Development of a marine propeller design method based on lifting line theory and lifting surface correction factors

Abstract

The marine propeller design method based on lifting line theory and lifting surface correction factors is presented in this thesis. The blade outline is chosen in such a way that no cavitation is occurred. The pitch and camber is determined by satisfying the requirements for the designed load distribution. The method is an adaptation of the vortex lattice method and used for wake adapted propeller. A propeller with symmetrical blades and with mean lines which are symmetric about the mid chord need no pitch correction due to lifting surface effect. In this thesis, the developed method is applied for the propeller whose blade outline is symmetrical about the mid-chord and the mean line chosen is parabolic which is also symmetrical about the mid-chord. Only camber correction is done. It is assumed that the circulation is zero at hub and tip in both lifting line and lifting surface calculation. Also in lifting surface calculation, the circulation is zero at Leading edge and trailing edge of the propeller blade. For the calculation of induced velocity at any point in the flow field, the Biot-Savart law is used. The pitch is calculated using trial and error method. The camber distribution is corrected by using camber correction factors and compared with published result.