The Influence of Yaw on the Unsteady Surface Pressures over a Two-Wheeled Landing-Gear Model

TL;DR

This study experimentally investigates how small yaw angles affect unsteady surface pressures and flow separation on a two-wheel landing gear model, revealing significant changes relevant to aircraft noise.

Contribution

It demonstrates that even minor yaw angles substantially alter flow topology and pressure fluctuations, highlighting the importance of including yaw effects in landing gear noise studies.

Findings

Yaw angles as small as 5° cause significant flow topology changes.

Large-scale separation occurs on the leeward wheel's outboard face with yaw.

Unsteady pressure frequencies shift into the audible range with yaw.

Abstract

Landing-gear noise is an increasing issue for transport aircraft. A key determinant of the phenomenon is the surface pressure field. Previous studies have described this field when the oncoming flow is perfectly aligned with the gear. In practice, there may be a cross-flow component; here its influence is investigated experimentally for a generic, two-wheel, landing-gear model. It is found that yaw angles as small as 5{\deg} cause significant changes in both overall flow topology and unsteady surface pressures. Most notably, on the outboard face of the leeward wheel, large-scale separation replaces predominantly attached flow behind a leading-edge separation bubble. The effect on unsteady surface pressures includes marked shifts in the content at frequencies in the audible range, implying that yaw is an important parameter for landing-gear noise, and that purely unyawed studies may not be fully representative of the problem.