On the Study of Axisymmetric Underexpanded Jets

Abstract

In the present paper, we investigated underexpanded sonic jets through axisymmetric conical nozzles both theoretically and experimentally and the effect of the convergence angle on those jets were investigated in all the range of the angles which can be used for practical purpose under various nozzle exit conditions as in our previous paper which had dealt with two-dimensional case.
The flowfield inside the nozzle was solved by expanding the velocity components into power series in y up to the fourth order after OSWATI-TSCH and ROTHSTEIN and we derived a new differential equation which may be applied to the case of considerably large inclination angle of the wall, Furthermore, we dealt with the boundary conditions with special attention. Then, we obtained the shape of the sonic line and the jet boundary along with the location of the shock wave analytically and experimentally and both the results are in a reasonable agreement. Calculated sonic lines were also compared with other authors' ones and some comments were added.