Experimental research on marine podded propulsors

This paper describes a research program on podded propulsors that combines parallel developments in numerical prediction methods and experimental evaluation. Amongst the hydrodynamic issues that have been identified and addressed are questions regarding the effects of hub taper angle, pod-strut configurations, static azimuthing conditions, pod-strut interactions, gap pressure, pod gap and pod-strut geometry on podded propulsors' performance. On the experimental side, a pod dynamometer system consisting of a six-component global dynamometer and a three-component pod dynamometer were designed, manufactured and used to perform measurements on propeller thrust and torque and unit forces and moments in the three orthogonal directions in pusher and puller configurations in open water conditions. Four propellers with the same blade sections but different hub taper angles were designed and used to fit with eighteen pod-strut shells. Among the shells, two pod-strut models were based on the average dimensions of commercial pods and used to study the hub angle, pod configuration, pod gap, gap pressure and azimuthing conditions effect on propulsive performance. The other sixteen pods were designed and manufactured to study the effect of five geometric parameters on hydrodynamic performance using a design of experiments technique. In another study, an experimental method was implemented in a cavitation tunnel to evaluate the wake/strut interaction of a podded propeller model. All of the measurements showed consistency.DOI: http://dx.doi.org/10.3329/jname.v4i2.989 Journal of Naval Architecture and Marine Engineering Vol.4(2) 2007 p 57-71