Rotor free-wake modeling using a pseudo-implicit technique including comparisons with experimental data

A pseudo-implicit predictor-corrector method with five-point central differencing in space has been developed for the solution of the governing differential equations of the rotor free-wake problem. It is shown that a relaxation implementation of this method exhibits good convergence characteristics for the rotor tip vortex locations. The method is also generalized to allow unequal azimuth and trailed vortex segment angles, which for some applications, help retain the fidelity of the results, while keeping computational requirements to a minimum. The results are compared with experimental measurements of the rotor tip vortex geometries and flow field velocities in hover and forward flight with good agreement.