Interaction between the reflected shock wave and the nonsteady jet in a shock tube experiment. (2nd report Theoretical base and proof for the behavior of reflected shock wave)

Abstract

Nitrogen gas is set to spurt from a small circular hole located at the end wall of a shock tube at about 35 ms before the shock wave arrives and reflects there. Interacting with the jet the reflected shock wave changes its shape from a plane shock wave to a curved one. We observed the phenomenon by the use of a schlieren system, time counters and pressure gauges. We calculated the pressure and the temperature behind the curved reflected shock wave by the use of its distance-time relations, the differentiation of cubic natural smoothing spline functions, and Rankine-Hugoniot equations. In this paper, we want to prove that the method, which we proposed in the previous work, is a reasonable and available one. The results are as follows: (1) From pressure profiles, we could show that the proposed method was a reasonable and available one. (2) When an unstable, curved, reflected shock wave turns back to a stable plane shock wave, it generates some expansion waves, which cause a temporary pressure-drop (about 120 μs) in the Kistler transducer on the side wall after the passing of a reflected shock wave. (3) The calculated results using the proposed method are supported by the experimental facts of (2), and the facts show that a strong inverse flow is made by the interaction between the reflected shock wave and jet behind the reflected shock wave.