Abstract

A finite difference code for predicting the high-speed flow over the advancing helicopter rotor is presented. The code solves the low-frequency, transonic small disturbance equation and is suitable for modeling the effects of advancing blade unsteadiness on blades of nearly arbitrary planform. The method employs a quasi-conservative mixed differencing scheme and solves the resulting difference equations by an alternating direction scheme. Computed results show good agreement with experimental blade pressure data and illus-trate some of the effects of varying the rotor planform. The flow unsteadiness is shown to be an indispensible part of a transonic solution. It is also shown that, close to the tip at high advance ratio, cross-flow effects can signifi-cantly affect the solution.