Spatial and temporal resolution of a thin-wire resistance thermometer

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Abstract
Based on a discussion of the heat balance equation for a resistance wire sensor a frequency-wavenumber transfer function is derived, which includes the thermal inertia of the wire, the conduction losses to the prongs, and the spatial averaging of the sensor. Based on this transfer function and a model for the frequency-wavenumber temperature spectrum, typical sensor distortions of a measured turbulent temperature spectrum are calculated. The consequences for estimates of the temperature dissipation are studied, and it is finally concluded that many of the complications introduced by the more complex models of both sensor transfer and temperature spectrum tend to cancel for many sensor-flow combinations, leaving much of the simple data interpretation fairly correct. However, in some cases the more complicated models are needed to avoid serious misinterpretations of the data.