Airfoil Self-Noise - Investigation with Particle Image Velocimetry

Abstract

Noise generated aerodynamically by the airflow over a lifting surface is often of concern for applications as diverse as air and ground transportation, heating, ventilation, air-conditioning systems, and wind turbines. The thesis describes the application of advanced optical flow measurements techniques for the visualization and description of the sources of sound on airfoils. These measurement techniques include high-speed stereoscopic and tomographic Particle Image Velocimetry (PIV) together with advanced methods for post-processing to obtain a representation of the aeroacoustic source field. Following this innovative and evolving approach in experimental aeroacoustics, a novel methodology for broadband trailing-edge noise diagnostics by tomographic PIV is proposed. Moreover, on the basis of simultaneous high-speed PIV and acoustic measurements, new and fundamental insights into the mechanism of tonal noise generation due to the interaction of amplified laminar boundary layer instability waves with the trailing edge are presented. Both examples demonstrate the potential impact of advanced PIV methods on present and future research in experimental aeroacoustics.