Research on Unsteady Pressure Fluctuation within the whole Flow Passage of a Fire Turbopump

Abstract

The unsteady pressure fluctuation is one of the major factors affecting the operational stability of a fire turbopump. Based on the experimental operation conditions of the turbopump, the inner unsteady flow field in the turbopump is simulated by computational fluid dynamics (CFD), and the pressure fluctuations at the zones near the turbine suction chamber, the turbine impeller inlet, the turbine outlet and the interface of pump impeller/volute are investigated by time-frequency analysis methods. The results show that high pressure fluctuation can be observed near the interface of turbine impeller-guide vane and the interface of pump impeller–volute caused by rotor-stator interaction (RSI). Moreover, turbine pressure fluctuation frequencies are identified as the 14 times and 26 times of rotating frequency and the fluctuant amplitude depends on the guide vane inlet angle; whereas, pump pressure fluctuation frequencies are observed at the times of the blade passing frequency (BPF), while the frequencies higher than 10 times of BPF have less effect on the pump vibrations. The results of unsteady pressure pulsation could be used to guide the optimum design of the fire turbopump, which is in favor of obtaining more stable performance of the turbopump.