A method to improve accuracy of hot-wire probe calibration under variable temperature field

The probe calibration wind tunnel of IFA300 hot-wire anemometer system cannot complete the probe calibration at a given temperature and low flow rate, because the side wall of the calibration wind tunnel has high thermal conductivity. That is to say, when the air flows through the calibration wind tunnel, its temperature will decrease sharply. In view of this structural defect, a measure method is put forward to maintain the temperature of the calibrated airflow by heating the side wall of the calibrated wind tunnel, which greatly widens the temperature range of the calibrated low-speed airflow. This measure adopts repetitive experimental methods to effectively improve the accuracy of the calibration results. The relative error of the test is controlled under 1% for the calibration airflow with temperature from 20 ℃ to 58 ℃, which is much higher than the design accuracy of the IFA300 hot-wire anemometer. In order to adapt to the test of the flow parameters in an enclosed cavity, a set of probe anti-collision control system is designed and manufactured, and the hot-wire probe has been protected well. The temperature and average velocity in the outer normal direction at different heights of the hot wall of the enclosed cavity are measured, which is in good agreement with the literature results.