Two Effects of Diaphragm Bulge on Shock Tubes

Summary

A computational study is presented that has uncovered two important effects in shock tube flows. They occur because the diaphragm has to support a static load before it breaks. This static load usually deforms the diaphragm before rupture. These effects can have significant consequence both in reflected-shock tunnels and in expansion tubes. The first effect is that the diaphragm bulge causes a shock wave to be propagated across the shock tube and to be repeatedly reflected at the axis and the wall. The second is that the contact surface rolls up to form a vortex ring. The sign of the vorticity in the vortex ring depends on the temperature ratio across the diaphragm.