Abstract:
A potential based Surface Panel Method (SPM) is applied to the hydrodynamic analysis
of modern marine propuslve device, i.e., podded propulsion system (PI'S) in steady flow.
At first the surface of the body is approximated by a number of small hyperboloidal
quadri lateral panel, with constant sources and doublet distributi(ms. The surface of the
trailing vortex sheet is also represented by hyperboloidal quadrilateral panels with
constant doublet distributions. The strengths of source <lnd doublet are determined by
solving the boundary vallie problem at control point of each panel surface satislYing some
boundaI)' cond itions. Effect of viscosity is incorporated to the potentia! solution using
Prandtl-Schlieting formula. The method Is first applied to analyze pod, strut and propeller
separately, then the combination of pod.strut geometry and finally the complete pod
propllision system, PI'S (Propeller +Pod + Strut).
Appling this method. the pressure distribution on the pod and strut lIsed in podded
propeller system are determined and compared with published re~ults. The method is also
u,ed to evaluate effects of h"b taper angle and pod-strut geometry on the open water
ehara~teriBtics of a fixed pitch SCrew propeller "sed in podded propulsion system in
pusher configuration. The method i~ validated by comparing the predicted reSlllts with
experimental measurements.
Effects of huh taper angle on hydrodynamic characteristics are studied numerically in
terms of thrust coefficient, torque coefficient, and propulsive efficiency for a wide range
of advance coefficient In case of hub taper angles of 0°, 5",10°,15°,20" and 25° in
pusher configuration. The effect of pod-strut geometry on the hydrodynamic
vi
characteristics of tapered fi"ed pitch SCrewpropellers used in pusher podded propulsion
system; has also been studicd nllmerically. Different pod-_,trut configllrations arc
modeled for tapered hub propellers with hub taper angles 01'0°,5", lIJo, 15°, 20a and 25°
respectively. 1n this case, only the characteristics of the propeller are predicted in
pre,ence of pod"strut geometry (propeller with pod-strut). In other word, blockage effect
due to the presence ofpod-,lrut body is taken into account ignoring the losses due to skin
friction imposed by that body.
Maior findings include well agreement of results predicted by the method with
measurement, ,ignitieant effects of hub taper angle On hydrodynamic characteristics of
propellers, c()llsiderable increase in hydmdynamic characteristics of propeller- when podstrut
body is aUaehed forward to it in pusher configuration.
