emitter efficiencies. The results illustrate that in both combustors (with/without thermal recuperator), by increasing the combustion air mass flowrate, the wall temperature increases while the wall temperature of combustor with thermal recuperator is higher. The emitter efficiency calculated based on the combustor wall temperature is significantly increased by using thermal recuperator. Thermal efficiency of the combustion system increases up to 10% when thermal recuperator is employed especially in moderate Reynolds numbers (combustion air flow rate is 120 mg/s).

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Wang, T., J. S. Kapat, W. R. Ryan, I. S. Diakunchak et R. L. Bannister. « Effect of Air Extraction for Cooling and/or Gasification on Combustor Flow Uniformity ». Journal of Engineering for Gas Turbines and Power 121, n^o 1 (1 janvier 1999) : 46–54. http://dx.doi.org/10.1115/1.2816311.

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Reducing emissions is an important issue facing gas turbine manufacturers. Almost all of the previous and current research and development for reducing emissions has focused, however, on flow, heat transfer, and combustion behavior in the combustors or on the uniformity of fuel injection without placing strong emphasis on the flow uniformity of fuel injection without placing strong emphasis entering the combustors. In response to the incomplete understanding of the combustor’s inlet air flow field, experiments were conducted in a 48 percent scale, 360 deg model of the diffuser-combustor section of an industrial gas turbine. In addition, the effect of air extraction for cooling or gasification on the flow distributions at the combustors’ inlets was also investigated. The following three different air extraction rates were studied: 0 percent (baseline), 5 percent (airfoil cooling), and 20 percent (for coal gasification). The flow uniformity was investigated for the following two aspects: (a) global uniformity, which compared the mass flow rates of combustors at different locations relative to the extraction port, and (b) local uniformity, which examined the circumferential flow distribution into each combustor. The results indicate that even for the baseline case with no air extraction there was an inherent local flow non uniformity of 10 ∼ 20 percent at the inlet of each combustor due to the complex flow field in the dump diffuser and the blockage effect of the cross-flame tube. More flow was seen in the portion further away from the gas turbine center axis. The effect of 5 percent air extraction was small. Twenty percent air extraction introduced approximately 35 percent global flow asymmetry diametrically across the dump diffuser. The effect of air extraction on the combustor’s local flow uniformity varied with the distances between the extraction port and each individual combustor. Longer top hats were installed with the initial intention of increasing flow mixing prior to entering the combustor. However, the results indicated that longer top hats do not improve the flow uniformity; sometimes, adverse effects can be seen. Although a specific geometry was selected for this study, the results provide sufficient generality to benefit other industrial gas turbines.

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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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Burunsuz, К. S., V. V. Kuklinovsky et S. I. Serbin. « Investigations of the emission characteristics of a gas turbine combustor with water steam injection ». Refrigeration Engineering and Technology 55, n^o 2 (30 avril 2019) : 77–83. http://dx.doi.org/10.15673/ret.v55i2.1356.

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The article is devoted to investigation of the possibilities of creating highly efficient and competitive Ukrainian gas turbine engines (GTEs), which correspond to modern environmental requirements for new generation energy modules. One of the most important directions of solving this problem is considered, namely, the possibility of realizing a complex thermal circuit of a gas turbine unit (GTU) - the scheme "Aquarius" with the utilization of exhaust gases heat and the injection of ecological and energy water steam into the flowing part of a combustor. The possibilities of reducing emission of harmful components, in particular, of nitrogen oxides, are analyzed, while organizing the process of a 25 MW gas turbine combustor with the supply of water steam to the primary and secondary chamber’s zones. Three-dimensional calculations of the aerodynamic structure of chemically reacting flows in a gas turbine combustor were performed with the help of methods of computational fluid dynamics (CFD). The results of theoretical investigations of gas turbine combustor’s emission characteristics at different ratios of the ecological and energy steam consumptions are presented, their rational values are revealed. The main results of the work can be used at power engineering enterprises for upgrading and modernizing existing and designing models of low-emission combustors of GTE.

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Kanta Mukherjee, Nalini. « Analytic description of flame intrinsic instability in one-dimensional model of open–open combustors with ideal and non-ideal end boundaries ». International Journal of Spray and Combustion Dynamics 10, n^o 4 (27 août 2018) : 287–314. http://dx.doi.org/10.1177/1756827718795518.

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This paper is concerned with the theoretical study of thermo-acoustic instabilities in combustors and focuses upon recently discovered flame intrinsic modes. Here, a complete analytical description of the salient properties of intrinsic modes is provided for a linearized one-dimensional model of open–open combustors with temperature and cross-section jump across the flame taken into account. The standard [Formula: see text] model of heat release is adopted, where n is the interaction index and τ is the time lag. We build upon the recent key finding that for a closed–lopen combustor, on the neutral curve, the intrinsic mode frequencies become completely decoupled from the combustor parameters like cross-section jump, temperature jump and flame location. Here, we show that this remarkable decoupling phenomenon holds not only for closed–open combustors but also for all combustors with the ideal boundary conditions (i.e. closed–open, open–open and closed–closed). Making use of this decoupling phenomenon for the open–open combustors, we derive explicit analytic expressions for the neutral curve of intrinsic mode instability on the [Formula: see text] plane as well as for the linear growth/decay rate near the neutral curve taking into account temperature and cross-section jumps. The instability domain on the [Formula: see text] plane is shown to be qualitatively different from that of the closed–open combustor; in open–open combustors it is not confined for large τ. To find the instability domain and growth rate characteristics for non-ideal open–open boundaries the combustor end boundaries are perturbed and explicit analytical formulae derived and verified by numerics.

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Fąfara, Jean-Marc. « Overview of low emission combustors of aircraft turbine drive units ». Combustion Engines 183, n^o 4 (15 décembre 2020) : 45–49. http://dx.doi.org/10.19206/ce-2020-407.

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It is important to notice that aircraft turbine drive units are commonly used in the modern aviation. The piston engines are often reserved for small and/or sportive aircraft. The turbine drive units are also combustion engine. This paper presents the most popular combustors used in the aeronautical turbine engines. Firstly there are listed the requirements that a combustor has to achieve. Then are presented the combustor designs that permit to achieve the firstly presented requirements. In this work are presented the LPP, TAPS, RQL, graduated combustion zone, VGC, exhaust recirculation system combustors. For each combustor design is enlighten its principle of work, described the etymology of the given name to this design and shown a scheme. The work is closed by a briefly conclusion about the described combustor.

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Saputro, Herman, Aris Purwanto, Laila Fitriana, Danar S. Wijayanto, Valiant L. P. Sutrisno, Eka D. Ariyanto, Marshal Bima et al. « Analysis of flame stabilization limit in a cylindrical of step micro-combustor with different material through the numerical simulation ». MATEC Web of Conferences 197 (2018) : 08003. http://dx.doi.org/10.1051/matecconf/201819708003.

