Application of CFD to analyze the propeller guard kits’ impact on hydrodynamic performance for Long-Tail Boat propellers in Thailand

The propeller guard is a device on the long-drive shaft of the Long-Tail Boats, which is significant for preventing the propeller from hitting submerged metal or rocks when the boat runs aground in shallow water. There is also a tab device attached to the propeller guard, it alleviates the lifting force in the vertical axial from the propeller force, when operating an inclined shaft angle while the boat is a high speed. As a result, the stern of the boat does not raise (reducing the boat's stern trim). Therefore, realistic fluid flow through a long-drive shaft and propeller guard kits is important. These affect the actual performance of the propeller. This research paper proposes the numerical evaluation of the propeller performance on a full scale with a long-drive shaft and inclined propeller guard kits using the Reynolds-averaged Navier-Stokes equations (RANS) solver. The SST k-ω turbulence model is adopted to the Reynolds-stress terms in the RANS equations. The computations are performed under oblique flow conditions. The results of propeller performance, pressure distribution, and wake fields around the propeller blades and the propeller guard kits have been examined. The results may be used to optimize the shape and characteristics of propeller guard kits for the Long-Tail Boats.