Noise control for nose landing gear by longitudinal wavy strut

Abstract

The noise of landing gears is a major contributor to the overall airframe noise of an aircraft during approach and landing. In this paper, a novel strut treatment method, termed the Longitudinal Wavy Strut (LWS), is proposed to improve the aeroacoustics performances of nose landing gear. The simplified and complete landing gear model with wavy strut are respectively investigated by a hybrid approach combines with IDDES and FW-H equations. For the simplified configuration, four different setups in terms of wavy parameter are analyzed. The wavy strut with three parameters can reduce the noise in the simplified model and the medium wave height is the best noise reduction. Then, an assessment of the solutions obtained from complete landing gear is presented for wavy strut with medium wave height. The results indicate that the low and medium frequency noise can be reduced by the incorporation of wave strut, thereby substantiating the noise reduction efficacy of the wavy strut in complete landing gear. Moreover, the underlying noise suppression mechanisms of wavy strut are explored by the process of vorticity generation and evolution. The suppression of periodic vortex shedding in the wake of the wavy strut appears to be a pivotal factor contributing to noise reduction. Furthermore, the modification in the distribution of boundary enstrophy flux on the strut surface suggests that the wavy strut effectively hampers the generation of vorticity within the flow field. The alteration in Lamb vector and helicity distribution elucidates the noise reduction mechanism from the perspective of sound source.