Measurement of temperatures in unsteady gas flows
Date
1969
Authors
Johnson, Robert Matthew Waller
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Abstract
The experimental research described in this thesis is devoted to providing instrumentation for the direct measurement of the temperature of unsteady gas flows in a shock tube. The range of mach numbers for which the present system is designed is 1.1 to 1.4. This corresponds to a temperature directly behind the shock front in the range of about 318° K. to 373° K.
The existing techniques of temperature determination are reviewed. It is evident that there is a lack of experimental temperature data for low mach number unsteady flows in which the temperature is only a few hundreds of degrees from ambient.
A thin platinum film resistance thermometer was developed, such that the temperature of the backing material could be varied independently of the temperature monitoring apparatus. From a knowledge of the temperature-time history of the platinum film, it was possible to calculate the heat transfer rate at the surface of the backing material at any time.
The temperature of the gas at any given time was measured by determining the gauge temperature for which the surface heat transfer rate was zero. Comparisons are made between the measured temperature and that calculated from pressure and shock velocity measurements for several initial conditions of the test gas. To the best of the author's knowledge, this is the first use of such a technique to determine the temperature of an unsteady gas flow over an extended period of time.