Unsteady Panel Method Calculation of Pressure Distribution on BO 105 Model Rotor Blades and Validation with DNW-Test Data

Abstract

An unsteady 3D panel method has been developed to compute the subsonic aerodynamics of finite thickness multiblade rotors. The free wake of the blades is simulated by a lattice of shed and trailing vortices.The method is applied to a two-blade and the four-blade BO 105 hingeless rotor in hover. The four-blade 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 are in fair agreement with the experiment. 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. No restrictions are placed on the prescribed blade motion, blade profile, planform, twist etc. so that a single code can treat multiblade rotors in a variety of flight conditions.