Calibration of a Hot-Wire/Hot-Film Anemometer over a Range of Temperatures, Velocities, and Pressures

摘要

An investigation was made of the possibility of developing a single calibration equation that would be applicable to a wide range of temperatures (68 F to 250 F), velocities (150 to 800 ft/sec), and pressures (15 to 33 psia). A platinum hot film, with a high enough operating temperature to provide good sensitivity to velocity, was calibrated at seven different temperature/pressure conditions. The data was used to calculate velocity, Reynolds number and Nusselt number, and a linear least squares curve fit was applied to the data as a function of Reynolds number raised to an exponent and as a function of Nusselt number times a load factor raised to an exponent. The exponents were chosen, through an iterative process, to provide the best agreement between the data and the curve fit equation. The results indicate that as the range of conditions is allowed to increase ao does the error between measured velocity and velocity derived from the calibration equation.