Design of quieter landing gears through lattice-Boltzmann CFD simulations

Abstract

This paper presents a design modification process carried out on a real two-wheel main landing gear configuration driven by a numerical prediction of its aeroacoustic performances. Extensive flow simulations performed using the lattice Boltzmann method are used to explore a wide range of design parameters and different combinations of low-noise devices applied to the inner and outer parts of the wheels. The search of optimal configurations is supported by a deep analysis of the source mechanisms performed by combining several flow and acoustic post-processing techniques, including standard FfowcsWilliams and Hawkings, planar and stereo beam-forming computations and an analysis of the volume source terms in different frequency bands. A combined use of brake and wheel fairings leads to a noise reduction of more than 1.5 EPNdB, corresponding to a 16% reduction of the on-ground surface where the EPNL exceeds 65 EPNdB, on a fully detailed geometry.

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

“…The acoustic response shows that the solid fairing is able to break the shedding mechanism and to deliver with a lower noise footprint that the original configuration. The present result is consistent with what found in previous literature ( [24,34]); however, due to solid surface exposed to the flow, this configuration offers with the maximum loading to the landing structure. Therefore, the usage of porous materials is proposed with the aim to obtain a compromise between the noise-reduction performance and the actual loading on the landing gear structure.…”

“…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].…”

Validation of a Transonic Lattice-Boltzmann Method on the NASA Common Research Model

“…LBM has recently been validated for a number of aerospace-related applications and, more importantly, it has also been used for a number of applications where it went beyond what was previously possible with CFD. [2][3][4] But despite those successes and the potential to overcome some of the major deficits RANS tools face, there has been one significant limitation for LBM up until recently. The standard LBM scheme, as it was also employed in the commercial LBM solver PowerFLOW ® , is restricted to subsonic Mach numbers.…”

Airfoil Tip Leakage Aeroacoustics Predictions using a Lattice Boltzmann Based Method

“…This module uses an innovative approach based on the dynamics of the flows structures and Alan Powell theoretical work on vortex sound 34 to calculate the noise sources topology and strength. FIND has already been applied in the literature as a noise sources detection tool for HVAC systems noise 35 , wind noise 36 and airframe noise 37 . In this figure, while some noise sources are located near the tip gap area, the major part of the noise sources are clearly located in the wake of the tip gap flow, where the eddy break-up of the merging tip vortices is happening as observed in Figure 10b).…”