Academic literature on the topic 'Rocket engines – Combustion – Mathematical models'
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Journal articles on the topic "Rocket engines – Combustion – Mathematical models"
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Sidlerov, D. A., and S. A. Fedorov. "Numerical Investigation of Work Cycle Characteristics in the Combustion Chamber of a Lox/Methane Liquid-Propellant Rocket Engine Featuring Reductant Power Gas Combustion." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 2 (141) (June 2022): 43–53. http://dx.doi.org/10.18698/0236-3941-2022-2-43-53.
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We performed a numerical investigation of cumulative efficiency and the structure in detail concerning the working process in the combustion chamber of a lox/methane liquid-propellant rocket engine operating in steady-state, boosted and throttled modes. In order to do it, we used tools developed by JSC SSC "Center Keldysh", that is, physical and mathematical models, numerical methods and software packages for numerical simulation of two-phase turbulent flows with combustion in liquid-propellant engine combustion chambers. The paper presents numerical simulation and investigation results concerning the specifics of fuel component flows, their mixing and combustion in the combustion chamber of a lox/methane liquid-propellant rocket engine using staged combustion cycle with reductant gas in steady-state, boosted (117 % by thrust) and throttled (30 % by thrust) operation modes. We performed a comparative analysis of work cycle parameters in combustion chambers at different fuel component consumption rates and pressure levels. The paper shows that the boosted mode increases the interaction of fuel jets, which intensifies mixing and burnout processes, while the deep throttling mode decreases the mixing and fuel burnout amplitudes as compared to the steady-state mode. The numerical simulation results may be used to investigate fuel combustion processes in combustion chambers of promising liquid-propellant rocket engines at the stages of development, design and refinement
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Chernova, A. A. "Validation of RANS Turbulence Models for the Conjugate Heat Exchange Problem." Nelineinaya Dinamika 18, no. 1 (2022): 61–82. http://dx.doi.org/10.20537/nd220105.
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This paper addresses problems of mathematical modeling of heat exchange processes in the pre-nozzle volume of a solid propellant rocket engine with a charge with starlike cross-section and a recessed hinged nozzle. Methods of mathematical modeling are used to solve the quasi-stationary spatial conjugate problem of heat exchange. An analysis is made of the influence of RANS turbulence models on the flow structure in the flow channels of the engine and on the computed heat flow distributions over the surface of the recessed nozzle. Methods of mathematical modeling are used to solve the quasi-stationary spatial conjugate problem of heat exchange. Results of validation of RANS turbulence models are presented using well-known experimental data. A comparison of numerical and experimental distributions of the heat-transfer coefficient over the inlet surface of the recessed nozzle for the engine with a cylindrical channel charge is made for a primary choice of turbulence models providing a qualitative agreement between calculated and experimental data. By analyzing the results of numerical modeling of the conjugate problem of heat exchange in the combustion chamber of the solid propellant engine with a starlike channel, it is shown that the SST $k-\omega$ turbulence model provides local heat-transfer coefficient distributions that are particularly close to the experimental data.
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Gorskiy, V. V., M. G. Kovalsky, and V. G. Resh. "Method of Calculating Carbon Ablation in the Jet of Liquid Rocket Engine Combustion Products." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 5 (128) (October 2019): 4–21. http://dx.doi.org/10.18698/0236-3941-2019-5-4-21.
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Nowadays carbon materials are widely used as ablating thermal protection for high-temperature structural elements in aerospace technology. Prediction of changes in the shape of the external surfaces of these elements, due to the burning of thermal protection, is closely related to the use of computational-theoretical methods describing the flow of various physicochemical and mechanical processes associated with the occurrence of the phenomenon under consideration. At the same time, it is crucial to test such methods on the results of experimental studies conducted under conditions which are implemented during the process of testing thermal protection in jets of aerodynamic units. The main elements of ablation of carbon materials include their erosion, i.e., mechanical ablation of mass, observed in high-pressure gas flows. In the process of experimental development, it is necessary to carry out research on large-scale models, which has led to widespread use of underexpanded jets of combustion products of liquid rocket engine combustion products for modeling the erosion process of thermal protection. The theoretical model of ablation of thermal protection in such jets requires taking into account the complex chemical composition of the gas mixture flowing into the model; physical and chemical interaction of this gas with thermal protection, which causes gasification of the latter; use of mathematical models describing the process of material erosion due to mechanical impact of high-pressure gas flow. The paper describes the development of the carbon material ablation calculating and theoretical methodology which could be used to determine the material erosion characteristics on the basis of solving a complex problem of circumfluence, heating, heat penetration and ablation of thermal protection.
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Ramesh, Davood, Hasan Karimi M., and Massoud Shahheidari. "Cycle optimization of the staged combustion rocket engines." Aircraft Engineering and Aerospace Technology 89, no. 2 (March 6, 2017): 304–13. http://dx.doi.org/10.1108/aeat-12-2013-0229.
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Purpose The purpose of this paper is to introduce new and modified “staged combustion” cycles in the form of engineering algorithm as a possible propulsion contender for future aerospace vehicle to achieve the highest possible “total impulse” to “mass” of propulsion system. Design/methodology/approach In this regard, the mathematical cycle model is formed to calculate the engine’s parameters. In addition, flow conditions (pressure, temperature, flow rate, etc). in the chamber, nozzle and turbopump are assessed based on the results of turbo machinery power balance and initial data such as thrust, propellant mixture ratio and specifications. The developed code has been written in the modern, object-oriented C++ programming language. Findings The results of the developed code are compared with the Russian RD180 engine which demonstrates the superiority and capability of new “thermodynamic diagrams”. Research limitations/implications This algorithm is under constraint to control the critical variation of combustion pressure, turbine rpm, pump cavitation and turbine temperature. It is imperative to emphasize that this paper is limited to “oxidizer-rich staged combustion” engines with “single pre-burner”. Originality/value This study sheds light on using fuel booster turbopump and the second-stage fuel pump to moderate the effect of cavitation on pumps which reduces tank pressure and, as a consequence, decreases the propulsion system weight.
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Betelin, V. B., R. M. Shagaliev, S. V. Aksenov, I. M. Belyakov, Yu N. Deryuguin, D. A. Korchazhkin, A. S. Kozelkov, V. F. Nikitin, A. V. Sarazov, and D. K. Zelenskiy. "Mathematical simulation of hydrogen–oxygen combustion in rocket engines using LOGOS code." Acta Astronautica 96 (March 2014): 53–64. http://dx.doi.org/10.1016/j.actaastro.2013.11.008.
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ONEL, Alexandru-Iulian, Oana-Iuliana POPESCU, Ana-Maria NECULAESCU, Tudorel-Petronel AFILIPOAE, and Teodor-Viorel CHELARU. "Liquid rocket engine performance assessment in the context of small launcher optimisation." INCAS BULLETIN 11, no. 3 (September 9, 2019): 135–45. http://dx.doi.org/10.13111/2066-8201.2019.11.3.12.
