Landing gears are an important noise source of aircraft during approach and landing, which makes the research on their aerodynamic noise reduction a topical problem. This paper experimentally studies the method of noise reduction developed by the authors, which consists in using truncated-cylinder elements for landing gears instead of circular-cylinder parts (e.g. struts, links, actuators, etc). The method stems from a theoretical interpretation of the experimental results obtained for bluff body noise measured with the help of azimuthal decomposition technique, and its efficiency has been many times demonstrated in tests with small-scale models. The present work continues these studies in application to large-scale generic landing gears and natural Reynolds numbers (up to Re = 2.4·10⁶); it reports the results of experimental tests performed in a large anechoic wind tunnel. The large-scale experiments have shown that the truncated-cylinder strut could lead to broadband noise reduction of landing gear noise by up to 2 dB, which thus validates the noise reduction method demonstrated earlier for the small scales only. Beamforming source localization shows that the noise source in the frequency region where noise reduction is observed is associated with the strut. These results obtained for the large-scale models at natural Reynolds numbers allow the noise reduction method of cross-section shape modification to be recommended for implementation in low-noise landing gear design for struts and other cylinder elements.

起落架是飞机进场和着陆过程中的重要噪声源，其气动降噪研究成为一个热点问题。本文通过实验研究了作者开发的降噪方法，该方法包括在起落架上使用截圆柱体元件代替圆柱体部件（例如支柱、连杆、执行器等）。该方法源于对借助方位分解技术测量的钝体噪声实验结果的理论解释，其效率已在小规模模型的测试中多次得到证明。目前的工作继续这些研究应用于大型通用起落架和自然雷诺数（高达 Re = 2.4·10 ⁶); 它报告了在大型消声风洞中进行的实验测试结果。大规模实验表明，截头圆柱支柱可以使起落架噪声的宽带噪声降低高达 2 dB，从而验证了前面演示的仅适用于小规模的降噪方法。波束成形源定位表明，观察到降噪的频率区域中的噪声源与支柱相关。在自然雷诺数下为大型模型获得的这些结果允许推荐使用横截面形状修改的降噪方法在支柱和其他圆柱体元件的低噪声起落架设计中实施。