A simple pendulum technique for the calibration of hot-wire anemometers over low-velocity ranges

A method for low velocity calibration of hot-wire anemometers, in which the probe is mounted on a pendulum arm, is presented. The calibration constants are determined from recorded traces of the anemometer signal obtained in the forward swing of the pendulum with the probe mounted at two different radii along the arm. Typical calibration results are presented and the use of a modified King's law in the low Reynolds number range is discussed.List of Symbols A, B, n calibration constants in King's law - E anemometer voltage output - E₀ anemometer voltage output for zero flow velocity - Re Reynolds number - r radius along the pendulum arm - T period of oscillation of the pendulum arm - t time - U velocity - y⁺ non-dimensional distance from the wallGreek Symbols root mean square of the velocity difference in half the forward swing - angular position of pendulum - angular velocity of pendulum armFinancial support for this work was provided by the Natural Sciences and Engineering Research Council of Canada and by the Atomic Energy of Canada Limited.