Steady and unsteady dynamics of an azimuthing podded propulsor related to vehicle maneuvering

While the implementation of azimuthing propulsors powered by interna l electric motors (often called “podded propulsors”) into the commercial ship market ha s been swift, the understanding of their hydrodynamics through research, particularly in t he area of maneuvering performance, has been very limited. This thesis research investigates the steady and unsteady dynamic maneuvering forces associated with an azimuthing podded propulsor, and provides supporting the oretical insight toward understanding their mechanisms and prediction. Because of th wide range of potential applications of azimuthing podded propulsion in the marine field, dynami c force phenomena applicable to maneuverability of both large and small scale vehi cles are investigated. These include quasi-steady vectored maneuvering forces, of importance to al l maneuvering vehicles or ships, as well as unsteady or transient maneuvering forces, whi ch have more significance to the maneuverability of smaller vehicles, particularly for preci sion control applications. The ultimate goal of the research is to provide a comprehensive understanding of t he maneuvering forces associated with an azimuthing podded propulsor, such that future maneuveri g and control applications, and computational fluid dynamics studies in the field, can be appropria tely focused. The research efforts are focused in four main areas. F irst, a number of relevant dynamic models for the maneuvering of a surface vehicle with an azimuthi ng propulsor are developed. Second, an extensive test program measures and characterizes t he nature of quasi-steady vectored maneuvering forces associated with a podded propulsor in azimuth to ±180° for the entire range of forward propeller speeds, as well as unsteady or transien t ma euvering forces due to rapid changes in azimuth angle or propeller rate. This test program is imed at quantifying the steady and unsteady parameters associated with the developed dynamic models . Third, two flow visualization techniques are utilized to visualize, document , a d correlate the helical wake characteristics, velocities and forces for both quasi-steady an unsteady propulsor states. A new fluorescent paint flow visualization technique is developed a nd applied for small, moderate and