DYNAMIC-RESPONSE OF A HOT-WIRE ANEMOMETER - PART-II - A FLUSH-MOUNTEDHOT-WIRE AND HOT-FILM PROBES FOR WALL SHEAR-STRESS MEASUREMENTS

The present study continues the work described in Part I of this paper in utilizing a specifically designed apparatus for generating a known near-wall fluctuating flow field for the purpose of quantifying the d ynamic response of a flush-mounted hot-element wall shear stress gauge . Two different types of wall shear stress gauges were tested: a flush -mounted hot wire in contact with the wall substrate and commercially available quartz substrate hot-film gauges with different thicknesses of quartz coating, It is found that the flush-mounted hot-wire gauge h as a much higher dynamic response than the quartz substrate gauges, al though it is still lower than the marginally elevated hot-wire configu ration, This may suggest the possible use of a marginally elevated hot wire as a wall shear stress gauge to ensure sufficient responsiveness for time-resolved wall shear stress measurements.