MAIN-CIRCULATING-SYSTEM MEASUREMENTS 



The velocity profiles measured in the throat of the condenser scoop are plotted in 

 Figure 9 and given in Table 4. The flow rates in Figure 10a were computed by assuming that 

 the flow in the throat was two-dimensional. The flow rate versus ship speed is plotted in 

 Figure 10a. The dotted line represents an extrapolation to the design condition at 38 knots. 

 Figure 10a shows that the flow through the condenser varies as the 1.3 power of the ship 

 velocity. This variation is possible since the scoop receives water from the boundary layer 

 where the kinetic energy is less than in the free stream. 



The pressure differences across portions of the main circulating system are plotted in 

 Figure 10b. The wide scatter of points is due in part to the large changes in the manometer 

 readings which occurred during runs. Part of the error may also be due to recording errors by 

 observers and to the difficulty of visually averaging the fluctuations. The condenser measure- 

 ments were requested subsequent to the initial planning, too late to provide a unified installa- 

 tion which could be photographed in the manner of the boundary-layer survey manometers. The 

 fairing used in Figure 10b was chosen to use the maximum number of data points consistent 

 with making the head loss curves approximately parallel. This choice of fairing shows the 

 pressure losses in the system to be directly proportional lo the rate of flow through the 

 condenser. Dimensional analysis and data on friction losses in piping systems show that the 

 head loss should be proportional to the square of the flow rate (i.e., the square of the velocity 

 through the system). Friction losses in the tubes and water boxes were calculated from data 

 in Reference 8 and plotted on Figure 10b for comparison. A recent paper by Dudley^ gives a 

 comprehensive series of measurements on a destroyer-type vessel. 



CONCLUSIONS 



The shape of the velocity profiles measured in the boundary layer of the destroyer is 

 similar to the shape of velocity profiles measured in the boundary layer of a flat plate at the 

 same Reynolds number. The thicknesses of the ship boundary layer and flat-plate boundary 

 layer are approximately the same at the same Reynolds number. Equation [6] provides a better 

 estimate of the boundary-layer thickness than does the Prandtl formula. The data on the 

 internal performance of the main circulating system are not accurate enough nor consistent 

 enough to provide a basis for significant conclusions about the performance of the condenser. 



ACKNOWLEDGMENTS 



The data forming the basis of this report were obtained by personnel of the Flow Studies 

 Section, under the general guidance and direction of Mr, M.S. Macovsky, 



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