Truster till förskeppet på NGU/A26 : Dimensionering och konceptgenerering

Sammanfattning: This thesis work has been conducted on the behalf of the Swedish Defense Material Administration, which by directive from the Swedish Armed Forces has procured two new submarines of type A26 for delivery in 2024. For certain operations A26 will need to be able to be dynamically positioned in water currents of various speeds. For this, it is estimated that there is a need for some type of thruster in the ship’s forebody. Such a solution has never previously been implemented on a Swedish submarine, and it is therefore necessary to conduct preliminary studies to calculate the resulting forces, powers and dimensions, as well as generate conceptual suggestions for the design of such a system. The main objective of the project is to generate one or more conceptual proposals for the Swedish Defense Material Administration. The eligibility of the proposals should be based on the acquired specified requirements.   An initial wide-ranging study has been performed to identify the types, sizes and installation solutions of already existing thrusters and their principle function. During the initial study, the materials, machine elements and components suitable for the given application were also examined.   In order to determine for which flow angles and speeds the system is able to position the submarine, simplified power and torque calculations have been made. These should be seen as a valid basis for general approximations regarding the positioning ability of the concepts although further development of the concepts requires more detailed calculations to be made.   During the concept generation, it was determined which type of thruster is best suited for the application. Subsequently, a number of simple, function-modeled suggestions were generated to evaluate possible ways of integrations. Two of these proposals were later selected for final detail modeling. The final choices of both thruster type and concepts have been based on listed set of advantages and disadvantages, which were then, evaluated using decision matrices.   The results of the calculations that have been carried out shows that it is possible to dynamically position the submarine using a thruster system. This is under the presumption of the rudders being able to contribute with transverse force generation. A thruster is also found to be able to position the submarine with transverse forces only, implying that the only argument for using a, in the horizontal plane, rotatable thruster is the “limp-home” function.   Two particularly detailed conceptual proposals have been modeled; one that strictly complies with the specified volume requirement and one which, with certain adaptation to the internal geometry of the ships forebody, goes beyond the volume restriction. Both concepts are considered to be principally and technically feasible, with reservations of some specific solutions. The definitive concepts are meant to serve as a basis for possible further development of the systems.   The designed models and the calculations underlying these are all of a generic nature. They are fully adequate as a basis for this project but should not be seen as representative of the A26 in its entirety.