Preliminary joint design of a split wind turbine blade

Thumbnail Image

URL

Journal Title

Journal ISSN

Volume Title

School of Engineering | Master's thesis
Checking the digitized thesis and permission for publishing
Instructions for the author

Authors

Date

2010

Department

Sovelletun mekaniikan laitos

Major/Subject

Lentotekniikka

Mcode

Kul-34

Degree programme

Language

en

Pages

102 + liitt. 12

Series

Abstract

This thesis focuses on the split blade concept, meaning that a wind turbine blade consists of two sections and a joint is made to connect them on the site of turbine installation. The objective of the thesis is to find the most appropriate joint for future applications and to launch the preliminary design for it. In the first part of the thesis, design aspects for blade design m general are reviewed and the motivation to make a two-part blade discussed. There are a wide range of related proposals, prototypes, research projects and patents, which are all presented here in order to find a set of optional joining methods for further evaluation. In the second part, the best-practice solution is chosen and preliminary design is launched for it. Firstly, a set of criteria are developed measuring economical and technical performance of the four joining options. A trade-off matrix is provided to evaluate the options against the criteria in different boundary conditions. In overall, a bonded joint design is considered to be the most appropriate solution, being superior in terms of blade weight and stiffness distribution, but yet having a lot of challenges to be solved. The concept evaluation is followed by some first-stage assignments of joint preliminary design. Finite element analysis is provided to determine the preliminary dimension for required overlap length (350 mm) and describe the failure behaviour of glass fibre laminate at the connection. Additionally, proposals for the manufacture and assembly processes are presented. Blade section manufacture is similar to normal vacuum injection process used for wind turbine blades, but includes the use of auxiliary moulds to make the joint connecting members. Onsite assembly of blades is done by a gluing process assisted by vacuum pressure. The biggest challenges in the whole process are related to the manufacture of connecting members and to the harsh environmental conditions in the site of installation.

Description

Supervisor

Saarela, Olli

Thesis advisor

Autio, Maija

Keywords

wind turbine blade, joint, glass fibre, composites, vacuum injection

Other note

Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-2020122356551

Collections

[dipl] Insinööritieteiden korkeakoulu / ENG