Studies of the Dynamic Stall or Airfoil Profiles for Helicopter Rotors.

摘要

The interaction of oscillations of the mean velocity of the relative flow with the periodic changes in angle of attack that are produced in the forward flight of helicopters on the airfoil profiles of the rotors has been investigated for the first time. The study conducted in the IIT 2 ft x 2 ft oscillating flow wind tunnel coupled with visual observations in a small water tunnel has revealed that the aerodynamic characteristics of oscillating flows in steady flow, documented by a number of investigators, may be altered significantly when oscillations of the flow velocity are superimposed on those of the angle of attack of the airfoil. (Author)