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The flame stabilization limit on micro-combustor had studied to support the micro power generator system. Micro-combustion became the crucial components in a micro power generation system as heat resource that will be converted into electricity. However, the unstable flame in micro-combustor became the main problem that faced by researchers, especially the excess of heat losses. The objective of this study is to observe the flame stabilization limit in a rearward facing step micro-combustor. This study was focused on the effect of micro-combustor material and flame stabilization through the numerical simulation. The micro-combustor material that was used in this study is quartz glass and stainless steel. Micro-combustor was divided into unburned region and burned region. The dimensions of micro-combustor are 3.5 mm inner diameter of unburned region, 4.5 mm inner diameter of burned region and 1 mm thickness. The results have shown that the material of micro-combustor and model of the flame holder have direct relationship with the characteristics of flame stabilization in the micro-combustors. The effects of the flame holder designs and micro-combustors dimensions on the flame stabilization were discussed in detail in this paper.

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9

Feitelberg, A. S., V. E. Tangirala, R. A. Elliott, R. E. Pavri et R. B. Schiefer. « Reduced NOx Diffusion Flame Combustors for Industrial Gas Turbines ». Journal of Engineering for Gas Turbines and Power 123, n^o 4 (1 octobre 2000) : 757–65. http://dx.doi.org/10.1115/1.1376722.

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This paper describes reduced NOx diffusion flame combustors that have been developed for both simple cycle and regenerative cycle MS3002 and MS5002 gas turbines. Laboratory tests have shown that when firing with natural gas, without water or steam injection, NOx emissions from the new combustors are about 40 percent lower than NOx emissions from the standard combustors. CO emissions are virtually unchanged at base load, but increase at part load conditions. Commercial demonstration tests have confirmed the laboratory results. The standard combustors on both the MS3002 and MS5002 gas turbine are cylindrical cans, approximately 10.5 inches (27 cm) in diameter. A single fuel nozzle is centered at the inlet to each can and produces a swirl stabilized diffusion flame. The walls of the cans are louvered for cooling, and contain an array of mixing and dilution holes that provide the air needed to complete combustion and dilute the burned gas to the desired turbine inlet temperature. The MS3002 turbine is equipped with six combustor cans, while the MS5002 turbine is equipped with twelve combustors. The new, reduced NOx emissions combustors (referred to as a “lean head end,” or LHE, combustors) retain all of the key features of the conventional combustors; the only major difference is the arrangement of the mixing and dilution holes in the cylindrical combustor cans. By optimizing the number, diameter, and location of these holes, NOx emissions can be reduced considerably. Minor changes are also sometimes made to the combustor cap. The materials of construction, pressure drop, and fuel nozzle are all unchanged. The differences in NOx emissions between the standard and LHE combustors, as well as the variations in NOx emissions with firing temperature, are well correlated using turbulent flame length arguments. Details of this correlation are presented.

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Chand, Dharmahinder Singh, Daamanjyot Barara, Gautam Ganesh et Suraj Anand. « Comparison of Efficiency of Conventional Shaped Circular and Elliptical Shaped Combustor ». MATEC Web of Conferences 151 (2018) : 02002. http://dx.doi.org/10.1051/matecconf/201815102002.

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There have been concerted efforts towards improving the fuel efficiency of the jet engines in the past, with an aim of reducing the incomplete combustion. The process of combustion in a jet engine takes place in the combustor. A study was conducted for enhancement of air-fuel mixing process by computational analysis of an elliptically shaped combustor for a gas turbine engine. The results of computational analysis of an elliptical shape combustor were compared with a circular shape combustor used in gas turbine engines with a identical cross sectional area. The comparison of the computationally derived parameters of the two combustors i.e. temperature, pressure, and velocity are studied and analyzed. The study intends towards the comparison of the combustion efficiencies of the circular and elliptically shaped combustors. The combustion efficency of elliptical chamber is found to be 98.72% at the same time it was observed 56.26% in case of circular type combustor.

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Wulff, A., et J. Hourmouziadis. « Staged combustor optimisation in the environmental aircraft envelope ». Aeronautical Journal 107, n^o 1071 (mai 2003) : 263–73. http://dx.doi.org/10.1017/s0001924000013336.

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Abstract A new semi-empirical one-dimensional approach for the prediction of aeroengine combustor emissions is presented. The model features a high level of versatility, resulting in a remarkable correlation quality of measurement data of different combustors. This combustion model was modified to reflect the design characteristics of staged combustors. After implementation in an optimisation procedure it was used for staged combustor design studies. For a typical aeroengine application an optimised combustor design was derived with respect to a predefined criteria. Potential exchange rates of combustion efficiency versus NOx emissions by rematching the fuel split for different operating conditions at extreme points of the environmental envelope (ISA/hot day/cold day) of a modern commercial aircraft were investigated. Conclusions regarding the suitable operation of the combustor were drawn. Finally the effect of changed design constrains on the optimisation result was investigated.

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Tahsini, AM. « Combustion efficiency and pressure loss balance for the supersonic combustor ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 234, n^o 6 (18 décembre 2019) : 1149–56. http://dx.doi.org/10.1177/0954410019895885.

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The purpose of this paper is to investigate the effects of intake’s compression process of the scramjet on its flight performance. The hydrogen injection to the supersonic cross-flow is considered as the problem configuration. The finite volume solver is developed to simulate the compressible reacting turbulent flow using the proper reaction mechanism as the finite rate chemistry. The combustion efficiency and the drag force are the most important parameters on the scramjet flight performance, and finding the design point to balance the higher combustion efficiency and the lower minimum drag, which depends on the total pressure loss, can be used to optimize the supersonic combustors. The performance of the supersonic intake is considered here using some oblique shock waves with equal flow-deflection angles to compute the combustor’s inlet condition. The variation of combustion efficiency and total pressure loss is presented for different combustor’s inlet conditions. The results are presented for the constant jet to inlet pressure ratios and also for the constant equivalence ratios, in which the last one is much appropriate and utilized to find the optimum design point of the intake and the combustor, for assumed flight condition.

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Tamanampudi, Gowtham Manikanta Reddy, Swanand Sardeshmukh, William Anderson et Cheng Huang. « Combustion instability modeling using multi-mode flame transfer functions and a nonlinear Euler solver ». International Journal of Spray and Combustion Dynamics 12 (janvier 2020) : 175682772095032. http://dx.doi.org/10.1177/1756827720950320.

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Modern methods for predicting combustion dynamics in high-pressure combustors range from high-fidelity simulations of sub-scale model combustors, mostly for validation purposes or detailed investigations of physics, to linearized, acoustics-based analysis of full-scale practical combustors. Whereas the high-fidelity simulations presumably capture the detailed physics of mixing and heat addition, computational requirements preclude their application for practical design analysis. The linear models that are used during design typically use flame transfer functions that relate the unsteady heat addition [Formula: see text] to oscillations in velocity and pressure ([Formula: see text] and [Formula: see text]) that are obtained from the wave equation. These flame transfer functions can be empirically determined from measurements or derived from theory and analysis. This paper describes a hybrid approach that uses high-fidelity simulations to generate flame transfer functions along with nonlinear Euler CFD to predict the combustor flowfield. A model rocket combustor that presented a self-excited combustion instability with pressure oscillations on the order of 10% of mean pressure is used for demonstration. Spatially distributed flame transfer functions are extracted from a high-fidelity simulation of the combustor and then used in a nonlinear Euler CFD model of the combustor to verify the approach. It is shown that the reduced-fidelity model can reproduce the unsteady behavior of the single element combustor that was both measured in the experiment and predicted by a high-fidelity simulation reasonably well.

