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1
Serbin, Sergey. „THERMO ACOUSTIC PROCESSES IN LOW EMISSION COMBUSTION CHAMBER OF GAS TURBINE ENGINE CAPACITY 25 MW“. Science Journal Innovation Technologies Transfer, Nr. 2019-2 (05.05.2019): 86–90. http://dx.doi.org/10.36381/iamsti.2.2019.86-90.
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The appliance of modern tools of the computational fluid dynamics for the investigation of the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. The aim of the research is to investigate and forecast the non-stationary processes in the gas turbine combustion chambers. The results of the numerical experiments which were carried out using three-dimensional mathematical models in gaseous fuels combustion chambers reflect sufficiently the physical and chemical processes of the unsteady combustion and can be recommended to optimize the geometrical and operational parameters of the low-emission combustion chamber. The appliance of such mathematical models are reasonable for the development of new samples of combustors which operate at the lean air-fuel mixture as well as for the modernization of the existing chambers with the aim to develop the constructive measures aimed at reducing the probability of the occurrence of the pulsation combustion modes. Keywords: gas turbine engine, combustor, turbulent combustion, pulsation combustion, numerical methods, mathematical simulation.
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Léger, Bruno, Patrick André, Guy Grienche und Gérard Schott. „Contrôle thermique de parois de chambre de combustion. Banc d'essai du laboratoire aquitain de recherche en aérothermique“. Revue Générale de Thermique 35, Nr. 417 (Oktober 1996): 625–30. http://dx.doi.org/10.1016/s0035-3159(96)80025-0.
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3
Kashdan, Julian. „Visualisation du mélange gazeux au sein de la chambre de combustion des moteurs par la fluorescence induite par laser“. Photoniques, Nr. 52 (März 2011): 34–36. http://dx.doi.org/10.1051/photon/20115234.
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4
Łapinski, Damian, und Janusz Piechna. „Improvements in the turbo-engine by replacement of conventional combustion chamber by a pulse combustion chamber“. Archive of Mechanical Engineering 60, Nr. 4 (01.12.2013): 481–94. http://dx.doi.org/10.2478/meceng-2013-0029.
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Abstract This paper comprises description of the turbo engine and evaluation of its analytical model. The analytical model was created to establish a benchmark for further evaluation of a wave rotor combustor (at constant volume). The wave rotor combustor concept was presented and discussed. Advantages of combustion at constant volume were described as well as the basic turbo engine updates required to reflect pulse combustor application. The calculation results for analytical model of a basic engine, and that equipped with pulse combustor are included in this paper. The paper describes the required changes in the engine structure and construction and the estimated thermodynamic improvements. Axial-type pulse multi-chamber combustion unit increasing the pressure and temperature of gases requires a special additional turbine utilizing additional energy and forming the interface between the standard compressor-turbine unit. Performance calculations done for an existing GTD-350 engine showed that constant-volume combustion process is valuable
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Arumugam, Sozhi, Pitchandi Kasivisvanathan, M. Arventh und P. Maheshkumar. „Effect of Re-Entrant and Toroidal Combustion Chambers in a DICI Engine“. Applied Mechanics and Materials 787 (August 2015): 722–26. http://dx.doi.org/10.4028/www.scientific.net/amm.787.722.
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This paper presents the experimental work to investigate the effect of Re-entrant and Toroidal combustion chambers in a DICI Engine. The two combustion chambers namely Re-entrant combustion chamber (RCC) and Toroidal combustion chamber (TCC) were fitted in a 4.4 kW single cylinder Direct Injection Compression Ignition (DICI) engine and tests were conducted with diesel. The influences of the combustion chamber geometry characteristics on combustion, performance and emissions characteristics have been investigated. This investigation shows the peak pressure of re-entrant chamber is higher than that of toroidal chamber. The heat release rate and brake thermal efficiency for re-entrant chamber are slightly higher than that of toroidal chamber. Specific fuel consumption is lower for toroidal chamber than that of re-entrant chamber. The enhancement in reduction of carbon monoxide, hydrocarbon is observed for Re-entrant chamber compared to the Toroidal chamber. Oxides of nitrogen are reduced for toroidal chamber than that of re-entrant chamber.
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Komarov, I. I., D. M. Kharlamova, A. N. Vegera und V. Y. Naumov. „Study on effect CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers“. Vestnik IGEU, Nr. 2 (30.04.2021): 14–22. http://dx.doi.org/10.17588/2072-2672.2021.2.014-022.
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Studying closed gas turbine cycles on supercritical carbon dioxide is currently a promising issue in the development of power energy sector in terms of increasing energy efficiency and minimizing greenhouse gas emissions into the atmosphere. Combustion of methane with oxygen in the combustion chamber occurs not in the nitrogen environment, but in the environment of carbon dioxide, that is the working fluid of the cycle, which is an inhibitor of chemical reactions. A large mass content of such a diluent of the reaction mixture in the volume of the chamber leads to the risks of significant chemical underburning, efficiency decrease of the combustion chamber and the cycle as a whole. The aim of the research is to study the kinetic parameters of the combustion of methane with oxygen in a supercritical CO2 diluent medium to ensure reliable and stable combustion of fuel by assessing the degree of the inhibitory effect of CO2 and determining its permissible amount in the active combustion zone of the combustion chamber. The research method is a numerical simulation of turbulent-kinetic processes of methane combustion in the combustion chamber using the reduced methane combustion mechanism. Ansys Fluent software package has been used. The authers have studied the impact of CO2 diluent on fuel cоmbustion in methane-oxygen combustion chambers. It is found that the combustor flame stabilization takes place if the content of СО2 diluent supplied to the mixture with oxidizer is 0,46–0,5 of mass fraction; additional СО2 diluent forms local low temperature zones which slow down the combustion process. When this happens, adding cooling СО2 into the flame stabilization zone should be eliminated. The study has found that no more than 20 % of the total carbon dioxide content should be supplied to the combustion chamber; to stabilize the flame and reduce its length, it is necessary to install blades to swirl the fuel and oxidizer mixed with CO2 at the inlet of the combustion chamber; CO2 supply for cooling should be carried out not less than 130 mm away from the burner mouth.
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Козел, Дмитрий Викторович. „Выбор геометрических характеристик фронтового устройства и длины камеры сгорания прямоточного типа“. Aerospace technic and technology, Nr. 4sup2 (27.08.2021): 19–28. http://dx.doi.org/10.32620/aktt.2021.4sup2.03.
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A method has been developed for selecting the geometric characteristics of the front and the length of the direct-flow combustion chamber. Afterburner combustion chambers are of the ramjet type and are used for a short-term increase in the thrust of a gas turbine engine during takeoff, for overcoming the sound barrier by an aircraft and for flying at supersonic speed, and for making maneuvers. As part of ramjet engines, ramjet combustion chambers are used as the main combustion chambers in which the process of fuel combustion and heat supply to the working fluid is ensured. The developed method for selecting the geometric characteristics consists in optimizing the main operating characteristics of the combustion chamber. Mathematical models are proposed for describing the dependence of the total pressure loss, the combustion efficiency and the range of stable operation of the combustion chamber against the parameters of the flow at the inlet to the combustion chamber and the geometric characteristics of the front device and the length of the combustion chamber. The analysis of the dependences of the combustion chamber working characteristics on the geometric characteristics of the front-line device and its length is carried out. As a result of the analysis of mathematical models, a list of the main geometric characteristics of the front device was determined, on which the total pressure loss, the combustion efficiency and the range of stable operation of the combustion chamber depend. Optimization parameters, optimization criterion and limits for solving the optimization problem are determined. As an implementation of the optimization method, it is proposed to use a diagram of the combustion chamber performance in the coordinates of the optimization parameters. The developed method makes it possible to ensure the optimal basic operating characteristics of the combustion chamber - total pressure loss, combustion efficiency and combustion stability limits.
