The temperature sensitivity of hot wires
Abstract
Significant errors in measurements of some velocity and joint velocity-temperature statistics arise from the non-negligible contamination of the measured hot-wire velocity signal by concomitant temperature fluctuations. Measurements of the temperature sensitivity of hot wires operated at high overheat ratios are considerably more difficult to obtain than measurements of the velocity sensitivity. Therefore to provide a check on the measured values, an analytical expression for the temperature sensitivity is derived which can be evaluated from parameters readily obtained from the velocity calibration data. The analysis, based on the convective heat transfer relation of Collis and Williams (1959), gives values of the temperature sensitivity which compare well with directly measured values. The present analysis is extended to show that the temperature and velocity sensitivities can be expressed entirely in terms of the linearized voltage output obtained by direct calibration for each hot-wire or hot-film sensor. Estimates of the errors in some measured statistics caused by the concomitant temperature fluctuation contamination of the hot-wire signal are determined.
- Publication:
-
Dynamic Measurements in Unsteady Flows
- Pub Date:
- 1979
- Bibcode:
- 1979dmuf.proc..101C
- Keywords:
-
- Hot-Wire Anemometers;
- Temperature Effects;
- Velocity Measurement;
- Convective Heat Transfer;
- Electric Bridges;
- Electric Potential;
- Linear Systems;
- Sensitivity;
- Instrumentation and Photography