Collected Works of H. S. Tsien (1938-1956)

On the Design of the Contraction Cone for a Wind Tunnel

Hsue-shen Tsien*

(California Institute of Technology)

In desicning the contraction cone for a wind tunnel, the usual design condition is that the velocity at the end of the cone must befairly uniform. However, if the curvature of the wall along the flow direction is too large at certain points, local velocities at these points may exceed the uniform velocity at the end of the contraction cone. There are then regions of adverse pressure gradient and the boundary layer may separate from the wall. Furthermore, if the velocity at the end of the contraction cone is very high, say about 0.9 that of the sound, an additional factor enters — namely, the danger of compressibility shock. This danger ...