Transactions of the Korean Society of Mechanical Engineers (대한기계학회논문집)
- Volume 18 Issue 7
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- Pages.1873-1880
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- 1994
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- 1225-5963(pISSN)
DOI QR Code
Measurement of Wall Shear Stress Using Preston Tubes
프레스톤 튜브를 이용한 벽면전단응력 측정에 관한 실험적 연구
Abstract
Fully developed turbulent flow in a circular pipe and laminar boundary layer on a flat plate were measured to develop a measuring technique of the wall sheat stress using Preston tubes. New empirical formulas to extimate displacement factor of Preston tube obtained through the present study. The displacement factor for turbulent flow was considerably different from that for the laminar flow. Measured wall shear stress was not pretty dependent on the displacement factor for Preston tubes in the inertia sublayer of turbulent boundary layer, however was considerably affected in the laminar boundary layer. Measuring error of skin friction using the CPM technique was 3% for turbulent and 5% for thin laminar boundary layers.