CHANGE IN THE SHAPE OF THE DIFFRACTING SHOCK-WAVE AT A CONVEX CORNER

The diffraction of shock waves in nitrogen was studied experimentally. The Mach number of the primary incident wave was varied between 2 and 6 and the wedge angle from 15 to 170°. The results were recorded by using the Schlieren method and by surface pressure measurements. The empirical formulae for the pressure on the surface have been determined. A modified version of the Whitham method has been proposed for calculating the shape of the diffracted shock wave that correctly predicts the inflection on the wave profile. It was assumed that the profile of the diffracted wave undergoes bending right up to the wall and the boundary conditions are satisfied due to the interaction of the curved shock with the wall. Such a calculation results in the elimination of the qualitative disagreement between the actual and the calculated profiles, namely, a point of inflection appears on the calculated profile. © 1979.