Landing Gear Wheel Hub-Cavity Noise Passive Control Using Novel Sonic Black Hole

The wheel hub-rim cavity serves as a significant noise source in landing gear, contributing primarily to narrowband and broadband noise. Extensive research has established that passive control methods, particularly flow control and acoustic absorption, are effective in mitigating such noise. This study evaluates the effectiveness of these methods in reducing noise generated by a simplified landing gear through cavity filling, aiming to optimize passive control schemes for maximum noise reduction. The sonic black hole, an acoustic metamaterial compatible with the wheel hub cavity structure, is selected for acoustic absorption. Two enhanced sonic black holes, incorporating perforated modulation and lattice structures, are introduced alongside reference groups for comparison. Results indicate that the sonic black hole offers considerable additional noise reduction over simple filled cavities, while the coupled acoustic metamaterial, integrating both flow control and acoustic absorption, achieves maximum noise reduction across various frequency bands. Specifically, the optimal configuration yields a noise reduction of up to 1.3 dB in the frequency range of 200 Hz–20 kHz, compared to the optimal simple covering configuration.