The evolution of secondary flow phenomena and their effect on primary shock conditions in shock tubes: Experimentation and numerical model
Fig 7
The shock pressure ratio along the longitudinal axis.
The shock pressure ratio, z, defined as the ratio of the shock front, pshock, to the ambient pressure, pambient, decays gradually along the shock tube and declines rapidly after expansion begins at the shock tube exit. The rate of decay within the shock tube and the following expansion was found to depend on the shock strength.