D'Yakov-Kontorovich Instability in Planar Reactive Shocks
The standard D'yakov and Kontorovich (DK) instability refers to planar shock waves that, once perturbed, oscillate with constant amplitude in the long-time regime. As a direct result, pressure perturbations generated right behind the shock propagate downstream as non-evanescent sound waves, an effect known as Spontaneous Acoustic Emission (SAE). For the DK-regime to be achieved, the slope of the Rankine-Hugoniot curve in the post-shock state must meet certain conditions, which have been usually related to non-ideal equations of state. It has been found that DK-instability, or SAE, can also occur in shocks moving in perfect gases when exothermic effects take place. In particular, a planar detonation, initially perturbed with a wavelength much larger than the detonation thickness, may exhibit constant-amplitude oscillations when the amount of heat release is positively correlated with the shock strength.