A Mathematical Model of Unsteady Aerodynamics and Radial Flow for Application to Helicopter Rotors
Final rept. May 1971-Jul 1972
BOEING VERTOL CO PHILADELPHIA PA
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The report documents the development of a mathematical model which represents force coefficients acting on an airfoil in an unsteady environment. In addition, the model is extended to account for the three-dimensional effects of radial flow experienced by rotor blade sections. The methods developed in this report are aimed at obtaining improved capability for predicting rotor blade section force coefficeints, particularly at or above stall conditions. The mathematical model has been incorporated into the Governments rotorcraft flight simulation program C-81 AGAJ71 version. The mathematical model was correlated with two-dimensional oscillating airfoil test data, and the Governments rotorcraft flight simulation program C-81 AGAJ71 version was correlated with full scale and model rotor test data. The results of the correlation indicate substantial improvement in rotor prediction capability at high speeds and rotor thrust coefficients above stall.