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Bowden, T. T., D. M. Carrier et L. W. Courtenay. « Correlations of Fuel Performance in a Full-Scale Commercial Combustor and Two Model Combustors ». Journal of Engineering for Gas Turbines and Power 110, n^o 4 (1 octobre 1988) : 686–89. http://dx.doi.org/10.1115/1.3240192.

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A statistically designed correlation exercise has shown excellent agreement between the performance of Shell and Phillips model combustors and a full-scale Rolls-Royce Tyne combustor. These results are a strong vindication of the model combustor approach to predicting the response and performance of full-scale systems.

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Kim, J., M. G. Dunn, A. J. Baran, D. P. Wade et E. L. Tremba. « Deposition of Volcanic Materials in the Hot Sections of Two Gas Turbine Engines ». Journal of Engineering for Gas Turbines and Power 115, n^o 3 (1 juillet 1993) : 641–51. http://dx.doi.org/10.1115/1.2906754.

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This paper reports the results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high-pressure turbine vanes. The specific materials tested were Mt. St. Helens ash and a soil blend containing volcanic ash (black scoria) from Twin Mountain, NM. Hot section test systems were built using actual engine combustors, fuel nozzles, ignitors, and high-pressure turbine vanes from an Allison T56 engine can-type combustor and a more modern Pratt and Whitney F-100 engine annular-type combustor. A rather large turbine inlet temperature range can be achieved using these two combustors. The deposition behavior of volcanic materials as well as some of the parameters that govern whether or not these volcanic ash materials melt and are subsequently deposited are discussed.

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Kentfield, J. A. C., et M. O’Blenes. « Methods for Achieving a Combustion-Driven Pressure Gain in Gas Turbines ». Journal of Engineering for Gas Turbines and Power 110, n^o 4 (1 octobre 1988) : 704–11. http://dx.doi.org/10.1115/1.3240195.

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The objective of the work was to compare on both an ideal and, where possible, an actual basis the approximate performances of four types of pressure-gain combustor. Such combustors are potentially suitable for use in gas turbines in place of conventional steady-flow combustors. The ideal theoretical performance comparison was based on a specially conceived, universal, analytical model capable of representing, in a fundamental manner, the dominant features of each of the systems studied. The comparisons of nonideal performance were based on actual test results and, where these were not available, on ideal performance characteristics suitably modified to take irreversibilities, etc., into account. It was found that in general the pressure-gain potential of the concepts studied increased with increasing system complexity. It was also found that with most concepts the combustor pressure ratio achievable increases with combustor temperature ratio.

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Sturgess, G. J., D. G. Sloan, A. L. Lesmerises, S. P. Heneghan et D. R. Ballal. « Design and Development of a Research Combustor for Lean Blow-Out Studies ». Journal of Engineering for Gas Turbines and Power 114, n^o 1 (1 janvier 1992) : 13–19. http://dx.doi.org/10.1115/1.2906297.

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In a modern aircraft gas turbine combustor, the phenomenon of lean blow-out (LBO) is of major concern. To understand the physical processes involved in LBO, a research combustor was designed and developed specifically to reproduce recirculation patterns and LBO processes that occur in a real gas turbine combustor. A total of eight leading design criteria were established for the research combustor. This paper discusses the combustor design constraints, aerothermochemical design, choice of combustor configurations, combustor sizing, mechanical design, combustor light-off, and combustor acoustic considerations that went into the final design and fabrication. Tests on this combustor reveal a complex sequence of events such as flame lift-off, intermittency, and onset of axial flame instability leading to lean blowout. The combustor operates satisfactorily and is yielding benchmark quality data for validating and refining computer models for predicting LBO in real engine combustors.

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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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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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Sturgess, G. J., S. P. Heneghan, M. D. Vangsness, D. R. Ballal et A. L. Lesmerises. « Lean Blowout in a Research Combustor at Simulated Low Pressures ». Journal of Engineering for Gas Turbines and Power 118, n^o 4 (1 octobre 1996) : 773–81. http://dx.doi.org/10.1115/1.2816993.

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A propane-fueled research combustor has been designed to represent the essential features of primary zones of combustors for aircraft gas turbine engines in an investigation of lean blowouts. The atmospheric pressure test facility being used for the investigation made it difficult to approach the maximum heat release condition of the research combustor directly. High combustor loadings were achieved through simulating the effects on chemical reaction rates of subatmospheric pressures by means of a nitrogen diluent technique. A calibration procedure is described, and correlated experimental lean blowout results are compared with well-stirred reactor calculations for the research combustor to confirm the efficacy of the calibration.

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Feitelberg, Alan S., Michael D. Starkey, Richard B. Schiefer, Roointon E. Pavri, Matt Bender, John L. Booth et Gordon R. Schmidt. « Performance of a Reduced NOx Diffusion Flame Combustor for the MS5002 Gas Turbine ». Journal of Engineering for Gas Turbines and Power 122, n^o 2 (3 janvier 2000) : 301–6. http://dx.doi.org/10.1115/1.483217.

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This paper describes a reduced NOx diffusion flame combustor that has been developed for the MS5002 gas turbine. Laboratory tests have shown that when firing with natural gas, without water or steam injection, NOx emissions from the new combustor are about 40 percent lower than NOx emissions from the standard MS5002 combustor. CO emissions are virtually unchanged at base load, but increase at part load conditions. The laboratory results were confirmed in 1997 by a commercial demonstration test at a British Petroleum site in Prudhoe Bay, Alaska. The standard MS5002 gas turbine is equipped with a conventional, swirl stabilized diffusion flame combustion system. The twelve standard combustors in an MS5002 turbine are cylindrical cans, approximately 27 cm (10.5 in.) in diameter and 112 cm (44 in.) long. A small, annular, vortex generator surrounds the single fuel nozzle that is centered at the inlet to each can. The walls of the cans are louvered for cooling, and contain an array of mixing and dilution holes that provide the air needed to complete combustion and dilute the burned gas to the desired turbine inlet temperature. The new, reduced NOx emissions combustor (referred to as a “lean head end,” or LHE, combustor) retains all of the key features of the conventional combustor; the only significant difference is the arrangement of the mixing and dilution holes in the cylindrical combustor can. By optimizing the number, diameter, and location of these holes, NOx emissions were substantially reduced. The materials of construction, fuel nozzle, and total combustor air flow were unchanged. The differences in NOx emissions between the standard and LHE combustors, as well as the variations in NOx emissions with firing temperature, were well correlated using turbulent flame length arguments. Details of this correlation are also presented. [S0742-4795(00)01602-1]

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Waitz, Ian A., Gautam Gauba et Yang-Sheng Tzeng. « Combustors for Micro-Gas Turbine Engines ». Journal of Fluids Engineering 120, n^o 1 (1 mars 1998) : 109–17. http://dx.doi.org/10.1115/1.2819633.

