Chapman-Jouget conditions

At a high level of superheat the liquid evaporates completely within a stable and stationary evaporation discontinuity at the liquid surface. This expansion discontinuity is a deflagration with sonic outflow velocity (Chapman-Jouget condition). The evaporation rate at the surface is given by gas... 

We conducted a quantiun-based molecular dynamics simulation of HMX at a density of 1.9 g/cm and temperature of 3500 K for up to 55 picoseconds has been conducted. These are conditions similar to those encountered at the Chapman-Jouget detonation state. Thus, although we do not model the entire shock process, we can provide some insight into the nature of chemical reactivity under similar conditions. Under the simulation conditions HMX was found to be in a highly reactive dense supercritical fluid state. We estimated effective reaction rates for the production of H2O, N2, CO2, and CO to be 0.48,... 

Thompson et al [3] have suggested on the basis of their evaporation wave experiments that the Chapman-Jouget (Ch-J) condition (sonic outflow in the reference frame of the wavefront) which applies to classical detonation also applies to evaporation waves. In our experiments, a choked exit is essentially the same as the Ch-J condition, since the wave motion relative to the exit is negligible compared to the two-phase flow velocity. We observe waves both with choked and unchoked flows (see Table 1) hence, subsonic outflow is also possible, and the Ch-J condition is not necessary for the propagation of evaporation waves. 

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