Experimental investigation of Reynolds number scaling on the aeroacoustics of a simple landing gear wheel

Ivanova, Zoya, Angland, David and Scotto, Aline (2024) Experimental investigation of Reynolds number scaling on the aeroacoustics of a simple landing gear wheel. In 30th AIAA/CEAS Aeroacoustics Conference, 2024. American Institute of Aeronautics and Astronautics.. (doi:10.2514/6.2024-3171).

Abstract

This paper details an experimental investigation of two different landing gear wheel models of different scale. The area ratio of the two wind tunnel models differs by a factor of 8.1. The velocity range is such that the Reynolds number range of both models overlap. The maximum Reynolds number tested in these experiments, based on the diameter of the wheel, is 1.68 × 10⁶. While the scaling laws for high aspect ratio cylinders are well known from literature, for a wheel (essentially a short aspect ratio cylinders with rounded edges) much less is understood. The aim of this paper is to understand the scale effects as typical airframe noise wind tunnel experiments are conducted at limited Reynolds numbers and/or model scale. Experimental data acquired includes farfield acoustic measurements, aerodynamic loads and on-surface pressure distributions at different Reynolds numbers. The force and pressure data show a clear Reynolds number dependency. In particular the side force shows a stronger Reynolds number dependency than the lift or drag forces. Above a Reynolds number (based on wheel diameter) of approximately 1.1 × 10⁶, the forces no longer have a strong dependency on Reynolds number. The scaling of the low Reynolds number acoustic results to ‘full scale’ results (assumed to be the results at the maximum Reynolds number tested), shows good agreement in the flyover arc assuming a constant Strouhal number. At lower Reynolds numbers, the scaled data slightly under-predicts the reference data but this effect is small. As the Reynolds number increased, this under-prediction became less. The Strouhal number dependency on Reynolds number is proposed using a method outlined in this paper, which does not require the identification of any particular tones or peaks, and is demonstrated on a circular cylinder dataset. The changes are much smaller than those for a circular cylinder. The paper contains a quantitative comparison of the effect of Reynolds number on a simplified landing gear wheel, which can be used as a guideline to the Reynolds numbers necessary to achieve representative loads and noise data corresponding to a high Reynolds number case.

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Contributors

Author: David Angland

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