Chapman-Jouget pressure

A consistent procedure was followed in measuring the records A median line was drawn through the oscillograph trace, starting at a point well beyond the wave front, and extending back up toward the peak to the point where it crossed the rise line. In this procedure, the contour of the expansion wave is extrapolated back to the shock front. The value obtained in this manner should be closely comparable to the Chapman-Jouget pressure. 

J. N. Fritz, R. S. Hixson, M. S. Shaw, C. E. Morris and R. G. McQueen Overdriven Detonations and Sound Speed Measurements in PBX-9501 and the Thermodynamic Chapman-Jouget Pressure , Journal of Applied Physics 80, 6129-6141 (1996). 

Fast deflagration—the flame position is much closer to the precursor shock wave. Overdriven detonation—a transition to detonation that has just occurred and the detonation is significantly overdriven with the peak pressure, well in excess (2-3 times) of the value usually associated with a steady Chapman-Jouget (CJ) detonation. This peak pressure generated during the transition process is a particular point of concern in the industry. 

Next to the - Chapman-Jouget theory, during the last 50 years, the principal methods of calculating detonation pressure and the velocity of flat detonation waves have been the Becker-Kistiakowsky-Wilson (BKW), the Lennard-Jones-Devonshire (LJD) and the Jacobs-Cow-perthwaite-Zwisler (JCZ) equations of state. 

Chapman-Jouget detonation velocities and pressures, which for a large number of explosives lie within the measurment accuracy of practically obtained values. 

R. Chirat and G. Pittion-Rossillion employ a simplified Weeks-Chan-dler-Andersen (WCA) perturbation theory while F. Ree uses the Man-soori-Canfield-Rasaiah-Stell (MCRS) hardsphere variational theory. Both methods build on the a-Exp-6 potential and yield the theoretical Chapman-Jouget detonation velocities and pressures, which for a large number of explosives lie within the measurment accuracy of practically obtained values. 

A plot of P vs. Up has the slope poDs and passes through the origin. If the Hugoniot curve for the detonation products of lead azide at the C-J point were known (the curve for unreacted RDX is known [40]), it would be possible to determine the strength of the shock wave generated in RDX by the detonation wave from lead azide. It is to be recalled that the Chapman-Jouget model as modified calls for a reaction zone at the end of which the reactants have been completely converted to products in equilibrium and travel at the local sonic velocity. The end of the reaction zone is often called the C-J plane, and the associated pressure and temperature called the C-J pressure and temperature. 

The nature of the Chapman-Jouget and other special thermodynamic states important to energetic materials is strongly influenced by the equation of state of stable detonation products. Cheetah can predict the properties of this state. From these properties and elementary detonation theory the detonation velocity and other performance indicators are computed. Thermodynamic equilibrium is found by balancing chemical potentials, where the chemical potentials of condensed species are just functions of pressure and temperature, while the potentials of gaseous species also depend on concentrations. In order to solve for the chemical potentials, it is necessary to know the pressure-volume relations for species that are important products in detonation... 

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