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Pošta, J., B. Kadleček und T. Hladík. „Engine combustion chamber tightness diagnostics“. Research in Agricultural Engineering 49, No. 3 (08.02.2012): 115–18. http://dx.doi.org/10.17221/4961-rae.
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The modern combustion engines and their systems are getting more complicated and sophisticated nowadays. It is no more possible to verify their function or actual technical state directly. Thus various methods of indirect diagnostics are being developed more and more rapidly. The on-board diagnostics is being increasingly applied to monitor and measure suitable diagnostic signals during operation, deviations from required or expected values are then recorded. This trend requires the application of completely disassembly-free techniques of measurements and the real-time analyzing of measured figures. This paper presents the results of the research on relation between the starter’s starting current and the engine combustion chamber tightness. The experiments were carried out for common four-cylinder engine.
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Naeemi, Saeed, und Seyed Abdolmehdi Hashemi. „Numerical investigations on the liftoff velocity of H2-air premixed combustion in a micro-cylindrical combustor with gradually changed section area“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, Nr. 17 (25.03.2020): 3497–508. http://dx.doi.org/10.1177/0954406220914925.
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Sustaining and stabilizing flames are crucial issues in micro-combustion. In some micro-electro-mechanical systems such as the micro-thermophotovoltaic system, the flame should be formed in the combustion chamber, not outside it (combustion without liftoff). So, study of the liftoff phenomenon is important and vital in these systems. The aim of this study is to evaluate effect of changing combustor section area on the critical liftoff velocity in a micro-cylindrical combustor. For this purpose, the critical liftoff velocities are numerically identified for four combustor configurations (convergent, divergent, convergent-divergent and divergent-convergent combustion chamber). Premixed mixture of hydrogen-air has been used as reactants for the current investigation. Turbulence model implemented in this paper is RNG k-epsilon and combustion reaction was modeled with 10 species and 21 steps scheme using Eddy Dissipation Concept model. Two non-dimensional numbers d1/d2 (inlet to outlet diameter ratio) and d1/d3 (inlet to throat diameter ratio) are defined. For d1/d2 > 1.0, the combustion chamber is convergent, otherwise it is divergent. When d1/d3 > 1.0, the micro combustor is convergent-divergent and for d1/d3 < 1.0, the micro combustor is divergent-convergent. The results indicate that with increasing d1/d2, the liftoff occurs in a lower inlet flow velocity. With varying d1/d3, from 0.71 (2.0/2.8) to 1.0 (2.0/2.0), the liftoff velocity is reduced. Based on the numerical results, it can be said that the use of convergent and convergent-divergent combustion chamber decreases liftoff velocity. Meanwhile, the combustor with diverging and diverging-converging structure can enhance liftoff velocity. In the same condition, critical liftoff velocity of divergent-convergent micro combustor is the highest among all cases and this configuration is appropriate for Micro Electro-Mechanical Systems that work with high inlet velocity.
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Shang, Yong, Fu Shui Liu, Xiang Rong Li und Jing Wu. „Research on Parametric Design Method of Combustion Chamber on Diesel Engine“. Advanced Materials Research 383-390 (November 2011): 1431–40. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.1431.
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One method of parametric design on combustion chamber is used in this paper. Several independent geometrical parameters of ω type and double swirl combustion chamber are brought forward. Different series of ω type and double swirl combustion chambers have been designed by using this method. The effect of the independent geometrical parameters on the performance of diesel engine has been studied by using CFD code AVL FIRE. According to this method of parametric design and calculation result, two pistons with ω type and double swirl combustion chamber has been designed with the target of the highest indicated heat efficiency. The test result shows that, contrasting with ω type chamber, BSFC and main combustion duration of double swirl combustion chamber is lower by 7.5 and 6.9 percent respectively, while indicated heat efficiency is 7.1 percent higher. And the calculation result has coherence with the experiment. It is proved that the method of parametric design on combustion chamber can satisfy the requirement of designing. At the same time, this method can be extended to design other combustion chambers.
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Qian, Yu Fen, Yan Ying Xu und Ti Hai Xu. „Combustion Characteristics of a Helmholtz-Type Valveless Self-Excited Pulse Combustor“. Applied Mechanics and Materials 291-294 (Februar 2013): 1719–22. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.1719.
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Combustion characteristics of a Helmholtz-type valveless self-excited pulse combustor with continuous supply of gas and air were studied. The physical and mathematical models are established based on the actual pulse combustor, and the combustion characteristics are simulated with CFD. The results show that the possible re-ignition sources for the pulse combustion may be three. The first source may be the hot remnant gas near gas/air mixture. The second re-ignition source may be the high-temperature combustion chamber wall. The third ignition source is the unburned mixture. The pressure, temperature and mass fraction of propane in the combustion chamber have the phase relations and the combustion process stimulates the acoustic oscillation.
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Hernando, Carmen M., André VG Cavalieri, Pedro T. Lacava und Rogério Corá. „Thermoacoustic analysis of combustion chambers with varying temperature: Numerical solutions and comparison with experiments“. International Journal of Aeroacoustics 18, Nr. 2-3 (05.12.2018): 351–67. http://dx.doi.org/10.1177/1475472x18812799.
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In the present work, a numerical and experimental study of the thermoacoustic instabilities of a combustor is performed. The numerical model is represented by the one-dimensional linearised Euler Equation and an n-τ formulation for flame transfer function that describes the unsteady combustion response to these acoustic disturbances. This approach is similar to other simplified models present in the literature. However, most theoretical works assume a constant density and speed of sound in the medium, which is not realistic for combustion chambers, as the mean temperature is expected to decrease spatially as one moves away from the combustion area. Hence, to compare with experiments where chamber temperature is spatially varying, we developed a numerical solution procedure, seeking eigenvalues (complex-valued frequencies ω) indicating the stability characteristics of a given mode. Due to the non-linear dependence of the flame transfer function with ω, eigenvalues are found with a non-linear root-finding method. The acquired results met those obtained experimentally, indicating that the proposed model is capable of predicting the thermoacoustic behaviour of the combustion chamber.
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Duan, Run Ze, Zhi Ying Chen und Li Jun Yang. „Modeling and Simulation of Combustion Chamber“. Applied Mechanics and Materials 513-517 (Februar 2014): 3543–47. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.3543.
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The work process of oil fuel burner consists of atomization and combustion of oil. In this process, different atomization and air-distribution methods would affect the quality of combustion and then bring out problems of life-span of the burner, energy efficiency and environmental pollution. Therefore, in this paper, different air distribution devices and different sizes of nozzles are designed, and the numerical simulation software, Fluent 6.3, was employed to simulate the flow field of different conditions in combustor,. Through the simulation, the best work condition was achieved, which could help to provide optimization design parameters of the combustor.
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Marudhappan, Raja, Chandrasekhar Udayagiri und Koni Hemachandra Reddy. „Combustion chamber design and reaction modeling for aero turbo-shaft engine“. Aircraft Engineering and Aerospace Technology 91, Nr. 1 (07.01.2018): 94–111. http://dx.doi.org/10.1108/aeat-10-2017-0217.
