Wind Energy in the built environment Book

Summary     III
List of Symbols     VII
Introduction     1
Basic Theory     3
Drag-driven rotor versus lift-driven rotor     3
Drag-driven wind turbines     3
Lift-driven wind turbines     4
Hybrid-driven wind turbines     6
Comparison of the wind turbines     7
Constraints     7
Built environment     8
Wind turbine     10
Building     12
The Building-Augmented Wind Turbine     13
The twisted H-Darrieus wind turbine     14
Wind Characteristics     18
Global wind in the built environment     18
Log-law     18
Step in roughness height     22
Turbulence     23
Local wind in the built environment     23
Building characterization     23
Flow characterization     25
Wind speed probability distribution     28
Wind at buildings     32
Stagnation point     32
Separation     33
Wake and recirculation zone models     34
Reattachment distance     39
The cavity model     39
Influencing the separation velocity and backpressure     42
Analysis Tools     44
Mathematical     44
Potential flow     44
Vortex sheets     45
Momentum theorem     47
Experimental     47
The open jet wind tunnel     47
Tunnel correction     48
Error in power coefficient from measurements     50
Scaling rules     51
Wind turbine power     51
Computational Fluid Dynamics     53
The turbulence model     53
Near-wall region     57
The grid     58
The atmospheric boundary layer     59
Some initial verifications     60
Wind Turbines Close to Buildings     65
The wind turbine's performance close to a building     65
Performance in partly accelerated flow     65
The acceleration at the roof     70
The lift-driven HAWT in skewed flow     72
The H-Darrieus in skewed flow     74
Induction factor at small load     74
Induction factor at high load     79
Power coefficient     82
Performance     85
Verification of the model      86
Discussion on the validity of the model     88
The energy yield at the roof     91
The energy yield at the sides of a building     93
Wind Turbines Between Airfoil-Shaped Buildings     96
Momentum theory     98
Shrouded wind turbine     99
Diffuser-augmented wind turbine     101
2D Vortex model for a shrouded rotor     103
Set-up of the model     104
Induced velocities     106
Resulting velocities     107
Power coefficient     109
Verification of the model     109
Discussion on the validity of the model     113
Application of vortex model results to momentum theory     115
Finite aspect ratio effects     115
The ducted small wind turbine     116
Allowed stream tube size     117
Velocity between the 1/4-chord points     118
The shrouded H-Darrieus     119
Yawed and opposite flow     119
Yawed flow     120
Opposite flow     121
Zero power output     122
The energy yield of the shrouded rotor     122
Wind Turbines in Ducts Through Buildings     124
The plate concentrator model     124
Power coefficient     125
Jet contraction     126
Verification of the plate concentrator model     128
Verification of the jet velocity     128
Verification of the jet contraction     129
Verification of the pressure drop across the actuator     130
Verification of the power coefficient     132
Approximated plate concentrator model     133
Discussion on the validity of the model     134
Yawed flow     134
The energy yield of a plate concentrator     135
Energy yield of a combined plate concentrator     136
Results and Conclusions     139
Summary of results for general use     139
Summary of results for wind energy in the built environment     141
Integration of wind turbine and building     141
Energy yield examples of Building-Augmented Wind Turbines     142
Wind Turbines for the built environment     144
Expectations     145
Expectations for wind energy in the built environment     145
Research on aerodynamics of Building-Augmented Wind Turbines     145
References     147
Appendices
Stream tube length in viscous flow      152
Measurements plate concentrator     154
Used turbulence models CFD calculations     155
Data high-lift cambered airfoil Da2-1999     156
Induced velocities by a wake     157
Prony brake     159
Triangular chord-wise vortex distribution     161
Suitable turbulence model for calculation of flow around airfoil     166
Calculated lift- and drag coefficient data for a NACA 0018 airfoil     167
Quick siting guideline     169