Analysis of the dynamic characteristics of the forced start-up procedure of H2O2/ kerosene gas generator cycle rocket engine system

Abstract

The pump-fed H₂O₂ propulsion system is an important direction for future aerospace development, and the start-up process is an accident-prone stage in launch missions. However, the start-up characteristics of the pump-fed H₂O₂/ kerosene liquid rocket engines remain unclear. This paper built the basic components and overall system of a promising H₂O₂/ kerosene gas generator cycle engine system. The dynamic characteristics of the forced start-up procedure were analyzed, and a single factor sensitivity analysis with 9 factors and 9 levels and a multi factor sensitivity analysis with a $L_{27}\left(3^{13}\right)$ orthogonal experiment based on range method were conducted. The distribution, threshold, and reliability of the dynamic processes were also obtained through Monte Carlo method and Pearson ${\chi }^2$ test. The results show that the parameter settings during the forced start-up process are reasonable, and the coupling between the combustion components and the turbopump is good without overshoot. The pressure inside the main combustion chamber changes steadily and takes about 1 second to reach 95 % of the rated pressure. The maximum temperature in the cooling channel during the start-up process is about 358 K, which is within the safe range. The factors that have the greatest impact on the start-up process include the rotational inertia of the turbopump, the pressure, temperature and molar mass of the start-up gas. The dynamic response time of the start-up process follows a normal distribution, just like the machining error of the components. The point estimation of the reliability of $t_{95}$, which reaches 95 % of the rated thrust, is 0.95297, and the point estimation of the reliability of the valve OGV opening time $t_4$ is 0.99322. The actual threshold of $t_{95}$ is 92.508 %∼107.610 %, and the actual threshold of $t_4$ is 99.656 %∼100.315 %. These findings will contribute to the design, manufacturing and hot test of H₂O₂/ kerosene gas generator cycle liquid rocket engines.