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Purpose The purpose of this paper is to formulate a structured approach to design an annular diffusion flame combustion chamber for use in the development of a 1,400 kW range aero turbo shaft engine. The purpose is extended to perform numerical combustion modeling by solving transient Favre Averaged Navier Stokes equations using realizable two equation k-e turbulence model and Discrete Ordinate radiation model. The presumed shape β-Probability Density Function (β-PDF) is used for turbulence chemistry interaction. The experiments are conducted on the real engine to validate the combustion chamber performance. Design/methodology/approach The combustor geometry is designed using the reference area method and semi-empirical correlations. The three dimensional combustor model is made using a commercial software. The numerical modeling of the combustion process is performed by following Eulerian approach. The functional testing of combustor was conducted to evaluate the performance. Findings The results obtained by the numerical modeling provide a detailed understanding of the combustor internal flow dynamics. The transient flame structures and streamline plots are presented. The velocity profiles obtained at different locations along the combustor by numerical modeling mostly go in-line with the previously published research works. The combustor exit temperature obtained by numerical modeling and experiment are found to be within the acceptable limit. These results form the basis of understanding the design procedure and opens-up avenues for further developments. Research limitations/implications Internal flow and combustion dynamics obtained from numerical simulation are not experimented owing to non-availability of adequate research facilities. Practical implications This study contributes toward the understanding of basic procedures and firsthand experience in the design aspects of combustors for aero-engine applications. This work also highlights one of the efficient, faster and economical aero gas turbine annular diffusion flame combustion chamber design and development. Originality/value The main novelty in this work is the incorporation of scoops in the dilution zone of the numerical model of combustion chamber to augment the effectiveness of cooling of combustion products to obtain the desired combustor exit temperature. The use of polyhedral cells for computational domain discretization in combustion modeling for aero engine application helps in achieving faster convergence and reliable predictions. The methodology and procedures presented in this work provide a basic understanding of the design aspects to the beginners working in the gas turbine combustors particularly meant for turbo shaft engines applications.
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Kidoguchi, Y., M. Sanda und K. Miwa. „Experimental and Theoretical Optimization of Combustion Chamber and Fuel Distribution for the Low Emission Direct-Injection Diesel Engine“. Journal of Engineering for Gas Turbines and Power 125, Nr. 1 (27.12.2002): 351–57. http://dx.doi.org/10.1115/1.1501077.
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Effects of combustion chamber geometry and initial mixture distribution on the combustion process were investigated in a direct-injection diesel engine. In the engine experiment, a high squish combustion chamber with a squish lip could reduce both NOx and particulate emissions with retarded injection timing. According to the results of CFD computation and phenomenological modeling, the high squish combustion chamber with a central pip is effective to keep the combusting mixture under the squish lip until the end of combustion and the combustion region forms rich and highly turbulent atmosphere. This kind of mixture distribution tends to reduce initial burning, resulting in restraint of NOx emission while keeping low particulate emission.
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Ghirardo, G., M. P. Juniper und J. P. Moeck. „Weakly nonlinear analysis of thermoacoustic instabilities in annular combustors“. Journal of Fluid Mechanics 805 (16.09.2016): 52–87. http://dx.doi.org/10.1017/jfm.2016.494.
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Rotationally symmetric annular combustors are of practical importance because they generically resemble combustion chambers in gas turbines, in which thermoacoustically driven oscillations are a major concern. We focus on azimuthal thermoacoustic oscillations and model the fluctuating heat release rate as being dependent only on the local pressure in the combustion chamber. We study the dynamics of the annular combustor with a finite number of compact flames equispaced around the annulus, and characterize the flames’ response with a describing function. We discuss the existence, amplitude and the stability of standing and spinning waves, as a function of: (i) the number of the burners; (ii) the acoustic damping in the chamber; (iii) the flame response. We present the implications for industrial applications and the future direction of investigations. We then present as an example the first theoretical study of thermoacoustic triggering in annular combustors, which shows that rotationally symmetric annular chambers that are thermoacoustically unstable do not experience only stable spinning solutions, but can also experience stable standing solutions. We finally test the theory on one experiment with good agreement.
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Patsch, Marek, und Peter Pilát. „Simulation of Combustion Air Flow in the Gasification Biomass Boiler“. MATEC Web of Conferences 168 (2018): 02015. http://dx.doi.org/10.1051/matecconf/201816802015.
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The article deals with the optimization of biomass combustion in a small heat source by means of an optimal distribution of combustion air. The uneven distribution of combustion air has been observed in certification tests and in real operation of used heat source and it has an influence on uneven combustion of biomass in the gasification chamber, on increase emissions and combustion losses. At this stage of the research, optimization of the combustion air distribution is performed by CFD simulations, which will be later verified by PIV measuring of the velocity fields in gasification and combustion chambers of the experimental heat source. CFD simulations and subsequent PIV measurements on the experimental device are realized without real combustion, only the air flow in the empty gasification chamber and in the combustion chamber is investigated. This approach has been chosen to simplify calculations and experiments, and on the assumption that when the combustion air distribution is optimal in empty chambers, it will be optimal even during real combustion. The primary air flow in the gasification chamber is in real operation affected by the size and shape of the inserted biomass and its placement in chamber and this effect is accidental and difficult to verifiable.
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Zhang, Cheng Cheng, Qian Wang, Zhi Xia He und Ping Jiang. „Simulation Research on Matching of Spray and Combustion Chamber Geometry in Diesel Engine“. Advanced Materials Research 199-200 (Februar 2011): 193–97. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.193.
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In order to investigate the influence of combustion chamber geometry on spray and combustion characteristics in diesel engine, universal CFD software STAR-CD is applied to simulate the combustion processes in three different types of combustion chambers of diesel engine. The effect of combustion chamber geometry on in–cylinder air motion, temperature field and exhaust emissions are researched in this paper. Comparing with experimental results, calculation models are proved to be validity. The results show that differences of combustion chamber shape change the characteristic of flow field in cylinder, which affects the formation of mixed gas and determines the combustion and emission characteristics.
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DUMITRACHE, Alexandru, und Florin FRUNZULICA. „A NUMERICAL ANALYSIS OF COMBUSTION PROCESS IN AN AXISYMMETRIC COMBUSTION CHAMBER“. SCIENTIFIC RESEARCH AND EDUCATION IN THE AIR FORCE 18, Nr. 1 (24.06.2016): 433–40. http://dx.doi.org/10.19062/2247-3173.2016.18.1.59.
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Lee, Dae Hoon, Dae-Eun Park, Euisik Yoon und Sejin Kwon. „A MEMS Piston-Cylinder Device Actuated by Combustion“. Journal of Heat Transfer 125, Nr. 3 (20.05.2003): 487–93. http://dx.doi.org/10.1115/1.1565095.
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Combustion measurement in a cylindrical micro combustor, the construction procedure and test run of a MEMS reciprocating device are described. The sizing of the MEMS device was based on the findings of combustion measurements. Thermodynamic analysis of the pressure measurement resulted in available work up to 2.4 Joules in a combustor height of 2 mm and more with combustion efficiency of 0.6∼0.7. With combustor height less than 2 mm, combustion was incomplete due to excessive heat loss to the wall. In order to achieve the chamber height imposed by the combustion measurement, a fabrication process and wafer material that allow deeper etching was used.
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Wang, Yun, und Zhuo Xiong Zeng. „Numerical Simulation of Combusting Flow Field in Ram-Compressed Rotor Chamber“. Advanced Materials Research 291-294 (Juli 2011): 2857–60. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.2857.
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The rotating ramjet is a new conceptive engine based on the ram-compressed technology rely on high-speed rotating rotor, the engine’s core component is an internal combustion rotor, which has the functions of compressing air, combusting and doing work by exhausting. In order to predict the combusting flow field in Ram-compressed Rotor chamber, the model of Ram-compressed Rotor was set up. The fuel composition was defined in software prePDF. Realizable was used for the gas phase turbulence. Fuel particles phase makes use of stochastic tracking model. The Structure characteristics of the combusting flow field and temperature field were found out by numerical simulation. The numerical simulation results show that the combusting flow field in the Ram-compressed Rotor Chamber has simple inlet and outlet is well, and offer the references to the design of combustion chamber especially the contour design of the scramjet nozzle.
