A Fluidic Temperature Control Using Frequency Modulation and Phase Discrimination

Methods of using fluidic devices for sensing and controlling temperature were developed for gas turbine engine application. Frequency modulation and phase discrimination techniques were used both in the sensing of the temperature and in the comparison of the sensed temperature with the reference value. These techniques proved to be practical for measurement at a point and can be adapted for average temperature measurements. Temperature information was transmitted 5 ft by a pneumatic carrier frequency signal. Key fluidic circuitry was built and tested at temperatures ranging from 70 F to 2000 F. The temperature limitations were found to be those inherent in the material from which the devices were fabricated. No degradation of performance was noted at high temperatures.