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The development of a hydrogen-air microcombustor is described. The combustor is intended for use in a 1 mm2 inlet area, micro-gas turbine engine. While the size of the device poses several difficulties, it also provides new and unique opportunities. The combustion concept investigated is based upon introducing hydrogen and premixing it with air upstream of the combustor. The wide flammability limits of hydrogen-air mixtures and the use of refractory ceramics enable combustion at lean conditions, obviating the need for both a combustor dilution zone and combustor wall cooling. The entire combustion process is carried out at temperatures below the limitations set by material properties, resulting in a significant reduction of complexity when compared to larger-scale gas turbine combustors. A feasibility study with initial design analyses is presented, followed by experimental results from 0.13 cm3 silicon carbide and steel microcombustors. The combustors were operated for tens of hours, and produced the requisite heat release for a microengine application over a range of fuel-air ratios, inlet temperatures, and pressures up to four atmospheres. Issues of flame stability, heat transfer, ignition and mixing are addressed. A discussion of requirements for catalytic processes for hydrocarbon fuels is also presented.

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Behrendt, T., et Ch Hassa. « A test rig for investigations of gas turbine combustor cooling concepts under realistic operating conditions ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 222, n^o 2 (1 février 2008) : 169–77. http://dx.doi.org/10.1243/09544100jaero288.

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In the current paper, a new test rig for the characterization of advanced combustor cooling concepts for gas turbine combustors is presented. The test rig is designed to allow investigations at elevated pressures and temperatures representing realistic operating conditions of future lean low emission combustors. The features and capabilities of the test rig in comparison to existing rigs are described. The properties of the hot gas flow are measured in order to provide the necessary data for a detailed analysis of the measured cooling effectivity of combustor wall test samples. Results of the characterization of the velocity and temperature distribution in the hot gas flow at the leading edge of the test sample at pressures up to p = 10 bar and global flame temperatures up to TF = 2000 K are presented.

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Athithan, A. Antony, S. Jeyakumar, Norbert Sczygiol, Mariusz Urbanski et A. Hariharasudan. « The Combustion Characteristics of Double Ramps in a Strut-Based Scramjet Combustor ». Energies 14, n^o 4 (5 février 2021) : 831. http://dx.doi.org/10.3390/en14040831.

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This paper focuses on the influence of ramp locations upstream of a strut-based scramjet combustor under reacting flow conditions that are numerically investigated. In contrast, a computational study is adopted using Reynolds Averaged Navier Stokes (RANS) equations with the Shear Stress Transport (SST) k-ω turbulence model. The numerical results of the Deutsches Zentrum für Luft- und Raumfahrt or German Aerospace Centre (DLR) scramjet model are validated with the reported experimental values that show compliance within the range, indicating that the adopted simulation method can be extended for other investigations as well. The performance of the ramps in the strut-based scramjet combustor is analyzed based on parameters such as wall pressures, combustion efficiency and total pressure loss at various axial locations of the combustor. From the numerical shadowgraph, more shock interactions are observed upstream of the strut injection region for the ramp cases, which decelerates the flow downstream, and additional shock reflections with less intensity are also noticed when compared with the DLR scramjet model. The shock reflection due to the ramps enhances the hydrogen distribution in the spatial direction. The ignition delay is noticed for ramp combustors due to the deceleration of flow compared to the baseline strut only scramjet combustor. However, a higher flame temperature is observed with the ramp combustor. Because more shock interactions arise from the ramps, a marginal increase in the total pressure loss is observed for ramp combustors when compared to the baseline model.

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Crocker, D. S., D. Nickolaus et C. E. Smith. « CFD Modeling of a Gas Turbine Combustor From Compressor Exit to Turbine Inlet ». Journal of Engineering for Gas Turbines and Power 121, n^o 1 (1 janvier 1999) : 89–95. http://dx.doi.org/10.1115/1.2816318.

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Gas turbine combustor CFD modeling has become an important combustor design tool in the past few years, but CFD models are generally limited to the flow field inside the combustor liner or the diffuser/combustor annulus region. Although strongly coupled in reality, the two regions have rarely been coupled in CFD modeling. A CFD calculation for a full model combustor from compressor diffuser exit to turbine inlet is described. The coupled model accomplishes the following two main objectives: (1) implicit description of flow splits and flow conditions for openings into the combustor liner, and (2) prediction of liner wall temperatures. Conjugate heat transfer with nonluminous gas radiation (appropriate for lean, low emission combustors) is utilized to predict wall temperatures compared to the conventional approach of predicting only near wall gas temperatures. Remaining difficult issues such as generating the grid, modeling Swirled vane passages, and modeling effusion cooling are also discussed.

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Lieuwen, Tim. « Online Combustor Stability Margin Assessment Using Dynamic Pressure Data ». Journal of Engineering for Gas Turbines and Power 127, n^o 3 (24 juin 2005) : 478–82. http://dx.doi.org/10.1115/1.1850493.

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This paper describes a strategy for determining a combustor’s dynamic stability margin. Currently, when turbines are being commissioned or simply going through day to day operation, the operator does not know how the stability of the system is affected by changes to fuel splits or operating conditions unless, of course, pressure oscillations are actually present. We have developed a methodology for ascertaining the stability margin from dynamic pressure data that does not require external forcing and that works even when pressure oscillations have very low amplitudes. This method consists of signal processing and analysis that determines a real-time measure of combustor damping. When the calculated damping is positive, the combustor is stable. As the damping goes to zero, the combustor approaches its stability boundary. Changes in the stability margin of each of the combustor’s stable modes due to tuning, aging, or environmental changes can then be monitored through an on-line analysis of the pressure signal. This paper outlines the basic approach used to quantify acoustic damping and demonstrates the technique on combustor test data.

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Agrawal, A. K., J. S. Kapat et T. T. Yang. « An Experimental/Computational Study of Airflow in the Combustor–Diffuser System of a Gas Turbine for Power Generation ». Journal of Engineering for Gas Turbines and Power 120, n^o 1 (1 janvier 1998) : 24–33. http://dx.doi.org/10.1115/1.2818084.

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This paper presents an experimental/computational study of cold flow in the combustor–diffuser system of industrial gas turbines employing can-annular combustors and impingement-cooled transition pieces. The primary objectives were to determine flow interactions between the prediffuser and dump chamber, to evaluate circumferential flow nonuniformities around transition pieces and combustors, and to identify the pressure loss mechanisms. Flow experiments were conducted in an approximately one-third geometric scale, 360-deg annular test model simulating practical details of the prototype including the support struts, transition pieces, impingement sleeves, and can-annular combustors. Wall static pressures and velocity profiles were measured at selected locations in the test model. A three-dimensional computational fluid dynamic analysis employing a multidomain procedure was performed to supplement the flow measurements. The complex geometric features of the test model were included in the analysis. The measured data correlated well with the computations. The results revealed strong interactions between the prediffuser and dump chamber flows. The prediffuser exit flow was distorted, indicating that the uniform exit conditions typically assumed in the diffuser design were violated. The pressure varied circumferentially around the combustor casing and impingement sleeve. The circumferential flow nonuniformities increased toward the inlet of the turbine expander. A venturi effect causing flow to accelerate and decelerate in the dump chamber was also identified. This venturi effect could adversely affect impingement cooling of the transition piece in the prototype. The dump chamber contained several recirculation regions contributing to the losses. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor–diffuser, much of it in the dump chamber where the fluid passed though narrow pathways. A realistic test model and three-dimensional analysis used in this study provided new insight into the flow characteristics of practical combustor–diffuser systems.

