Very Low Speed Wind Tunnel for Anemometer Calibration

Abstract

This paper describes a wind tunnel for anemometer calibration in the range from 0.045 to 1.4 m/s. This wind tunnel is an open-circuit suction type with a circular test section 300 mm in diameter. Combinations of five sonic Venturi nozzles connected downstream of the wind tunnel generate highly stable flow at 31 speeds. The velocity profile at the test section was measured with a LDV. The nonuniformity of the profile was less than ±2% except the wall boundary layer. The relationship between the flow velocity at the center and the cross sectional average velocity of the test section has been obtained experimentally, so that an anemometer inserted in the test section can be calibrated against the flow rate. Also, reproducibility of the standard velocity for two wind tunnels manufactured under the proposed design has been proven.