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The paper presents a fast mathematical model that can be used to quickly asses the propulsive characteristics of liquid propelled rocket engines. The main propulsive parameters are computed using combustion surfaces obtained after a nonlinear data fitting analysis. This approach is much more time efficient than using standard codes which rely on frequent calls of the Fuel Combustion Charts and interpolating their data. The tool developed based on the proposed mathematical model can be used separately or it can be integrated in a multidisciplinary optimisation algorithm for a preliminary microlauncher design.
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Vasiliev, Igor, Boris Kiforenko, and Yaroslav Tkachenko. "COMPARATIVE ANALYSIS OF THE EFFICIENCY OF CONSTANT POWER THROTTLED ROCKET ENGINES FOR INTERORBITAL FLIGHTS TO GEOSTATIONAR." Journal of Automation and Information sciences 6 (November 1, 2021): 66–77. http://dx.doi.org/10.34229/1028-0979-2021-6-7.
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Carrying out low-thrust transfers of spacecrafts in the near-earth space from intermediate elliptic to the geostationary orbit using electric rocket engines seems to be one of the most important tasks of modern cosmonautics. Electric rocket engines, whose specific impulse of the reactive jet is an order of magnitude more than in chemical RD, are preferable for interorbit flights with a maximum payload in the case when a significant increase in the duration of the maneuver is permissible. Ability to throttling the rocket engine thrust is traditionally considered as one of the ways to reduce both the engine mass and the required fuel assumptions for performing the specified maneuver. Using the concept of an ideal-rocket engine provides the upper estimates of the payload mass of interborbital flights for the given power level. Accounting for the properties of real engines leads to the need of considering the mathematical models with more strict limits on control functions. A study of the efficiency of three modes of thrust control of an electric propulsion rocket engine was carried out when performing practically interesting spacecraft flights from highly elliptical intermediate near-earth orbits to geostationary orbits. A mathematical model of constant power relay rocket engine has been built. The formulation of the variational problem of the Maer type is given about the execution of a given dynamic maneuver for the throttled and unregulated electric rocket engines of constant power. Using the Pontryagin maximum principle, an analysis of the optimal control functions was carried out, for which the final relations were written out, which allowed to write down the system of differential equations of the optimal movement of the spacecraft, equipped with relay electric rocket engine. The obtained numerical and quality results of the study of the effectiveness of various modes of thrust control of an electric propulsion engine to increase the payload of a given orbital maneuver confirmed the correctness of mathematical models of throttled and relay engines and, in general, the efficiency of using solutions of the averaged equations of optimal motion of a spacecraft for numerical solution of the corresponding boundary value problems in an exact formulation.
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Strelnikov, G. A., A. D. Yhnatev, N. S. Pryadko, and S. S. Vasyliv. "Gas flow control in rocket engines." Technical mechanics 2021, no. 2 (June 29, 2021): 60–77. http://dx.doi.org/10.15407/itm2021.02.060.
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In the new conditions of application of launch vehicle boosters, space tugs, etc., modern rocket engines often do not satisfy the current stringent requirements. This calls for fundamental research into processes in rocket engines for improving their efficiency. In this regard, for the past 5 years, the Department of Thermogas Dynamics of Power Plants of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine has conducted research on gas flow control in rocket engines to improve their efficiency and functionality. Mechanisms of flow perturbation in the nozzle of a rocket engine by liquid injection and a solid obstacle were investigated. A mathematical model of supersonic flow perturbation by local liquid injection was refined, and new solutions for increasing the energy release rate of the liquid were developed. A numerical simulation of a gas flow perturbed by a solid obstacle in the nozzle of a rocket engine made it possible to verify the known (mostly experimental) results and to reveal new perturbation features. In particular, a significant increase in the efficiency of flow perturbation by an obstacle in the transonic region was shown up, and some dependences involving the distribution of the perturbed pressure on the nozzle wall, which had been considered universal, were refined. The possibility of increasing the efficiency of use of the generator gas picked downstream of the turbine of a liquid-propellant rocket engine was investigated, and the advantages of a new scheme of gas injection into the supersonic part of the nozzle, which provides both nozzle wall cooling by the generator gas and the production of lateral control forces, were substantiated. A new concept of rocket engine thrust vector control was developed: a combination of a mechanical and a gas-dynamic system. It was shown that such a thrust vector control system allows one to increase the efficiency and reliability of the space rocket stage flight control system. A new liquid-propellant rocket engine scheme was developed to control both the thrust amount and the thrust vector direction in all planes of rocket stage flight stabilization. New approaches to the process organization in auxiliary elements of rocket engines on the basis of detonation propellant combustion were developed to increase the rocket engine performance.
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Vaulin, S. D., and K. I. Khazhiakhmetov. "The State-of-the-Art and Prospects of Aerospike Engines." Proceedings of Higher Educational Institutions. Маchine Building, no. 10 (739) (October 2021): 74–83. http://dx.doi.org/10.18698/0536-1044-2021-10-74-83.
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Currently, there is a worldwide trend of growing interest in projects aimed at reducing the cost of spacecraft launches. The search for solutions to this topical issue reveals new requirements for the rocket engines. However, existing rocket engines are incapable of fully meeting modern requirements. Consideration of new technical solutions indicates the prospects of using aerospike engines, which have the property of self-regulation and can operate with optimal flow expansion throughout the entire operation. This property allows this type of engine to be used as a propulsion system for single-stage return launcher. However, aerospike engines have not been sufficiently studied at the moment and haven’t found widespread use. Therefore it is necessary to summarize the existing knowledge about aerospike and the aerospike research has been performed. As a result mathematical models of the workflows were created, methods of designing and optimization of the contour were determined, and a number of design and technological solutions were found. However, the mathematical models verified by experimental data were not found.
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Pylypenko, O. V., O. O. Prokopchuk, S. I. Dolgopolov, O. D. Nikolayev, N. V. Khoriak, V. Yu Pysarenko, I. D. Bashliy, and S. V. Polskykh. "Mathematical modelling of start-up transients at clustered propulsion system with POGO-suppressors for CYCLON-4M launch vehicle." Kosmìčna nauka ì tehnologìâ 27, no. 6 (2021): 3–15. http://dx.doi.org/10.15407/knit2021.06.003.
