With the rapid development of aviation industry, aircraft noise emission has attracted an increasing amount of attention. During take-off and landing, the aircraft flies at a low altitude and is at the vicinity of the airport, causing substantial noise pollution to the surrounding area. As a main contributor to the total noise production, the landing gear system has become a key research topic. In addition to the "self-noise" of the landing gear, the flow-induced oscillation within the landing gear bay cavity can also cause acoustic radiation during dropping or retracting the landing gear, significantly influencing the noise level of the undercarriage system. As such, it is necessary to explore the underlying mechanism and find an effective way to suppress the noise level. Concentrating on a simplified model of landing gear/bay assembly, this study develops a noise control approach at 0.2Ma and 0.25Ma, namely sawtooth spoiler is used to suppress the coupling noise induced by the landing gear/bay. All experimental tests are conducted in the 0.55 m×0.4 m aeroacoustic wind tunnel. Firstly, the respective contribution of the landing gear and the bay to the coupling noise is characterized. Then, the sawtooth spoiler is mounted to the leading edge of the pure cavity to perturb the flow separation and cavity pressure oscillation. Through parametric study, the approaches of noise control are investigated and the effects of sawtooth inclination angle on the noise level are analyzed. Finally, the landing gear is installed in the bay cavity, and the spoiler's ability to suppress the coupling noise is tested. The results show that all cases with the sawtooth leading edge spoiler can attenuate the noise level. Moreover, under the conditions of this study, when the inclination angle is 30°, the optimal reduction is achieved. It is expected that the results of this research can be implemented in the future engineering practice to suppress the landing gear/bay coupling noise level.
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