Full-Scale Trials of Pre-Swirl Vanes and Modified Propellers on a 41 Ft. Utility Boat

摘要

The rotational energy which is normally lost in the slip stream of a propeller can be reduced by properly designed pre-swirl vanes, thus improving the propulsive efficiency. More recently, vanes have designed which also reduce the circumferential wake variations in the inflow to the propeller, thus reducing cavitation and vibration. In these experiments an asymmetric vane set, designed to reduce the circumferential wake variations caused by an inclined propeller shaft, is tested on a 41 ft. USCG twin-screw utility boat (UTB). Fuel consumption, shaft torque, RPM and panel acceleration above the propellers are measured for two different propeller designs, with and without vane sets. Without the vanes, the new propellers show fuel savings (compared to the original non-vaned propellers) which range from 1-7%, depending on boat speed. When the vanes are added to the new propellers, the fuel savings (compared to the original non-vaned propellers) increase to between 5-10%, depending on boat speed. Thus, significant reductions in fuel consumption are achieved, and even better results may be possible with more optimal design procedures. (FR)