NSWC/WOL TR 7 6-15 5 



Parameter. In Figure 3.4.1b those data points where the bladder 

 response calculation showed more than one oscillation during the posi- 

 tive phase (Tables 3.1.3 and 3.1.4) have been removed. The curve is 

 Equation 3.4.2, the kill-probability result from Yelverton et al 

 (1975) . Thus, their 24-hr mortality is approximately equivalent to 

 our level 3 dissection injuries;* and, perhaps more important, the 

 Impulse Damage Parameter is shown to describe only those explosion 



phase . 



Figure 3.4.1c shows for comparison all of the level 3 injury 

 results plotted as a function of the Bladder Oscillation Parameter. 

 The curve is Equation 3.2.1 derived from the Spot level 3 injury 

 data. 



3.5 DISCUSSION OF INJURY CORRELATIONS 



It is not accidental that both the bladder oscillation 

 parameter and the impulse damage parameter can be used to describe 

 the fish-kill for shallow explosion geometries. To see how this 

 comes about we examine the response of an air bubble to impulsive 

 pressure loading . 



"Let the pressure be applied suddenly and let it disappear 

 again before the bubble has had time to change appreciably in size. 

 Then, the bubble will begin contracting inward at a certain radial 

 velocity v. given by 



v. = — (3.5.1) 



pA i 



*In examining dead and disabled fish which have been collected from the water 



surface following underwater explosions Martin Wiley and Greig Peters (Chesapeake 



Biological Laboratory, Solomons, Md.) have found only fish having injuries of 



level 3 or greater. This indicates that fish having received lesser injuries do 



not show up in the visible fish kill although they may later fall victim to 

 predation. 



49 



