Boundary layer diagnostics by means of an infrared scanning radiometer

✍ Scribed by L. Luca; G. M. Carlomagno; G. Buresti

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 823 KB
• Volume: 9
• Category: Article
• ISSN: 0723-4864
• DOI: 10.1007/bf00187411

✦ Synopsis

A computerized infrared (IR) scanning radiometer is employed to characterize the boundary layer development over a model wing, having a G6ttingen 797 cross-section, by measuring the temperature distribution over its heated surface. The Reynolds analogy is used to relate heat transfer measurements to skin friction. The results show that IR thermography is capable of rapidly detecting location and extent of transition and separation regions of the boundary layer over the whole surface of the tested model wing. Thus, the IR technique appears to be a suitable and effective diagnostic tool for aerodynamic research in wind tunnels.

List of symbols

c airfoil chord cj local skin friction coefficient = 2r/(~o V 2) Cp specific heat coefficient at constant pressure h local convective heat transfer coefficient Nu Nusselt number = h x/.;. Nu, Nusselt number based on airfoil chord = hc/2 Pr Prandtl number %tl/St Qj wall heat flux due to Joule heating Ql heat flux loss Re Reynolds number ~o Vx/# Re c Reynolds number based on airfoil chord = ~ Vc/la St Stanton number = h/~ % V T,. wall temperature T,, w adiabatic wall temperature V velocity of the free stream x chordwise spatial coordinate angle of attack fi thermal conductivity coefficient /l dynamic viscosity coefficient o mass density r wall shear stress