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Liquid-propellant rocket propulsion systems of the first stages of launch vehicles of medium, heavy, and super-heavy class usually include POGO-suppressors, which are one of the most widely used methods to eliminate launch vehicle longitudinal structural vibrations (POGO phenomena). However, until now, the theoretical studies and analysis of the effect of the POGO-suppressors’ installation in the feedlines of main liquid rocket engines on transient processes in systems during rocket engine starting have not been carried out due to the complexity of such analysis and the lack, first of all, reliable nonlinear models of cavitation phenomena in rocket engine pumps. A mathematical model for the start-up of a clustered rocket propulsion of the Cyclone-4M launch vehicle has been developed that takes into account the low-frequency dynamics of the POGO-suppressors and the asynchronous start-up timeline sequences of the rocket engines. The first stage of the launch vehicle propulsion system includes four RD-870 rocket engines. A nonlinear mathematical model of low-frequency dynamic processes of the POGO-suppressor with bellows separation of liquid and gaseous media is presented. A significant effect of cavitation in the pumps of engines and the POGO-suppressor installation to the LOX feedline on the propulsion system dynamic gains is shown. Based on the developed mathematical model of the clustered rocket propulsion start-up, the studies of the Cyclone-4M main engines’ start-up transients were carried out. The asynchronous start-up timeline sequences of the rocket engine and the places of installation of the POGO-suppressors in the LOX feedline branches to the RD-870 rocket engine – near the general feedline collector as standard placement or directly at the entrance to the engines – were investigated. The analysis of start-up transients in the oxidizer feed system of the considered propulsion (the time dependences of the flowrate and pressure at the engine inlet) showed the following. Firstly, while the synchronous start-up of the engines, the installation of the POGO-suppressors near the feedline collector makes it possible to eliminate all engine inlet overpressures that exist in the rocket propulsion system in case of the absence of the POGO-suppressors. Secondly, the RD-870 engine asynchronous start-up operation affects negatively the time dependences of the propellant flowrate and pressure at the engine inlet if the POGO-suppressors are located near the feedline collector. So, in the propulsion system’s start-up timeline interval 0.95 s - 1.35 s, for some computational variants of the initial moments of the engine operation start, an abnormally large drop in the LOX flow rate and the overpressures at the engine inlet is observed. The asynchronous start-up of the RD-870 engines with the installation of the POGO-suppressors at the engine inlet does not significantly change the start-up transients compared to the synchronous starting of the engines. Thirdly, thus, it is shown that the installation of the POGO-suppressors both at the engine inlet and at the RD-870 branches near the collector has a significant positive effect on the quality of start-up transient processes for the main engines of the 1st stage of the Cyclone-4M launch vehicle. Placing the POGO-suppressors at the engine inlets is not standard and is considered without reference to the propulsion system layout. Nevertheless, the POGO-suppressors installed at the inlet to the engines are an effective means of preventing overshoots and dips in the parameters of the liquid-propellant rocket engine, including the conditions of asynchronous starting of the liquid rocket engines in the clustered propulsion system. The results obtained can be used in mathematical modeling of the start-up of the first stage propulsion system either for multistage sustainer rockets used in parallel with booster rockets or for the clustered multi-engine rocket propulsion system containing POGO-suppressors.
Dissertations / Theses on the topic "Rocket engines – Combustion – Mathematical models"
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Sone, Kazuo. "Unsteady simulations of mixing and combustion in internal combustion engines." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12171.
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Laurent, Charlelie. "Low-order modeling and high-fidelity simulations for the prediction of combustion instabilities in liquid rocket engines and gas turbines." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0038.
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Au cours des dernières décennies, les instabilités de combustion ont constitué un important défi pour de nombreux projets industriels, en particulier dans la conception de moteurs-fusées à ergols liquide et de turbines à gaz. L'atténuation de leurs effets nécessite une solide compréhension scientifique de l'interaction complexe entre la dynamique de flamme et les ondes acoustiques qu'elles impliquent. Au cours de cette thèse, plusieurs directions ont été explorées pour fournir une meilleure compréhension de la dynamique des flammes dans les moteurs-fusées cryogéniques, ainsi que des méthodes numériques plus efficaces et robustes pour la prédiction des instabilités thermoacoustiques dans les chambres de combustion à géométries complexes. La première facette de ce travail a consisté en la résolution de modes thermoacoustiques dans les chambres de combustion complexes comportant à injecteurs multiples, une tâche qui nécessite souvent des simplifications pour être abordable en termes de coût de calcul. Ces hypothèses physiques nécessaires ont conduit à la popularité croissante des modèles bas-ordre acoustiques, parmi lesquels ceux utilisant l'expansion de Galerkin ont démontré une efficacité prometteuse tout en conservant une précision satisfaisante. Ceux-ci sont cependant limités à des géométries simples qui n'intègrent pas les caractéristiques complexes des systèmes industriels. Une grande partie de ce travail a donc consisté tout d'abord à identifier clairement les limitations mathématiques de l'expansion classique de Galerkin, puis à concevoir un nouveau type d'expansion modale, appelé expansion sur frame, qui ne souffre pas des mêmes restrictions. En particulier, l'expansion sur frame est capable de représenter avec précision le champ de vitesse acoustique près des parois de la chambre de combustion autres que des murs rigides, une capacité cruciale qui manque à la méthode Galerkin. Dans ce travail, le concept d'expansion modale de surface a également été introduit pour modéliser des frontières topologiquement complexes, comme les plaques multi-perforées rencontrées dans les turbines à gaz. Ces nouvelles méthodes numériques ont été combinées avec le formalisme state-space pour construire des réseaux acoustiques de systèmes complexes. Le modèle obtenu a été implémenté dans le code STORM (State-space Thermoacoustic low-ORder Model), qui permet la modélisation bas-ordre des instabilités thermoacoustiques dans des géométries arbitrairement complexes. Le deuxième ingrédient de la prédiction des instabilités thermoacoustiques est la modélisation de la dynamique de flamme. Ce travail a traité de ce point, dans le cas spécifique d'une flamme-jet cryogénique caractéristique d'un moteur-fusée à ergols liquides. Les phénomènes contrôlant la dynamique de flamme ont été identifiés grâce à des Simulations aux Grandes Échelles (SGE) du banc d'essai expérimental Mascotte, où les deux réactifs (CH4 et O2) sont injectés dans des conditions transcritiques. Une première simulation donne un aperçu détaillé de la dynamique intrinsèque de la flamme. Plusieurs SGE avec modulation harmonique de l'injection de carburant, à différentes fréquences et amplitudes, ont été effectués afin d'évaluer la réponse de la flamme aux oscillations acoustiques et de calculer une Fonction de Transfert de Flamme (FTF). La réponse non-linéaire de la flamme, notamment les interactions entre les oscillations intrinsèques et forcées, a également été étudiée. Enfin, la stabilisation de cette flamme dans la région proche de l'injecteur, qui est d'une importance primordiale sur la dynamique globale de la flamme, a été étudiée grâce à une simulation directe multi-physique, où un problème couplé de transfert de chaleur est résolu au niveau de la lèvre de l'injecteurOver the last decades, combustion instabilities have been a major concern for a number of industrial projects, especially in the design of Liquid Rocket Engines (LREs) and gas turbines. Mitigating their effects requires a solid scientific understanding of the intricate interplay between flame dynamics and acoustic waves that they involve. During this PhD work, several directions were explored to provide a better comprehension of flame dynamics in cryogenic rocket engines, as well as more efficient and robust numerical methods for the prediction of thermoacoustic instabilities in complex combustors. The first facet of this work consisted in the resolution of unstable thermoacoustic modes in complex multi-injectors combustors, a task that often requires a number of simplifications to be computationally affordable. These necessary physics-based assumptions led to the growing popularity of acoustic Low-Order Models (LOMs), among which Galerkin expansion LOMs have displayed a promising efficiency while retaining a satisfactory accuracy. Those are however limited to simple geometries that do not incorporate the complex features of industrial systems. A major part of this work therefore consisted first in clearly identifying the mathematical limitations of the classical Galerkin expansion, and then in designing a novel type of modal expansion, named a frame expansion, that does not suffer from the same restrictions. In particular, the frame expansion is able to accurately represent the acoustic velocity field, near non-rigid-wall boundaries of the combustor, a crucial ability that the Galerkin method lacks. In this work, the concept of surface modal expansion is also introduced to model topologically complex boundaries, such as multi-perforated liners encountered in gas turbines. These novel numerical methods were combined with the state-space formalism to build acoustic networks of complex systems. The resulting LOM framework was implemented in the code STORM (State-space Thermoacoustic low-ORder Model), which enables the low-order modeling of thermoacoustic instabilities in arbitrarily complex geometries. The second ingredient in the prediction of thermoacoustic instabilities is the flame dynamics modeling. This work dealt with this problem, in the specific case of a cryogenic coaxial jet-flame characteristic of a LRE. Flame dynamics driving phenomena were identified thanks to three-dimensional Large Eddy Simulations (LES) of the Mascotte experimental test rig where both reactants (CH4 and O2) are injected in transcritical conditions. A first simulation provides a detailed insight into the flame intrinsic dynamics. Several LES with harmonic modulation of the fuel inflow at various frequencies and amplitudes were performed in order to evaluate the flame response to acoustic oscillations and compute a Flame Transfer Function (FTF). The flame nonlinear response, including interactions between intrinsic and forced oscillations, were also investigated. Finally, the stabilization of this flame in the near-injector region, which is of primary importance on the overall flame dynamics, was investigated thanks to muulti-physics two-dimensional Direct Numerical Simulations (DNS), where a conjugate heat transfer problem is resolved at the injector lip
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Cordesse, Pierre. "Contribution to the study of combustion instabilities in cryotechnic rocket engines : coupling diffuse interface models with kinetic-based moment methods for primary atomization simulations." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC016.
