Unsteady Panel Method Calculation of Pressure Distribution on BO 105 Model Rotor Blades.

Abstract

An unsteady 3-D Panel method has been developed to compute the subsonic aerodynamics of finite thickness multi-bladed rotors. The full span free wake of the blades is simulated by a lattice of shed and trailing vortices. The method is applied to a two-bladed and the four-bladed BO 105 hingeless rotor in hover. The four-bladed rotor has also been studied in the forward flight descent and climb modes. Prediction of pressure distribution on blade surface during hover agrees very well with wind tunnel test data and Euler solver results. Results for descent flight where severe blade vortex interaction (BVI) takes place in fair agreement with the experiment. Also results for the climb mode correlate well with test data. The time-stepping scheme employed permits a detailed study of the wake development. This is done for the descent case to indicate areas of possible severe BVI.