ABSTRACT 



A lifting-surface theory and numerical procedure for 

 designing supercavitating propellers are presented. 



Both a subcavitating and a supercavitating propeller 

 are represented by vortex and source distributions. Unlike 

 the subcavitating propeller, however, source strengths for 

 a supercavitating propeller are related to cavity thick- 

 ness, which is not known without examination, and have to 

 be obtained by solving related integral equations. 

 Numerical solution of the integral equations is obtained as 

 a correctional function for a stripwise supercavitating 

 cascade theory which, with lifting-line theory, is used for 

 preliminary design of supercavitating propellers. The in- 

 duced axial, radial, and tangential velocities are obtained 

 on a blade reference surface that allows arbitrary skew, 

 rake, and radial pitch variations. The blade shape is 

 obtained as a correction to the shape obtained from strip- 

 wise supercavitating cascade theory. Thrust and torque 

 coefficients are obtained from pressures on the blade 

 surface. 



The method is applied in designing several super- 

 cavitating propellers that have design conditions the same 

 as those of existing supercavitating propellers. 



Numerical computations were also used to design two 

 additional supercavitating propellers which were built and 

 tested. The design predictions are compared to the experi- 

 mental data, both for blade cavity height and performance 

 characteristics, and good correlation is obtained. 



ADMINISTRATIVE INFORMATION 

 The Naval Material Command (NAVMAT 08T) funded this investigation in support 

 of an ongoing Ship Performance and Hydromechanics Exploratory Development Program 

 (Program Element 62543N, Task Area ZF43421001) assigned to the David W. Taylor Naval 

 Ship Research and Development Center (the Center) . This work has been completed 

 under the High-Speed Propulsor Task portion of this program, (Center Work Unit 

 1500-103), and partly under the Naval Sea Systems Command's General Hydrodynamic 

 Research Program (Center Work Unit 1542-817) . 



INTRODUCTION 



Ever since supercavitating propellers were first investigated systematical- 



12* 3,4 



ly, ' steady progress has been made in understanding associated problems. 



Designers of supercavitating propellers have been urged to consider the interference 



*A complete listing of references is given on page 83, 



