Numerical Simulation Research On The Flow-states And Fluctuation Characteristics In A High-speed Lox Pump

High-speed liquid-oxygen pump is widely applied to important industrial fields,especially as chemical industry, aviation and aerospace industry. It will seriouslythreat the stability and safety of liquid-oxygen pump when vibration occurs duringoperating. A certain type of high speed liquid-oxygen pump occured abnormalvibration problem at its actual working condition (18000r/min-308kg/s). To analysethe mechanism of this problem from the aspcet of flow fluctuation, some stead andunsteady numerical simulations were conducted by using the SST turbulence modelto figure out its distribution-characteristics of pressure, velocity and vortex. Somereasurch were done and mainly summarized as following aspects:1. Steady numerical simulations of different massflow rates were operated tofiguring out the performance curve of LOX pump. Then the performance characterof actual working condition (18000r/min-308kg/s) was estimated based on thiscurve.2. The steady numerical simulation results of actual working condition(18000r/min-308kg/s) were visualized by varied mothods, including pressure-method, velocity-method, streamline-method, Q-Criterion, entropy-generation-method, to acquire the flow states of internal field.3. The unsteady numerical simulation results of actual working condition(18000r/min-308kg/s) were visualized into vortex-core structure based on methodof Q-Criterion, which reveals the prossess of the flow condition changing with time.4. From unsteady numerical simulation results of actual working condition(18000r/min-308kg/s), the force data on pump wall and casing and the fluctuationdata from internal flow monitors were transformed into spectrum by methods ofFFT and STFT, acqiring the spectrum characteristic of pump vibration.The results shows that the phenomena such as serious energy loss, complexvortex flow and strong flow fluctuation are usually occured in the same region,especially in the region between inducer outlet and impller inlet and the region ofdiffusers, which leads a significant impact into the performance of the pump.