Study on Dynamic Characteristics of RBCC Variable Structure Combustion Chamber

Variable structure combustion chamber is one of the effective ways to improve the performance of RBCC (Rocket-Based Combined-Cycle) engine operating in a wide range. The purpose of this paper is to study the feasibility of dynamic mesh CFD simulation of RBCC variable structure combustion chamber, and to reveal the dynamic characteristics of the aerodynamic thermodynamic process of the inner channel with the structural change of the combustion chamber, access to structural adjustment control law. In this paper, a wide range of variable structure combustion chamber is designed for (2∼7) Ma flow conditions. CFD simulation and experimental study on the dynamic characteristics of combustion chamber under 4 Ma flow conditions are carried out to verify the accuracy of CFD method. The results show that the smaller time step (1E-6 s) can better capture the details of the flow field, and the appropriate time step (1E-5 s) can basically reflect the change of combustion flow field characteristics and save the calculation time. The pressure response time of the combustion chamber expansion ratio and geometric throat step change is 0.015 s. It is feasible to complete the structural control law by the constant velocity regulation within 0.5 s, which can realize the smooth transition of the aerodynamic parameters of the RBCC flow path.