ANALYSIS OF CAVITATION AND DESIGN OF HIGH-PRESSURE PUMP INDUCER

초록

The onset of cavitation causes head and efficiency of the pump to be reduced significantly and generates noise. Most of the inducer is designed at a maximum efficiency point of the pump, therefore suction performance drop due to effects of flow separation and inlet inverse flow is often observed at off-design points. The motivation of this study is to understand the cavitation phenomena at various conditions by applying event detection technique and to design an inducer reducing cavitation. Variation of output energy as NPSH (Net Positive Suction Head) decreases was measured in this experiment. The pressure fluctuations at cavitating conditions were measured at inducer inlet and outlet using pressure transducers and their time-frequency characteristics were analyzed by using Choi-Williams distribution. To test cavitation-resistive performance of a high-swept inducer at off-design points, the unsteady flow-fields in inducer impellers were numerically simulated using large-eddy simulation. The computed pressure distributions by assuming single-phase/multi-phase flows were analyzed to predict the onset of cavitation and the mode of cavitation.