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Gaudron, Renaud, et Aimee S. Morgans. « Thermoacoustic stability prediction using Deep Learning ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, n^o 7 (1 février 2023) : 582–91. http://dx.doi.org/10.3397/in_2022_0079.

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Thermoacoustic instabilities are an undesirable physical phenomenon that can occur in a wide range of combustors such as gas turbines, rocket engines, and boilers. These instabilities are typically loud, vibration-inducing, and can increase parietal heat transfer in the combustion chamber. As a consequence, mechanical fatigue increases and can sometimes lead to a catastrophic failure of the combustor. A well-established formalism to predict thermoacoustic stability is based on network models where the combustor is represented by a sequence of connected acoustic modules. The frequency of the modes appearing inside the combustor are then given by the eigenvalues of a characteristic equation obtained using conservation equations. This approach has been successfully used to predict the stability of a variety of combustors. However, this operation needs to be repeated many times in order to optimise the shape of an unstable combustor at an early design stage. One option to reduce the computational cost of predicting the thermoacoustic stability of a given configuration is to use a data-driven approach as opposed to a physics-based approach. In the former approach, a Machine Learning algorithm is trained to discriminate between thermoacoustically stable and unstable combustors using examples generated by a (physics-based) acoustic network model. The ML model is then able to predict the thermoacoustic stability of an unknown configuration much faster than a traditional acoustic network model and with a very high accuracy. This approach has been validated in a previous study using classical Machine Learning algorithms, but it is restricted to somewhat simple geometries. The objective of this study is to investigate whether Deep Learning architectures can be used to generalise those results to complex geometries with a large number of elements.

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Li, Qingqing, Jiansheng Wang, Jun Li et Junrui Shi. « Fundamental Numerical Analysis of a Porous Micro-Combustor Filled with Alumina Spheres : Pore-Scale vs. Volume-Averaged Models ». Applied Sciences 11, n^o 16 (16 août 2021) : 7496. http://dx.doi.org/10.3390/app11167496.

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Inserting porous media into the micro-scale combustor space could enhance heat recirculation from the flame zone, and could thus extend the flammability limits and improve flame stability. In the context of porous micro-combustors, the pore size is comparable to the combustor characteristic length. It is insufficient to treat the porous medium as a continuum with the volume-averaged model (VAM). Therefore, a pore-scale model (PSM) is developed to consider the detailed structure of the porous media to better understand the coupling among the gas mixture, the porous media and the combustor wall. The results are systematically compared to investigate the difference in combustion characteristics and flame stability limits. A quantified study is undertaken to examine heat recirculation, including preheating and heat loss, in the porous micro-combustor using the VAM and PSM, which are beneficial for understanding the modeled differences in temperature distribution. The numerical results indicate that PSM predicts a scattered flame zone in the pore areas and gives a larger flame stability range, a lower flame temperature and peak solid matrix temperature, a higher peak wall temperature and a larger Rp-hl than a VAM counterpart. A parametric study is subsequently carried out to examine the effects of solid matrix thermal conductivity (ks) on the PSM and VAM, and then the results are analyzed briefly. It is found that for the specific configurations of porous micro-combustor considered in the present study, the PSM porous micro-combustor is more suitable for simplifying to a VAM with a larger Φ and a smaller ks, and the methods can be applied to other configurations of porous micro-combustors.

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Amoroso, Francesco, Angelo De Fenza, Giuseppe Petrone et Rosario Pecora. « A Sensitivity Analysis on the Influence of the External Constraints on the Dynamic Behaviour of a Low Pollutant Emissions Aircraft Combustor-Rig ». Archive of Mechanical Engineering 63, n^o 3 (1 septembre 2016) : 435–54. http://dx.doi.org/10.1515/meceng-2016-0025.

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Abstract The need to reduce pollutant emissions leads the engineers to design new aeronautic combustors characterized by lean burn at relatively low temperatures. This requirement can easily cause flame instability phenomena and consequent pressure pulsations which may seriously damage combustor’s structure and/or compromise its fatigue life. Hence the need to study the combustor’s structural dynamics and the interaction between elastic, thermal and acoustic phenomena. Finite element method represent a largely used and fairly reliable tool to address these studies; on the other hand, the idealization process may bring to results quite far from the reality whereas too simplifying assumptions are made. Constraints modelling represent a key-issue for all dynamic FE analyses; a wrong simulation of the constraints may indeed compromise entire analyses although running on very accurate and mesh-refined structural models. In this paper, a probabilistic approach to characterize the influence of external constraints on the modal behaviour of an aircraft combustor-rig is presented. The finite element model validation was performed at first by comparing numerical and experimental results for the free-free condition (no constraints). Once the model was validated, the effect of constraints elasticity on natural frequencies was investigated by means of a probabilistic design simulation (PDS); referring to a specific tool developed in the ANSYS®software, a preliminary statistical analysis was at performed via Monte-Carlo Simulation (MCS) method. The results were then correlated with the experimental ones via Response Surface Method (RSM).

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Tang, Ai Kun, Jian Feng Pan, Xia Shao et Yang Xian Liu. « Numerical Study on Combustion Performance Comparison of Premixed Methane-Air in Micro-Combustors with and without Heat Recirculating Channel ». Applied Mechanics and Materials 394 (septembre 2013) : 179–84. http://dx.doi.org/10.4028/www.scientific.net/amm.394.179.

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Recently£¬research interests of micro-power generation devices which are based on micro-combustion process have been stimulated by the persistent breakthrough of MEMS techniques. A new type micro-heat recirculating combustor was presented in this paper, and the computation model for premixed methane-air was established which adopting a skeletal reaction mechanism. Combustion characteristics both in heat recirculating combustor and single-channel combustor are analyzed which containing the flame shape, location and temperature at the same simulation conditions. It is found that not only the flame location can be better fixed by heat recirculation measure, but although the flame temperature can be raised for some degrees when compared to the single channel combustor. These results provide some useful information for the design of micro-scale combustors.

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Sturgess, G. J., S. P. Heneghan, M. D. Vangsness, D. R. Ballal et A. L. Lesmerises. « Isothermal Flow Fields in a Research Combustor for Lean Blowout Studies ». Journal of Engineering for Gas Turbines and Power 114, n^o 2 (1 avril 1992) : 435–44. http://dx.doi.org/10.1115/1.2906609.

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A propane-fueled research combustor has been designed and developed to investigate lean blowouts in a simulated primary zone of the combustors for aircraft gas turbine engines. To understand the flow development better and to ensure that the special provisions in the combustor for optical access did not introduce undue influence, measurements of the velocity fields inside the combustor were made using laser-Do¨ppler anemometry. These measurements were made in isothermal, constant density flow to relate the combustor flow field development to known jet behavior and to backward-facing step experimental data in the literature. The major features of the flow field appear to be consistent with the expected behavior, and there is no evidence that the provision of optical access adversely affected the flows measured.

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Sturgess, G. J., R. G. McKinney et S. A. Morford. « Modification of Combustor Stoichiometry Distribution for Reduced NOx Emission From Aircraft Engines ». Journal of Engineering for Gas Turbines and Power 115, n^o 3 (1 juillet 1993) : 570–80. http://dx.doi.org/10.1115/1.2906745.

