An Integrated Pressure-Velocity Sensor for Correlation Measurements in Turbulent Gas Flows

Paper i proceeding, 1995

A new integrated pressure-flow sensor has been specially designed for measurements in turbulent gas flows. The pressure sensor is based on polysilicon diaphragm technology and the flow sensor on the gas cooling of a polymide-insulated heated mass. With a pressure-sensor diaphragm area of 100 μm x 100 μm, a flow-sensor hot-chip area of 300 μm x 60 μm and an edge-to-edge distance of 100 μm between the different sensor areas, the smallest eddies in technically interesting turbulent flows can be resolved and measured. The pressure-sensor design shows a flat frequency response curve within ___ 2dB between 10 Hz and 10 kHz with an acoustic sensitivity of ___ for a supply voltage of 10 V. The flow sensor has a thermal response with a time constant of 7 ms and a response time of 25 μs when the sensor is operated at constant temperature using feedback electronics. The measured steady-state flow-sensor power dissipation in a turbulent wall boundary layer at an overtemperature of 100 degrees Celsius was ___ mW where ___ is the time-average flow-dependant wall shear stress. The integrated sensor has been used for simultaneous measurements of fluctuating pressure and wall shear stress in a turbulent boundary layer yielding pressure-wall shear stress correlation coefficients never previously presented.