两级火箭RBCC发动机地面零速引射模态性能影响规律

The ground zero-velocity takeoff is a critical phase for the ejector mode of a Rocket-Based Com⁃ bined Cycle（RBCC）engine. At this stage，the mass of the vehicle is at its maximum，and the traditional single-stage rocket operation mode struggles to meet the thrust requirements for takeoff. Therefore，this paper proposes an engine configuration with a two-stage rocket and investigates the influence law of rocket operating parameters on the zero-velocity takeoff phase of the RBCC engine through numerical simulations. The results show that when the chamber pressure of the first-stage rocket is maintained at 5 MPa and the total mass flow of the first-stage rocket is maintained at 0.4 kg/s，the ejector ratio is maximized，with the induced airflow increasing by 30% com⁃ pared with the condition of the mass flow of the first-stage rocket at 0.2 kg/s. The ejector ratio increases as the chamber pressure of the first-stage rocket increases. When the chamber pressure reaches 20 MPa，the ejector ra⁃ tio and specific impulse performance are improved by 19% and 26%，respectively. However，increasing the chamber pressure from 10 MPa to 20 MPa only results in an approximately 2% improvement in the ejector ratio，while significantly increasing the design and manufacturing challenges. Reducing the throttling ratio of the sec⁃ ond-stage rocket leads to a decrease in the engine-specific impulse，whereas increasing the throttling ratio reduc⁃ es the induced airflow. Simultaneously，increasing the expansion ratio of the rocket nozzle with a higher throttling ratio significantly enhances the engine’s specific impulse performance. This study identifies the matching rules between rockets and the ramjet duct in the two-stage rocket RBCC engine configuration，providing valuable guid⁃ ance for the design of the ejector mode in future two-stage rocket RBCC engines.