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Gardiens de l’espace, les lanceurs de fusée font l’objet d’une amélioration continue et concurrentielle, grâce à des campagnes de tests expérimentaux et numériques. Les simulations prédictives sont devenues indispensables pour accroître notre compréhension de la physique. Ajustables, elles se prêtent parfaitement à la conception et l’optimisation, en particuliers de la chambre de combustion, pour garantir la sureté et maximiser l’efficacité. L’atomisation primaire est l’un des phénomènes déterminants de la combustion du combustible et de l’oxydant, pilotant à la fois la distribution de gouttes et les potentielles instabilités hautes-fréquences en conditions sous-critiques. Elle couvre un large spectre de topologies d’écoulement diphasique, depuis ceux de type phases séparées jusqu’à la phase dispersée, en passant par une région mixte caractérisée par la complexité de la physique à petites échelles et de la topologie de l’écoulement. Les modèles d’ordre réduit constituent de bons candidats pour réaliser des simulations numériques prédictives et relativement peu coûteuses en ressource de calcul sur des configurations industrielles. Cependant, jusqu’à présent ils ne décrivent correctement que la dynamique des grandes échelles et doivent donc être couplés à des modèles de phase dispersée nécessitant un réglage minutieux de paramètres pour prédire la formation du spray. Afin de décrire à la fois les régions mixte et dispersée, l’amélioration de la hiérarchie de modèles d’ordre réduit repose sur quelques principes clefs au cœur de la thèse ci-présente et fournit des problèmes interdisciplinaires faisant appel tant à l’analyse mathématique et la modélisation physique de ces systèmes d’EDP qu’à leur discrétisation numérique et leur implémentation dans des codes de CFD à des fins industriels. Grâce d’une part à l’extension de la théorie des équations de conservation supplémentaires à des systèmes impliquant des termes non-conservatifs et d’autre part à un formalisme de thermodynamique multi-fluide tenant compte des effets non-idéaux, nous proposons de nouvelles pistes pour définir une entropie de mélange strictement convexe et consistante avec le système d’équation et les lois de pression, dans le but de permettre la symmétrisation entropique des modèles diphasiques, de prouver leur hyperbolicité et d’obtenir des termes sources généraux. De plus, en rompant avec la vision géométrique de l’interface, nous proposons une description multi-échelle de l’interface pour décrire un mélange multi-fluide comportant une dynamique interfaciale complexe. Le Principe de Moindre Action a permis de dériver un modèle bifluide à une vitesse couplant grandes et petites échelles de l’écoulement. Nous avons ensuite développé une stratégie de séparation d’opérateurs basée sur la discrétisation par Volumes Finis, et nous avons implémenté le nouveau modèle dans le logiciel industriel multiphysique de CFD, CEDRE, de l’ONERA afin d’évaluer numériquement ce dernier. Enfin, nous avons construit et analysé les fondations d’une hiérarchie de cas tests accessibles à la DNS tout en étant au plus proche de configurations industrielles, dans le but d’évaluer les résultats de simulations du nouveau modèle ou de tout autre modèle à venirGatekeepers to the open space, launchers are subject to intense and competitive enhancements, through experimental and numerical test campaigns. Predictive numerical simulations have become mandatory to increase our understanding of the physics. Adjustable, they provide early-stage optimization processes, in particular of the combustion chamber, to guaranty safety and maximize efficiency. One of the major physical phenomenon involved in the combustion of the fuel and oxidizer is the jet atomization, which pilotes both the droplet distributions and the potential high-frequency instabilities in subcritical conditions. It encompasses a large sprectrum of two-phase flow topologies, from separated phases to disperse phase, with a mixed region where the small scale physics and topology of the flow are very complex. Reduced-order models are good candidates to perform predictive but low CPU demanding simulations on industrial configurations but have only been able so far to capture large scale dynamics and have to be coupled to disperse phase models through adjustable and weakly reliable parameters in order to predict spray formation. Improving the hierarchy of reduced order models in order to better describe both the mixed region and the disperse region requires a series of building blocks at the heart of the present work and give on to complex problems in the mathematical analysis and physical modelling of these systems of PDE as well as their numerical discretization and implementation in CFD codes for industrial uses. Thanks to the extension of the theory on supplementary conservative equations to system of non-conservation laws and the formalism of the multi-fluid thermodynamics accounting for non-ideal effects, we give some new leads to define a strictly convex mixture entropy consistent with the system of equations and the pressure laws, which would allow to recover the entropic symmetrization of two-phase flow models, prove their hyperbolicity and obtain generalized source terms. Furthermore, we have departed from a geometric approach of the interface and proposed a multi-scale rendering of the interface to describe multi-fluid flow with complex interface dynamics. The Stationary Action Principle has returned a single velocity two-phase flow model coupling large and small scales of the flow. We then have developed a splitting strategy based on a Finite Volume discretization and have implemented the new model in the industrial CFD software CEDRE of ONERA to proceed to a numerical verification. Finally, we have constituted and investigated a first building block of a hierarchy of test-cases designed to be amenable to DNS while close enough to industrial configurations in order to assess the simulation results of the new model but also to any up-coming models
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Sullwald, Wichard. "Grain regression analysis." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86526.
