Radiated Sound and Structural Vibration Induced by Flow over Asymmetrical Trailing Edges

This dissertation presents experimental results regarding the phenomenon of flows around a family of asymmetric beveled trailing edges. Trailing edge flow-induced noise and structural vibration occur in many engineering applications and can be challenging to predict because of its complexity. The objectives of the present research were divided into four parts. The first part focused on the influence of trailing edge geometry on velocity fields. The second part characterized the unsteady surface pressure. The third and fourth part developed an understanding of sound and vibration induced by trailing edge flows, respectively.

Two-component velocity measurements were obtained by Particle Image Velocimetry in order to spatially and temporally resolve the velocity fields around the trailing edges. The unsteady surface pressure fields were measured by Remote Microphone Probes. They provided a unique database for understanding the mechanisms and analyzing the characteristics of sound and vibration induced by trailing edge flows. The far-field sound was obtained by phased microphone arrays combining with beamforming techniques. The predicted sound based on improved half-plane theory and statistics of flow fields were compared with experimental data. The structural vibration was measured by Laser Doppler Vibrometers. The mode shapes and modal vibration were acquired by Magnitude-Phase Identification and modal decomposition algorithms. The modal vibration was predicted from vibration theory and an empirical model of surface pressure cross-spectral density.