Effects of geometry variations on the performance of podded propulsors

This paper presents results and analyses of an experimental study into the effects of geometric parameters on the propulsive characteristics of puller and pusher podded propulsors in straight course open water conditions. Five geometric parameters were chosen for the current study and a design of experiment technique was used to design a series of 16 pods that combined the parameters. Tests on the 16 different pod-strut-propeller combinations in puller and pusher configurations were completed using a custom designed podded propeller test rig. The dynamometry consisted of a six-component global dynamometer and a three-component pod dynamometer. The test rig was used to measure the thrust and torque of the propellers, and forces and moments on the whole unit in the three orthogonal directions. The design of experiment analysis technique was then used to identify the most significant geometric parameters and interaction of parameters that affect propeller thrust, torque and efficiency as well as unit thrust and efficiency in both the puller and pusher configurations. An uncertainty analysis of the measurements is also presented.