Influence of heat transfer on high pressure flame structure and stabilization in liquid rocket engines

摘要

This research work deals with the problem of the flame stabilization in the context of high pressure liquid rocket engines. Flame stabilization in a rocket engine is a critical feature. An instability can lead to important damages of the engine or the destruction of the launcher and the satellite. The engines (Vulcain 2 and Vinci) of the Ariane 5, and the future Ariane 6, use the hydrogen/oxygen propellants. One characteristic of this couple is its high specific impulse. The launcher performance is linked to the ratio of the payload to the total mass of propellants. For volume reasons the propellants are stored at low temperature of the order of a few tens of Kelvin. When injected in the combustion chamber, their combustion releases a huge amount of heat leading to temperature of 3500K. In order to predict the heat transfer between the flame, the solid injector and the cold propellants the Large Eddy Simulation, which allows to capture the unsteady features of the flow, is used in association with a thermal solver for the injector. This approach is validated with a low pressure experiment conducted at Centrale Paris, then a basic 1D configuration allows to understand the phenomena of high pressure flame-wall interaction. Finally a configuration representative of a coaxial rocket engine injector allows to evaluate the structure and the stabilization mechanisms of a cryogenic flame, the heat flux and the temperature of the injector.