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Song, Ruitao, Gerald Gentz, Guoming Zhu, Elisa Toulson und Harald Schock. „A control-oriented model of turbulent jet ignition combustion in a rapid compression machine“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, Nr. 10 (13.11.2016): 1315–25. http://dx.doi.org/10.1177/0954407016670303.
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Turbulent jet ignition combustion is a promising concept for achieving high thermal efficiency and low NOx (nitrogen oxides) emissions. A control-oriented turbulent jet ignition combustion model with satisfactory accuracy and low computational effort is usually a necessity for optimizing the turbulent jet ignition combustion system and developing the associated model-based turbulent jet ignition control strategies. This article presents a control-oriented turbulent jet ignition combustion model developed for a rapid compression machine configured for turbulent jet ignition combustion. A one-zone gas exchange model is developed to simulate the gas exchange process in both pre- and main-combustion chambers. The combustion process is modeled by a two-zone combustion model, where the ratio of the burned and unburned gases flowing between the two combustion chambers is variable. To simulate the influence of the turbulent jets on the rate of combustion in the main-combustion chamber, a new parameter-varying Wiebe function is proposed and used for the mass fraction burned calculation in the main-combustion chamber. The developed model is calibrated using the least-squares fitting and optimization procedures. Experimental data sets with different air-to-fuel ratios in both combustion chambers and different pre-combustion chamber orifice areas are used to calibrate and validate the model. The simulation results show good agreement with the experimental data for all the experimental data sets. This indicates that the developed combustion model is accurate for developing and validating turbulent jet ignition combustion control strategies. Future work will extend the rapid compression machine combustion model to engine applications.
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Rajesh, T. N., T. J. S. Jothi und T. Jayachandran. „Preliminary Studies on Non-Reactive Flow Vortex Cooling“. Recent Patents on Mechanical Engineering 12, Nr. 3 (26.09.2019): 262–71. http://dx.doi.org/10.2174/2212797612666190510115403.
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Background: The impulse for the propulsion of a rocket engine is obtained from the combustion of propellant mixture inside the combustion chamber and as the plume exhausts through a convergent- divergent nozzle. At stoichiometric ratio, the temperature inside the combustion chamber can be as high as 3500K. Thus, effective cooling of the thrust chamber becomes an essential criterion while designing a rocket engine. Objective: A new cooling method of thrust chambers was introduced by Chiaverni, which is termed as Vortex Combustion Cold-Wall Chamber (VCCW). The patent works on cyclone separators and confined vortex flow mechanism for providing high propellant mixing with improved degree of turbulence inside the combustion chamber, providing the required notion for studies on VCCW. The flow inside a VCCW has a complex structure characterised by axial pressure losses, swirl velocities, centrifugal force, flow reversal and strong turbulence. In order to study the flow phenomenon, both the experimental and numerical investigations are carried out. Methods: In this study, non-reactive flow analysis was conducted with real propellants like gaseous oxygen and hydrogen. The test was conducted to analyse the influence of mixture ratio and injection pressure of the propellants on the chamber pressure in a vortex combustion chamber. A vortex combustor was designed in which the oxidiser injected tangentially at the aft end near the nozzle spiraled up to the top plate and formed an inner core inside the chamber. The fuel was injected radially from injectors provided near the top plate and the propellants were mixed in the inner core. This resulted in enhanced mixing and increased residence time for the fuel. More information on the flow behaviour has been obtained by numerical analysis in Fluent. The test also investigated the sensitivity of the tangential injection pressure on the chamber pressure development. Results: All the test cases showed an increase in chamber pressure with the mixture ratio and injection pressure of the propellants. The maximum chamber pressure was found to be 3.8 bar at PC1 and 2.7 bar at PC2 when oxidiser to fuel ratio was 6.87. There was a reduction in chamber pressure of 1.1 bar and 0.7 bar at PC1 and PC2, respectively, in both the cases when hydrogen was injected. A small variation in the pressure of the propellant injected tangentially made a pronounced effect on the chamber pressure and hence vortex combustion chamber was found to be very sensitive to the tangential injection pressure. Conclusion: VCCW mechanism has been to be found to be very effective for keeping the chamber surface within the permissible limit and also reducing the payload of the space vehicle.
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Gonzalez-Duran, Jose Eli Eduardo, Alejandro Estrada-Baltazar und Leonel Lira-Cortes. „Development of combustion chamber of a reference calorimeter with numerical analysis“. ACTA IMEKO 4, Nr. 4 (23.12.2015): 26. http://dx.doi.org/10.21014/acta_imeko.v4i4.265.
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<p class="Abstract">The present work focuses on the numerical modeling of two combustion chambers to be used inside an isoperibolic calorimeter to measure the Superior Calorific Value (SCV) from natural gas. This work shows performance of both chambers working under isoperibolic principle, through simulations based on Computational Fluid Dynamics (CFD). The aim of the work is expose the performance of chamber combustion published in the literature versus another one proposed in this work, and show how was improved the performance of the chamber which proposed in this work by changing the geometry. And it is checked by analyzing temperature of burned gases at exit of combustion chamber.</p>
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Fortunato, Valentina, Andres Giraldo, Mehdi Rouabah, Rabia Nacereddine, Michel Delanaye und Alessandro Parente. „Experimental and Numerical Investigation of a MILD Combustion Chamber for Micro Gas Turbine Applications“. Energies 11, Nr. 12 (01.12.2018): 3363. http://dx.doi.org/10.3390/en11123363.
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In the field of energy production, cogeneration systems based on micro gas turbine cyclesappear particularly suitable to reach the goals of improving efficiency and reducing pollutants.Moderate and Intense Low-Oxygen Dilution (MILD) combustion represents a promising technologyto increase efficiency and to further reduce the emissions of those systems. The present work aims atdescribing the behavior of a combustion chamber for a micro gas turbine operating in MILD regime.The performances of the combustion chamber are discussed for two cases: methane and biogascombustion. The combustor performed very well in terms of emissions, especially CO and NOx,for various air inlet temperatures and air-to-fuel ratios, proving the benefits of MILD combustion.The chamber proved to be fuel flexible, since both ignition and stable combustion could be achievedby also burning biogas. Finally, the numerical model used to design the combustor was validatedagainst the experimental data collected. The model performs quite well both for methane and biogas.In particular, for methane the Partially Stirred Reactor (PaSR) combustion model proved to be thebest choice to predict both minor species, such as CO, more accurately and cases with lower reactivitythat were not possible to model using the Eddy Dissipation Concept (EDC). For the biogas, the mostappropriate kinetic mechanism to properly model the behavior of the chamber was selected
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KAEWKOHKIAT, Yingyong, Smith EIAMSA-ARD, Khwanchit WONGCHAREE, D. THUNGSOTANON und Pongjet PROMVONGE. „D102 COMBUSTION OF RICE HUSK IN A FLUIDIZED BED COMBUSTOR WITH WAVY-SURFACED CHAMBERS(Biomass-1)“. Proceedings of the International Conference on Power Engineering (ICOPE) 2009.1 (2009): _1–195_—_1–199_. http://dx.doi.org/10.1299/jsmeicope.2009.1._1-195_.
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Chen, Yi, Li Fei, Liming He, Lei Zhang, Chunchang Zhu und Jun Deng. „The Influence of Dielectric Barrier Discharge Plasma on the Characteristics of Aero-Engine Combustion Chamber“. Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, Nr. 2 (April 2019): 369–77. http://dx.doi.org/10.1051/jnwpu/20193720369.
