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ACCURACY OF WALL-SHEAR STRESS MEASUREMENTS USING MICRO-PILLARS

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The micro-pillar shear-stress sensor MPS3 is used to assess the quantitative wall-shear stress distribution in a flat plate turbulent boundary layer (TBL) at low to moderate Reynolds numbers. The sensor is based on a novel measurement concept comprising an array of highly flexible micro-pillars which are flush mounted on the surface measured. Figure 1(a) shows an array of micro-pillars similar to the array used for this work. The micro-structures protrude into the flow but are immersed in the viscous sublayer of the boundary layer thus experiencing a linear velocity gradient along its length. The micro-pillars bend due to the fluid forces on the structures and the recorded deflection is correlated with the locally prevailing wall-shear stress such that the wall-shear stress distribution can be determined.

Author(s):

Bernardo Nottebrock    
Institute of Aerodynamics, RWTH Aachen University
Germany

Wolfgang Schröder    
Institute of Aerodynamics, RWTH Aachen University
Germany