Boat Propeller Cavitation CFD Simulation Tutorial

Description

This project simulates cavitation on a boat propeller using ANSYS Fluent. Cavitation strongly affects propeller performance and service life. It occurs when local pressure around the blades drops low enough for water to vaporize, and the resulting vapor degrades propulsive efficiency, wears the blade surfaces, and adds noise and vibration to the vessel. Understanding where and when it forms is central to propeller design, which has to balance performance against cavitation reduction.

The propeller geometry was designed in Design Modeler and meshed in ANSYS Meshing using an unstructured grid, with mesh quality optimized for the rotating fluid domain around the blades.

Methodology

The interaction between liquid water and water vapor was captured with the Mixture multiphase model. Phase change was handled by the Schnerr-Sauer cavitation model, with vaporization pressure limits set to trigger vapor formation where local pressure falls below the threshold.

The propeller's rotation was modeled with mesh motion, and the simulation was run as transient so that the time-dependent growth and development of cavitation could be captured. Turbulence in the external flow around the blades was resolved with the SST k-omega model.

Conclusion

The results show the pressure distribution around the propeller blades and the vapor volume fraction on the propeller surfaces. Together they show where cavitation begins and how far it grows. The pressure fields explain why vapor forms in particular regions of the blades, and the vapor fraction contours show the extent of the cavity in each region.

The simulation also shows how rotational speed affects the cavitation extent, including the supercavitation that can develop at high rotational speeds. These results are useful for evaluating propeller designs and for choosing mitigation strategies that protect efficiency and blade life while limiting noise and vibration.