{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Notes Topic 5 - 1 2 3 4 5 1 2 3 4 5 The blades must also be...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
5-1 1 INTRODUCTION 2 WIND RESOURCES 3 WIND TURBINE COMPONENTS AND CONCEPTS 4 WIND TURBINE AERODYNAMICS 5 WIND TURBINE BLADE DESIGN AND BLADE MANUFACTURE 1 Introduction .................................................................................................................................................. 1 2 Wind Resources ........................................................................................................................................... 1 3 WIND TURBINE COMPONENTS AND CONCEPTS ............................................................................. 1 4 WIND TURBINE AERODYNAMICS ....................................................................................................... 1 5 WIND TURBINE BLADE DESIGN AND BLADE MANUFACTURE ................................................... 1 5.1 Design Considerations ........................................................................................................................... 1 5.2 Design Parameters ................................................................................................................................. 2 5.2.1 Aerodynamic Design Parameters ................................................................................................... 2 5.2.2 Structural Design Parameters ......................................................................................................... 3 5.2.3 Operating Design Parameters ......................................................................................................... 4 5.3 Design Methods ..................................................................................................................................... 5 5.4 Materials and methods ........................................................................................................................... 7 5.4.1 Wood or Wood Laminate Blades ................................................................................................... 7 5.4.2 Steel or Aluminium Blades ............................................................................................................. 8 5.4.3 Fibreglass or Carbon-fibre .............................................................................................................. 8 5.4.4 Small Wind Turbine Blades .......................................................................................................... 10 5.5 Protecting Wind Turbine Blades ......................................................................................................... 10 5.6 Testing Wind Turbine Blades .............................................................................................................. 13 5.6.1 Fatigue Testing ............................................................................................................................. 13 5.6.2 Modal Testing ............................................................................................................................... 13 5.6.3 Static-strength testing ................................................................................................................... 13 Figure 5-1Cross-section of a wind turbine blade showing structural composition ............................................ 3 Figure 5-2 3-D computer simulation of buckling in wind turbine blades ......................................................... 4 Figure 5-3 Influence of drag/lift ratio and blade number on turbine performance ............................................. 5 Figure 5-4 Finite Element Analysis of a wind turbine blade revealing the stresses on the blade ..................... 6 Figure 5-5 Illustration of the vacuum-moulding process ................................................................................... 7 Figure 5-6 Schematic diagram showing the structure of a fibreglass blade section ........................................... 9 Figure 5-7 Illustration of the filament winding process ..................................................................................... 9 Figure 5-8 Illustration of the process of pultrusion .......................................................................................... 10 Figure 5-9 Using black blades on wind turbines to absorb heat and melt ice .................................................. 11 Figure 5-10 Lightning protection system in an LM blade ................................................................................ 12 Figure 5-11 Modal testing of a wind turbine blade .......................................................................................... 13 Figure 5-12 Static-strength testing of a wind turbine blade ............................................................................ 14 5.1 Design Considerations In general, the cost of the rotor of a medium-large HAWT is roughly 30% of the cost of the entire turbine so much emphasis is placed on producing reliable, efficient blades. HAWT blades have to be designed to survive the bending forces placed on them due to extreme winds. Extreme winds are rare, occurring for e.g. a period of 10 minutes every 50 years, but potentially destructive if the HAWT blades are poorly designed. 5-2 The blades must also be able to withstand repeated bending due to fluctuating winds. Fluctuating forces causes fatigue stresses on the blade and, if poorly designed, the blades may crack and ultimately break. The 3MW Growian machine built in Germany in 1982 illustrates this point. It was a huge machine with both rotor diameter and tower height equal to 100m but after three weeks of operation was removed from service due to blade fatigue. In addition to fluctuating and extreme winds, the turbine may be sited in a region where the environmental conditions are harsh e.g. where there is high humidity that leads to corrosion of the blades or where there are high levels of ice or snow accumulation affecting the performance and the loading on the blades. Finally the impact on the blades of dirt and insects (particularly on the leading edge), and by birds and hail has to be taken in to account.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}