Heat transfer and skin-friction in a turbulent boundary layer under a non-equilibrium longitudinal adverse pressure gradient

2021 ◽  
Vol 89 ◽  
pp. 108801
Author(s):  
N.A. Kiselev ◽  
A.I. Leontiev ◽  
Yu.A. Vinogradov ◽  
A.G. Zditovets ◽  
S.S. Popovich
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Skin Friction ◽  
Adverse Pressure Gradient ◽  
Non Equilibrium

Direct measurements of skin friction in a turbulent boundary layer with a strong adverse pressure gradient

1980 ◽  
Vol 101 (1) ◽  
pp. 79-95 ◽  
Author(s):  
D. Frei ◽  
H. Thomann
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Skin Friction ◽  
Circular Cross Section ◽  
Adverse Pressure Gradient ◽  
Small Element ◽  
Pressure Gradients ◽  
Local Pressure ◽  
Friction Forces

This paper describes a new balance, suitable for direct measurement of skin friction in turbulent boundary layers with severe pressure gradients. The gaps between the floating element and the surrounding wall are filled with a liquid in order to eliminate disturbing pressure forces on the element. The resulting friction forces are measured with piezo-electric transducers with high sensitivity and extremely small element displacement.Skin friction measurements were taken in the turbulent boundary layer of a wind tunnel with circular cross-section at M [les ] 0·25. Severe adverse pressure gradients were generated by means of a step on the wall or, alternatively, by a conical centre body.The new apparatus was mainly used to investigate the error of Preston tubes in adverse pressure gradients. It was necessary to develop a new measuring technique to improve the repeatability of the Preston tube readings.The Preston tube error was found to depend on both the local pressure gradient P = (dp/dx) ν/ρ3τ and on the Preston tube diameter uτd/ν and to be independent of the upstream pressure distribution for the range of parameters covered by the experiments.

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