Theory of Unsteady Propeller Forces 



Table 5 

 Amplitudes of the Vibrating Parts of the Bearing Forces 



forces and the bearing forces. Then, for the numerical calculations, we reformu- 

 lated the expressions of the bearing forces of a propeller placed in a given non- 

 uniform flow, which was assumed to coincide with the measured hull wake of the 

 ship without a propeller. 



Finally, numerical calculations were performed for nine examples of four- 

 bladed propellers with a constant pitch ratio which have various skews and blade 

 area ratios to examine their effect on the characteristics of bearing forces. The 

 results obtained are as follows. The absolute mean values and the magnitudes 

 of the vibrating parts of the bearing forces decrease with decrease of the ad- 

 vance coefficient, excepting the thrust and torque coefficients, which increase 

 with decrease of the advance coefficient. We compared the bearing forces of 

 various propellers on the basis of the idea of thrust identity. For a given value 

 of the blade area ratios the mean values of the bearing forces are independent of 

 the skew, while the magnitudes of the vibrating parts of the bearing forces in 

 general decrease with increase of backward skew. For the case of a constant 

 skew the bearing forces vary a little with the variations of blade area ratio. 



The numerical calculations for the effects of the number of blades and the 

 pitch ratio on the bearing forces and also on the surface forces are left to later 

 works. 



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