Termografia Aplicada à Visualização de Transição de Camada Limite em Aerofólios

Abstract

The Aeronautical industry has great interest in studying aerodynamic laminar flows, since they produce lower drag force, resulting in fuel economy on aircraft. This kind of flow determination around aerodynamic surfaces and its transition to turbulent becomes therefore of great interest for aeronautical design and Computational Fluid Dynamics model validation. However such determination presents experimental difficulties, often related with invasive methods, which can influence the flow and the surface boundary layer, making the data unrepresentative. This paper presents a methodology for determining the boundary layer transition from laminar to turbulent using high sensitivity infrared cameras. This method relies on the fact that a temperature difference on the airfoil surface under laminar and turbulent flow is induced by a difference in the heat exchange of two regimes. The heat exchange is higher in turbulent flows and can be detected by these cameras. Its main advantage lies in the fact that it is non-invasive and therefore provides more consistent experimental data, in order to validate theoretical models with better accuracy. The work is based on a theoretical presentation of applied concepts and wind tunnel tests conducted at the Laboratory of Aerodynamics of the Engineering School of São Carlos - USP, by members of this institution, together with researchers from Bombardier Aviation and Federal University of São Carlos - UFSCar.