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Measurements of the emissions from an experimental engine were analyzed to construct a design chart for the reduction of oxides of nitrogen (NOx) in conventional combustors. The design chart was used to reconfigure the stoichiometry distribution of the combustor of a production engine so as to reduce NOx while holding the emissions of carbon monoxide, unburned hydrocarbons, and smoke well below existing regulations. Combustion section pressure loss and combustor outlet temperature distributions were substantially unchanged. The modified design was refined with the aid of computational fluid dynamics calculations to optimize the emissions reduction. Worthwhile reductions in NOx were obtained with combustor modifications that are transparent to the engine user.

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Song, Rui Yin, Xian Cheng Wang et Mei Qin Zhang. « Research for Combustor Based on Micro-Thermoelectric Generator Device ». Advanced Materials Research 97-101 (mars 2010) : 2509–13. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.2509.

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Micro-thermoelectric generator device (MTGD) is used to supply lasting electrical energy for Micro-electro-mechanical systems (MEMS). As an important part of MTGD, micro-combustor with high energy density has direct influence on the total electrical generating efficiency for MTG. D In this paper, Considering some parameters such as material, dimension, flux of fuel and shape of thermal conductive tunnel for micro-combustor, some simulation models such as thermal transfer, combustion for micro-combustor were built up, and some simulation results were got. Based upon, optimized micro flat combustors were designed and tested. The experiment results illustrated that the conduct efficiency of micro-combustor was well controlled by adjusting heat flux, and the combustor with shape of zigzag combustion tunnel has high thermal exchange efficiency in experiment models. By adjusting flux of fuel and the structure of micro premixed combustor, the heat loss of MTGD was reduced and output power was improved in a degree.

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Richards, G. A., M. J. Yip, E. Robey, L. Cowell et D. Rawlins. « Combustion Oscillation Control by Cyclic Fuel Injection ». Journal of Engineering for Gas Turbines and Power 119, n^o 2 (1 avril 1997) : 340–43. http://dx.doi.org/10.1115/1.2815580.

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A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle/combustor arrangement. The fuel is natural gas. Cyclic injection of 14 percent control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., −10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

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Kawahara, Hideo, Konosuke Furukawa, Koichiro Ogata, Eiji Mitani et Koji Mitani. « Experimental Study on the Stabilization Mechanism of Diffusion Flames in a Curved Impinging Spray Combustion Field in a Narrow Region ». Energies 14, n^o 21 (1 novembre 2021) : 7171. http://dx.doi.org/10.3390/en14217171.

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HVAF (High Velocity Air Flame) flame spraying can generate supersonic high-temperature gas jets, enabling thermal spraying at unprecedented speeds. However, there is a problem with the energy cost of this device. This study focused on combustors that used cheap liquid fuel (kerosene) as the fuel for HVAF. In this research, we have developed a compact combustor with a narrow channel as a heat source for the HVAF heat atomizer. Using this combustor, the stability of the flame formed in the combustor, the morphology of the flame, and the temperature behavior in the combustion chamber were investigated in detail. As a result, the magnitude of the swirling airflow had a great influence on the structure of the flame formed in the combustor, and the stable combustion range of the combustor could be determined. As the swirling air flow rate changes, the equivalent ratio of the entire combustor changes significantly, and the flame structure also transition from the premixed flame to the diffusion flame. From this study, it was confirmed that the temperature inside the combustor has great influence on the flame structure.

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Suzuki, Y., T. Satoh, M. Kawano, N. Akikawa et Y. Matsuda. « Combustion Test Results of an Uncooled Combustor With Ceramic Matrix Composite Liner ». Journal of Engineering for Gas Turbines and Power 125, n^o 1 (27 décembre 2002) : 28–33. http://dx.doi.org/10.1115/1.1501916.

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A reverse-flow annular combustor with its casing diameter of 400 mm was developed using an uncooled liner made of a three-dimensional woven ceramic matrix composite. The combustor was tested using the TRDI high-pressure combustor test facility at the combustor maximum inlet and exit temperature of 723 K and 1623 K, respectively. Although both the material and combustion characteristics were evaluated in the test, this report focused on the combustion performance. As the results of the test, the high combustion efficiency and high heat release ratio of 99.9% and 1032 W/m3/Pa were obtained at the design point. The latter figure is approximately twice as high as that of existing reverse-flow annular combustors. Pattern factor was sufficiently low and was less than 0.1. Surface temperatures of the liner wall were confirmed to be higher than the limit of the combustor made of existing heat-resistant metallic materials.

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Chorpening, B. T., J. D. Thornton, E. D. Huckaby et K. J. Benson. « Combustion Oscillation Monitoring Using Flame Ionization in a Turbulent Premixed Combustor ». Journal of Engineering for Gas Turbines and Power 129, n^o 2 (30 août 2006) : 352–57. http://dx.doi.org/10.1115/1.2431390.

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To achieve very low NOx emission levels, lean-premixed gas turbine combustors have been commercially implemented that operate near the fuel-lean flame extinction limit. Near the lean limit, however, flashback, lean blow off, and combustion dynamics have appeared as problems during operation. To help address these operational problems, a combustion control and diagnostics sensor (CCADS) for gas turbine combustors is being developed. CCADS uses the electrical properties of the flame to detect key events and monitor critical operating parameters within the combustor. Previous development efforts have shown the capability of CCADS to monitor flashback and equivalence ratio. Recent work has focused on detecting and measuring combustion instabilities. A highly instrumented atmospheric combustor has been used to measure the pressure oscillations in the combustor, the OH emission, and the flame ion field at the premix injector outlet and along the walls of the combustor. This instrumentation allows examination of the downstream extent of the combustion field using both the OH emission and the corresponding electron and ion distribution near the walls of the combustor. In most cases, the strongest pressure oscillation dominates the frequency behavior of the OH emission and the flame ion signals. Using this highly instrumented combustor, tests were run over a matrix of equivalence ratios from 0.6 to 0.8, with an inlet reference velocity of 25m∕s(82ft∕s). The acoustics of the fuel system for the combustor were tuned using an active-passive technique with an adjustable quarter-wave resonator. Although several statistics were investigated for correlation with the dynamic pressure in the combustor, the best correlation was found with the standard deviation of the guard current. The data show a monotonic relationship between the standard deviation of the guard current (the current through the flame at the premix injector outlet) and the standard deviation of the chamber pressure. Therefore, the relationship between the standard deviation of the guard current and the standard deviation of the pressure is the most promising for monitoring the dynamic pressure of the combustor using the flame ionization signal. This addition to the capabilities of CCADS would allow for dynamic pressure monitoring on commercial gas turbines without a pressure transducer.

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Zelina, J., et D. R. Ballal. « Combustor Stability and Emissions Research Using a Well-Stirred Reactor ». Journal of Engineering for Gas Turbines and Power 119, n^o 1 (1 janvier 1997) : 70–75. http://dx.doi.org/10.1115/1.2815564.