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A test platform was developed to investigate the performance of aero-engine combustor by the dielectric barrier discharge (DBD) plasma assisted combustion (PAC) in the simulated maximum condition. Conventional combustion experiments and plasma-assisted combustion conditions were conducted to study the effect of PAC on the performances including average outlet temperature, combustion efficiency and pattern factor under four different excessive air coefficients five different voltages. The comparative experiment shows that the combustion efficiency is improved after PAC compared with the normal conditions, the combustion efficiency of PAC increases 2.31% in the fuel-rich condition when Up-p is 40 kV. The uniformity of the outlet temperature field is also improved after PAC, the decrease of the pattern factor is more than 5% in the fuel-rich condition. These results offer certain reference value for the future application of PAC in aero-engine combustor and improving its performance.
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Lee, Y. W., und T. L. Jiang. „Effects of Fuel Impingement-Cooling on the Combustion Flow in a Small Bipropellant Liquid Rocket Thruster“. Journal of Mechanics 31, Nr. 2 (23.01.2015): 161–70. http://dx.doi.org/10.1017/jmech.2014.81.
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ABSTRACTIn the present study, a three-dimensional computer code, based on the computer software KIVA-3, was developed for the combustion-flow simulation of a bipropellant liquid rocket thruster. A jets-impingement model is proposed for the unlike-doublet jet impingement issue. The computer code is employed to simulate a small bipropellant liquid rocket engine installed with three unlike-doublet injectors of NTO and MMH as well as six fuel injectors injecting MMH toward the combustor wall for cooling. Effects of the fuel-injection cooling on the combustion flow, combustion efficiency, and wall temperature were investigated. The results obtained from the present study show that under the present injector configuration and a constant total fuel-flow rate, higher cooling-fuel ratios make the atomized mixing flow of NTO and MMH shift toward the combustor wall, resulting in lower combustion efficiency and chamber pressure; however, low cooling-fuel ratios are unable to keep the wall-temperature sufficiently low. To overcome this issue, the proposed three-dimensional computer code calculates/locates the optimal cooling-fuel ratio that bears high combustion efficiency for a bipropellant liquid rocket combustor while keeping the chamber wall sufficiently cool.
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Pries, Michael, Andreas Fiolitakis und Peter Gerlinger. „Numerical Investigation of a High Momentum Jet Flame at Elevated Pressure: A Quantitative Validation with Detailed Experimental Data“. Journal of the Global Power and Propulsion Society 4 (18.12.2020): 264–73. http://dx.doi.org/10.33737/jgpps/130031.
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The development of efficient low emission combustion systems requires methods for an accurate and reliable prediction of combustion processes. Computational Fluid Dynamics (CFD) in combination with combustion modelling is an important tool to achieve this goal. For an accurate computation adequate boundary conditions are crucial. Especially data for the temperature distribution on the walls of the combustion chamber are usually not available. The present work focuses on numerical simulations of a high momentum jet flame in a single nozzle FLOX® type model combustion chamber at elevated pressure. Alongside the balance equations for the fluid the energy equation for the solid combustor walls is solved. To assess the accuracy of this approach, the temperature distribution on the inner combustion chamber wall resulting from this Conjugate Heat Transfer (CHT) simulation is compared to measured wall temperatures. The simulation results within the combustion chamber are compared to detailed experimental data. This includes a comparison of the flow velocities, temperatures as well as species concentrations. To further assess the benefit of including the solid domain in a CFD simulation the results of the CHT simulation are compared to results of a CFD computation where constant temperatures are assumed for all walls of the combustion chamber.
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Seume, J. R., N. Vortmeyer, W. Krause, J. Hermann, C. C. Hantschk, P. Zangl, S. Gleis, D. Vortmeyer und A. Orthmann. „Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine“. Journal of Engineering for Gas Turbines and Power 120, Nr. 4 (01.10.1998): 721–26. http://dx.doi.org/10.1115/1.2818459.
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During the prototype shop tests, the Model V84.3A ring combustor gas turbine unexpectedly exhibited a noticeable “humming” caused by self-excited flame vibrations in the combustion chamber for certain operating conditions. The amplitudes of the pressure fluctuations in the combustor were unusually high when compared to the previous experience with silo combustor machines. As part of the optimization program, the humming was investigated and analyzed. To date, combustion instabilities in real, complex combustors cannot be predicted analytically during the design phase. Therefore, and as a preventive measure against future surprises by “humming,” a feedback system was developed which counteracts combustion instabilities by modulation of the fuel flow rate with rapid valves (active instability control, AIC). The AIC achieved a reduction of combustion-induced pressure amplitudes by 86 percent. The Combustion instability in the Model V84.3A gas turbine was eliminated by changes of the combustor design. Therefore, the AIC is not required for the operation of customer gas turbines.
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Chand, Dharmahinder Singh, Daamanjyot Barara, Gautam Ganesh und 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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Komarov, E. M. „Methods for Reducing Emission of Harmful Substances in the Combustion Chambers of GTE and GTP“. Mechanical Engineering and Computer Science, Nr. 5 (21.06.2018): 9–29. http://dx.doi.org/10.24108/0518.0001394.
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A combustion chamber, as one of the crucial GTE components, plays a significant role in ensuring its environmental characteristics. Therefore, understanding the mechanisms of forming harmful substances (pollutants) and a possibility to predict their emission values, when changing the engine operation parameters and the external conditions, are some of the key issues to ensure ICAO (International Civil Aviation Organization) standards. The solution of these issues allows us to estimate the emission characteristics at the stage of engine design and to develop effective methods for preventing the formation of air pollutants, as well as to increase the efficiency of burning fuels. Since the first limitation introduced by the Committee on Aviation Environmental Protection (CAEP / 1) in 1986 there were several amendments. The (CAEP / 8) standard, which has come into force since January 1, 2014, is already being ready to be replaced by more stringent requirements, i.e. reducing emissions of nitrogen oxides (NOx) by 40% by 2020 (as compared to the (CAEP / 2). As to other pollutants (CO, HC, SN), the trend is similar.Main difficulties in creating combustion chambers with low-emission pollutants arise from the fact that reducing CO and NOx requires mutually opposite measures. A rational combustion chamber design should represent some trade-off between the requirements arising from the task of reducing emissions of these two groups of polluting components. This can be achieved through improving operation of the primary, burnout, and mixing zones, rationally chosen volume of the flame tube (FT), and residence time in the combustion chamber.To have a clearer idea of possible ways to reduce pollutant emission of the GTE combustion chamber, it is necessary to take into account the basic mechanisms of their formation.The main methods of reducing CO emission are based on the physical-and-chemical patterns of its formation:Supporting the mixture composition in the combustion zone to be closer to α = 1.1 ... 1.3;Increasing the combustion zone volume and the residence time in it.The above methods of reducing CO emissions are difficult to implement in low-emission combustion chambers because their using leads to the sharp increase of NOх formation. It is found that only in a very narrow temperature range (flame temperature Тпл = 1650 ... 1900 K) desirable levels of NOх and CO emissions can be simultaneously achieved.To reduce the level of NOх emission, are used the following approaches:- liquid fuel combustion implemented at a small length of FT with a residence time in the high temperature zone (over 1920 K) 5 ... 6 milliseconds followed by intensive quench in the mixing zone, that is, the principle of "quick burn and quick quench» is used;- fuel combustion at the temperature of 1750 ± 50 K (i.e. below 1920 K), with an outlet temperature pattern formed through the air feed in the mixing zone or- from the zone of a combustion chamber flame tube head with no quench of product of combustion.The analytical results of a total scope of developments in reducing pollutant emissions allow us to distinguish the following standard fuel combustion technologies in GTE combustion chambers, which meet the available environmental requirements:1) use of burning the lean pre-mixed fuel in "dry" combustion chambers (This technology process uses the following schemes: RQL (Rich-Quench-Lean) – rich mixture combustion, followed by rapid air blending and lean mixture afterburning; LPP (Lean Premixed Pre-vaporized) - combustion of a lean premixed and vaporized mixture; LDI (Lean Direct-Injection) - combustion with lean mixture injection directly into the combustion zone;2) catalytic combustion of a fuel-air mixture;3) use of "wet" combustion chambers with diffusion flame and water injection (steam);4) additional use of catalytic cleaning of GTP outlet gases.At present, natural gas combustion chambers with emission of NOx and CO <10ppm are under design. This is almost the lowest achievable level for the operating conditions under consideration. In designing such combustion chambers a main task is to develop and improve methods that allow calculating the combustion kinetics of a gas mixture, improving the software systems for calculating and obtaining reliable data on emission of harmful substances, and also to develop experimental methods for creating and full-scale engineering of the low-emission combustion chambers for stationary units and advanced aircraft engines. The presented methods for reducing emission of harmful substances, namely improving techniques to feed fuel, zone arrangement of combustion, use of catalysts in the combustion chamber and at the outlet of the plant, when used, should result not only to reducing emissions, but also to improving the other important combustion chamber characteristics, especially extension of steady combustion limits. Studies to obtain ultra-low emission levels, based on the burning concept of the lean homogeneous mixture in the combustion chamber, are at an early stage. It is necessary to solve a number of important problems, such as a problem of «lean» flameout, of flash back, and also ensuring a sufficient evaporation of fuel and its mixing with air.
