NSWC/WOL TR 76-155 



p. + p n (TPOS) + p_(TPOS) = PVAP (C9 ) 



1 D i\ 



Calculation of PNEG when Reflected Ray is Beyond Region of 

 Cavitation . If the total pressure, p. + p (TPOS) + p (TPOS) , 



ID R 



3 

 upon arrival of the surface refection at depth, y = 4.4 W 



(Equation C7) , was greater than or equal to PVAP, the reflected ray 



was considered to lie beyond the region of cavitation. When this 



happened PNEG was approximated by 



PNEG = |[p D (TPOS) + p R (TPOS)] (CIO) 



calculated at the location of the fish. 



CALCULATION OF DTNEG, DURATION OF NEGATIVE PRESSURE, PNEG . 

 DTNEG was also determined by a calculation along the surface" 

 reflected ray from the charge to the fish. If the surface-reflected 

 ray went thru the region of cavitation and the condition, 



R/W 1/3 < 80 (Cll) 



where 



R = slant range from charge to fish in feet 

 W = explosive weight (pentolite) in pounds 



was true, then DTNEG was calculated from the time-of-f light of the 

 water layer on top of the cavitated region. Otherwise, DTNEG was 

 computed from the linear superposition of the direct and surface- 

 reflected pressure waves. 



C-7 



