Hydrodynamic design of a bi-directional, rim-driven ducted thruster suitable for underwater vehicles

This report describes the hydrodynamic design process of an integrated thruster used for position control on a Remotely Operated Vehicle. The numerical analysis of the performance of the thruster is carried out using a lifting surface panel code with the Interaction Velocity Field method. The complete process is described from setting up the geometry model and validation, to selecting the optimised design.The theory for the lifting surface panel method briefly described. The geometry of a marine propeller is described and the process of the mesh generation presented. The wake model is discussed in detail.The numerical model was validated against the standard DTMB4119 open water propeller. The ducted model was validated with a standard Kaplan K470 series propeller in a Marin 37 duct and the experimental data from the two prototype bi-directional thrusters. The optimisation process of the thruster is presented and results presented

Flow feature identification for capture of propeller tip vortex evolution

The application of a regional based mesh adaptation scheme is applied to a ship propeller. The meshing strategy adopted aims to capture the downstream tip vortex track while maintaining the flow quality within its Rankine vortex structure. A prescribed mesh density is used across the viscous vortex core and an outer annulus of lower density cells around the high tangential velocity zone immediately outside the viscous core. An initially coarse mesh provides enough information to identify the initially diffused vortex. A semi-automated system of progressive mesh refinement allows the vortex to be tracked as far downstream as required. The limitation on this tracking process arises from the total mesh size available on a given computer system. A detailed validation study has been carried out using the DTMB P4119 propeller. The influence, on the propeller forces developed, of the tip vortex refinement process is shown to be significant. Overall, good comparisons are achieved with force data and LDV measurements. The work has demonstrated the effectiveness of the VORTFIND identification scheme when used to control a regional mesh refinement scheme for prolonged resolution of propeller tip vortices. Such schemes become even more essential when analyzing unsteady propeller performance or the behaviour of the propeller subject to the influence of a downstream appendage

Investigating the roots of political disengagement of young Greek Cypriots

This study attempted to disentangle the issues underlying the marked drop recorded in political engagement of young Greek Cypriots. To reveal the dynamic processes through which people debate, disagree or convince each other towards the formation of political attitudes, eight focus-groups were carried out with a total of forty participants, equally distributed according to age and gender. The analysis showed that young Greek Cypriots appear uncertain for their future, pessimistic, cynical, and highly disillusioned with traditional politics. Contrary to what is observed in other European countries, young Greek Cypriots do not experiment with alternative forms of political action, remain inactive, and although the country's politicised culture of the past is still reflected in their theoretical discussions about social issues, they express embarrassment and confusion when asked to elaborate on how theory could be transformed into practice. They associate politics with corruption and economic interests, they are scornfully disillusioned with the European Union, and they emotionally distance themselves from important changes to come with the possible reunification of Cyprus. Young Greek Cypriots appear insecure, pessimistic, disoriented, uninspired, and in an urgent need to rediscover passion for ideas which they cannot any more find in traditional politics and forms of political action. © 2017 Academy of Social Sciences

SCC casting prediction for the realization of prototype VHPC-precambered composite beams

info:eu-repo/semantics/publishe