LARGE VORTEX IN FRONT STAGNATION REGION OF A SQUARE PLATE INDUCED BY A FINE INTERFERENCE WIRE

Using hydrogen bubble technique, the great change in flow field caused by weak interference in the stagnation region has been observed. When a fine interference wire was set in the upstream of a square plate, t he wake of the wire invoked a large counter rotating vortex pair in th e front stagnation region of the square plate. This large vortex pair and the reverse flow region might occupy a region larger than half par t of the model, with a size over a 100 times greater than the diameter of the interference wire. The formation and development process of th e large vortex pair are investigated in this paper.