Dynamic behaviors of blade cavitation in a water jet pump with inlet guide vanes: Effects of inflow non-uniformity and unsteadiness

Abstract

The waterjet pump cavities would unavoidably interact with inlet guide vanes (IGVs) wakes and thus to bring about dynamic loading impingements. This work jointly conducts experiments, numerical simulations, and time-frequency analysis to shed light on the dynamic behaviors of blade cavitation under the IGVs perturbations. As observed, the blade cavitation subjected to a lower incidence angle presents a highly dynamic pattern, which non-uniformly develops and globally performs a typical periodic cycle of generation, developing, and collapsing as each blade passes through the IGVs wake in sequence. At the same instant, the cavitation patterns on the adjacent blade would perform a distinctive tendency due to the initial phase difference. It is illuminated that the spatial-temporal incidence angle determined by inflow non-uniformity and unsteadiness majorly contribute to the uneven and intermittent development of blade cavitation. The cavitation evolutions and excited pressure and thrust deterministically oscillate with the IGVs passing frequency. The resultant cavity variations would additionally introduce broadband low-frequency thrust fluctuations that are interpreted as the non-uniform loading impacts on the blade surface. This work comparatively studies the dynamic behaviors of blade cavitation that are commonly encountered for a pump with inflow distortions, which aims to provide a fundamental understanding for cavitation dynamics in pumps.