Computational investigation into the influence of yaw & rotation on the bluff-body aerodynamics of an isolated wheel

Abstract

A computational study was conducted, to understand the aerodynamic flow-field around isolated wheel configurations in free-air. Landing gear is known to be one of the most prominent noise sources on approach generating significant aircraft noise, due to the complex configurations consisting of many small components interacting with the oncoming airstream within close proximity to one another. This noise produces disruption and discomfort affecting millions of people in the vicinity of airports on a daily basis. In order to fully understand the aerodynamics around this complex configuration, focusing on specific components of a landing gear would fundamentally provide insight to the complex flow interactions related to these components. As a first step, the aerodynamic flow-field around a single stationary isolated wheel was analysed, as a baseline case, with subsequent application of wheel rotation, wheel yaw, and both yaw and rotation combined to model the take-off phase, and landing and take-off phase with the presence of a crosswind respectively. The ‘A2’ wheel geometry, primarily introduced by Fackrell, was computationally modelled for this study, due to the literature available for comparisons, although previous investigations using this geometry were conducted with ground effect. Wheel rotation was applied with a peripheral velocity of 192.31rad/s, equivalent to the free-stream velocity of 40m/s, providing a Reynolds number of 1.1 × 10 to be power of 6 based on wheel diameter. Time-averaged Unsteady Reynolds-Averaged Navier-Stokes (URANS) were simulated on a structured hexahedral grid consisting of 5 million cells. Results obtained from the CFD simulations provided data such as surface pressure distribution, velocity, central vortex core vorticity magnitude and position with downstream propagation into the wake, and aerodynamic force coefficients. The data was compared to the available literature where possible, although investigations regarding ‘free-air’ wheel configurations are limited. Overall, results showed good agreement to the available literature. Additionally, comparisons were made between the cases to identify the key effects of the baseline case, influence of rotation, influence of applied wheel yaw and the influence of both yaw and rotation combined.