Computation of the free vortex system of multi-component propulsors

ABSTRACT A method is presented to compute the geometry of the free vortex system of single- and multi-component propulsors. The method is based on the numerical integration of the Biot-Savart law for the induced velocities, which is equivalent to the numerical computation of the Goldstein factor. The computations have been extended for helix pitches close to zero and to infinity. On the basis of these new Goldstein factors, the shape of the free vortex system of all kinds of propulsors can easily be obtained, including possible interactions of the different free vortex systems. This approach can in a later stage be used for any numerical propulsor method which requires the free vortex locations or the propulsor interactions as input. The application to propeller rudder interaction has shown some interesting aspects which can be useful for the design of rudder sections.