Fast-response piezoresistive pressure transducers for thermofluids experiments

Abstract

Thermofluids experiments often require the use of fast-response pressure transducers that maintain their accuracy over a wide range of operating temperatures. Existing pressure sensing technologies are available which suit these demanding applications, however these transducers are usually relatively expensive. This project investigates the use of inexpensive piezoresistive pressure transducers in the measurement of transient fluid pressures. A temperature compensation routine was developed which improved the accuracy of the piezoresistive pressure transducers over a substantial range of operating temperatures. A dynamic response analysis indicated that the diaphragm resonant frequency of these sensors was 246.7 kHz (without the addition of latex or grease) and that the response times could be improved from approximately 12.5 'ms' to 0.38 'ms' with simple case modifications. These results demonstrated the suitability of piezoresistive pressure transducers for use in fast-response thermofluids experiments. A piezoresistive pressure transducer produced very similar results to a piezoelectric sensor when both devices were tested simultaneously in the USQ Gun Tunnel. This indicated that the piezoresistive sensor was capable of accurately recording rapid fluctuations in pressure levels. The cylinder pressures of an internal combustion engine recorded by a piezoresistive and piezoelectric sensor also compared well. The high operational temperatures of the engine verified the success of the piezoresistive sensor temperature compensation routine.