13 

 by Faulkner for the calculation of aerodynamic forces on an arbitrary wing shape. 



14 

 The accuracy of this simple method has been found very satisfactory and in two- 

 dimensional flow "remarkable". The primary advantage in using the discrete 

 vortex/source lattice method is the ease and the flexibility to model the complex 

 geometries of the propeller blades and their trailing vortex wake. With the advent 

 of large computers, panel methods are widely used for the design and analysis of 

 three-dimensional aerodynamic configurations both as the simple vortex/source 

 lattice approximation and as more complex local elements. 



1 /; 



In the area of marine hydrodynamics, Kerwin and Lee developed a discrete 

 vortex/source method and corresponding computer code, PUF2, for the prediction of 



steady and unsteady performance of subcavitating propellers, Kobayashi and 



18 

 Kim developed a procedure to compute the pressure distribution based on the 



1 f-i ] 9 



method developed by Kerwin and Lee. More recently, Greeley and Kerwin 



developed design and analysis procedures and corresponding computer codes, PBD-10 



for design and PSF for analysis, for propellers operating in steady flow. Greeley 



12 

 and Kerwin made improvements to the steady part of the procedure developed by 



1 f) 

 Kerwin and Lee in two major areas; one is the improved semi-empirical description 



of the trailing vortex sheet and the other is the capability to model the flow 



over the outer portion of the blade more accurately. In the present work, only 



12 

 the global part of the procedure developed by Greeley and Kerwin has been 



investigated for the pressure distribution. The more accurate local flow model 



near the tip is yet to be examined. 



A computer code, named the Propeller Steady Pressure (PSP) program, has been 



19 

 developed by extending the propeller analysis program, PSF, presented by Greeley 



12 

 and Greeley and Kerwin. This report describes the computer code and presents 



some comparisons of the predictions made by PSP with experimental measurements and 



predictions by other theories. 



OVERVIEW OF PSP 



The Propeller Steady Pressure (PSP) code is basically the same as the Propeller 



12 

 Steady Flow (PSF) analysis program developed by Greeley and Kerwin, except for 



the additional capability in PSP of calculating the pressure distribution on the 



blade surface. The PSF code assumes that the propeller operates in an axisymmetric 



onset flow consisting of axial, radial, and tangential components. The presence 



of the propeller hub and any other boundaries to the flow is ignored. The blade 