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Rajashekhar, Chandrashekharapua Ramachandraiah, Tumkur Krishnamurthy Chandrashekar, Chebbiyyan Umashankar und Rajagopal Harish Kumar. „STUDIES ON EFFECTS OF COMBUSTION CHAMBER GEOMETRY AND INJECTION PRESSURE ON BIODIESEL COMBUSTION“. Transactions of the Canadian Society for Mechanical Engineering 36, Nr. 4 (Dezember 2012): 429–38. http://dx.doi.org/10.1139/tcsme-2012-0030.
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Combustion of biodiesels has inherent problems due to their high viscosity and low volatility. This paper relates the modification of engine combustion chamber design, for inducing turbulence to improve the combustibility of combustible mixture. A survey of literature shows that experimental studies have not been done on a tri-chambered piston for evaluating influence on the performance and emission characteristics using diesel blends as well. The objective of this work is to study the effect of combustion chamber geometry and injection pressure on performance and emissions of a biodiesel (Jatropha) fuelled multi-chambered piston diesel engine. The performance and emission characteristics were studied and it has been noticed that for the engine under consideration 200 bar injection pressure gives optimum performance.
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Yu, Xin, Zhen Cao, JiangBo Peng, Yang Yu, Guang Chang, Yufei Ma, XiaoHui Li, Chaobo Yang und ZhiQiang Wang. „Statistical Analysis of Flame Oscillation Characterization of Oxy-Fuel in Heavy Oil Boiler Using OH Planar Laser-Induced Fluorescence“. Journal of Spectroscopy 2019 (02.07.2019): 1–10. http://dx.doi.org/10.1155/2019/7085232.
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The present work investigated the flame structures and oscillations of oxy-fuel combustions in a heavy oil boiler using OH planar laser-induced fluorescence imaging. Combustion instabilities, such as flame oscillation and combustion fluctuation, can assess the performance of an industrial burner in the boiler. The peak position variation in OH concentration was associated with the change of the reaction zone that corresponded with the fluctuation of the heat-release zone in the combustion chamber, which provides a valuable reference for the design of the combustion chamber. The experimental results suggest that the phenomenon of stratified flame combustion is related to the characteristic of flame oscillation. The substitution of N2 with CO2 will not significantly influence the flame oscillation frequency but increases the number of flame surface. As O2 concentration increased in the O2/CO2 atmosphere, the phenomenon of stratified flame combustion disappeared, and the flame presented an island-like structure. The bimodal oscillation of the combustion center was demonstrated by means of the probability density method; CO2 played a role in the extension of the combustion center. The combustion fluctuation of inner regions was quantitatively described; CO2 could maintain interregional stabilization to some extent. Compared with traditional measurement methods, PLIF technology has great advantages in evaluating burner performance and optimizing the design of the combustion chamber.
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Pan, J. F., Z. Y. Hou, Y. X. Liu, A. K. Tang, J. Zhou, X. Shao, Z. H. Pan und Q. Wang. „Design and working performance study of a novel micro parallel plate combustor with two nozzles for micro thermophotovotaic system“. Thermal Science 19, Nr. 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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Pielecha, Ireneusz, Krzysztof Wislocki, Wojciech Cieslik und Lukasz Fiedkiewicz. „Prechamber selection for a two stage turbulent jet ignition of lean air-gas mixtures for better economy and emission“. E3S Web of Conferences 70 (2018): 03010. http://dx.doi.org/10.1051/e3sconf/20187003010.
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The paper presents the results of thermodynamic and exhaust emission analyses of the combustion process using three combustion chambers. The combustion process research was performed on a single-cylinder AVL 5804 engine equipped with a dual-band compressed natural gas system supplied at different fuel pressures to the inlet channel and to the pre-chamber. Based on the performed analyses, the thermodynamic indicators of the combustion process and the emission factors were determined. Having the thermodynamic and emission analyses of the Turbulent Jet Ignition (TJI) combustion system, the pre-chamber was selected with the best collective features. The selection of the best chamber was made using the weighted-purpose method for average indicated pressure, CO and NOx emissions as well as the indicated engine efficiency, taking into account the impact factors.
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Sengupta, Anal Ranjan, R. Gupta und A. Biswas. „Computational Fluid Dynamics Analysis of Stove Systems for Cooking and Drying of Muga Silk“. Emerging Science Journal 3, Nr. 5 (01.10.2019): 285–92. http://dx.doi.org/10.28991/esj-2019-01191.
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In India, Silk industry plays an important part in textile industry. Muga silk, the golden yellow silk is quite unique to Assam, North-east India where its production is regarded as an important tool for economic development. But, outdated manufacturing technology is followed during the silk production in Assam. The existing cooking process of silk cocoons consists of boiling of silk cocoons in a stainless steel vessel along with water and soda in an open fireplace which is highly energy inefficient. Therefore, two modified systems have been designed; one having cylindrical boiling chamber (vessel) and the other having spherical boiling chamber (vessel). Both the chambers are having a cocoon heating chamber associated with them for cooking and drying of silk cocoons simultaneously. These designs are further classified into two types of designs based on channel and nozzle type combustion chambers. Therefore, the main objective of this paper is to improve the existing designs to maximize the utilization of heat carried by the combustion gases. These modified systems are analysed by using Computational Fluid Dynamics (CFD) selecting standard k–є model. From the analysis, it is seen that these new systems having nozzle type combustion chambers are more efficient than the systems having cylindrical combustion chambers and if these systems are used in silk production, it will be very beneficial for the silk industry as well as for our society.
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Gao, Huanhuan, Zaiguo Fu, Zhuoxiong Zeng, Jiang Liu und Peifen Weng. „Effects of Swirling Strength of the Premixed Gas Flow on Pollutant Emission in a Heavy-Duty Gas Turbine“. E3S Web of Conferences 118 (2019): 04038. http://dx.doi.org/10.1051/e3sconf/201911804038.
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The combustion process and pollutant emission of an annular combustion chamber for a heavy-duty gas turbine were investigated by numerical method. The realizable k-ε model and finite rate/eddy dissipation model were adopted for calculations of turbulence and combustion. The effects of different swirling numbers of the double-swirler inlet on the temperature distribution and the thermal NOx formation in the combustion chamber were analyzed. The results show that the change of the swirling number of the outer swirling flow has a greater influence on the generation of the thermal NOx when compared with that of the inner swirling flow. The maximum average temperature of the central cross section of the combustor does not exceed 1760K. The average mass fraction of the generated thermal NOx at the exit decreases with the increasing outer swirling number. When the outer swirling number is less than 0.8, the generation of the thermal NOx is severe at the side wall of the combustion chamber.
