Experiments on Air Flow in the 7-Foot Open Jet No. 1 Wind Tunnel and Application to Wind-Tunnel Design

摘要

Experiments on the flow in the 9-ft. x 7-ft. open-jet tunnel No. 1 at the National Physical Laboratory have been made in order to find the cause of and cure for irregularities in pitch and yaw at the working section. Detailed exploration of velocity and direction showed that general rotation was present in the airstream as well as local vortex motion near the centre of the jet. The general rotation was eliminated at a chosen speed of 65 ft. per second by fixing anti-rotation fins to the walls of the ducts. After numerous tests both on the full-scale and a model tunnel, the irregularities were traced to faulty action of the cascade of aerofoils preceding the working section and were cured by fitting an additional cascade.