Comanche pressure distribution. Courtesy of the Rotorcraft CFD Group at Ames Research Center
During a single revolution, the flexible rotor blade of a modern rotorcraft encounters flow conditions ranging from low-speed dynamic stall to supersonic flow with shocks. In between it may also collide violently with strong vortices, and experience sudden pressure changes as it moves over the fuselage. Rotorcraft Aerodynamics engineers work to improve the aerodynamic performance of rotary wing aircraft. They develop and evaluate methods to predict the air loads on rotorcraft components, and the interaction between the flows around different components. Predicting flows around rotorcraft is a challenge which requires intricate algorithms, even on the most powerful computers. Measuring and visualizing rotorcraft flows requires a wide variety of measurement techniques, again. It is crucial to be able to predict and measure such flows accurately, because the air loads are the input to the methods used to predict performance, dynamics and vibrations, handling qualities, and noise generation .
Vorticity contours and velocity vectors in a vertical plane above a wing, averaged within a 1-degree interval of rotor azimuth. with a 2-bladed rotor running at 1050 rpm above it. Red indicates counter-clockwise rotation, blue clockwise. Laser Velocimeter data acquired at Georgia Tech.