196 



2/+ = 



2|/2' 





iii + 





;i2] 



see Equation [45] . 



In the example of a Number 8 detonator, where R^ = 2 inches, R^/R^= 

 2.6, R^/Rf, = 0.l6, Tj = 0.015 second, p^ = 15 pounds per square inch, at r = 

 l8 inches from the center of the detonator, Equation [12] gives, for the total 

 positive impulse due to the first compression and re-expansion, 0.059 pound- 

 second per square inch. The part of this that arises from the central peak, 

 in which the pressure exceeds a quarter of the maximum pressure, as found by- 

 substituting R = 2Ri in Equation [11] and multiplying / by 2, is about 0.024 

 pound-second per square inch. This accounts for rather less than half of the 

 total. Even so, it probably exceeds the impulse due to the high-pressure part 

 of the primary pressure-wave, which should not exceed 0.02 pound-second per 

 square inch. 



In Figure 3 the pressure p is shown as a function of the time t, 

 for a contraction from a maximum radius R^ = 2.^ R^ and a subsequent re- 

 expanslon. The ordinates represent values of p/p„„ ; the maximum pressure 

 p„„ is given by Equation [8b]. The abscissa represents t/T, where T is the 

 period of oscillation of the gas globe. Part of the curve is repeated on an 

 expanded scale. The curve is independent of the quantity of the gas, which 

 determines the value of R.. 



t/T for Curve B 

 0.004 0.008 0.012 



0.3 0.2 0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 I.I 



t/T (or Curve A 



Figure 5 - Curve showing the Calculated Pressure p developed in the Water 

 during the Oscillation of a Bubble or Gas Globe under Water, 

 in Terms of the Maximum Pressure p„„ 



Acoustic radiation of energy is ignored. Time ( is plotted in terms of the period 

 of oscillation T. Part of the curve is repeated on an enlarged time scale. 



