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Simulation numérique et modélisation de l'influence d'ondes acoustiques de haute amplitude sur un jet diphasique : application au domaine de la propulsion fusée à ergols liquides

Abstract : The occurrence of high-frequency combustion instabilities in liquid-propellant rocket engines can be detrimental to propulsion systems. Consequently, space actors need to strengthen their understanding of the mechanisms that cause these instabilities. To this end, numerical simulation has become more and more attractive over time. Under subcritical operating conditions, the oxidizer inside the combustion chamber is in a liquid state. In such a case, numerical simulation must be able to reproduce every interaction mechanism between acoustics and the atomization of the liquid phase, because it may influence the combustion stability. In this perspective, this study consists in 1) setting up a methodology for the numerical simulation of an atomized two-phase jet under acoustic modulation, 2) validating the restitution of all the response mechanisms of the jet to acoustics, and 3) using the results of the simulations to progress in the understanding of the involved physical phenomena. The simulation strategy that is used is based on the coupling between a 4-equation diffuse interface method to simulate the gas and the largest liquid structures of the flow, and an Eulerian statistical approach to model the spray. In this work, the numerical simulation of an atomized two-phase jet subjected to a high amplitude acoustic modulation shows a good restitution of the flattening of the liquid core and its influence on the atomization process of the jet. In particular, the liquid core is shortened and the spray widens in one particular direction. The coupling between the injection system and the acoustic cavity and its influence on the atomization process of the liquid are also reproduced. Finally, a simplified modeling of the flow used to complement the simulation results reveals a progressive deviation of the liquid core, and therefore of the drops resulting from its atomization, by the acoustic radiation force. Thus, this work opens the way to reactive simulations capable of faithfully reproducing two-phase flames under acoustic disturbances in order to study their impact on combustion stability.
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https://tel.archives-ouvertes.fr/tel-02919916
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Submitted on : Monday, August 24, 2020 - 11:27:08 AM
Last modification on : Wednesday, September 9, 2020 - 3:25:46 AM

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  • HAL Id : tel-02919916, version 1

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Nicolas Rutard. Simulation numérique et modélisation de l'influence d'ondes acoustiques de haute amplitude sur un jet diphasique : application au domaine de la propulsion fusée à ergols liquides. Génie des procédés. Université Paris Saclay (COmUE), 2019. Français. ⟨NNT : 2019SACLC088⟩. ⟨tel-02919916⟩

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