Abstract
Rocket engine turbopumps equip balance piston (BP) which is a self-thrust balancing mechanism, because turbopump generates large axial load derived from its high discharged pressure. BP has a stable characteristic quasi-statically, but in some cases it becomes unstable and goes into the condition of self-excited vibration. In recent studies, linearized model of BP was used and their dynamic characteristics have investigated. However, non-linear behavior of BP is not studied sufficiently yet. In this paper, non-linear simulation including axial contact between the shaft and the casing is conducted. It uses the model based on 1 dimensional model developed by Hayashi. In the simulation, bulk modulus of fluid is used as a parameter, and stability and the vibration characteristics are investigated. Particularly, the transition of the dynamical characteristics of BP from the stable condition to the self-excited vibration without/with contacting to the casing are explained. As a result, the necessity of using non-linear model including wall-contact in numerical simulation of BP's dynamic behavior is indicated.
