Detecting boundary-layer separation point with a micro shear stress sensor array

At the boundary layer's separation point, the mean of the shear stress drops to a small value while its fluctuation increases dramatically. Based on the thermal method, we can fabricate a MEMS-based shear stress sensor array to bend with the curved surface, which can measure the shear stress profile of the boundary layer. This paper presents two methods, mean and RMS of the shear stress difference max value and the second order of the array signals difference algorithm, to calculate the location of the flow separation point. Through combination of the two methods and analyzing the 2D circular column CFD simulation data, the position of the separation point can be determined accurately.

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A flexible micromachine-based shear-stress sensor array and its application to separation-point detection

Sensors and Actuators A Physical ◽

10.1016/s0924-4247(99)00277-0 ◽

2000 ◽

Vol 79 (3) ◽

pp. 194-203 ◽

Cited By ~ 92

Author(s):

Fukang Jiang ◽

Gwo-Bin Lee ◽

Yu-Chong Tai ◽

Chih-Ming Ho

Keyword(s):

Shear Stress ◽

Sensor Array ◽

Separation Point ◽

Stress Sensor ◽

Shear Stress Sensor ◽

Point Detection

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On turbulent boundary-layer separation

Journal of Fluid Mechanics ◽

10.1017/s0022112068000728 ◽

1968 ◽

Vol 32 (2) ◽

pp. 293-304 ◽

Cited By ~ 36

Author(s):

V. A. Sandborn ◽

C. Y. Liu

Keyword(s):

Boundary Layer ◽

Shear Stress ◽

Turbulent Boundary Layer ◽

Analytical Study ◽

Boundary Layer Separation ◽

Mean Velocity ◽

Laminar Separation ◽

Layer Separation ◽

Turbulent Separation ◽

Separation Model

An experimental and analytical study of the separation of a turbulent boundary layer is reported. The turbulent boundary-layer separation model proposed by Sandborn & Kline (1961) is demonstrated to predict the experimental results. Two distinct turbulent separation regions, an intermittent and a steady separation, with correspondingly different velocity distributions are confirmed. The true zero wall shear stress turbulent separation point is determined by electronic means. The associated mean velocity profile is shown to belong to the same family of profiles as found for laminar separation. The velocity distribution at the point of reattachment of a turbulent boundary layer behind a step is also shown to belong to the laminar separation family.Prediction of the location of steady turbulent boundary-layer separation is made using the technique employed by Stratford (1959) for intermittent separation.

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High Reynolds number turbulent wind tunnel boundary layer wall-shear stress sensor

Journal of Turbulence ◽

10.1080/14685240902953798 ◽

2009 ◽

Vol 10 ◽

pp. N14 ◽

Cited By ~ 13

Author(s):

Sebastian Große ◽

Wolfgang Schröder

Keyword(s):

Boundary Layer ◽

Reynolds Number ◽

Shear Stress ◽

Wind Tunnel ◽

Wall Shear Stress ◽

High Reynolds Number ◽

Stress Sensor ◽

Turbulent Wind ◽

Shear Stress Sensor ◽

High Reynolds

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Analysis of Laminar Boundary-Layer Separation in Retarded Flow over Bodies of Revolution

Canadian Journal of Physics ◽

10.1139/cjp-2021-0211 ◽

2021 ◽

Author(s):

Ahmer Mehmood ◽

Babar Hussain Shah ◽

Muhammad Usman ◽

Iqrar Raza

Keyword(s):

Boundary Layer ◽

Shear Stress ◽

Flow Separation ◽

Boundary Layer Separation ◽

The Body ◽

Bodies Of Revolution ◽

Layer Separation ◽

Transverse Curvature ◽

Favorable Pressure Gradient ◽

Curvature Parameter

Laminar boundary-layer separation phenomenon is one of the interesting and important aspects of boundary-layer flows. It occurs in various physical situations because of decreasing wall shear stress. Retarded flow velocities are one of the reasons to happen this event. Flow separation can be prevented or delayed by utilizing bodies of revolution as surface transverse curvature produces the effects of the nature of favorable pressure-gradient which in turn increases wall shear stress that keeps the flow attached to the surface. Bodies of revolution whose body contour follows power-law form also play a vital role to delay flow separation. Bodies of revolution of varying cross-sections and involving surface transverse curvature (TVC) are utilized to examine their effects on flow separation. Particularly, a convex transverse curvature has been considered due to its effects of the nature of favorable pressure-gradient which causes to delay the flow separation. A retarded flow velocity of Görtler’s type is considered in this study to investigate flow separation process. A detailed analysis is provided to understand the flow separation by calculating separation points under various assumptions. It has been observed that the body contours exponent n and the convex transverse curvature parameter k play an assistive role in the delaying of boundary-layer separation even under the influence of strong retardation. Results are presented through various Tables and graphs in order to highlight the role of the power-law exponent of external velocity m, the convex transverse curvature parameter k, and the body contours exponent n on separation points.

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