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Tian, Hua, Jingchen Cui, Tianhao Yang, Yao Fu, Jiangping Tian und Wuqiang Long. „Experimental Research on Controllability and Emissions of Jet-Controlled Compression Ignition Engine“. Energies 12, Nr. 15 (31.07.2019): 2936. http://dx.doi.org/10.3390/en12152936.
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Low-temperature combustions (LTCs), such as homogeneous charge compression ignition (HCCI), could achieve high thermal efficiency and low engine emissions by combining the advantages of spark-ignited (SI) engines and compression-ignited (CI) engines. Robust control of the ignition timing, however, still remains a hurdle to practical use. A novel technology of jet-controlled compression ignition (JCCI) was proposed to solve the issue. JCCI combustion phasing was controlled by hot jet formed from pre-chamber spark-ignited combustion. Experiments were done on a modified high-speed marine engine for JCCI characteristics research. The JCCI principle was verified by operating the engine individually in the mode of JCCI and in the mode of no pre-chamber jet under low- and medium-load working conditions. Effects of pre-chamber spark timing and intake charge temperature on JCCI process were tested. It was proven that the combustion phasing of the JCCI engine was closely related to the pre-chamber spark timing. A 20 °C temperature change of intake charge only caused a 2° crank angle change of the start of combustion. Extremely low nitrogen oxides (NOx) emission was achieved by JCCI combustion while keeping high thermal efficiency. The JCCI could be a promising technology for dual-fuel marine engines.
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Hosseini, Seyed, Evan Owens, John Krohn und James Leylek. „Experimental Investigation into the Effects of Thermal Recuperation on the Combustion Characteristics of a Non-Premixed Meso-Scale Vortex Combustor“. Energies 11, Nr. 12 (04.12.2018): 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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Hwang, Won-Sub, Bu-Kyeng Sung, Woojoo Han, Kang Y. Huh, Bok Jik Lee, Hee Sun Han, Chae Hoon Sohn und Jeong-Yeol Choi. „Real-Gas-Flamelet-Model-Based Numerical Simulation and Combustion Instability Analysis of a GH2/LOX Rocket Combustor with Multiple Injectors“. Energies 14, Nr. 2 (13.01.2021): 419. http://dx.doi.org/10.3390/en14020419.
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A large eddy simulation (LES) and combustion instability analysis are performed using OpenFOAM for the multiple shear-coaxial injector combustor DLR-BKD (in German Deutsches Zentrum für Luft–Brennkammer D, German Aerospace Center–Combustion Chamber D), which is a laboratory-scale combustor operating in a real-gas environment. The Redlich–Kwong–Peng–Robinson equation of state and steady-laminar flamelet model are adopted in the simulation to accurately capture the real-gas combustion effects. Moreover, the stable combustion under the LP4 condition is numerically analyzed, and the characteristics of the combustion flow field are investigated. In the numerical simulation of the combustion instability, the instability is generated by artificially superimposing the 1st transverse standing wave solution on the stable combustion solution. To decompose the combustion instability mode, the dynamic mode decomposition method is applied. Several combustion instability modes are qualitatively and quantitatively identified through contour plots and graphs, and the sustenance process of the limit cycle is investigated.
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Wei, Sheng Li, Kun Peng Ji, Xian Yin Leng und Xuan Liu. „Numerical Analysis of Swirl Chamber Combustion System in DI Diesel Engines with the Conical-Spray“. Applied Mechanics and Materials 752-753 (April 2015): 922–27. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.922.
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In order to promote the quality of mixture and improve the fuel spray spatial distribution, enhancing airflow movement in a combustion chamber, a new swirl chamber combustion system in DI (direct injection) diesel engines is proposed based on conical-spray. Numerical simulations have been conducted by using the FIRE v2008 code. Several different widths of passage and spray angles are investigated in a single cylinder 135 diesel engine. The combustion and emissions performance were investigated by different conical-spray nozzles and combustion chambers with a constant compression ratio. The results show that using this combustion system, the mixture formation and combustion processes have been improved by a certain longitudinal swirl when the air is squished into the swirl chamber through the relative narrow passage. Moreover, the formation of homogeneous mixture is accelerated and the combustion is improved compared with that of conventional combustion system. The cases show the passage width of 5mm and conical spray cone angle of 140° has a better performance in the new combustion system.
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Nakata, T., M. Sato, T. Ninomiya und T. Hasegawa. „A Study on Low NOx Combustion in LBG-Fueled 1500°C-Class Gas Turbine“. Journal of Engineering for Gas Turbines and Power 118, Nr. 3 (01.07.1996): 534–40. http://dx.doi.org/10.1115/1.2816680.
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Developing integrated coal gasification combined-cycle systems ensures cost-effective and environmentally sound options for supplying future power generation needs. The reduction of NOx emissions and increasing the inlet temperature of gas turbines are the most significant issues in gas turbine development in Integrated Coal Gasification Combined Cycle (IGCC) power generation systems. The coal gasified fuel, which is produced in a coal gasifier of an air-blown entrained-flow type has a calorific value as low as 1/10 of natural gas. Furthermore, the fuel gas contains ammonia when a gas cleaning system is a hot type, and ammonia will be converted to nitrogen oxides in the combustion process of a gas turbine. This study is performed in a 1500°C-class gas turbine combustor firing low-Btu coal-gasified fuel in IGCC systems. An advanced rich-lean combustor of 150-MW class gas turbine was designed to hold stable combustion burning low-Btu gas and to reduce fuel NOx emissions from the ammonia in the fuel. The main fuel and the combustion air are supplied into a fuel-rich combustion chamber with strong swirl flow and make fuel-rich flame to decompose ammonia into intermediate reactants such as NHi and HCN. The secondary air is mixed with primary combustion gas dilatorily to suppress the oxidization of ammonia reactants in fuel-lean combustion chamber and to promote a reducing process to nitrogen. By testing under atmospheric pressure conditions, the authors have obtained a very significant result through investigating the effect of combustor exit gas temperature on combustion characteristics. Since we have ascertained the excellent performance of the tested combustor through our extensive investigation, we wish to report on the results.
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Erdiwansyah, Mahidin, Husni Husin, Nasaruddin, Muhtadin, Muhammad Faisal, Asri Gani, Usman und Rizalman Mamat. „Combustion Efficiency in a Fluidized-Bed Combustor with a Modified Perforated Plate for Air Distribution“. Processes 9, Nr. 9 (24.08.2021): 1489. http://dx.doi.org/10.3390/pr9091489.
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Combustion efficiency is one of the most important parameters especially in the fluidized-bed combustor. Investigations into the efficiency of combustion in fluidized-bed combustor fuels using solid biomass waste fuels in recent years are increasingly in demand by researchers around the world. Specifically, this study aims to calculate the combustion efficiency in the fluidized-bed combustor. Combustion efficiency is calculated based on combustion results from the modification of hollow plates in the fluidized-bed combustor. The modified hollow plate aims to control combustion so that the fuel incorporated can burn out and not saturate. The combustion experiments were tested using palm oil biomass solid waste fuels such as palm kernel shell, oil palm midrib, and empty fruit bunches. The results of the measurements showed that the maximum combustion temperature for the palm kernel shell fuel reached 863 °C for M1 and 887 °C for M2. The maximum combustion temperature measurements for M1 and M2 from the oil palm midrib fuel testing reached 898 °C and 858 °C, respectively, while the maximum combustion temperature for M1 and M2 from the empty fruit bunches fuel was 667 °C and M2 847 °C, respectively. The rate of combustion efficiency with the modification of the hole plate in the fluidized-bed combustor reached 96.2%. Thermal efficiency in fluidized-bed combustors for oil palm midrib was 72.62%, for PKS was 70.03%, and for empty fruit bunches was 52.43%. The highest heat transfer rates for the oil palm midrib fuel reached 7792.36 W/m2, palm kernel shell 7167.38 W/m2, and empty fruit bunches 5127.83 W/m2. Thus, the modification of the holed plate in the fluidized-bed combustor chamber showed better performance of the plate than without modification.
