A single crystal SiC plug-and-play high temperature drag force transducer

Abstract

A novel fully packaged single crystal piezoresistive 6H-silicon carbide (6H-SiC) drag force transducer based on cantilever beam deflection was demonstrated for the first time in a hot (/spl sim/600/spl deg/C) section of a gas turbine engine to study turbulence. The beam deflection was directly proportional to the force induced by the flow stream. The induced strain was transferred to the piezoresistors etched into the 6H-SiC epilayer, which changes in resistance and read out externally as the output of the Wheatstone bridge circuit. The transducer natural frequency was measured to be 35 kHz and was in good agreement with the calculated value of 35.7 kHz. The presumed turbulence was extracted by subtracting the ensemble mean waveform signal and averaging the results. The post engine test at lower temperature and up to Mach 0.8 indicated the typical second order, /spl nu//sup 2/, where /spl nu/ is the average flow velocity. This result confirmed that the transducer survived the high temperature test. The result provided further confirmation of the potential application of semiconductor SiC as a piezoresistive sensor in temperatures that are beyond the functional capability of conventional silicon based sensors.