APPENDIX B: NONRESONANT ACOUSTIC SOURCE OUTPUT POWER* 
Nava! Ocean Systems Center 
San Diego, California 92152 
2 June 1980 
MEMORANDUM 
From: HA Wilcox, Code 5304 
To: TE Stixrud, Code 5313 : 
Subj: Nonresonant Acoustic Source (NRAP) output power 
1. The diameter of each of the two piston faces used in NRAP is 11.25 inches. Each 
piston is centered in a circular aperture of !2-inch diameter. A rolling rubber seal fills the 
annular gap between each piston and the housing, whence it follows that the rolling seal has 
an-amplitude of motion which is half that of its associated piston. Hence the volume dis- 
placement amplitude for the combination piston plus seal is 
oo) 9) po) 
AV = (n/4)Dy°s + [(a/4oD2 - (/4)1D 5|(s/2) 
a) 9) ) } 
= (n/4) [D2 + (COZ - ID2)/2] 5. (1) 
where 
Dy = piston dia 
OD, = OD of seal 
ID, = ID of seal 
Ss = amplitude of piston motion (half the peak-to-peak throw of 
the piston). 
Since 
IDES Dp> : (2) 
equation (1) can be written 
AV = (n/4) (ODZ + IDZ)/2 5. (3) 
This AV is the same as for an “effective” piston diameter, Doe in the equation 
: a) 3 
AV = (7/4)D ers, (4) ; 
*In this appendix the HAW-15 accoustic projector is referred to as the NRAP. i 
40 
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