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Fixed bolted propeller (FBP): Concept study
Karlstad University, Faculty of Technology and Science, Department of Mechanical and Materials Engineering.
2011 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Fast bultad propeller (FBP) : Koncept studie (Swedish)
Abstract [en]

A propeller for marine use transforms rotational motion to propulsive thrust by producing a difference in pressure between the two surfaces of each propeller blade. The water is accelerated away from the propeller when it is rotating and a force is created which moves the ship forward. There are a lot of different propellers on the marine market, but all works according to this phenomenon.

Rolls-Royce AB in Kristinehamn has been supplying propellers for ship propulsion systems since 1937. There are four different main types of propellers which they construct and provide; Controllable Pitch Propellers (CPP), Fixed Pitch Propellers (FPP), Fixed Bolted Propellers (FBP) and Adjustable Bolted Propellers (ABP).

FBP’s are propellers with fixed pitch and are built-up by several parts and thereafter bolted together. In the origin of propeller construction, FBP’s were the most common ones, but during the last century the FPP’s (mono-block moulded propellers with fixed pitch) and the CPP’s (controllable pitch) has been the most frequently used. FBP’s have been and are still very rare on marine market, but Rolls-Royce believes that the market for FBP’s will grow during the upcoming years. This is due to demands of quick replacement of a damaged propeller underwater and easier transport conditions and back-up storage on ships and vessels, where a FBP is superior to a FPP. Electric propulsion systems are also more commonly used today which favours propellers with fixed pitch in contrast to CPP’s.

This thesis work is a concept study of FBP’s and will be a pre-study for future research and development projects atRolls-RoyceAB.The overall goal of this thesis work is to scan the market for different solutions of FBP’s and to evaluate, compare and rank different concepts. Secondary goals are to develop new concepts and analyze the suitability of the concepts in different marine segments.

A competitor analysis and a literature survey were carried out, which scan the marine market of potential FBP’s designs and performed scientific research around the subject. New concepts were generated and all designs were thereafter collected in a body of ideas. A list of requirements was made with the important demands of a FBP and Olsson’s criteria matrix was used to get a solution neutral and measurable criterion.

Methods and matrices by Pahl and Beitz and by Pugh were used to eliminate bad ideas and to screen all the concepts. Weighted matrices by Kesselring were used to compare, score and rank the concept designs in three different segments; merchant, offshore and naval. A deeper comparison of benefits and disadvantages were also carried out between the best concepts and they were also all modelled in PROEngineer for better explanation and 3D-viewing.

The strength of two different concepts (Concept 1 and Concept 21) was also analyzed deeper and compared in a finite element analysis (FEA). Concept 21 is a new, odd and interesting design with “custard slice-shaped” blade flanges bolted together without any need of a hub. Concept 1 is the existing design used by Rolls-Royce and was chosen for comparison and was during this study considered to have a general design and acceptable strength.

The investigation was performed in ABAQUS and was simplified to a static problem, representing a propeller operating in a steady state. Cyclic symmetries were used and a resulting force (centrifugal and thrust force) was applied to the propeller blade. The screw joints were modelled by “tying” the threaded interfaces, defining contact interactions and applying pre-tension forces.

The result from the FEA showed that the overall strengths of the two analyzed concepts are comparable and the critical points were in both concepts the guiding/dowel pins.

A conclusion from this study is that there are only a few different FBP-designs provided on the marine market today. This study has however collected the existing designs and generated many other concepts and ideas which can be used for further research and development of FBP’s. After the screening process were nine concepts selected for deeper analysis. Seven out of the nine concepts (Concept 1-6 and Concept 21) showed very good qualities in general and should be considered as potential designs of FBP’s. Concept 18 can also be a prospect if the problem with shear stresses in the screws can be sorted out.

Summarizing this thesis work leads to a suggestion to Rolls-Royce to continue with the design of Concept1 ingeneral and continue with designs of Concept2 inmore advanced and specialized operating conditions. The other appropriate concepts needs to be investigated deeper and can maybe be used in the future, where Concept 5 and Concept 21 seems to be the most promising ones.

Place, publisher, year, edition, pages
2011. , 109 p.
Keyword [en]
Propeller
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-7463Local ID: MTK D-5Archive number: MTK D-5OAI: oai:DiVA.org:kau-7463DiVA: diva2:419783
Subject / course
Materials Engineering, Master of Science
Presentation
2011-04-21, 09:15 (Swedish)
Uppsok
Technology
Supervisors
Examiners
Available from: 2011-06-07 Created: 2011-05-28 Last updated: 2017-02-08Bibliographically approved

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