On the transient cavitation characteristics of viscous fluids around a hydrofoil

Cavitation is a transient phase transition process between liquid and vapour, and it often occurs in machines using viscous fluids as working media owing to complex operating environments and the trend toward high temperature, high velocity, and high power density. To investigate the cavitation properties of viscous fluids, a visualization experimental system was proposed and developed in this study. In addition, a three-dimensional computational fluid dynamics (CFD) model considering cavitation was developed based on the finite volume method (FVM) to study the cavitation characteristics and unsteady cavitation behaviors of the cavitating flow in viscous oil around a NACA0012 (National Advisory Committee for Aeronautics) hydrofoil under various conditions. The results showed that cavitation started on the suction surface of the hydrofoil near the head, and the critical cavitation number and the critical velocity were 5.2 and 10 m/s at an operating pressure of zero. Smaller cavitation numbers and higher fluid velocity induced and intensified the cavitation. Additionally, the cavitation process of the viscous oil around the hydrofoil was highly unstable and periodic, and its development included birth, growth, separation, and disintegration, with an evolution frequency of 47 Hz. This study provides a theoretical basis, experimental means, and data support for cavitation of viscous fluids, especially oil. It has significant engineering applications for the development of fluid machinery.