221 



Measuring the vorticity distribution around the 

 full stern of the geositn models, the authors 

 determined the structure of the stern vortices 

 and found the presence of a concentrated vorticity 

 line in the vortex core which corresponds to the 

 separating vortex sheet of the stern vortex. 



As an application of the results, the effect on 

 the propeller operation due to the induced flow of 

 the stern vortices has been studied. The effect is 

 fairly limited to a few components of forces and 

 moments generated by the propeller. Consequently, 

 it can be said that the effect of the stern 

 vortices on the performance of the propeller and 

 propeller excited vibratory shaft forces and 

 moments is relatively small. However, in the case 

 of this ship model, this effect appears to change 

 the direction of the vertical force and the 

 horizontal bending moment acting through the pro- 

 peller shaft. 



ACKNOWLEDGMENT 



This research program has been carried out mainly 

 under the foundation of the Research Panel SR 159 

 of Shipbuilding Research Association of Japan. 

 The authors would like to express their apprecia- 

 tion to Profs. H. Sasajima and I. Tanaka, who led 

 the Panel, for their valuable suggestions. 



The materials described in the present paper have 

 been kindly prepared by the members of the Ship 

 Research Institute among whom the authors are 

 especially grateful to Mr. K. Takahashi, Mr. T. 

 Haraguchi, Mr. Z. Ishizaka, Mr. N. Sugai, and 

 Miss H. Handa, for their helpful support. 



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