Propeller Pressure Field in a Nonuniform Flow 



I have only one question regarding the application of a factor of 2.0 to ac- 

 count for the effect of the ship model boundary, I am sure that Mr. Bavin well 

 appreciates that this represents a rough approximation when the surface is not 

 flat. Were all the data obtained on a stern frame line or on a flat boundary in 

 the case of data with screens ? 



I agree with Mr. Bavin that the pressure field of a propeller in a wake re- 

 quires the application of unsteady lifting surface theory, 1 wish the authors fur- 

 ther successes in this work. 



REPLY TO DISCUSSION 



V. F. Bavin 



Kryloff Ship Research Institute 



Leningrad, U.S.S.R. 



The authors are grateful to the contributors to the discussion for their in- 

 terest in this work. 



Replying to Mr. Cox we must note that when calculating vibratory pressures 

 we took into account the tangential wake components as well as the axial ones 

 (with the exception of the propeller behind the screen, because there was no tan- 

 gential wake in that case) . 



Mr. Breslin draws attention to the fact that in principle all of the wake har- 

 monics play a role in the makeup of the total blade frequency pressure. The 

 authors are fully aware of this fact. 



The authors agree with Mr. Breslin that the factor 2 is only a rough approx- 

 imation in the case of an actual ship hull surface. It was used due to the lack of 

 precise knowledge of the magnitude of the boundary surface effect. 



In the case of the propeller operating behind the screen the pressures were 

 measured in the free stream around the propeller and not on the hull surface. 



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