ROTOR FREE-WAKE MODELING USING A PSEUDO-IMPLICIT TECHNIQUE INCLUDING COMPARISONS WITH EXPERIMENTAL-DATA

A pseudo-implicit predictor-corrector method with five-point central d ifferencing in space has been developed for the solution of the govern ing differential equations of the rotor free-wake problem. It is shown that a relaxation implementation of this method exhibits good converg ence 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 r esults, while keeping computational requirements to a minimum. The res ults are compared with experimental measurements of the rotor tip vort ex geometries and flow field velocities in hover and forward flight wi th good agreement.