An Experimental Characterization on the Acoustic Performance of Forward/Rearward Retraction of a Nose Landing Gear

Abstract

The modern undercarriage system of a large aircraft normally requires the landing gear to be retractable. The nose landing gear, installed in the front of the fuselage, is retracted either forward or rearward. In the forward/rearward retraction system, the landing gear is normally installed to the trailing/leading side of the bay. When the incoming flow passes the landing gear as well as the bay, the installation that corresponds to the forward/rearward retraction system has a significant impact on the coupling flow and the associated noise of the landing gear and the bay. In this paper, acoustic performance of the forward/rearward retraction of the nose landing gear was discussed based on experiment. The landing gear bay was simplified as a rectangular cavity, and tests were conducted in an aeroacoustics wind tunnel. The cavity oscillation was first analyzed with different incoming speeds. Then, the landing gear model was installed close to the trailing and the leading side of the cavity, respectively. It was observed that installation close to the leading side can help disturb the shear layer so as to suppress the oscillation, while the trailing one can make the landing gear itself produce lower noise. Accordingly, conclusions on the acoustic performance of the forward/rearward retraction of the nose landing gear are made.

Flow Control and Passive Low Noise Technologies for Landing Gear Noise Reduction

“…An additional way to obtain a similar noise reduction is by adding small, locally mounted solid/perforated fairings [17,18], meshes [19][20][21] or hub caps [22][23][24][25] to landing gear in order to improve the local aerodynamic shape or reduce local velocities, as well as some more advanced concepts such as; optimised bay door design [26], wheel bay treatments [23,27,28] and an upstream solid, retractable flow deflector [29][30][31]. A full review of noise reduction technologies for aircraft landing gear can be found in Zhao et al [32] and a review of bio-inspired aerodynamic noise control in Wang et al [33].…”

Experimental study of flow in a cavity with the variable shape at a low Reynolds number

“…In the last few decades, cavity flow has gained much attention as it is fully applied in practical engineering and life. Cavity flow has a wide range of applications in aircraft landing gear bays [1,2] , recessed parts of airframes [3,4] , as well as in pipeline gas transport [5], and some electronic devices. The main applications in low velocities are heat exchangers [6] and flow over ribbed surfaces on microelectronic chips and electronics on printed circuit boards.…”

A Numerical Study of the Wind Speed Effect on the Flow and Acoustic Characteristics of the Minor Cavity Structures in a Two-Wheel Landing Gear

“…It mainly studied some more advanced low-noise designs for aircraft landing gear and the high lift wing. At present, there are still many projects to study airframe noise [9][10][11][12], fairing [13] technology has been widely studied, and some novel noise reduction approach such as air curtain [14,15] and wire mesh screen model [16] have been proposed. For further information, please refer to a review paper by Zhao et al [17].…”