Page 10 - Wind Energy Handbook

x CONTENTS

5.11.2 Cladding loads 299
5.12 Tower Loading 300
5.12.1 Extreme loads 300
5.12.2 Dynamic response to extreme loads 300
5.12.3 Operational loads due to steady wind (deterministic component) 304
5.12.4 Operational loads due to turbulence (stochastic component) 305
5.12.5 Dynamic response to operational loads 308
5.12.6 Fatigue loads and stresses 309
References 311
Appendix: Dynamic Response of Stationary Blade in Turbulent Wind 313
A5.1 Introduction 313
A5.2 Frequency Response Function 313
A5.2.1 Equation of motion 313
A5.2.2 Frequency response function 314
A5.3 Resonant Displacement Response Ignoring Wind Variations along the
Blade 315
A5.3.1 Linearization of wind loading 315
A5.3.2 First mode displacement response 315
A5.3.3 Background and resonant response 315
A5.4 Effect of Ac-Wind Turbulence Distribution on Resonant Displacement
Response 317
A5.4.1 Formula for normalized co-spectrum 319
A5.5 Resonant Root Bending Moment 320
A5.6 Root Bending Moment Background response 322
A5.7 Peak Response 324
A5.8 Bending Moments at Intermediate Blade Positions 326
A5.8.1 Background response 326
A5.8.2 Resonant response 327
References 327

6 Conceptual Design of Horizontal Axis Wind Turbines 329
6.1 Introduction 329
6.2 Rotor Diameter 329
6.2.1 Cost modelling 330
6.2.2 Simplified cost model for machine size optimization—an illustration 330
6.3 Machine Rating 333
6.3.1 Simplified cost model for optimizing machine rating in relation to
diameter 333
6.3.2 Relationship between optimum rated wind speed and annual mean 336
6.3.3 Specific power of production machines 336
6.4 Rotational Speed 337
6.4.1 Ideal relationship between rotational speed and solidity 338
6.4.2 Influence of rotational speed on blade weight 339
6.4.3 Optimum rotational speed 339
6.4.4 Noise constraint on rotational speed 339
6.4.5 Visual considerations 340