SMALL SILICON-BASED PRESSURE TRANSDUCERS FOR MEASUREMENTS IN TURBULENT BOUNDARY-LAYERS

Small silicon based sensors for the measurement of wall-pressure in tu rbulent flows have been designed and fabricated using microelectronic technology. The sensor diaphragms have a side length of 100 and 300 mu m, and polysilicon piezoresistive gauges were used for detection of th e deflection. A two-dimensional flat plate boundary layer was employed to determine the performance of the pressure transducers, and compari sons with established data from the literature were made. A threshold value for the pressure fluctuations of about the double Kolmogorov len gth scale was estimated independently from the probability distributio n as well as from the power spectra. In good agreement with theoretica l predictions of Blake (1986), the slope of the power spectra was foun d to be omega-1 in the intermediate and omega-5 in the high frequency range.