In the context of "Lifting Line Methodology", this thesis presents a rational approach to Marine Screw Propeller design and its applications in combination with a "Stator" device for further performance improvement. The rational nature of the approach is relative to the Classical Lifting Line procedure and this is claimed by more realistic representation of the propeller slipstream tube which contracts in radial direction along the tube at downstream. Therefore, in accordance with the Lifting Line Methodology, the design procedure presented in this thesis involves the representation of the slipstream shape by a trailing vortex system. The deformation of this system is considered by means of the so-called "Free Slipstream Analysis Method" in which the slipstream tube is allowed to deform and to align with the direction of local velocity which is the sum of the inflow velocity and induced velocities due ,to the trailing vortices. This deformation is neglected in the Classical Lifting Lin~ approach. The necessary flow field data or the wake for the design is predicted by using a three-dimensional "Panel Method" for the outer potential flow, whilst a "Thin Shear Layer Method" is used for the inner boundary layer flow. The theoretical procedures in both methods neglect the effect of the free surface and therefore the implemented software for the flow prediction caters only for deeply submerged bodies. However, the overall design software is general and applicable to surface ships with an external feedback on the wake. Since the realistic information on the slipstream shape is one of the key parameter in the design of performance improvement devices, the proposed design methodology has been combined with a stator device behind the propeller and the hydrodynamic performance of the combined system has been analysed. The design analysis involved the torque balancing characteristics of the system and the effects of systematic variations of the key design parameters on the performance of torpedo shape bodies and surface ships at varying loading conditions. The ·overall conclusions from the thesis indicate that a more realistic representation of the slipstream shape presents a higher efficiency in comparison to the regular slipstream shape assumption, in particular for heavily loaded propellers. Moreover, this representation is essential for sound design of the stator devices as it will determine the radius of the stator. From the investigation on the stator it was found that the undesirable effect of the unbalanced propeller torque can be avoided by the stator. The efficiency of the system will increase with the increase in the number of stator blades and the distance between the stator and the propeller over a practical range of the design parameters. It is believed that the procedure and software tool provided in this thesis could provide the designer with capability for more sound propeller and the stator design for, partly, surface ships and for submerged ships in particular torpedos, Autonomous Underwater Vehicles (AUV) and submarines. Although the improvement gained by the present procedure will be accompanied by an increase in computer time, this is not expected to be a major problem considering the enormous power of existing computers. In fact, this has been the major source of encouragement for the recommendation in this thesis to improve the present procedure by using the "Lifting Surface Methodology" as the natural extension of the Lifting Line Methodology.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor: McNelley, Terry R. Second Reader: Menon, Sarath. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: friction stir processing, nickel aluminum bronze, propellers, microstructural properties, grain refinement, volume fraction-temperature relationship. Includes bibliographical references (p. 45-46). Also available in print.

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Two-stroke outboard boat engines using total loss lubrication deposit a significant proportion of their lubricant and fuel directly into the water environment. Extensive atmospheric emission testing of outboard motors has taken place, however, emissions to the water are largely unaddressed in the literature and could be critical because the exhaust of most outboard engines is released below the water and mixed by the action of the propeller. The purpose of this work is to document the velocity and scalar field characteristics of a submerged swirling jet emanating from a propeller. The aim is to provide guidance on fundamental characteristics of such a jet, far enough downstream that it is relevant to the eventual modelling of this mixing problem (i.e. the mixing of engine emissions with water). Measurements of the velocity field (axial, tangential, and radial) and scalar field (concentration) were performed in a turbulent jet generated by a model boat propeller (0.02 m diameter) operating in a weak co-flow of 0.04 ms-1. The measurements were carried out up to 50 propeller diameters downstream of the source which was placed in a glass-walled flume, 0.4 m wide with a free surface depth of 0.15 m. The jet and scalar plume development were compared to that of a classical free round jet. Further, results with respect to velocity distribution, turbulence decay and integral flow properties plus scalar distribution, dilution and integral plume properties were all calculated and compared to existing literature. The velocity field results are the first published results to show the development of the flow fifty propeller diameters downstream. Up to ten propeller diameters downstream the results corroborate the earlier work of Petersson [1, 2]. Beyond ten propeller diameters downstream, the walls of the flume affected the flow. The concentration field results show that under these experimental conditions the propeller induced mixing exhibited a complete mixing length some 300 times shorter than for the wall-shear induced diffusion alone. Furthermore, a first principles relation was derived that illustrates the link between engine emission rate and propeller kinematics in generating the propeller-jet source concentration of pollutants. Using experimental results an estimate for benzene concentration fifty propeller diameters downstream of a 74 kW vessel was calculated to be around one third of the regulatory threshold for that chemical.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Helsinki University of Technology, 1992. / Includes bibliographical references (p. 75-79).