Visualization of shock wave–grid turbulence interaction in the counter–driver shock tube

We have developed a “counter-driver shock tube (CD-ST) in which we can generate two sets of a planar shock wave and a post-shock flow in the opposite directions. The initiations of a planar shock wave and a counter flow are done with sending electrical signals to the diaphragm opening devices on both ends with an appropriate time difference. The experiments were conducted using a newly-developed CD-ST with a total length of 10.1 m. Using side-view shadowgraph, we have successfully visualized shock wave deformation made by the grid turbulence. With a shock Mach number of 1.04 and a turbulent Mach number of 0.024, the side-viewed shock front became much dispersed with a sufficiently long interaction length than 0.3 m; the shock wave front became “wrinkled” and then “broken,” thereby claiming that we have successfully visualized the formation of “broken” shock wave as was suggested by the numerical simulation in Larsson et al. J. Fluid Mech. 717, 293 (2013).