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Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Grain regression analysis forms an essential part of solid rocket motor simulation. In this thesis a numerical grain regression analysis module is developed as an alternative to cumbersome and time consuming analytical methods. The surface regression is performed by the level-set method, a numerical interface advancement scheme. A novel approach to the integration of the surface area and volume of a numerical interface, as defined implicitly in a level-set framework, by means of Monte-Carlo integration is proposed. The grain regression module is directly coupled to a quasi -1D internal ballistics solver in an on-line fashion, in order to take into account the effects of spatially varying burn rate distributions. A multi-timescale approach is proposed for the direct coupling of the two solvers.
AFRIKAANSE OPSOMMING: Gryn regressie analise vorm ’n integrale deel van soliede vuurpylmotor simulasie. In hierdie tesis word ’n numeriese gryn regressie analise model, as ’n alternatief tot dikwels omslagtige en tydrowende analitiese metodes, ontwikkel. Die oppervlak regressie word deur die vlak-set metode, ’n numeriese koppelvlak beweging skema uitgevoer. ’n Nuwe benadering tot die integrasie van die buite-oppervlakte en volume van ’n implisiete numeriese koppelvlak in ’n vlakset raamwerk, deur middel van Monte Carlo-integrasie word voorgestel. Die gryn regressie model word direk en aanlyn aan ’n kwasi-1D interne ballistiek model gekoppel, ten einde die uitwerking van ruimtelik-wisselende brand-koers in ag te neem. ’n Multi-tydskaal benadering word voorgestel vir die direkte koppeling van die twee modelle.
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Deng, Tian. "LES combined with statistical models of spray formation closely to air-blast atomizer." Thesis, Ecully, Ecole centrale de Lyon, 2011. http://www.theses.fr/2011ECDL0037/document.
Full textAbstract:
Cette thèse présente une extension de l'approche stochastique de l'atomisation primaire de type air assisté près d'un injecteur. Cette approche avait déjà été introduite dans les publications de Gorokhovski et al. Dans le cadre de la simulation des grandes échelles, la zone d'atomisation primaire est simulée comme un corps immergé avec une structure stochastique. Ce dernier est défini par la simulation stochastique de la position et de la courbure de l'interface entre le liquide et le gaz. La simulation de la position de l'interface est basée sur l'hypothèse de symétrie d'échelle pour la fragmentation. La normale extérieure à l'interface est modélisée en supposant une relaxation statistique vers l'isotropie. Les statistiques de la force du corps immergé servent de conditions aux limites pour le champ de vitesse issu de la LES ainsi que pour la production des gouttes de l'atomisation primaire. Celles-ci sont ensuite transportées par une approche lagrangienne. Les collisions entre les gouttes dans la zone d'atomisation primaire sont prises en compte par analogie avec l'approche standard de la théorie cinétique des gaz. Une fermeture est proposée pour la température statistique des gouttelettes. Cette approche est validée par des comparaisons avec les mesures expérimentales de la thèse de Hong. Les résultats numériques pour la vitesse et de la taille des gouttes dans le spray à différentes distances du centre du jet et de l'orifice de la buse sont relativement proches des résultats expérimentaux. Différentes conditions d'entrée pour la vitesse sont testées et comparées aux résultats expérimentaux. Par ailleurs, le rôle spécifique de la zone de recirculation devant le dard liquide est soulignée par le battement du dard liquide et la production de gouttelettesThis thesis introduced an extension to stochastic approach for simulation of air-blast atomization closely to injector. This approach was previously proposed in publications of Gorokhovski with his PHD students. Our extension of this approach is as follows. In the framework of LES approach, the contribution of primary atomization zone is simulated as an immersed solid body with stochastic structure. The last one is defined by stochastic simulation of position-and-curvature of interface between the liquid and the gas. As it was done previously in this approach, the simulation of the interface position was based on statistical universalities of fragmentation under scaling symmetry. Additionally to this, we simulate the outwards normal to the interface, assuming its stochastic relaxation to isotropy along with propagation of spray in the down-stream direction. In this approach, the statistics of immersed body force plays role of boundary condition for LES velocity field, as well as for production of primary blobs, which are then tracked in the Lagrangian way. In this thesis, the inter-particle collisions in the primary atomisation zone are accounted also by analogy with standard kinetic approach for the ideal gas. The closure is proposed for the statistical temperature of droplets. The approach was assessed by comparison with measurements of Hong in his PHD. The results of computation showed that predicted statistics of the velocity and of the size in the spray at different distances from the center plane, at different distances from the nozzle orifice, at different inlet conditions (different gas velocity at constant gas-to-liquid momentum ratio, different gas-to-liquid momentum ratio) are relatively close to measurements. Besides, the specific role of recirculation zone in front of the liquid core was emphasized in the flapping of the liquid core and in the droplets production
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Nahorniak, Matthew T. "Feasibility of Lorentz mixing to enhance combustion in supersonic diffusion flames." Thesis, 1996. http://hdl.handle.net/1957/34208.
Full textAbstract:
The purpose of this research was to determine if it is feasible to apply Lorentz
mixing to supersonic diffusion flames, such as those found in SCRAMjet engines. The
combustion rate in supersonic diffusion flames is limited by the rate at which air and fuel
mix. Lorentz mixing increases turbulence within a flow, which increases the rate at which
species mix and thus increases the rate of combustion.
In order to determine the feasibility of Lorentz mixing for this application, a two-dimensional model of supersonic reacting flow with the application of a Lorentz force has been examined numerically. The flow model includes the complete Navier-Stokes equations, the ideal gas law, and terms to account for diffusion of chemical species, heat release due to chemical reaction, change in species density due to chemical reaction, and the Lorentz forces applied during Lorentz mixing. In addition, the Baldwin-Lomax turbulence model is used to approximate turbulent transport properties.
A FORTRAN program using the MacCormack method, a commonly used computational fluid dynamics algorithm, was used to solve the governing equations. The accuracy of the program was verified by using the program to model flows with known solutions.
Results were obtained for flows with Lorentz forces applied over a series of power levels and frequencies. The results show significant increases in the rate of combustion
when Lorentz mixing is applied. The amount of power required to drive Lorentz mixing is small relative to the rate at which energy is released in the chemical reaction. An optimum frequency at which to apply Lorentz mixing was also found for the flow being considered.
The results of the current study show that Lorentz mixing looks promising for increasing combustion rates in supersonic reacting flows, and that future study is warranted. In particular, researchers attempting to improve combustion in SCRAMjet engines may want to consider Lorentz mixing as a way to improve combustion.Graduation date: 1997
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Hansen, Alan Christopher. "A diagnostic quasi-dimensional model of heat transfer and combustion in compression-ignition engines." Thesis, 1989. http://hdl.handle.net/10413/9595.
Full textAbstract:
Investigations into the combustion of alternative fuels in
compression-ignition engines in South Africa have underlined the
inadequacies of existing zero-dimensional combustion models. The
major aspect of concern in these models was the computation of
heat transfer which had been singled out by a number of
researchers as the leading cause of inaccuracies in heat release
computations.
The main objective of this research was to develop a combustion
model that was less empirically based than the existing zerodimensional
models for use in evaluating the combustion and
resulting thermal stresses generated by alternative fuels. in
diesel engines. Particular attention was paid to the development
of a spatial and temporal model of convective heat transfer that
was based on gas flow characteristics and to the introduction of
a radiation heat transfer model that made use of fuel properties
and fuel-air ratio. The combustion process was divided into two
zones representing burnt and unburnt constituents and the
resulting temperatures in each zone were used in the calculations
of convective and radiative heat transfer. The complete model
was formulated in such a way that it could be applied with the
aid of a micro-computer.
