抄録
Selection of optimum sets and kinds of damping screens for a low turbulence wind tunnel settling chamber is investigated. Existing low turbulence wind tunnel settling chamber is used as test section preparing hot wire traversing holes after rapid expansion diffuser, honeycomb, and ten screens. Hot wire anemometer with temperature compensation circuit is used for measuring the velocity profiles and turbulence intensity levels inside the settling chamber and working section of the tunnel. The results show that the number of screens determined by classical method is not appropriate when the number increase more than about five. Turbulence level produced by a damping screen itself becomes important when the turbulence level of on-coming flow is already low enough (less than 1%). It is also found out that the distance needed for the natural damping of the turbulence level after the final screen becomes very important for a low turbulence wind tunnel.
