Measurement of high-frequency turbulent temperature

Abstract

In many areas of turbulence research of current interest, it is of increasing importance to make reliable measurements of high frequency, small scale temperature fluctuations. Platinum wire resistance thermometers provide adequate spatial resolution, but may, after a period of time, suffer a degradation in frequency response when used in air. Relative effects of various sensor parameters on sensor performance under various flow conditions are also discussed as a guide to sensor selection. However, measurements of actual frequency response of wires in turbulent flow systems using circuits especially developed for the purpose show substantial deviations from the analytic results, as well as a dependence of the frequency response on a probe aging effect, which is possibly due to surface contamination. The measured frequency response was used to correct a temperature spectrum measured in a heated jet. The corrected spectrum agreed well with the expected shape.