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The design and development of low-emissions, lean premixed aero or industrial gas turbine combustors is very challenging because it entails many compromises. To satisfy the projected CO and NOx emissions regulations without relaxing the conflicting requirements of combustion stability, efficiency, pattern factor, relight (for aero combustor), or off-peak loading (for industrial combustor) capability demands great design ingenuity. The well-stirred reactor (WSR) provides a laboratory idealization of an efficient and highly compact advanced combustion system of the future that is capable of yielding global kinetics of value to the combustor designers. In this paper, we have studied the combustion performance and emissions using a toroidal WSR. It was found that the toroidal WSR was capable of peak loading almost twice as high as that for a spherical WSR and also yielded a better fuel-lean performance. A simple analysis based upon WSR theory provided good predictions of the WSR lean blowout limits. The WSR combustion efficiency was 99 percent over a wide range of mixture ratios and reactor loading. CO emissions reached a minimum at a flame temperature of 1600 K and NOx increased rapidly with an increase in flame temperature, moderately with increasing residence time, and peaked at or slightly on the fuel-lean side of the stoichiometric equivalence ratio. Finally, emissions maps of different combustors were plotted and showed that the WSR has the characteristics of an idealized high-efficiency, low-emissions combustor of the future.

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Carl, M., T. Behrendt, C. Fleing, M. Frodermann, J. Heinze, C. Hassa, U. Meier, D. Wolff-Gassmann, S. Hohmann et N. Zarzalis. « Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions ». Journal of Engineering for Gas Turbines and Power 123, n^o 4 (1 octobre 2000) : 810–16. http://dx.doi.org/10.1115/1.1378298.

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Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6, and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD, and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurements and calculations of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, quantitative light scattering, OH* chemiluminescence, and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.

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Cui, Tao, et Yang Ou. « Modeling of Scramjet Combustors Based on Model Migration and Process Similarity ». Energies 12, n^o 13 (30 juin 2019) : 2516. http://dx.doi.org/10.3390/en12132516.

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Contributed by the low cost, the simulation method is considered an attractive option for the optimization and design of the supersonic combustor. Unfortunately, accurate and satisfactory modeling is time-consuming and cost-consuming because of the complex processes and various working conditions. To address this issue, a mathematical modeling for the combustor on the basis of the clustering algorithm, machine learning algorithm, and model migration strategy is developed in this paper. A general framework for the migration strategy of the combustor model is proposed among the similar combustors, and the base model, which is developed by training the machine learning model with data from the existing combustion processes, is amended to fit the unexampled combustor using the model migration strategy with a few data. The simulation results validate the effectiveness of the development strategy, and the migrated model is proved to be suitable for the new combustor in higher accuracy with less time and calculation.

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Rizk, N. K., et H. C. Mongia. « Three-Dimensional Gas Turbine Combustor Emissions Modeling ». Journal of Engineering for Gas Turbines and Power 115, n^o 3 (1 juillet 1993) : 603–11. http://dx.doi.org/10.1115/1.2906749.

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An emission model that combines the analytical capabilities of three-dimensional combustor performance codes with mathematical expressions based on detailed chemical kinetic scheme is formulated. The expressions provide the trends of formation and/or the consumption of Nox, CO, and UHC in various regions of the combustor utilizing the details of the flow and combustion characteristics given by the three-dimensional analysis. By this means, the optimization of the combustor design to minimize pollutant formation and maintain satisfactory stability and performance could be achieved. The developed model was used to calculate the emissions produced by several engine combustors that varied significantly in design and concept, and operated on both conventional and high-density fuels. The calculated emissions agreed well with the measurements. The model also provided insight into the regions in the combustor where excessive emissions were formed, and helped to understand the influence of the combustor details and air admissions arrangement on reaction rates and pollutant concentrations.

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Yuliati, Lilis, Mega Nur Sasongko et Slamet Wahyudi. « Flammability Limit and Flame Visualization of Gaseous Fuel Combustion Inside Meso-scale Combustor with Different Thermal Conductivity ». Applied Mechanics and Materials 493 (janvier 2014) : 204–9. http://dx.doi.org/10.4028/www.scientific.net/amm.493.204.

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This study experimentally investigated effect of thermal conductivity on the combustioncharacteristics of gaseous fuel inside a meso-scale combustor. Combustion characteristics that wereobserved in this research include flame visualization and flammability limit. Quartz glass, stainlesssteel and copper tubes with inner diameters of 3.5 mm were used as combustors. Stainless steel wiremesh was inserted inside meso-scale combustor as a flame holder. Liquid petroleum gas (LPG),which is common fuel use by Indonesian people, was used as a gaseous fuel. A stable blue flame wasestablished inside meso-scale combustor at the downstream of wire mesh for all combustor withdifferent thermal conductivity. Furthermore, flame color is blue for combustion of fuel lean orstoichiometric mixture, and blue-green for combustion of fuel rich mixture. Meso-scale combustorwith the highest thermal conductivity has the narrowest flame cross section area, especially at lowerreactant velocity. Vice versa, this combustor has the widest flammability limit, mainly at the higherreactant velocity.

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Touchton, G. L. « Influence of Gas Turbine Combustor Design and Operating Parameters on Effectiveness of NOx Suppression by Injected Steam or Water ». Journal of Engineering for Gas Turbines and Power 107, n^o 3 (1 juillet 1985) : 706–13. http://dx.doi.org/10.1115/1.3239792.

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Steam or water injection has become the state-of-the-art abatement technique for NOx, with steam strongly preferred for combined-cycle application. In combined-cycle plants, the degradation of the plant efficiency due to steam injection into the gas turbine combustor provides a powerful incentive for minimizing this flow over the entire plant operating map. This paper presents the results of extensive tests carried out on a variety of gas turbine combustor designs. Both test stand and field test data are presented. The usual fuel in the tests is methane; however, some data are presented for combustion of No. 2 distillate oil and intermediate Btu gas fuel. Similarly, the usual inert injected is steam, but some water injection data are included for comparison. The results support the conclusions: 1. Steam and water injection suppress NOx exclusively through thermal mechanisms, i.e., by lowering the peak flame temperature. 2. Design changes have little effect on NOx suppression effectiveness of steam or water in jet-stirred or swirl-mixed combustors. 3. Primary zone injection of steam in methane-fueled, jet-stirred combustors is equally effective whether the steam enters with an air stream or with the fuel stream. 4. Water-to-fuel ratio corrected to equivalent energy content correlates NOx suppression effectiveness for turbulent diffusion flame combustors.

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Fan, Weijie, Shijie Liu, Jin Zhou, Haoyang Peng et Siyuan Huang. « Effects of Annular Combustor Width on the Ethylene-Air Continuous Rotating Detonation ». International Journal of Aerospace Engineering 2020 (14 septembre 2020) : 1–12. http://dx.doi.org/10.1155/2020/8863691.

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The realization and stable operation of Continuous Rotating Detonation (CRD) in the annular combustor fueled by hydrocarbon-air are still challenging. For further investigation of this issue, a series of ethylene-air CRD tests with the variation of combustor width is conducted, and the effects of combustor width are well analyzed based on high-frequency pressure and high-speed photograph images. The results show that the combustor width plays a significant role in the realization and sustainability of the ethylene-air CRD. In this paper, the critical combustor width for the CRD realization and stable single wave are 20 mm and 25 mm, respectively. In wide combustors, the backward-facing step at the combustor forepart makes the main flow slow down, and thus, the mixing quality is promoted. Besides, the pilot flame at the recirculation zone contributes to sustaining the CRD wave. As the width increases, the propagation mode changes from counter-rotating two-wave mode to single wave mode with higher propagation velocity and stability. The highest propagation velocity reaches 1325.56 m/s in the 40 mm wide combustor, accounting for 71.51% of the corresponding Chapman-Jouguet velocity. Despite large combustor volume, high combustor pressure is obtained in detonation combustion mode indicating that a better propulsive performance could be achieved by CRD.

