Numerical Simulation of Cavitation Generation in Tandem Cascades

Abstract

Theory and numerical prediction remain the most difficult and worthwhile subjects in investigation of cavitation, whether in mechanism of cavitation or in practical cavitation in fluid machinery. Cavitation in flows passing through combined hydrofoils often leads to serious effects on hydrofoils’ performance. As the flow structure in hydrofoil cascade is relatively complex, generation of cavitation is difficult to define and the interaction between flow and cavitation keeps even secret. To discover the cavitation around hydrofoil, twin hydrofoils were arranged with several configurations. A new model was set up to simulate the flows passing through the cascades. The results show that different cascade solidity and transverse distance have deep influence on cavitation bubble generation condition. The cavitation number can be changed accordingly. Additionally, the distributions of pressure and velocity are given to support the obtained cavitation characteristics. It is proved that the increase of vertical distance of two hydrofoils enlarge the cavitation zone and the low-pressure zone’s diffusion tendency gets more obvious. However, the cavitation generation position does not vary with transverse distance between the two hydrofoils. The conclusions obtained here can be applied in design practice of fluid machinery.