Dynamic characteristic comparison between 1D model and 3D flow coupling with moving part model of liquid rocket engine flow regulator

Reusable spacecraft development demands precise engine thrust regulation, with flow regulators in variable-thrust engines facing extreme operational demands. This study investigates a staged combustion cycle engine flow regulator's dynamics through comparative 1D and 3D simulations. Experimental validation showed both models effectively captured dynamics, with 3D simulations achieving 3% error. Key findings revealed significant model divergences: Under 100%–60% operation, 1D and 3D models showed 2.5% vs 1.3% overshoot respectively, with 3D exhibiting stronger nonlinearity. Sinusoidal disturbances demonstrated matching frequency responses but distinct flow characteristics - 3D displayed double the mass flow rate amplitude yet 30% smaller sleeve displacement versus 1D predictions. Vortex dynamics near the second-stage throttle assembly contributed to these variations. Under 4 MPa step disturbances, 3D simulations exhibited threefold longer peak and setting times compared to 1D predictions, demonstrating distinct transient response patterns attributed to enhanced vortex persistence in flow stabilization processes. The 3D approach better captured complex fluid–structure interactions critical for precision control. This comparative analysis reveals the critical role of high-fidelity 3D simulations in capturing nonlinear flow dynamics and vortex-induced stabilization mechanisms under transient conditions, offering key insights for optimizing variable thrust regulators in reusable propulsion systems.