Abstract
Free-jets issuing from a circular, square, rectangular with different values of aspect ratio, and a regular triangle orifices are visualized by means of a laser-induced fluorescent method. It is shown that for the circular orifice, axisymmetiy is collapsed by increasing the stagnation pressure. For the square orifice the cross section of the jet becomes also square, but the side inclines 45 degree to the side of the orifice. For the rectangular orifice the shape of the cross section becomes rhomb and the direction of the longer diagonal is in direction of the orifice width. The longer diagonal becomes longer than the other with increasing the aspect ratio of the orifice. The distance of the normal shock on the jet-axis increases with square root of the pressure ratio between the stagnation and the ambient pressures and the proportionality constant is about the same as for a circular orifice. It increases almost with square root of the aspect ratio. For the regular triangle orifice the side of the cross section is orthogonal to the line connecting the apex of the slit and the center. Radially expanded jets due to the strong interaction of shocks were observed for all orifices presently tested.
