Experimental and Theoretical Analysis of Bio-Inspired Trailing Edge Noise Control Devices

Abstract

© American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This work focuses on new experimental investigations into the function of bio-inspired trailing edge noise reduction treatments, and complementary theoretical analysis. Aeroacoustic wind tunnel tests of an instrumented DU96-W180 airfoil model at high (~2.5 million) Reynolds number reveal various effects of these treatments, termed “finlets.” Data collected include far-field noise, measured using a phased array microphone system, unsteady surface pressure near the trailing edge, lift and mean surface pressure distribution over the entire airfoil, and drag measured in its wake. Downstream effects of the finlets are investigated by positioning them at various distances upstream of the trailing edge. Off-design conditions are investigated by skewing the finlets to simulate the presence of spanwise flow. The results demonstrate the robustness of the present design and reveal additional insight into the effects of finlets on the structure of the boundary layer turbulence approaching the trailing edge. A simple mathematical model is introduced which demonstrates the noise-reducing capability of finlets through the displacement of noise-producing vortices. The influence of shape and position is investigated through the model, and results are qualitatively similar to the experimental findings.