Rocket Engine Dynamic Simulator REDS

A simulator has been developed for the computer modeling of the hyclrodynamical and thermodynamical events inside a rocket engine. Called REDS, for "rocket engine dynamic simulator," it is a tool to simulate and examine unsteady behavior in a rocket engine system. A rocket engine is modeled as a system of pipes with various hydraulic elements such as turbopumps, turbines, valves, orifices, etc. Flows of fuel, oxidizer and combustion gas are simulated by solving conservation equations that take into account the materials' phase changes and physical properties. The physical properties of fuel and oxidizer are computed with GASP, a computer program that deals with the thermodynamic and transport properties of rocket engine propellants. The motions of turbopumps and turbines are coupled to the system with flow equations. The heat exchange between fluid and walls is also calculated and incorporated into the energy state of fluids. In the present version of REDS, the code has been developed to simulate unsteady behavior such as the startup and the shutdown of a staged combustion cycle engine, and has been applied to Japanese launch vehicles H-II and H-IIA. The validity of REDS has been checked by comparing its output with combustion test data. This showed that REDS does well at reproducing the unsteady responses seen at startup and shutdown, as well as in the steady-state working condition. To reduce computation time, the code of REDS is parallelized and can be run on a PC cluster. REDS has been constructed with sufficient flexibility to model any configuration of rocket engine and is expected to contribute to the R&D of the next generation rocket engine.