The Influence of Tip Vortex on Propeller Performance

Abstract

In recent years, the techniques of numerical analysis of the propeller performance have been developed remarkably, by the advances of the studies on the trailing vortex geometry.
Although many numerical methods give us the results that agree pretty well with the measured data of the open-water characteristics of propeller at design advance speed, the agreements are sometimes poor at low advance speed, especially in case of the propellers with high pitch ratio and large blade area ratio.
This paper proposes a new mathematical model to present the procedure of the flow separation from the tips, and tries to show that the separation leads to increase the thrust, torque coefficients at low advance speed.
The results of our numerical study show that the influence of the separated tip vortex appears on the trailing vortex geometry, as well as on the loads and pressure distributions over the blade surface, especially at low advance speed.
The present method is advantageous, this author believes, enabling us to calculate the performance of propellers of various types accurately, over the wide range of advance speed.