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Zhu, M., A. P. Dowling et K. N. C. Bray. « Self-Excited Oscillations in Combustors With Spray Atomizers ». Journal of Engineering for Gas Turbines and Power 123, n^o 4 (1 octobre 2000) : 779–86. http://dx.doi.org/10.1115/1.1376717.

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Combustors with fuel-spray atomizers are susceptible to a low-frequency oscillation, particularly at idle and sub-idle conditions. For aero-engine combustors, the frequency of this oscillation is typically in the range 50–120 Hz and is commonly called “rumble.” In the current work, computational fluid dynamics (CFD) is used to simulate this self-excited oscillation. The combustion model uses Monte Carlo techniques to give simultaneous solutions of the Williams’ spray equation together with the equations of turbulent reactive flow. The unsteady combustion is calculated by the laminar flamelet presumed pdf method. A quasi-steady description of fuel atomizer behavior is used to couple the inlet flow in the combustor. A choking condition is employed at turbine inlet. The effects of the atomizer and the combustor geometry on the unsteady combustion are studied. The results show that, for some atomizers, with a strong dependence of mean droplet size on air velocity, the coupled system undergoes low-frequency oscillations. The numerical results are analyzed to provide insight into the rumble phenomena. Basically, pressure variations in the combustor alter the inlet air and fuel spray characteristics, thereby changing the rate of combustion. This in turn leads to local “hot spots,” which generate pressure fluctuations as they convect through the downstream nozzle.

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Pan, J. F., Z. Y. Hou, Y. X. Liu, A. K. Tang, J. Zhou, X. Shao, Z. H. Pan et Q. Wang. « Design and working performance study of a novel micro parallel plate combustor with two nozzles for micro thermophotovotaic system ». Thermal Science 19, n^o 6 (2015) : 2185–94. http://dx.doi.org/10.2298/tsci141109069p.

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Micro-combustors are a key component in combustion-driven micro power generators, and their performance is significantly affected by their structure. For the application of micro-thermophotovoltaic (MTPV) system, a high and uniform temperature distribution along the walls of the micro combustor is desired. In this paper, a three-dimensional numerical simulation has been conducted on a new-designed parallel plate micro combustor with two nozzles. The flow field and the combustion process in the micro combustor, and the temperature distribution on the wall as well as the combustion efficiency were obtained. The effects of various parameters such as the inlet angle and the fuel volumetric flow rate on the performance of the micro combustor were studied. It was observed that a swirl formed in the center of the combustor and the radius of the swirl increased with the increase of the inlet rate, and the best working condition was achieved at the inlet angle ?=20?. The results indicated that the two-nozzle combustion chamber had a higher and more uniform mean temperature than the conventional combustor under the same condition.

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Narayanaswami, L., et G. A. Richards. « Pressure-Gain Combustion : Part I—Model Development ». Journal of Engineering for Gas Turbines and Power 118, n^o 3 (1 juillet 1996) : 461–68. http://dx.doi.org/10.1115/1.2816668.

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A model for aerodynamically valved pulse combustion is presented. Particular emphasis is placed on using the model equations to identify characteristic length and time scales relevant to the design of pressure-gain combustors for gas turbine applications. The model is a control volume description of conservation laws for several regions of the pulse combustor. Combustion is modeled as a bimolecular reaction. Mixing between the fresh charge and the combustion products is modeled using a turbulent eddy time estimated from the combustor geometry and flow conditions. The model equations identify two characteristic lengths, which should be held constant during combustor scaleup, as well as certain exceptions to this approach. The effect of ambient operating pressure and inlet air temperature is also discussed.

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Gordon, R., et Y. Levy. « Optimization of Wall Cooling in Gas Turbine Combustor Through Three-Dimensional Numerical Simulation ». Journal of Engineering for Gas Turbines and Power 127, n^o 4 (20 septembre 2005) : 704–23. http://dx.doi.org/10.1115/1.1808432.

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This paper is concerned with improving the prediction reliability of CFD modeling of gas turbine combustors. CFD modeling of gas turbine combustors has recently become an important tool in the combustor design process, which till now routinely used the old “cut and try” design practice. Improving the prediction capabilities and reliability of CFD methods will reduce the cycle time between idea and a working product. The paper presents a 3D numerical simulation of the BSE Ltd. YT-175 engine combustor, a small, annular, reversal flow type combustor. The entire flow field is modeled, from the compressor diffuser to turbine inlet. The model includes the fuel nozzle, the vaporizer solid walls, and liner solid walls with the dilution holes and cooling louvers. A periodic 36 deg sector of the combustor is modeled using a hybrid structured/unstructured multiblock grid. The time averaged Navier-Stokes (N-S) equations are solved, using the k-ε turbulence model and the combined time scale (COMTIME)/PPDF models for modeling the turbulent kinetic energy reaction rate. The vaporizer and liner walls’ temperature is predicted by the “conjugate heat transfer” methodology, based on simultaneous solution of the heat transfer equations for the vaporizer and liner walls, coupled with the N-S equations for the fluids. The calculated results for the mass flux passing through the vaporizer and various holes and slots of the liner walls, as well as the jet angle emerging from the liner dilution holes, are in very good agreement with experimental measurements. The predicted location of the liner wall hot spots agrees well with the position of deformations and cracks that occurred in the liner walls during test runs of the combustor. The CFD was used to modify the YT-175 combustion chamber to eliminate structural problems, caused by the liner walls overheating, that were observed during its development.

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Wadwankar, N., G. Kandasamy, N. Ananthkrishnan, VS Renganathan, Ik-Soo Park et Ki-Young Hwang. « Dual combustor ramjet engine dynamics modeling and simulation for design analysis ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 233, n^o 4 (9 janvier 2018) : 1307–22. http://dx.doi.org/10.1177/0954410017749867.

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An integrated low-order, medium-fidelity model for a dual combustor ramjet engine configuration is derived for use in mission analysis and controller design. Each of the individual components – intake, isolator, ram diffuser and combustor, scram combustor and nozzle – are modeled using either empirical data or analytical relations, or in case of the two combustors by using a quasi-one-dimensional code. The components are appropriately linked to capture the key physical phenomena inherent in the dual combustor ramjet engine operation and the ongoing dynamic processes. Feedback loops due to the upstream influence of the pressure and time lags due to acoustic and flow-related delays are modeled. Sample results are generated for a dual combustor ramjet engine configuration with Jet-A fuel at a design condition of Mach 7 at 27.5 km altitude, and stability and dynamic behavior, steady-state performance, and response to fuel throttling input are assessed. Its low order and the ability to be easily reconfigured for a new geometry/parametric input make the model useful for mission analysis studies with a quick turn-around time.

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