Abstract: The electric pump-fed liquid rocket engine boasts unique advantages including a simplified system architecture and flexible thrust modulation, enabling it to satisfy the diverse demands of modern aerospace missions and garnering widespread attention within the field. As an innovative cycle configuration, the impact of its start-up transient dynamics on engine performance represents a subject of significant research value. To this end, this paper takes a dual-motor-driven electric pump-fed rocket engine concept as its foundation, designing two distinct ignition sequences—“ignition first followed by thrust ramp-up under tank pressure” and “thrust ramp-up first then ignition”—and developing a dedi-cated simulation model for the engine. Building on this model, an in-depth investigation into the dynamic behaviors of the engine’s start-up phase is conducted.The results indicate that both start-up schemes give rise to fluctuations in pressure and mixture ratio, a phenomenon attributed to the phase transition of methane within the cooling jacket. A comparative analysis reveals that the “ignition first then ramp-up under tank pressure” sequence yields more stable operating conditions during start-up alongside a streamlined ignition process. Conversely, the “ramp-up first then igni-tion” sequence delivers a considerably faster thrust ramp-up rate during the engine’s start-up phase.

Key words: Electric pump-fed engine, Liquid oxygen-methane engine, Startup process, System simulation, Dynamic characteristics