Fully Cavitating Propeller for a Hydrofoil Ship 



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 20,000 

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 40,000 

 30,000 

 20,000 

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-I 30,000 



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40,000 



30,000 



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O )0 20 30 40 SO 60 70 80 90 )00 

 PERCENTAGE CHORD FROM LEADING EDGE 



Fig. 25 - Chordwise distribution of 

 maximum principal tensile stresses 



to lead to a reduced thrust and an increased torque as a consequence of the 

 higher section drag and lower propeller efficiency. 



Hydroelastic Model Tests 



The NPL tests on hydroelastically scaled models were performed simply 

 for the purpose of obtaining general background information on the effect of 

 blade deflection on fully cavitating propeller performance and to obtain steady- 

 strain measurements on an operating propeller. It was not intended that the 

 models should be used to predict the dynamic behaviour of the blades from the 

 vibration standpoint. Again, since this work was planned early in the experi- 

 ment programme and before the Bras d'Or screws were finalised, the tests 

 were conducted on the T95 design. 



The conditions that must be satisfied when testing hydroelastically scaled 

 model propellers, based on the assumption that the blades behave as thin plates 



993 



