In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monit...

The measurement of scalar fluxes employing the eddy covariance method is a widely used experimental approach, for which the flow distortion due to obstacles (e.g., sensor mounts and mast) is a well-known but not fully solved problem. In order to reduce flow distortion we installed a sonic anemometer in a surface-normal orientation relative to the terrain slope, and a second instrument in a vert...

By combining the aeroelastic and vortex-forced flutter modes of a thin plastic strip, its oscillation frequency can be confined to scale monotonically with fluid velocity. This principle has been used to produce a low-cost, mm-scale anemometer that measures air speed to ±(5% + 0.5m/s) from 118m/s. The device uses a 2mm slot-type photointerrupt detector to monitor the fundamental frequency of a ...

The problem of particle number density measurements with a laser Doppler anemometer is addressed. Analytical expressions for the instrument measurement cross section are given. An automatic calibration method for determining unknown scattering parameters, which promises good accuracy in changeable optical conditions, is described. Estimates of the measurement uncertainty are derived and the met...