Effect analysis for the shape of submarine bow pressure bulkhead upon the acoustic target strength

High level of acoustic Target Strength(TS)from the bow of submarine forms great threat to submarines' acoustic stealth. According to the TS contribution curves,it's adduced that the bow pressure bulkheads are the main source of a submarine's bow target strength. There are two types of bow pressure bulkhead:ellipsoidal and planar bulkheads. And the TS of a rigid plane is much bigger than that of a ellipsoidal one. Based on Plane Element Method(PEM),the relationship of a submarine's bow TS with the bulkheads' curvature is analyzed,and logarithmic fitting is made by calculating the TS of a series of ellipsoidal pressure bulkhead with different curvatures. Then,the acoustic scattering pressure images near pressure bulkhead are obtained via indirect Boundary Element Method(BEM),and it suggests that the scattering pressure field of ellipsoidal surfaces have less directivity index compared to those of the planar bulkhead,which results in significant lower TS level(more than 10 dB). If the curvature is bigger than a certain value,the bow TS of an ellipsoidal pressure bulkhead tends to be stable.