Aerodynamics of a Gulfstream G550 Nose Landing Gear Model

Abstract

In this paper we discuss detailed steady and unsteady aerodynamic measurements of a Gulfstream G550 nose landing gear model. The quarter-scale, high-fidelity model includes part of the lower fuselage and the gear cavity. The full model configuration allowed for removal of various gear components (e.g. light cluster, steering mechanism, hydraulic lines, etc.) in order to document their effects on the local flow field. The measurements were conducted at a Reynolds number of 7.3!10 4 based on the shock strut (piston) diameter and a freestream Mach number of 0.166. Additional data were also collected at lower Mach numbers of 0.12 and 0.145 and correspondingly lower Reynolds numbers. The boundary layer on the piston was tripped to enable turbulent flow separation, so as to better mimic the conditions encountered during flight. Steady surface pressures were gathered from an extensive number of static ports on the wheels, door, fuselage, and within the gear cavity. To better understand the resultant flow interactions between gear components, surface pressure fluctuations were collected via sixteen dynamic pressure sensors strategically placed on various subcomponents of the gear. Fifteen of the transducers were flush mounted on the gear surface at fixed locations, while the remaining one was a mobile transducer that could be placed at numerous varying locations. The measured surface pressure spectra are mainly broadband in nature, lacking any local peaks associated with coherent vortex shedding. This finding is in agreement with off-surface flow measurements using PIV that revealed the flow field to be a collection of separated shear layers without any dominant vortex shedding processes.

Aeroacoustic Simulation of a Nose Landing Gear in an Open Jet Facility using FUN3D

“…Although the Reynolds number based on a free-stream Mach number of 0.166 and the main strut (piston) diameter in UFAFF tests is 6.6 × 10 4 , the computations here were performed at a Reynolds number of 7.3 × 10 4 to match the test conditions of the experimental study of Neuhart et al 16 in the BART at NASA Langley. This was done to provide a direct comparison of computational results between the BART and UFAFF configurations run with the same input conditions.…”

“…A series of wind tunnel experiments for a 1/4 scale model of a Gulfstream G550 aircraft nose landing gear have been performed at NASA Langley Research Center in BART, 16 which is a closed-wall tunnel, and in the open-jet University of Florida Aeroacoustic Flow Facility (UFAFF). 17 The BART facility is well suited for aerodynamic measurements including particle image velocimetry (PIV) measurements.…”

“…In a previous paper, Vatsa et al 15 examined the same configuration installed in the BART at NASA Langley. 16 A set of three successively finer unstructured tetrahedral grids comprised of approximately 9, 25, and 71 million nodes (54, 150, and 420 million cells) were generated using the VGRID grid generation software 32 for the G550 PDCC-NLG configuration including the tunnel walls. For each grid refinement level, the average cell size was reduced by a factor of √ 2 in each coordinate direction.…”

Aeroacoustic Study of a High-Fidelity Aircraft Model: Part 1-Steady Aerodynamic Measurements

“…Given the relative structural isolation of the nose landing gear, a decision was made to investigate that source independently from the other sources; the aeroacoustic studies of a nose landing gear have been documented in previous papers. 9,10 To facilitate detailed analyses of the remaining noise sources, a relatively large-scale semi-span replica of a Gulfstream aircraft has been designed and fabricated. This high-fidelity model will be used to better understand the principles of airframe noise generation, improve and advance airframe noise prediction tools, and develop and evaluate efficient noise reduction concepts.…”

Landing Gear Noise Identification Using Phased Array with Experimental and Computational Data

“…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][7][8][9][10] and/or numerical simulation [11][12][13][14][15][16][17][18]. In particular, some of these past experimental and numerical efforts offered a ground for the present work, which constitutes a step further toward the characterization of the aeroacoustics by landing gears.…”