Calibration and verification of the gas flow sub-models which
involved the squish, swirl and turbulence components necessitated
the use of published data. Good agreement for the squish and
swirl components was obtained between the present model and the
experimental data from three engines, two with a bowl-in-piston
and the other with a flat piston. These gas flow components
dominated the gas velocities in the combustion chamber and
provided a reliable foundation for the calculation of convective
heat transfer. In spite of the well documented difficulties of
characterising turbulence, after calibration the model generated
turbulence levels with acceptable trends and magnitudes. Tests were carried out on a naturally aspirated ADE 236 engine
involving the measurement of cylinder pressure and heat flux at
a single point. Motored engine data were used to verify the
convective heat transfer rates and to ascertain the effects of
soot deposition on the heat flux probe. Close correlation
between predicted and measured heat flux was achieved after
accounting for the effects of chamber geometry at the probe site.
Soot deposition on the probe caused a significant attenuation of
the heat flux within a short period of the engine running under
fired conditions.
The results from fired engine tests showed that the two zone
combustion model was providing plausible trends in the burnt and
unburnt zone temperatures and that the model generated combined
heat transfer rates which were credible not only on a global
basis but also in terms of point predictions in the combustion
chamber. The results also highlighted the considerable variation
in heat transfer that could occur from one point in the chamber
to another. Such variations added considerable weight to the
objective of moving away from a zero-dimensional model to a
quasi-dimensional type where predictions could be made on a more
localised rather than global basis. It was concluded that the
model was a definite improvement over zero-dimensional models and
competed favourably with existing quasi-dimensional models with
advantages in both simplicity and accuracy.Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.
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"A Numerical Study of a Rotary Valve Internal Combustion Engine." University of Technology, Sydney. Faculty of Engineering, 2001. http://hdl.handle.net/2100/248.
Full textAbstract:
A Computational Fluid Dynamics (CFD) simulation of the Bishop Rotary Valve (BRV) engine is developed. The simulation used an existing commercial CFD code, CFX 4.3, with a number of new routines written to allow it to simulate the conditions and motions involved in an internal combustion engine. The code is extensively validated using results from other researchers, and several new validations are performed to directly validate the code for simulating internal combustion engine flows. Firstly, tumble vortex breakdown during the compression stroke of a square piston model engine is modelled. The results of the simulation are validated against published high quality experimental data. Both two- and three-dimensional models are tested, using the k-e and Reynolds stress turbulence models. The Reynolds stress turbulence model simulations successfully predicted the tumble break down process during the compression stroke. A simple three-dimensional Large Eddy Simulation model is also presented. The numerical simulation is then applied to the BRV engine. An in-cylinder flow field not previously described is discovered, created by the unique combustion chamber shape of the BRV engine. The flow field is not adequately described by the traditional descriptions of engine flows, being squish, swirl and tumble. The new flow structure is named 'dual cross tumble', and is characterised by two counter-rotating vortices in the cross tumble plane on either side of the inlet air jet. Analysis of the dual tumble structure indicates that it is most beneficial in high bore to stroke ratio engines. This flow structure has been predicted or visualised by a small number of previous researchers, however no published research has recognised its significance or potential benefits. The validated code is then used to predict the effect of modifying the valve cross sectional area, the effect of the inlet manifold wave, the effect of heat transfer from the inlet manifold walls, the effect of bore to stroke ratio, and the effect of engine speed. This work presents a numerical simulation of a new rotary valve engine technology. This opens up a whole new area of engine aerodynamics research as no detailed examination of the flows in a rotary valve engine have been presented previously. In the process, it discovers a new compression stroke turbulence generation mechanism, 'dual cross tumble', which offers the potential of performance levels not possible using poppet valve engines.
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Ekici, Özgür 1973. "Computational study of arc discharges : spark plug and railplug ignitors [sic]." 2007. http://hdl.handle.net/2152/11950.
Full text
10
Fitzpatrick, John Nathan. "Coupled thermal-fluid analysis with flowpath-cavity interaction in a gas turbine engine." Thesis, 2013. http://hdl.handle.net/1805/4441.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)This study seeks to improve the understanding of inlet conditions of a large rotor-stator cavity in a turbofan engine, often referred to as the drive cone cavity (DCC). The inlet flow is better understood through a higher fidelity computational fluid dynamics (CFD) modeling of the inlet to the cavity, and a coupled finite element (FE) thermal to CFD fluid analysis of the cavity in order to accurately predict engine component temperatures. Accurately predicting temperature distribution in the cavity is important because temperatures directly affect the material properties including Young's modulus, yield strength, fatigue strength, creep properties. All of these properties directly affect the life of critical engine components. In addition, temperatures cause thermal expansion which changes clearances and in turn affects engine efficiency. The DCC is fed from the last stage of the high pressure compressor. One of its primary functions is to purge the air over the rotor wall to prevent it from overheating. Aero-thermal conditions within the DCC cavity are particularly challenging to predict due to the complex air flow and high heat transfer in the rotating component. Thus, in order to accurately predict metal temperatures a two-way coupled CFD-FE analysis is needed. Historically, when the cavity airflow is modeled for engine design purposes, the inlet condition has been over-simplified for the CFD analysis which impacts the results, particularly in the region around the compressor disc rim. The inlet is typically simplified by circumferentially averaging the velocity field at the inlet to the cavity which removes the effect of pressure wakes from the upstream rotor blades. The way in which these non-axisymmetric flow characteristics affect metal temperatures is not well understood. In addition, a constant air temperature scaled from a previous analysis is used as the simplified cavity inlet air temperature. Therefore, the objectives of this study are: (a) model the DCC cavity with a more physically representative inlet condition while coupling the solid thermal analysis and compressible air flow analysis that includes the fluid velocity, pressure, and temperature fields; (b) run a coupled analysis whose boundary conditions come from computational models, rather than thermocouple data; (c) validate the model using available experimental data; and (d) based on the validation, determine if the model can be used to predict air inlet and metal temperatures for new engine geometries. Verification with experimental results showed that the coupled analysis with the 3D no-bolt CFD model with predictive boundary conditions, over-predicted the HP6 offtake temperature by 16k. The maximum error was an over-prediction of 50k while the average error was 17k. The predictive model with 3D bolts also predicted cavity temperatures with an average error of 17k. For the two CFD models with predicted boundary conditions, the case without bolts performed better than the case with bolts. This is due to the flow errors caused by placing stationary bolts in a rotating reference frame. Therefore it is recommended that this type of analysis only be attempted for drive cone cavities with no bolts or shielded bolts.
Books on the topic "Rocket engines – Combustion – Mathematical models"
1
Etele, Jason. Computational study of variable area ejector rocket flowfields. [Downsview, Ont: University of Toronto, Institute for Aerospace Studies], 2004.
