Holographic interferometry technique for rotary wing aerodynamics and noise

Abstract : In this paper, the concepts of holography and holographic interferometry, as applied to the visualization and measurement of the three- dimensional flow field near a rotor tip, are previewed, and initial experimental results of investigations of local shock structures and tip vortices behind the blade are presented. An additional method to visualize the flow in a three- dimensional manner is demonstrated, and finally, a method to quantitatively measure the three-dimensional flow, which will provide the necessary information to help improve helicopter performance and reduce noise, is introduced.