Influence of the rising rate of backpressure on the upstream motion characteristics of the shock train in a scramjet isolator

The distance over which a normal shock motion passes is generally considered to be negatively correlated with the rising rate of backpressure; however, our experiments show that distance is independent of the rising rate of backpressure for oblique shock trains. Single-pulse backpressure was constructed to decouple the amplitude and the rising rate of backpressure and remove its cumulative effects for the first time at Ma = 1.95. Unlike normal shock, when backpressure begins to fall, the shock train does not immediately retreat but rather moves upstream to the terminal position. The mixing region may play an important role in this dynamic process.