Chapman-Jouguet points

Figure 1 A thermodynamic picture of detonation The unreacted material is compressed by the shock front and reaches the Chapman-Jouguet point. From there adiabatic expansion occurs, which leads to a high-volume state. Finally, detonation products may mix in air and combust.

Fig. 3.6 Detonation wave formation from shock wave to von Neumann spike, and then to the Chapman-Jouguet point.

The characteristic values at the Chapman-Jouguet point are also obtained from Eqs. (9.2) and (9.4) asW... 

Chapman-]auguet Layer. See under Detonation, Chapman-Jouguet Point... 

Fig 2 Pressure in rarefaction wave behind Chapman-Jouguet point according to Taylor and to Langweilcr... 

In the case of a freely spreading detonation wave (in a cartridge not closed with plate 2), pM is not equal to pD, which is the pressure of detonation at the Chapman-Jouguet Point (ie in the plane of completion of chemical reaction), but can be calculated. If detonation velocity, D, and its density, are known, pD may be calcd... 

Dunkle s Lecture at Picatinny Arsenal, 21 Nov 1955, p 3 (One-dimensional steady-state process and Rankine-Hugoniot equation) 78) Ibid, 13 Dec 1955, p 5 (Nature of shock waves) p 8 (Chapman-Jouguet point) pp 8-9 (Basic equations of deton) p 9... 

D<6)- D)/D ° = 3.5 f /S, where D = detonation velocity along the charge axis in the direction of wave propagation D = one-dimensional, steady-state, Chapman-Jouquet deton vel = Chapman-Jouguet point and S = radius of curvature of the shock front... 

This means that at the Chapman Jouguet points the Hugoniot curve and the adiabat are both tangent to the Rayleigh-Mikhel son line... 

In conclusion it was stated that the results of his calcn indicate possible ways of obtg high temperatures and pressures thru the use of detonation at velocities corresponding to the points of the Hugoniot curve which are above the Chapman-Jouguet points... 

From the previous classification of combustion waves, the region 0 < M <1 corresponds to deflagrations and the region M > 1 to that of detonations. Point B at which M = 1 is the Chapman-Jouguet point. It is seen from the above that detonativc combustion... 

The detailed analysis of the chemical and thermal structure of a detonation wave performed by Ya.B. revealed its important features, in particular the presence of high pressure behind the leading shock wave which is approximately twice as high as the pressure at the Chapman-Jouguet point. A number of Ya.B. s papers are summarized in a monograph by Ya.B. and A. S. Kompaneets.2... 

Aleksandrov et al (Ref 19) used an electromagnetic technique to get particle velocity (y) vs time profiles. They conclude that the breaks observed in such profiles coincide with the Chapman-Jouguet point, ie, the time of the break corresponds to the chem reaction time in a detonation. The reaction zone width, a, is then a = r (D — u)... 

Chapman-Jouguet waves assume a special significance in many systems, particularly those involving detonations. It is therefore of interest to investigate the properties of the Chapman-Jouguet points in greater detail. 

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