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2
Ye ti huo jian fa dong ji ran shao guo cheng jian mo yu shu zhi fang zhen: Modeling and numerical simulations of internal combustion process of liquid rocket engines. Beijing: Guo fang gong ye chu ban she, 2012.
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3
Rocker, M. Modeling on nonacoustic combustion instability in simulations of hybrid motor tests. Marshall Space Flight Center, Ala: National Aeronautics and Space Administration, Marshall Space Flight Center, 2000.
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4
Ye ti huo jian fa dong ji ran shao dong li xue mo xing yu shu zhi ji suan. Beijing Shi: Guo fang gong ye chu ban she, 2011.
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5
Shi, Yu. Computational optimization of internal combustion engines. London: Springer, 2011.
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6
Ramos, J. I. Internal combustion engine modeling. New York: Hemisphere Pub. Corp., 1989.
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7
Zeleznik, Frank J. Modeling the internal combustion engine. Washington, D.C: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.
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8
Zeleznik, Frank J. Modeling the internal combustion engine. Washington, D.C: NASA, 1985.
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9
Modeling of combustion systems: A practical approach. Boca Raton, FL: CRC Press, 2006.
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10
Gerke, Udo. Numerical analysis of mixture formation and combustion in a hydrogen direct-injection internal combustion engine. Göttingen: Cuvillier, 2007.
Find full textBook chapters on the topic "Rocket engines – Combustion – Mathematical models"
1
Traxinger, Christoph, Julian Zips, Christian Stemmer, and Michael Pfitzner. "Numerical Investigation of Injection, Mixing and Combustion in Rocket Engines Under High-Pressure Conditions." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 209–21. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_13.
Full textAbstract:
Abstract The design and development of future rocket engines severely relies on accurate, efficient and robust numerical tools. Large-Eddy Simulation in combination with high-fidelity thermodynamics and combustion models is a promising candidate for the accurate prediction of the flow field and the investigation and understanding of the on-going processes during mixing and combustion. In the present work, a numerical framework is presented capable of predicting real-gas behavior and nonadiabatic combustion under conditions typically encountered in liquid rocket engines. Results of Large-Eddy Simulations are compared to experimental investigations. Overall, a good agreement is found making the introduced numerical tool suitable for the high-fidelity investigation of high-pressure mixing and combustion.
2
Perakis, Nikolaos, and Oskar J. Haidn. "Experimental and Numerical Investigation of CH$$_4$$/O$$_2$$ Rocket Combustors." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 359–79. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_23.
Full textAbstract:
Abstract The experimental investigation of sub-scale rocket engines gives significant information about the combustion dynamics and wall heat transfer phenomena occurring in full-scale hardware. At the same time, the performed experiments serve as validation test cases for numerical CFD models and for that reason it is vital to obtain accurate experimental data. In the present work, an inverse method is developed able to accurately predict the axial and circumferential heat flux distribution in CH$$_4$$/O$$_2$$ rocket combustors. The obtained profiles are used to deduce information about the injector-injector and injector-flame interactions. Using a 3D CFD simulation of the combustion and heat transfer within a multi-element thrust chamber, the physical phenomena behind the measured heat flux profiles can be inferred. A very good qualitative and quantitative agreement between the experimental measurements and the numerical simulations is achieved.
3
Pearson, Ronald K. "Motivations and Perspectives." In Discrete-time Dynamic Models. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195121988.003.0003.
Full textAbstract:
This book deals with the relationship between the qualitative behavior and the mathematical structure of nonlinear, discrete-time dynamic models. The motivation for this treatment is the need for such models in computerized, model-based control of complex systems like industrial manufacturing processes or internal combustion engines. Historically, linear models have provided a solid foundation for control system design, but as control requirements become more stringent and operating ranges become wider, linear models eventually become inadequate. In such cases, nonlinear models are required, and the development of these models raises a number of important new issues. One of these issues is that of model structure selection, which manifests itself in different ways, depending on the approach taken to model development (this point is examined in some detail in Sec. 1.1). This choice is critically important since it implicitly defines the range of qualitative behavior the final model can exhibit, for better or worse. The primary objective of this book is to provide insights that will be helpful in making this model structure choice wisely. One fundamental difficulty in making this choice is the notion of nonlinearity itself: the class of “nonlinear models” is defined precisely by the crucial quality they lack. Further, since much of our intuition comes from the study of linear dynamic models (heavily exploiting this crucial quality), it is not clear how to proceed in attempting to understand nonlinear dynamic phenomena. Because these phenomena are often counterintuitive, one possible approach is to follow the lead taken in mathematics books like Counterexamples in Topology (Steen and Seebach, 1978). These books present detailed discussions of counterintuitive examples, focusing on the existence and role of certain critical working assumptions that are required for the “expected results” to hold, but that are not satisfied in the example under consideration. As a specific illustration, the Central Limit Theorem in probability theory states, roughly, that “sums of N independent random variables tend toward Gaussian limits as TV grows large.” The book Counterexamples in Probability (Stoyanov, 1987) has an entire chapter (67 pages) entitled “Limit Theorems” devoted to achieving a more precise understanding of the Central Limit Theorem and closely related theorems, and to clarifying what these theorems do and do not say.
Conference papers on the topic "Rocket engines – Combustion – Mathematical models"
1
Ferrero, Andrea, Filippo Masseni, and Dario Pastrone. "Low-order models for low-frequency combustion instability in hybrid rocket engines." In INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0026694.
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Guo, J., Y. P. Cao, W. P. Zhang, and X. Y. Zhang. "A New Numerical Method for Developing the Lumped Dynamic Model of Valve Train." In ASME 2014 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icef2014-5530.
Full textAbstract:
The dynamics of valve train is influenced by stiffness, size and mass distribution of its components and initial valve clearance and so on. All the factors should be taken into consideration correctly by dynamic model and described qualitatively and quantitatively through mathematical variables. This paper proposes a new simplified method for valve train components, namely mode matching method (MMM) for camshaft, pushrod, rocker arm, valve and valve spring. In this method the amount of lumped masses for each flexible component is determined based on its natural frequencies and the considered frequency range. As a result, the dynamic model of each component is required to match its low order modes within the considered frequency range. The basis of this method is that the contributions of each component to valve train vibration are mainly in the low order modes. The numerical model of valve train is verified by an experiment conducted on a motor driven valve train system.
3
Coclite, Alessandro, Luigi Cutrone, Giuseppe Pascazio, and Pietro De Palma. "Numerical investigation of high-pressure combustion in rocket engines using Flamelet/Progress-variable models." In 53rd AIAA Aerospace Sciences Meeting. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-1109.
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Danov, Stanislav N., and Ashwani K. Gupta. "Influence of Imperfections in the Working Media on Diesel Engine Indicator Process: Part 2 — Results." In ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/cie-6027.
