Characteristics of Boundary Layer Transition and Reynolds Number Sensitivity of Three Dimensional Wings of Varying Complexity Operating in Ground Effect

Abstract

The influence of Reynolds number on the aerodynamic characteristics of various wing geometries was investigated through windtunnel experimentation. The test models represented racing car front wings of varying complexity: from a simple singleelement wing to a highly complex 2009specification formulaone wing. The aim was to investigate the influence of boundarylayer transition and Reynoldsnumber dependency of each wing configuration. The singleelement wing showed significant Reynoldsnumber dependency, with up to 320% and 35% difference in downforce and drag, respectively, for a chordwise Reynolds number difference of 0.81 أ— 105. Across the same test range, the multielement configuration of the same wing and the F1 wing displayed less than 6% difference in downforce and drag. Surfaceflow visualization conducted at various Reynolds numbers and ground clearances showed that the separation bubble that forms on the suction surface of the wing changes in both size and location. As Reynolds number decreased, the bubble moved upstream and increased in size, while reducing ground clearance caused the bubble to move upstream and decrease in size. The fundamental characteristics of boundary layer transition on the front wing of a monoposto racing car have been established.