Small silicon based pressure transducers for measurements in turbulent boundary layers

Small silicon-based sensors for the measurement of wall pressure in turbulent flows have been designed and fabricated using microelectronic technology. The sensor diaphragms have a side length of 100 and 300 microns, and polysilicon piezoresistive gauges were used for detection of the deflection. A 2D flat plate boundary layer was employed to determine the performance of the pressure transducers, and comparisons with established data from the literature were made. A threshold value for the pressure fluctuations of about the double Kolmogorov length scale was estimated independently from the probability distribution as well as from the power spectra. In good agreement with theoretical predictions of Blake (1986), the slope of the power spectra was found to be omega exp -1 in the intermediate and to omega exp -5 in the HF range. (Author)