Turbine inlet temperature effects on the start process of an expansion cycle liquid propellant rocket engine

The main objective of this study is to investigate the effect of turbine inlet temperature on the transient phase of expansion cycle liquid propellant rocket engines during start. For this purpose, the non-linear differential mathematical model for 15 main components of the engine is derived, and the corresponding interaction between them is established. Afterward, the model is simulated using MATLAB Simulink, and 150 equations are solved with the Newton-Raphson method. The RL10 expansion cycle liquid propellant rocket engine is selected as a case study, and its dynamic behavior is simulated, and the results are compared with the experimental data. The simulation results showed that the present model for engine dynamic parameters, including thrust-chamber pressure, fuel, oxidizer mass flow rate, and turbo-pump speed, has less than 5% error compared to previous literatures. Using the prepared modeling software, the effect of turbine inlet temperature is studied on the engine start process. The obtained results demonstrated that inappropriate temperature profile during start transient might cause an engine malfunction while entering the nominal working regime.