The Modification Of Single-Stage Blade And Lobed Ejector In Low-Speed Wind Turbines

With the increase of population and the increasing of economy, energy consumption is rising all over the world. The current global primary energy sources are from non-renewable energy sources, causing the depletion of resources, climate change and other issues. The adjustment of energy structure has become an urgent problem to be solved for every country. Wind energy, as the most rapid development of renewable energy, is abundant and widely distributed. In recent years, our country’s wind power developes quickly, but the research on wind turbine airfoil is less and later. This paper proposed a wind turbine for utilizing low speed wind, consisting of single-stage blade and lobed ejector. The single-stage blade was designed and modified. Finally, the ultimate modified blade was proposed, and the lobed ejector was designed. This paper also presented monolithic numerical simulation and comparative analysis.Starting from the design point parameters, 1-D calculation, the controlled vortex design and parametric modeling were applied to obtain initial profile. Commercial software CFX has been used to revise initial profile and obtain original profile, which is close to the design requirements. Numerical results of original profile in design point shows that there are two high loss zone near the two end walls of the rotor, which are corresponding to the upper and lower passage vortex. It is also found that lower passage vortex controls larger range and the intensity is stronger. In view of the poor flow of rotor root, modification in slope angel of stator, rotor axial chord, sweep angle of rotor root, circumferential sweep angle of rotor and bowed angle of stator were invstigated to obtain the effects of different modification structure on wind turbine performance.On the basis of modification research results, the ultimate modified blade was proposed. Software UG was used to the parametric design of a lobed ejector geometry, and monolithic numerical simulation of the wind turbines with lobed ejector was investigated. Comparative analysis results indicate that the efficiency of the modified turbine has been reduced, but the mass flow is larger, the power is higher, which meets the design targets. The generation and development of steamwise vortex and normal vortex in proposed wind turbine were subsequently explained. It is found that the steamwise vortex is caused by the reverse pressure gradient on both sides of the lobed ejector wall, and the normal vortex is caused by the axial velocity difference between internal and external duct. Finally, the comparative analysis results between the wind turbines with and without lobed ejector indicate that the lobed ejector can construct strong steamwise and normal vortex, which can decrease the static pressure of the rotor outlet and increase the mass flow and power of wind turbines.