THE DETONATION PROCESS 



91 



The results on a large number of different explosives, and some at 

 several loading densities, as computed by Brinkley and Wilson (11), 

 show similarly good agreement with detonation rate data, the differences 

 being in most cases within experimental error. The values for pressure 

 and density are of unknown accuracy but are very probably not as good. 

 The values obtained by Jones are less accurate, the calculated rate be- 

 ing seventeen per cent higher than the experimental value. This lack 

 of agreement is hardly surprising when one considers the approxima- 

 tions involved and the fact that no experimental data from explosive 

 measurements are used. 



3.5. Adiabatic Pressure-Density Relation after Detonation 



In order to compute the form of the detonation wave behind its front 

 it is necessary to know the adiabatic law for the products. Jones has 

 made calculations of the adiabatic relation for TNT (51), based on con- 

 siderations similar to those in his calculations for the head of the wave. 



Table 3.3. Calculated quantities for TNT at the detonation front. 



as described in sections 3.2 and 3.3. As in such calculations, the prob- 

 lem is made difficult by the necessities of choosing an equation of state 

 applicable to the high pressures and temperatures and determining ap- 

 propriate compositions of the products. Both the density and com- 

 position are, for any very realistic representation, rather complicated 

 functions of pressure and temperature. 



The most fundamental procedure in fixing the initial conditions 

 would, of course, be to employ a calculation of the type made by Jones 

 Avhich made no use of explosion data at all. Jones' calculations, how- 

 ever, led to a detonation velocity some fifteen per cent higher than 

 experimental values, and the initial pressure and density are presumably 

 liable to a similar error. In order to improve the adiabatic results, the 

 pressure and density predicted by the theory for the observed detonation 

 velocity, taken to be 6,790 m./sec. at an initial density of 1.50, are as- 

 sumed. These data, together with the observed variation of detonation 



