Experimental study on stability of axial direction of balance piston mechanism (Translated)

Abstract

Vibration problems often occur in development of rocket engine turbopump, and an axial vibration is one of these problems. Rocket turbopumps often use the balance piston mechanism (BP), which is a self-balancing system, to balance the large axial thrust derived from the high discharged pressure. Turbopump rotor with BP is movable in the axial direction and supported by fluid stiffness generated by the BP. Although BP has a stable characteristic statistically, it becomes dynamically unstable in some cases owing to the compressibility of the fluid in the BP chamber. The stability of the BP has been studied in analysis approaches, but the experimental approach has yet to be conducted. In this study, an experimental research is conducted to confirm the occurrence of self-excited oscillation, and the results are compared to one dimensional theoretical analyses. From the experimental results, the effect of the BP parameters on stability is revealed. Here, it is concluded that there is a contradictory relationship between the BP static and dynamic characteristics.