Experimental Study on Aerodynamic Noise Characteristics of Tandem Asymmetric Airfoils at Different Angles of Attack

Abstract

In this paper, the aerodynamic noise characteristics of a tandem asymmetric airfoil-airfoil at different angles of attack are investigated experimentally in the 0.5m✕0.4m acoustic wind tunnel at Wenzhou University. The Reynolds number is between 2.2×105 and 3.5×105 based on the airfoil chord length and the wind speed. Each attack angle (α1 and α2) of both tandem airfoils varies between 0~20°, and the noise is measured using a far/near-field microphone array. The results showed that when the attack angle α1 of the upstream airfoil is low (α1<15°), its wake hardly interacts with the downstream airfoil, and the noise source is concentrated mainly at the trailing edge of the upstream airfoil. When the angle of attack α1>15°, the upstream wake interacts with the downstream airfoil, and the noise radiates from the leading edge of the downstream airfoil, while the source location changes slightly at different frequencies. Compared to the upstream attack angle α1, the downstream airfoil attack angle α2 has less influence on the aerodynamic noise of the tandem airfoils. The particle imaging velocimetry (PIV) technique is used to measure the flow field characteristics and analyze the mechanism of noise production.

Keywords: Tandem asymmetric airfoil-airfoil, Angles of attack, Aerodynamic noise, turbulence-surface interaction