Research On Effect Of Main Structural Parameters On Performance Of Straight-bladed Vertical Axis Wind Turbine

Straight-blade Vertical Axis Wind Turbine, SB-VAWT for short, is a kind of lift type windturbine with simple structure. SB-VAWT is good at utilization of wind energy and can bemaintained convenient. Recently, with the development of Small and medium-sized wind powermarket, SB-VAWT has been focused by more and more people. The performance of SB-VAWTincludes starting performance and output performance. A high starting performance means VAWTcan run at a low wind speed and a high output performance means VAWT can output more power atrated speed.For SB-VAWT, its development is mainly restricted by its low starting performance. Usually,there are two ways to improve the starting performance of SB-VAWT, the one is to change itsstructure and the other way is installing assist equipment. The main structural parameters ofSB-VAWT contain airfoil of blade, radius of wind turbine, number of blades. It is important toverify structural parameters effect on starting performance of SB-VAWT. Combined with Savoniusrotor is an effective way to improve starting performance of SB-VAWT and its feasible has beenproved. However, a wrong combined way can lead to Savonius rotor keeping the blade of VAWTout, then starting performance of Savonius rotor is decreased. So it is necessary to researchcombination angle’s effect on starting performance of SB-VAWT. In the research of airfoil of blade,NACA0018, NACA5520and FX63-145are chosen. Among these blades, NACA0018meanssymmetric airfoil, NACA5520means asymmetric and stick airfoil, FX63-145means asymmetricand thin airfoil. Wind tunnel test is used to test the starting wind speed of VAWT with differentairfoils at different angle of attacks. According to the results, symmetric airfoil is better thanasymmetric airfoil and stick airfoil is better than thin airfoil. In the research of combination angle,the best starting area of Savonius is combined with the best starting area and the worst starting areaof SB-VAWT. Wind tunnel test is used to test the starting wind speed of VAWT with differentcombination method at different angle of attacks. According to the results, the best starting area ofSavonius rotor should be combined with the best starting area of SB-VAWT.The research of output performance of SB-VAWT at low rotation speed is based on theresearch of starting performance in this article. Nowadays, most of researching about outputperformance of SB-VAWT is focus on its rated running and output performance at low rotation isignored. However, output performance of SB-VAWT at low rotation speed is very important to starting performance and rated output performance of SB-VAWT. So it is necessary to researchoutput performance of SB-VAWT at low rotation speed. In this research, airfoil of blade, radius ofwind turbine, number of blades and combination angle effect on output performance of SB-VAWTat low rotation speed is researched by wind tunnel test. Among of these parameters, NACA0018and NACA5520are chosen; different blades are chosen;0.3m and0.4m of diameter are chosen.Wind tunnel test is used to test structural parameters effect on output performance of SB-VAWT atlow rotation speed. For SB-VAWT without drag type rotor, output performance of SB-VAWT atlow rotation speed is affected by airfoil and number of blade and radius of rotor. After the Savoniusrotor is installed, output performance of SB-VAWT at low rotation speed is improved. Comparedimproving rate of different structural parameters knows that SB-VAWT with symmetric airfoil isbetter than SB-VAWT with asymmetric.On the side, the diameter ratio effect on performance of SB-VAWT is researched by numericalsimulation. Computational method is verified by wind tunnel test in this research. According to theresults, SB-VAWT with Savonius rotor has a high output performance when the diameter ratio isΦ=0.5. at this situation, the starting performance of SB-VAWT with Savonius rotor is twice of itwithout Savonius rotor.From the above, structural parameters effect on performance of SB-VAWT are systematicallyresearched by wind tunnel test and numerical simulation. There are two main innovations in thisarticle. First, combination angle with Savonius rotor effects on starting performance of SB-VAWTis tested by wind tunnel test and a better combined method is raised. Second, output performance ofwind turbine at low rotation is researched by wind tunnel test and some rules that provide beneficialreference to design of SB-VAWT are required.