DESIGN OF A LOW-SPEED AXISYMMETRICAL WIND-TUNNEL CONTRACTION

Most three-dimensional contraction designs are based on the expansion of the Stokes stream function in a series in terms of the distance in the longitudinal direction and the radial distance from the axis of contraction. This method of design requires selection of a suitable function for the variation of velocity along the axis of the contraction. In this work the velocity variation along the axis of the contraction is selected such that the velocity increases gradually in the upstream direction and converges rapidly to the value of exit velocity in the downstream direction. In this way the velocity peak on the wall of the contraction is decreased without increasing the length of the contraction. The design method is applied to a contraction that has an area ratio of 10:1 and the result is compared with the previous result.