WhalePower Corp, a Toronto-based company, is redesigning wind turbine blades with a humpback-inspired bumpy leading edge, allowing a turbine to capture more of the wind's energy, and at much lower speeds. The new "Tubercle Technology" blades produce more energy more efficiently than conventional smooth blades. ...
Studi di riferimento:
Explanation of the effects of leading-edge tubercles on the aerodynamics of airfoils and finite wings Mehdi Saadat (University of Virginia), Hossein Haj-Hariri (University of Virginia), Frank Fish (West Chester University) A computational study was conducted to explain the aerodynamic effect of leading edge tubercles on maximum lift coefficient, stall angle of attack (AoA), drag, and post stall characteristics for airfoils as well as finite wings. Past experiments demonstrated airfoils with leading edge tubercles do not improve Cl$_{max}$, drag, or stall AoA but smoothen post stall characteristics to a great degree. In contrast to airfoils, finite wings with L.E. tubercles improved all aerodynamic characteristics. We explain the stall mechanism of the tubercled wing by considering each L.E. tubercle as a combination of a swept forward and a swept backward wing.There are 3 mechanisms (streamline curvature, accelerated stall, and upwash) that cause Cl$_{max}$ of airfoils with L.E. tubercles always be lower than that of smooth airfoils. We also identify two additional mechanisms which are responsible for improved post-stall characteristics of airfoils with L.E. tubercles. Finally, we discuss why finite wings with L.E. tubercles have higher Cl$_{max}$ and lower drag than their smooth L.E. counterparts by studying effects of wing tip, sweep, and taper ratio.
Effect of Leading Edge Tubercles on Marine Tidal Turbine Blades Mark Murray (U.S. Naval Academy), Timothy Gruber (U.S. Naval Academy), David Fredriksson (U.S. Naval Academy) This project investigated the impact that the addition of leading edge protuberances (tubercles) have on the effectiveness of marine tidal turbine blades, especially at lower flow speeds. The addition of leading edge tubercles to lifting foils has been shown, in previous research, to delay the onset of stall without significant hydrodynamic costs. The experimental results obtained utilizing three different blade designs (baseline and two tubercle modified) are compared. All blades were designed in SolidWorks and manufactured utilizing rapid prototype techniques. All tests were conducted in the 120 ft tow tank at the U.S. Naval Academy using a specifically designed experimental apparatus. Results for power coefficients are presented for a range of tip speed ratios. Cut-in velocity is also compared between the blade designs. For all test criteria, the tubercle modified blades significantly outperformed the smooth leading edge baseline design blades.
Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers.pdf By biomechanicist Frank Fish of West Chester University, Pa., fluid dynamics engineer Laurens Howle of the Pratt School of Engineering at Duke University and David Miklosovic and Mark Murray at the U.S. Naval Academy. "The humpback whale flipper is unique because of the presence of large protuberances or tubercles located on the leading edge which gives this surface a scalloped appearance. We show, through wind tunnel measurements, that the addition of leading-edge tubercles to a scale model of an idealized humpback whale flipper delays the stall angle by approximately 40%, while increasing lift and decreasing drag." (Physics of Fluids; May 2004 issue)
Passive and Active Flow Control by Swimming Fishes and Mammals.pdf What mechanisms of flow control do animals use to enhance hydrodynamic performance? Animals are capable of manipulating flow around the body and appendages both passively and actively. Passive mechanisms rely on structural and morphological components of the body (i.e., humpback whale tubercles, riblets)... (Annual Review of Fluid Mechanics; 2006. 38:193–224)
Turbo 5 S Diametro rotore 1.5 m Diametro totale concentratore 3 m Peso (alluminio) 183 kg PMG Generatore a magneti permanenti 4 kW Energia con vento a 10 m/sec 2.4 kW Rotazioni al minuto con con vento a 10 m/sec 126 giri al minuto Vento minimo di avvio 0.4 m/sec Velocita' del vento per generare da 3 a 12 m/sec Velocita' massima del vento 54 m/sec (194 km/h)
Wind power concentration system "Wind Lens" Un nuovo miglioramento nella produzione di energia dall'Eolico, chiamato "Wind Lens" Lenti per il Vento, usa un sistema che crea una bassa pressione dell'aria, "Low-pressure", dietro le pale, rispetto alla direzione del vento, sfruttando il flusso di vento laterale alle pale. Crea cosi' una specie di risucchio che aumenta la velocita' del vento sulle pale eoliche, principio forse derivato dall'effetto venturi. Il sistema e' stato messo a punto in Giappone alla Kyushu University.
Forti vortici creati dal diffusore e dal bordo della Lente per il Vento "Wind Lens", producono una regione di bassa pressione dietro la turbina. Questo aumenta la differenza di pressione che aiuta il vento a fluire in maggior quatita' nella Wind Lens. Strong vortices created by the diffuser and the brim of the Wind Lens produce low pressure region behind the turbine. This increased pressure difference that helps the wind to flow more into the Wind Lens.
Gli straordinari meriti delle Wind Lens: 1. Incremento da 2 a 5 volte della potenza di uscita, comparata alle turbine eoliche convenzionali. 2. Controllo dell'imbardata tramite la bordatura. 3. Significativa riduzione del rumore della turbina dovuta alla soppressione dei vortici di estremita'. 4. Sicurezza migliorata. 5. Possibile riduzione dell'interferenza sui Radar Doppler.
