多重プロセス型キャビテーションモデルにおける輸送方程式に関する考察

：遠心ポンプモデルを対象としたケーススタディ

抄録

Cavitation in fluid machinery can cause several problems such as degradation of performance, erosion, and so on. Therefore, the development of prediction methods for cavitation flow is an important research topic, and several cavitation models have been proposed. Multi-Process (MP) model, which is a homogenous one composed of multiple equations, can take account of main elementary processes in cavitation using the moment method for a size distribution function of cavitation bubbles. It is necessary to formulate the transport equations for each state variable based on appropriate assumptions. In this study, unsteady RANS simulation of the final stage model of a three-stage centrifugal pump using MP model was carried out to investigate the influence of the formulation of two kinds (types) of transport equations, i.e., advection-type and conservation-type. As a result, both types showed agreement with experiments in terms of head degradation curves, although differences were observed for cavity growth. In the conservation-type, bubble number density decreases in contrast to the increase in void fraction. It was confirmed that this suppresses the growth of cavities.