PRESSURE FIELD AROUND A 



PROPELLER OPERATING IN A 



SPATIALLY NONUNIFORM FLOW 



V. F. Bavin, M. A. Vashkevich, and I. Y. Miniovich V / ,- . .. 

 Kryloff Ship Research Institute . , : ■ 



.... ' « Leningrad, U.S.S.R. , ,• ,. ,. . J., , 



./ ' ' ABSTRACT 



The theory for determining the pressures generated by a ship propeller 

 is extended by deriving the relation between propeller -induced pres- 

 sures and the circulation around the blade of a propeller operating in 

 a wake. 



Expressions are presented which make it possible to compute the am- 

 plitudes of blade -frequency pressure harmonics. 



The calculations and experimental results show that an increase of 20 

 to 60 percent is possible over the maximum pressures generated by a 

 propeller operating in a uniform flow. 



INTRODUCTION ' -..-. ,;;r 



A number of theoretical and experimental studies concerned with the pres- 

 sures induced by the propeller in the ambient fluid have been carried out in the 

 past decade. An extensive bibliography and a review of the principal works on 

 this subject published before 1964 have been given by Breslin (1,2). A compari- 

 son of theoretical and experimental results for the pressure generated by a ship 

 propeller in a uniform flow (2) showed good agreement if the blade thickness 

 contribution to the pressure field, as well as that of the blade loading, was taken 

 into account. 



In 1966 an investigation treating the pressure in the neighborhood of a pro- 

 peller in uniform flow as a function of propeller geometry was completed in the 

 Soviet Union. In this work a more consistent mathematical model was used than 

 in earlier works by Breslin (1), Babaev (3), and Pohl (4); i.e., the propeller 

 blade was replaced by a suitable distribution of vortices and sources over the 

 part of a helical surface bounded by the blade contour, whereas in Ref. (1), for 

 example, load-associated pressure was calculated in the usual lifting-line the- 

 ory manner and the effect of blade thickness was estimated on the assumption of 

 a zero-pitch propeller. 



By using a more consistent mathematical model it became possible to study 

 the influence of such propeller characteristics as blade area ratio and pitch 



