Vortex theory was developed in the late 1970s and early 1980s. As with the horizontal axis wind turbine, the wake vortex system of the vertical axis wind turbine lift is first established, then the Biot-Saffa theorem is used to calculate the induced velocity generated by the wake vortex system. By superimposing the induced velocity on the incoming wind speed, the velocity flow field everywhere near the wind rotor is established.
Assume a vertical axis wind turbine with thin lifting blades. The blades do not move in a circular path around the axis, but are constrained to move at a constant speed along a square path. The angle of attack of the road is 0. When a blade advances from the leeward side, according to Kelvin's theorem, in order to maintain conservation of circulation, it must escape a starting vortex and a pair of trailing vortices.When the blade moves forward, the lift force is assumed to be 0 and the attached vortex is released. Continuing on the windward side, the situation is similar.
As the tip speed ratio and number of blades increase, the longitudinal vortex component of the tail vortex disappears, forming an annular vortex system.
As the blade rotates around a fixed axis, its angle of attack changes continuously, that is, the circulation around the blade does not change, so the vortex is continually rejected in the wake of the wind wheel.
Bladeless wind turbines should be the newest type.
The principle behind Vortex wind power generation is the Karman vortex effect in fluid dynamics, which refers to the fact that when a constant incoming flow bypasses certain objects under certain conditions, the two sides of the object fall periodically. VorDouble linear texes with opposite directions of rotation and regular arrangement are produced after nonlinear action, a Karman vortex street is formed. For example, water flowing through the pillars of a bridge and wind blowing through towers, chimneys, cables, etc. will form Karman vortices. Once the vortices are large enough, they can cause the structure to oscillate. Vortex takes advantage of this aerodynamic instability to maximize oscillation and capture mechanical energy, then use this mechanical energy to generate electricity. Of course, the design of this device is completely different from that of a classic turbine. It mainly consists of a fixed mast, a generator and a hollow, lightweight, semi-rigid fiberglass cylinder on top. Vortex automatically changes stiffness and “synchronizes” with wind speed to maintain resonance without any intervention mmechanical or human. The use of the vortex spill effect for wind power generation represents a technological leap forward in wind power that will produce power more efficiently, cheaper and more environmentally friendly. 'environment. The technology has attracted interest from Harvard University as well as SunEdison's TerraForm renewable energy division, Power, Inc. and Dat Venture.