Simulations of LAGOON landing-gear noise using Lattice Boltzmann Solver

Abstract

This paper aims at investigating and analyzing numerical simulations of landing-gear configurations of increasing complexity using the Lattice-Boltzmann solver "LaBS". The LAGOON (LAnding-Gear nOise database for CAA validatiON) project, supported by Airbus, 1, 2 provides an accurate experimental database on simplified landing-gear configurations perfectly suitable for this purpose. First, an assessment of the numerical approach accuracy is carried out on LAGOON1 configuration by comparing both aerodynamic and near-field acoustic results with the LAGOON database disclosed in the frame of the NASA BANC workshop. Then, further investigations are focused on the influence of mesh refinement, subgrid scale model and wall law parameters. Finally, the best practices obtained are applied on LAGOON2 & 3 configurations and allow to capture the impact of some geometrical components added onto LAGOON1 baseline.

Recursive regularization step for high-order lattice Boltzmann methods

“…This is usually done using a cartesian grid coupled with an octree-based refinement technique [19]. Combining these numerical tools with the particulate nature and the local dynamics of the LBM, the simulation of complex phenomena around realistic geometries is greatly eased [20][21][22]. Moreover, the method is simple to implement, induces a very low computational cost per degree of freedom, and presents a compact stencil, all of which contribute to its intrinsic advantage for parallel computations [23].…”

“…Latt & Chopard [36,37] emphasized its importance for the simulation of flows at high Reynolds number, while Chen and coworkers [38] focused on flows at high Knudsen number. It is now one of the standard stabilization procedures available for both academic studies [39][40][41] and engineering computations [20][21][22]. Even more recently, a Recursive Regularized (RR) collision operator was introduced by Malaspinas [42] for isothermal LBMs only.…”

Numerical characterization of landing gear aeroacoustics using advanced simulation and analysis techniques

“…it was sunk within an incoming flow corresponding to that of the anechoic test section. Indeed, contrarily to what was assumed in the previous CFD-CAA calculation (as well as in any other CFD-IM simulation performed so far [7][8][9][10][11][12][13][14][15][16][17][18]), the flow surrounding the NLG during the acoustic experiment was far from being homogeneous. More precisely, when exiting the nozzle it is initially confined in, C19 jet logically spreaded out itself within the ambient medium, thus leading to the creation of shear layers whose strength goes decreasing with the axial distance.…”

“…1). The underlying mechanisms of noise emissions by landing gears are complex, as shown by various efforts to characterize them via experimentation [1][2][3][4][5][6] and/or numerical simulation [7][8][9][10][11][12][13][14][15][16][17][18]. As will be seen hereafter, some of these past experimental and numerical efforts offered a ground for the present work, which constitutes a step further towards the characterization of the aeroacoustics by landing gears.…”

“…To this end, and contrarily to what was achieved by all other teams (that classically employed a traditional hybrid approach relying on an Integral Method (IM) such as the Acoustic Analogy by Ffowcs-Williams & Hawkings (FWH) [11][12][13][14][15][16][17][18]), Fig. 1.…”