Numerical and experimental study on unsteady behavior of cavitating flow around a two-dimensional wedge-shaped body

摘要

In this study, the numerical analysis of unsteady cavitating turbulent flow behind a two-dimensional wedge-shaped body is performed using the commercial program STAR-CCM+ as a part of a fundamental study on the control fin of supercavitating underwater vehicles. We explore the vortex structures in the near and far wake fields and investigate the effect of cavity growth on the periodic characteristics of wake flow (sigma = 1.0 2.0). Pressure fluctuations above the wedge are converted to sound pressure levels in the frequency domain via the fast Fourier Transform. As a result, we confirm that the shedding frequency of the vortices behind the body is strongly affected by the development of cavitation. As the cavitation number decreases, the frequency of the vortex in the near wake region decreases, and the force accelerating the Karman vortex in the far wake region decreases. In addition, we clearly validate the wake flow characteristics of a two-dimensional wedge-shaped body by comparing our numerical results with the experimental results carried out at the Chungnam National University Cavitation Tunnel (CNU-CT) at three different cavitation numbers (sigma = 1.3, 1.5, and 2.0). Observations using a high-speed camera and measurements of pressure fluctuation above the test model are carried out to demonstrate the wake flow characteristics.