Hot-film/hot-wire anemometer calibration for low velocities using image processing

Abstract

Calibration of hot-wire and hot-lm probes at low velocities is a di cult task because the dynamic pressure at these velocities is quite low and may not be easily measured. To solve this problem, substituent techniques have been presented in the literature that rely on other phenomena and utilize di erent hardware. This study described a simple and low-cost method which proposes moving the anemometer probe in the quiescent air (here by means of a swinging arm) and tracked this motion with a camera. After processing the images, the time history of the probe velocity was measured by numerical calculations. Calibration curve was, then, obtained without any predetermined relationship. Using a medium-speed video camera, which is often found in laboratories, would obviate the need for a position sensor and a complicated arm on which this sensor is mounted. This technique can be used for not only pendulums but also other means of moving probes in a quiescent medium.

Experimental Stand for Very-Low-Velocity Gas Flow Generation

“…There are also methods for calibrating measuring instruments by moving the sensors at a known velocity in stagnant air. Typical solutions include placing the calibrated hot-wire anemometer probe on a support: moving in a straight line [ 5 , 6 , 7 ], or moving in a rotating or pendulous motion [ 8 , 9 , 10 , 11 ]. The use of moving objects for calibration requires air stagnation around the calibrated probe and a reduction in vibration with the use of mechanical devices that support the probe.…”