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Lee, Je Jun, Young Shin Lee, Jae Hoon Kim, Seong Woo Byun, Song Heo Koo und Soon Il Moon. „Thermal Strength Evaluation of the Super Alloy Structure with Various Thermal Insulation Performances by FEM and Stress-Rupture Experiment“. Key Engineering Materials 353-358 (September 2007): 1064–67. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1064.
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The combustor chamber, diffuser and nozzle are the main components of the ramjet engine. In this study, the thermal strength of the combustion chamber of the ramjet engine was evaluated. The combustion chamber consists of an Inconel alloy 718 liner and a 17-4Ph stainless steel housing. The liner is rapidly heated to a high temperature. The heated liner is cooled with a film cooling method that forms a cold boundary layer to separate the hot gas from the surface of the liner. The thermo-structural analysis is evaluated the thermal strength of super alloy structure with various thermal insulation performances by finite element method with code MSC/Nastran. The result of the analysis is compared with accelerated stress rupture test. The experiment is performed to get safety design and estimate actually life-time for combustor chamber under high temperature. In general, the work in this paper is helpful to further improve the understanding and evaluation of thermal strength of the super alloy structure with various thermal insulation performances.
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TULWIN, Tytus, Mirosław WENDEKER und Zbigniew CZYŻ. „The swirl ratio influence on combustion process and heat transfer in the opposed piston compression-ignition engine“. Combustion Engines 170, Nr. 3 (01.08.2017): 3–7. http://dx.doi.org/10.19206/ce-2017-301.
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In order to maximise engine heat efficiency an engines charge flow must be properly designed -especially its swirl and tumble ratio. A two-stroke compression-ignition opposed piston engine reacts to engine swirl differently compared to a standard automotive engine with axially symmetric combustion chamber. In order to facilitate direct fuel injection, high-pressure injectors must be positioned from the side of combustion chamber. Depending on the combustion chamber geometry the swirling gases impact greatly how the injection stream is formed. If the deformation is too high the high temperature combustion gases can hit the piston surface or get into gaps between the pistons. This greatly affects the heat lost to the pistons and raises their local temperature. More atomised injection stream is more prone to swirling gas flow due to its reduced droplet size and momentum. The paper presents simulation results and analyses for different intake process induced swirl ratios and different types of combustion chambers in an experimental aviation opposed piston engine.
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Kru¨ger, U., J. Hu¨ren, S. Hoffmann, W. Krebs, P. Flohr und D. Bohn. „Prediction and Measurement of Thermoacoustic Improvements in Gas Turbines With Annular Combustion Systems“. Journal of Engineering for Gas Turbines and Power 123, Nr. 3 (01.10.2000): 557–66. http://dx.doi.org/10.1115/1.1374437.
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Environmental compatibility requires low emission burners for gas turbine power plants. In the past, significant progress has been made developing low NOx and CO burners by introducing lean premixed techniques in combination with annular combustion chambers. Unfortunately, these burners often have a more pronounced tendency to produce combustion-driven oscillations than conventional burner designs. The oscillations may be excited to such an extent that the risk of engine failure occurs. For this reason, the prediction of these thermoacoustic instabilities in the design phase of an engine becomes more and more important. A method based on linear acoustic four-pole elements has been developed to predict instabilities of the ring combustor of the 3A-series gas turbines. The complex network includes the whole combustion system starting from both compressor outlet and fuel supply system and ending at the turbine inlet. The flame frequency response was determined by a transient numerical simulation (step-function approach). Based on this method, possible improvements for the gas turbine are evaluated in this paper. First, the burner impedance is predicted theoretically and compared with results from measurements on a test rig for validation of the prediction approach. Next, the burner impedance in a gas turbine combustion system is analyzed and improved thermoacoustically. Stability analyses for the gas turbine combustion system show the positive impact of this improvement. Second, the interaction of the acoustic parts of the gas turbine system has been detuned systematically in circumferential direction of the annular combustion chamber in order to find a more stable configuration. Stability analyses show the positive effect of this measure as well. The results predicted are compared with measurements from engine operation. The comparisons of prediction and measurements show the applicability of the prediction method in order to evaluate the thermoacoustic stability of the combustor as well as to define possible countermeasures.
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Xue, Xiao Chun, Yong Gang Yu und Qi Zhang. „Experimental Study on Expansion Process of High Pressure Twin Combustion-Gas Jets in Liquid“. Applied Mechanics and Materials 148-149 (Dezember 2011): 212–15. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.212.
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In order to investigate the multipoint ignition process and the combustion stability controlling mechanism of the bulk-loaded liquid propellant gun, the cylindrical stepped-wall observation chambers and cylindrical observation chambers are designed. The expansion process and interaction of high-speed twin combustion-gas jets in liquid are studied by high speed photographic system. The influence of chamber structure, nozzle diameter, dual-orifice interval, jet pressure on twin gas jets expansion process has been discussed.
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Judt, Wojciech. „Numerical and Experimental Analysis of Heat Transfer for Solid Fuels Combustion in Fixed Bed Conditions“. Energies 13, Nr. 22 (23.11.2020): 6141. http://dx.doi.org/10.3390/en13226141.
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The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner for hard coal and biomass combustion. During the research, a numerical and experimental study is performed. The analysis is prepared for various heat load of the combustion chamber, which allowed for the reconstruction of real working conditions for heating devices working with solid fuels combustion. The temperature distribution obtained by the experimental way is compared with results of the numerical modeling. Local distribution of principal heat transfer magnitudes like a heat flux density and a heat transfer coefficient that occurred on the sidewall of the combustion chamber is analyzed. The analysis showed, that the participation of convection and radiation in the overall heat transfer process has resulted from the heat load of the heating device. Research results may be used for improving an analytical approach of design process taking place for domestic and industrial combustion chambers.
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Wang, Hongcai, Hongru Fang, Bingqian Lou, Shitu Abubakar, Yuqiang Li und Lei Meng. „Exploring the Benefits of Annular Rectangular Rib for Enhancing Thermal Efficiency of Nonpremixed Micro-Combustor“. Journal of Chemistry 2020 (13.02.2020): 1–13. http://dx.doi.org/10.1155/2020/9410389.
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Micro-combustor can provide the required thermal energy of micro-thermal photovoltaic (MTPV) systems. The performance of MTPV is greatly affected by the effectiveness of a micro-combustor. In this study, a numerical simulation was conducted to explore the benefits of annular rectangular rib for enhancing the thermal performance of a nonpremixed micro-combustor. Based on the investigations under various rib heights, rib positions, and inlet mass flow rates, it is found that the addition of annular rectangular ribs in the micro-combustor creates a turbulent zone in the combustion chamber, thereby enhancing the heat transfer efficiency between the inner wall of the combustion chamber and the burned gas. The micro-combustor with annular rectangular rib shows a higher and more uniform wall temperature. When the H2 mass flow is 7.438 × 10−8 kg/s and the air mass flow is 2.576 × 10−6 kg/s, the optimum dimensionless rib position is at l = 6/9 and r = 0.4. At this condition, the micro-combustor has the most effective and uniform heat transfer performance and shows significant decreases in entropy generation and exergy destruction. However, the optimum l and r significantly depend on the inlet mass flow of H2/air mixture.