Deflagrations Chapman-Jouguet

Detonation, Chapman- ouguet Process. It is either Chapman-Jouguet Deflagration or Chap-man-Jouguet Detonation (qv)... 

Classification Weak deflagration Chapman-Jouguet deflagration Strong deflagration Weak detonation Chapman-Jouguet detonation Strong detonation... 

A Chapman-Jouguet detonation wave may be described as an exothermic supersonic wave that propagates itself at the minimum possible velocity consistent with the conservation laws, whereas a Chapman-Jouguet deflagration is an exothermic subsonic wave that propagates itself at the maximum possible velocity consistent with the conservation laws. 

The pressure developed by decomposition of acetylene in a closed container depends not only on the initial pressure (or more precisely, density), but also on whether the flame propagates as a deflagration or a detonation, and on the length of the container. For acetylene at room temperature and pressure, the calculated explosion pressure ratio, / initial > deflagration and ca 20 for detonation (at the Chapman-Jouguet plane). At 800 kPa (7.93... 

Thermodynamic cycles are a useful way to understand energy release mechanisms. Detonation can be thought of as a cycle that transforms the unreacted explosive into stable product molecules at the Chapman-Jouguet (C-J) state,15 which is simply described as the slowest steady-state shock state that conserves mass, momentum, and energy (see Figure 1). Similarly, the deflagration of a propellant converts the unreacted material into product molecules at constant enthalpy and pressure. The nature of the C-J state and other special thermodynamic states important to energetic materials is determined by the equation of state of the stable detonation products. 

HMX and RDX are heated, deflagration combustion occurs with a burning rate of about 1 mm s" at 1 MPa. However, when these nitramines are ignited by primers giving rise to shock waves, detonation combustion occurs with a burning rate of more than 7000 m s . The characteristics of combustion wave propagation are determined by the Chapman-Jouguet relationship described in Refs. [1-5]. 

Chapman-Jouguet Process. It is either CJ Deflagration or CJ Detonation... 

Deflagration, Chapman-]ouguet. See a brief definition given under Detonation, Chapman-Jouguet... 

Detonation, Predetonation Phase. This is an intermediate phase in the DDT (Deflagration to Detonation Transition) between deflagration (or combustion) and detonation Oppenheim (Ref 3, p 475) describes how during this phase a combustion front is accelerated by a shock process until the shock front is overtaken and a (CJ) Chapman-Jouguet detonation sets in. 

Fig Hugoniot curve iff111 = of reaction products, with sections corresponding to strong, Chapman—Jouguet, and weak detonations and deflagrations... 

Detonation and deflagration) 110) J. Herschkowitz, "The Chapman-Jouguet Plane for a Granular Explosive , PATM 1474(1964) (Based on the deton vel of a granular mixt of K perchlorate and powdered A1 confined in a Lucite tube and an ideal deton velocity calcd by the Ruby computer, H. found that the C-J plane is ca 0.9cm behind the plane at which the expln reaction begins) 111) W.H. Rinken-bach, formerly of PicArsn, Private communication, Oct 1964) 112) F.J, Cheselske, "In-... 

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 process from E to B via A is a process made up of a shock from E to A and a deflagration from A to B. In this case, the high temperatures necessary for initiating the combustion are supplied by the shock rather than by the diffusion processes previously mentioned. This explanation for detonation phenomena was advanced independently by Chapman, and by Jouguet, around 1900. If Q/CPTX is sufficiently large to carry the process to point C, this is a Chapman-Jouguet detonation. As a consequence of the physical means by which detonations are produced, this is the type of detonation usually encountered. 

As in consideration of deflagration phenomena, other parameters are of import in detonation research. These parameters—detonation limits, initiation energy, critical tube diameter, quenching diameter, and thickness of the supporting reaction zone—require a knowledge of the wave structure and hence of chemical reaction rates. Lee [6] refers to these parameters as dynamic to distinguish them from the equilibrium static detonation states, which permit the calculation of the detonation velocity by Chapman-Jouguet theory. 

For the mixture described in the previous problem, calculate the adiabatic (deflagration) temperature when the initial cold temperature is 298 K and the pressure is the same as that calculated for the Chapman-Jouguet point. 

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