VAWT Alessandro Croce tecnico lano MI April 2016 POLI di HAWT VS VAWT ► TN535 Tozzi Nord ► TN1.5 Tozzi Nord (source: http://www.tozzinord.it/, April 2016) (source:http://www.ravenna2008.it/lang/it/ho me/eventi-culturali/mostra-in-piazza-del- popolo/tozzi-nord April 2016 ) The Wind Resource The 4 POLI-Wind Research Lab Drag-type VAWT - Savonius • Solidity ≈ 1 (high torque) • No yaw system • Easy start-up • Inexpensive • Low Cp • Difficult to protect @ high wind The Wind Resource The 5 POLI-Wind Research Lab Lift-type VAWT - Darrieus • Straight/curved blade • No yaw system • Difficult start-up • Better Cp (wrt Savonius) • High-wind protected by stall • Easy blade shape (wrt HAWT) • High vibration loads (fatigue) ► SA70 Ropatec (source: http://www.ropatec.it/, April 2016) ► TN1.5 Tozzi Nord (source:http://www.ravenna2008.it/lang/it/ho me/eventi-culturali/mostra-in-piazza-del- popolo/tozzi-nord April 2016 ) The Wind Resource The 6 POLI-Wind Research Lab Combined lift-drag VAWT ► 1500W Hi-VAWT Technology Co., Ldt. (source: http://hivawt.en.ec21.com/1500W_VAWT_Wind_Sy stem--4092839_4092840.html April 2016) The Wind Resource The 7 POLI-Wind Research Lab Aerodynamics of VAWT Let’s consider here a H-Darrieus wind turbine (i.e. straight blades) source: Manwell, J. F., J. G. McGowan, and Anthony L. Rogers. "Aerodynamics of wind turbines." Wind Energy Explained: Theory, Design and Application, Second Edition (2009). 2 Ω푅 푈푟푒푙 2 2 λ = = 휆 + (1 − 푎) sin 휙 + (1 − 푎) cos 휙 푈 푈 (1 − 푎) cos 휙 tan 훼 = 1 − 푎 sin 휙 + 휆 The Wind Resource The 8 POLI-Wind Research Lab Aerodynamics of VAWT (1 − 푎) cos 휙 tan 훼 = 1 − 푎 sin 휙 + 휆 stall ► TSR = 2 ► TSR = 8 The Wind Resource The 9 POLI-Wind Research Lab Aerodynamics of VAWT Single Stream Tube Momentum Theory 2휋 2 퐵푐 푈푟푒푙 (1 − 푎) cos 휙 푎 1 − 푎 = 퐶 cos 훼 + 휙 + 퐶 sin 훼 + 휙 푑 휙 and tan 훼 = 8휋푅 푈 퐿 퐷 1 − 푎 sin 휙 + 휆 0 solved iteratively. Then compute power from torque to get: 2휋 2 휆퐵푐 푈푟푒푙 퐶푃 = 퐶퐿 sin 훼 − 퐶푑 cos 훼 푑휙 4휋푅 0 푈 Multiple Stream Tube Momentum Theory Not covered here. For details see, for instance, Manwell, J. F., J. G. McGowan, and Anthony L. Rogers. "Aerodynamics of wind turbines." Wind Energy Explained: Theory, Design and Application, Second Edition (2009). The Wind Resource The 10 POLI-Wind Research Lab .