Numerical Simulation Of The Tip Vortex Flow On The Elliptical Hydrofoil

Cavitation is an important topic in engineering problem and could occur in many hydrodynamic mechanical systems. Cavitation will change the flow characteristics and thereby cause many problems. One example is high-speed rotating marine propeller. Cavitation starts up in the vortex flow at the tip of blade, named tip cavitation. This kind of cavitation is a source of noise and not conductive to ships’ concealment. So it’s of great significance to understand the characteristics of this kind of unsteady vortex flow. Tip vortex is not the ideal line vortex. Lots of domestic and foreign scholars explored its mechanism by means of experiments, theory and numerical simulations. However, the vortex nucleus whose magnitude is millimeter is hard to simulate. In addition, the pulsating features and multi-vortex formation inside are still unknown. Further investigations are needed.The open source code OpenFoam is widely adapted in fluid simulation. Its calculation is based on implicit pressure correction algorithm. Comparisons with test results demonstrated its validity.In this paper, the wetted flow and vortex around an elliptical hydrofoil is simulated, using the delayed-detached eddy simulation (DDES) technique. Special mesh treatment is utilized. The value transfer between internal and external domain is handled by GGI. Mesh should be refined in the region where tip vortex appears. In order to make a better refinement, the coordinate of tip vortex was found by pre-calculation using a set of simplified meshes. Then, the calculation with high-revolution cells in the tip vortex region were carried out. For the above two conditions, pulsating and average field are fully analyzed. The difference between theoretical and dissipative vortex model were clarified.