UO 



THEORY OF THE SHOCK WAVE 



experimental points. The curve predicted by Penney and Dasgupta 

 lies approximately the same amount below the points, but rises much 

 more rapidly near the charge. It should be mentioned that later ex- 

 perimental values of peak pressures are slightly lower than the ones 

 plotted in Fig. 4.6 (see section 7.4 for exact values), but the differences 

 are unimportant for the present purpose. 



The qualitative difference between the curve from the theory de- 

 veloped by Penney and Dasgupta and that of Kirkwood and Bethe is 

 consistent with the fact that the former starts from the spherical det- 

 onation wave calculated by G. I. Taylor, whereas the latter is based 



60 



40 



q: 

 < 



CD 



3 20 



v9 



10 



I 2 4 6 8 O 20 40 



REDUCED DISTANCE R/q^ 

 Fig. 4.6 Comparison of calculated pressures for TNT. 



on an artificial detonation condition of adiabatic explosion at constant 

 volume. The former is the preferable of the two and should lead to 

 higher pressures very near the charge, because the front of the detona- 

 tion wave is at higher pressure than exists behind it. This difference 

 should, however, be decreased at greater distances because of dissipa- 

 tion in the shock front, as a result of which the initially higher pressures 

 developed by the front of the detonation wave are not realized. It is, 

 however, to be noted that the extrapolation by the Kirkwood-Brinkley 

 theory, which involves no assumptions as to the detonation process be- 

 cause it works in from greater distances, resembles the Kirkwood-Bethe 

 curve more closely than that of Penney and Dasgupta. Kirkwood and 

 Brinkley have not presented this as a final conclusion, and it is possible 

 that the approximations in the similarity restraint of their theory are 

 responsible for the resemblance. 



