324 



HYDRODYNAMICS IN SHIP DESIGN 



Sec. 57.15 



through them. The action is much the same as 

 the flow through a heat exchanger with its inlet 

 forward and its discharge aft. The energy re- 

 quired to maintain this flow within the free- 

 flooding spaces is necessarily taken from that 

 developed by the propulsion device (s). 



It is not possible at present (1955) to calculate 

 this effect in terms of numbers; the designer must 

 resort to large-scale model tests. However, one 

 method of eliminating this waste of power is to 

 fit (if practicable) transverse bulkheads within the 



free-flooding spaces so that little or no circulatory 

 flow occurs in any one compartment. Another 

 method is to so fashion the flooding (and venting) 

 openings that entry and egress, and circulatory 

 flow, is discouraged. 



Eddying, with separation drag, is liable to 

 occur around the edges of shell openings improper- 

 ly formed. While this drag may be minute for 

 any one opening it can assume sizable proportions 

 for multiple openings, such as often occur by 

 the hundreds in submarines. 



