Mathematical Modeling of Hydrodynamic Instability of the Flows in Combustion Chambers Liquid Propellant Rocket Engines

The phenomenon of hydrodynamic instability of flows in combustion chambers of liquid-propellant rocket engines and its influence on occurrence and development of high-frequency oscillations of working process parameters are considered. Based on the numerical solution of two model problems, it is shown that hydrodynamic instability of the flow can directly cause high-frequency oscillations in the engine chamber. The first of the above tasks corresponds to uniform blowing of combustion products into the chamber through the section. In this formulation, the expected pulsations are not observed, and the flow parameters at the steady-state mode correspond to the conditions of thermodynamic equilibrium, which can be taken as verification of the proposed mathematical model. Second task corresponds to slotted injection of combustion products into chamber simulating operation of injector head with concentric rows of mixing elements arranged on it. The presence of slotted injection leads to the emergence of hydrodynamic instability of the flow with the formation of intense vortex zones in the working volume of the combustion chamber and the subsonic part of the nozzle. This process is accompanied by the appearance of high-frequency oscillations in the values of the flow parameters. Calculation results are given and the obtained numerical solution is tested.