Flow topology around a simplified two-wheel landing gear

Abstract

Flow topology around a simplified model of a two-wheel landing gear is studied using the hydrogen-bubble visualization technique. The complete test model consists of two wheels, an axle, a main strut and a support strut. A number of wheel models with varying geometric details are considered. During the analyses, the flow field around the wheels is divided into three main regions: upper, central and lower. (1) In the upper (wing side) flow region, the flow along the inner side surface of the wheels either remains attached until the wheel aft or it separates prematurely and periodically forms slant vortices in the near wake. The wheel geometry is found to control the type of separation. (2) In the central flow region, comparison of the flow sections above and below the axle shows that main strut blockage has a significant influence on the separation behavior of the flow between the wheels. Furthermore, the addition of interior wells to the wheel geometry is found to result in a cross-stream jet at the level of the axle. This highly-erratic fluid ejection has the potential to be a source of aeroacoustic noise. (3) In the lower (ground side) flow region, the near wake is shown to accommodate periodically forming large-scale structures.