Experimental Study of Wheel Contribution to Large-Scale Landing Gear Noise

Landing gears are an important noise source of aircraft during approach, which makes the research on their aerodynamic noise a topical problem. The majority of previous studies on landing gear noise were limited to scaled models, which necessitates their validation in large-scale tests. Therefore, the objective of the present work has been to perform an exhaustive parametric study for large-scale generic landing gears and to investigate the effect of their different geometric parameters on aerodynamic noise generation process: this paper focuses on the role of the wheels in landing gear noise. The tests were carried out by a joint Russian-Chinese team in large anechoic wind tunnel FL-17 CARDC (Mianyang, China) and included both noise directivity measurements by linear microphone arrays and noise source localization by a beamforming array. The height of landing gear models (up to 2.4 m), wheel diameter (up to 0.72 m) and flow velocity (up to 75 m/s), which were considered in the tests, are representative for real landing gears and make it possible to obtain empirical trends and dependencies for realistic Reynolds numbers. Since wheels are one of the major contributors to landing gear noise, the present paper addresses the effect of different number and diameters of wheels on aerodynamic noise produced by the large-scale generic landing gears. For specific frequency regions, noise source localization is applied to determine which elements of the wheel bogie are dominant sources in landing gear noise.