Comparison of Temperature Correction Methods for Hot Wire Anemometers

ABSTRACT HOT wire anemometer readings for air velocity and mass flux need to be corrected for temperature whenever the test temperature differs from the calibration temperature. Three correction methods to account for differences between the test and calibration temperatures were compared. Anemometer mass flux data were taken at 23.4°C and 40.0°C. The 40.0°C data was corrected to a predicted mass flux at 23.4°C by using the three methods. The Bremhorst procedure, which linearly related the square of the anemometer voltage to the test temperature, was more accurate than either the method recommended by manufacturers, involving temperature difference only, or another method that included both temperature differences and property temperature dependence. For mass fluxes from 1 to 6 kg/m^s, the percent error of the Bremhorst procedure ranged from —8.8% to 2.7% while the latter two methods ranged between 56.1% and 9.1%. The Bremhorst procedure corrected the 40.0°C data to 23.4°C data with resulting mass fluxes being within the 5% accuracy of the anemometer for mass fluxes of 2 kg/m^s or greater.