Deflagrations strong

Flow fields resulting from these combustion modes were computed by means of similarity methods (Section 4.2.1) and used to provide initial conditions for numerical computations. The main conclusion was that blast waves at some distance from the charge were very similar, regardless of whether the combustion mode was detonation or strong deflagration. 

Weak deflagration since 2 > Y (subsonic flow to subsonic) Strong deflagration since P2 < Py(ll/i2 > l/pY) (subsonic flow to supersonic)... 

Region V Pi < Pk supersonic flow to supersonic flow, strong deflagration... 

The other waves are classified as follows weak detonations, strong detons, weak deflagrations and strong deflagrations (Ref 38,... 

Region IV p2 > Pk subsonic flow to subsonic flow, weak deflagration Region V P2 < Tk supersonic flow to supersonic flow, strong deflagration... 

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

A process from E to A is an adiabatic process from supersonic conditions to subsonic conditions and is recognized as a shock wave. The entropy for this process increases from E to A, hence the reverse process from A directly to E entails an entropy decrease and is impossible. A strong deflagration, A to D, is therefore impossible except via C, a path involving an exothermic process from C to Z), followed by an endothermic process D to E. It seems unlikely that such a combustion process would be found in nature, although it is not impossible. 

Red phosphorus as a flammable substance shows very strong deflagration, and aluminium powder is rated next... 

From considerations of combustion-wave structure, it will be indicated in Section 6.1.3 that strong deflagrations do not occur hence the physically meaningful section of the deflagration branch of the Hugoniot curve is DE. Most deflagrations are, in fact, nearly isobaric. 

FIGURE 6.2. Schematic diagram illustrating the properties of various Rayleigh lines. End states at points a, b, c, d correspond to strong and weak detonations and weak and strong deflagrations, respectively. 

Equation (7) shows that for a detonation (that is, for Mq > 1), equation (8) identifies the cold-boundary point [(tp, t, c) = (1,0,0)], while for a deflagration (that is, for Mq < 1), equation (9) represents the cold-boundary point. By using equation (7) and the results of Section 2.2 (for example. Figure 2.5), it can be seen that equation (10) is the hot-boundary point for a weak detonation or a strong deflagration and equation (11) is the hot-boundary point about T = 0, (p — (p+ (0) then yields the equidimensional equation... 

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