Full textAbstract:
Abstract In the companion Part 1 of this two-part series paper several improvements to the mathematical model of the energy conversion processes, taking place in a diesel engine cylinder, have been proposed. Analytical mathematical dependencies between thermal parameters (pressure, temperature, volume) and caloric parameters (internal energy, enthalpy, specific heat capacities) have been obtained. These equations have been used to provide an improved mathematical model of diesel engine indicator process. The model is based on the first law of thermodynamics, by taking into account imperfections in the working media which appear when working under high pressures and temperatures. The numerical solution of the simultaneous differential equations is obtained by Runge-Kutta type method. The results show that there are significant differences between the values calculated by equations for ideal gas and real gas under conditions of high pressures and temperatures. These equations are then used to solve the desired practical problem in two different two-stroke turbo-charged engines (8DKRN 74/160 and Sulzer-RLB66). The numerical experiments show that if the pressure is above 8 to 9 MPa, the working medium imperfections must be taken into consideration. The mathematical model presented here can also be used to model combustion process of other thermal engines, such as advanced gas turbine engines and rockets.
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Danov, Stanislav N., and Ashwani K. Gupta. "Influence of Imperfections in Working Media on Diesel Engine Indicator Process: Part 1 — Theory." In ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/cie-6026.
Full textAbstract:
Abstract Several improvements to the mathematical model of the indicator process, taking place in a diesel engine cylinder, are proposed. The thermodynamic behavior of working media is described by the equation of state, valid for real gases. Analytical mathematical dependencies between thermal parameters (pressure, temperature, volume) and caloric parameters (internal energy, enthalpy, specific heat capacities) have been obtained. These equations have been applied to the various products encountered during the burning of fuel and the gas mixture as a whole in the engine cylinder under conditions of high pressures and temperatures. An improved mathematical model, based on the first law of thermodynamics, has been developed by taking into account imperfections in the working media that appear under high pressures and temperatures. The numerical results show that there are significant differences between the values calculated using ideal gas behavior and the real gas, in particular at high pressure and high temperature conditions. The numerical experiments show that if the pressure is above 8 to 9 MPa, the imperfections in working medium must be taken into consideration. The results obtained from the mathematical dependency of the caloric parameters can also be used to model any energy conversion and combustion process, such as, advanced gas turbine engines which operate at high pressure ratios, rockets.
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Lanzafame, R., and M. Messina. "Fuels Characterization for Use in Internal Combustion Engines." In ASME 2001 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-ice-421.
Full textAbstract:
Abstract It is important provide mathematical functions able to fit with great precision experimental data on gases properties, in order to obtain reliable results when computerized models on IC engines are used. On the basis of experimental data on equilibrium constants (for dissociation phenomena occurring during combustion process in IC engines) new mathematical functions have been determined to fit experimental data. In comparison to traditional fitting polynomials, these new mathematical functions present a great accuracy in matching experimental data. These new mathematical functions have the functional forms of a V order Logarithmic Polynomial, and their coefficients have been evaluated on the basis of the least square method. The new V order Logarithmic Polynomials have been determined for several dissociation reactions according to internal combustion processes applications. V order Logarithmic Polynomials have been implemented also to describe the trend of specific heat at constant pressure Vs temperature and enthalpy Vs temperature. These new Logarithmic Polynomials have been calculated for several gases and fuels for IC engines applications. The new Logarithmic Polynomials pointed out a better precision in comparison to the others polynomial functions used in literature, and the possibility to utilize a single Logarithmic Polynomial for a wide temperature range, according to a good accuracy with experimental data. Another advantage of the Logarithmic Polynomials is the possibility to extrapolate experimental data on a wide temperature range (25% of experimental T range) in order to supply to the experimental data shortage.
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Benelli, G., L. Carrai, S. Sigali, I. Brunetti, and L. Castellano. "Thermoacoustic Models for Evaluating the Sensitivity to Instabilities of Multi-Burner Annular Combustion Chambers." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51246.
Full textAbstract:
The work described here has been developed in the context of the initiative TACE® (ThemoACoustic Enel Program) which has the aim to implement the use of mathematical models in the routinary control and diagnostics operations on GT systems for the production of electric power. The background of the models chosen to achieve that objective is the frequency domain approach. The engines of interest are of industrial size and have annular combustion chamber equipped with 24 premixed burners. The subject treated in this paper is the influence on the humming by interactions between undesired or, on the contrary, suitably conceived and designed differences in the actual working mode of each single burner. The underlying idea is that in such a type of machine the assembly of the burners behaves like a chorus line that has to be properly tuned.
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De Giorgi, Maria Grazia, Aldebara Sciolti, and Antonio Ficarella. "Spray and Combustion Modeling in High Pressure Cryogenic Jet Flames." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69544.
Full textAbstract:
The aim of the present work is the investigation of the combustion phenomenon in liquid-propellant rocket engines. The combustion of liquid oxygen and gaseous methane in a shear coaxial injector under supercritical pressure was analyzed. To realize an efficient numerical description of the phenomena, it is important to treat the LOx jet in a manner which takes into account its real behavior. In the present work different kinetics, combustion models and thermodynamics approaches were used in association with the description of the jet as a discrete phase. For all the approaches used, a comparison with experimental data from literature was performed.
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Borissov, Anatoli, and James J. McCoy. "Supersonic Injection of Gaseous Fuel Described as Possible Solution for NOx Emissions From Large-Bore Gas Engines." In ASME 2002 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ices2002-448.
Full textAbstract:
Both physical and mathematical models were built to describe the main processes in large-bore gas engines. Based on the detail modeling and analysis of cylinder airflow, fuel injection, mixing, combustion and NOx generation, it was possible to pinpoint the problem of abnormal NOx production, even for lean mixtures, that occurs in these engines. In addition, analysis of the experimental data of jet mixing using high-speed photographic evidence, as well as engine performance data, has helped in the understanding of the mixing process. This has resulted in the development of a new way of the mixing of fuel and air utilizing multiple-nozzle supersonic injection. The fuel injection system is designed to optimize the mixing of the methane fuel with the air in the cylinder of a large bore natural gas engine. The design goals of low-pressure (<130 psi), all-electronic valve actuation, and optimal mixing were all achieved with a unique valve/nozzle arrangement. Later, a laser induced fluorescence method was used to take high-speed photographs of the development of the fuel jet exiting the newly developed supersonic electronic fuel injector (SSEFI). This result, together with the results of numerous experimental testing of SSEFI on different engines (GMVH-6, GMW-10, V-250, UTC-165) are presented as evidence of the success of the SSEFI application for the improvement of engine performance, engine control and NOx reduction.
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Brusca, S., S. Collura, R. Lanzafame, and M. Messina. "The Influence of Specific Heats Variability on Heat Release Analysis Using Two-Zone Models." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13456.
Full textAbstract:
Heat release and burn rate analysis in Internal Combustion Engines (ICEs) are usually based on a zero-dimensional application of First-Law of thermodynamics. In order to evaluate the heat release models available in literature use the differential form of the energy conservation equation, generally neglecting specific heats derivative terms. In this work the effects of specific heats derivative terms on a two-zone heat release model, for a Spark Ignition (SI) engine, have been evaluated. Results obtained with and without considering specific heats derivative terms have been compared. These comparisons show that proposed modifications allow to obtain more regular curves especially for mass fraction burned and heat release according to the combustion phenomenology. Besides, taking into account the specific heats derivative terms, the model's calibration constants do not need to be tuned, and the combustion efficiency can be evaluated directly by the mathematical model (otherwise experimentally measured).