The differences between horizontal axis and vertical axis wind turbines lie in the following aspects:
1. Design method
Horizontal axis wind turbine blade design is commonly used by Momentum-leaf element theory, the main methods include Glauert method, Wilson method, etc. However, because the blade element theory ignores the flow interference between each blade element, and at the same time ignores the airfoil resistance when designing blades using blade element theory, this simplification inevitably leads to inaccuracy in the results. This simplification has little impact. on the design of the blade shape, but has a greater impact on the wind energy utilization rate of the wind wheel. At the same time, the interference between the blades of the wind wheel is also very strong, and the whole flow is very complex.e. It is impossible to obtain accurate results based on blade element theory alone.
The design of vertical-axis wind turbine blades was formerly based on the horizontal-axis design method and relied on blade element theory. Since the flow of vertical axis wind turbine is more complex than that of horizontal axis, it is a typical large separation unsteady flow and is not suitable for analysis and design using blade element theory. This is also an important reason for the vertical axis. The wind turbine has not been developed for a long time.
2. Wind power utilization rate
The wind power utilization rate of large horizontal axis wind turbines is mainly calculated by blade designers and is generally above 40%. As mentioned earlier, due to the flaws in the design method itself,the accuracy of wind energy use calculated in this way is highly questionable. Of course, wind turbines at wind power plants will plot wind power curves based on measured wind speed and power output. However, the wind speed at that time is the wind speed measured by the anemometer on the back of the wind wheel. as the speed and power of the incoming wind. The curve is too high and needs to be corrected. After applying the correction method, the wind energy utilization rate of the horizontal axis will be reduced by 30-50%. Regarding the wind energy utilization rate of small horizontal axis wind turbines, the China Aerodynamic Research and Development Center has conducted relevant wind tunnel experiments, and the measured utilization rate is between 23% and 29%. %.
3. Structural characteristics
During a rotation, the blades of the horizontal axis wind turbine areaffected by the combined effects of the force of inertia and gravity. The direction of the inertial force changes at. at any time. The direction of gravity remains unchanged, the blade is therefore subjected to an alternating load, which is very detrimental to the fatigue life of the blade. In addition, horizontal axis generators are placed at an altitude of tens of meters, which brings a lot of inconvenience to the installation, maintenance and inspection of generators.
The blades of the vertical axis wind turbine are much better stressed during rotation than those of the horizontal axis. Since the direction of the force of inertia and gravity always remains unchanged, the blades are subjected to a constant load. The fatigue life is longer than that of horizontal axis wind rotors. At the same time, the vertical axis generator can be placed under the wind wheel or on the ground for easy installation and maintenance.
4. Speede of start-up wind
There is a consensus that the start-up performance of horizontal axis wind turbines is good. However, depending on the wind speed of small horizontal axis wind turbines driven. the China Aerodynamics Research and Development Center. According to tunnel experiments, the starting wind speed is generally between 4 and 5 m/s, with a maximum It actually reached 5.9 m/s. Such startup performance is obviously not satisfactory. There is also an industry consensus that the starting performance of vertical axis wind turbines is poor, especially for Darrieus Ф-type wind turbines, which have no self-starting capability, which is also a reason which limits the application of the vertical wind turbine. axis wind turbines. However, for the Darrieus-type H-shaped wind wheel, the conclusion is the opposite. According to research by auteur, as long as the aerodynamic profile and installation angle are correctly selected, fairly good starting performance can be obtained. Judging from tunnel experiments, the starting wind speed of this Darrieus type H-shaped wind rotor only needs 2 m/s. , which is better than the horizontal axis wind turbine mentioned above.
Wind power is a clean energy technology that uses wind energy to produce electricity. Its power generation efficiency is affected by many factors, including the following aspects:
Wind speed: Wind speed is one of the most important factors affecting the efficiency of the wind power. The higher the wind speed, the faster the wind turbine spins and can produce more electricity. Normally, wind turbines start producing electricity when the wind speed is greater than 3 meters per second, and the efWind power production efficiency is highest when the wind speed is greater than 10 meters per second.
Wind direction: Wind direction also affects the efficiency of wind power generation. Different wind directions will cause the blades of the wind turbine to be affected by different wind forces and directions, thereby affecting the efficiency of power generation.
Altitude: Altitude also affects the efficiency of wind power generation. In higher altitude areas, the air density is lower and the wind force on the wind turbine blades is also lower, which in turn affects the efficiency of electricity generation.
Temperature: Temperature also affects the efficiency of wind power generation. When the temperature is higher, the air density is lower and the wind force on the wind turbine blades is also greater.s low, which in turn affects the efficiency of electricity production.
Wind Turbine Design and Quality: The design and quality of a wind turbine also affect its power generation efficiency. Excellent design can enable wind turbines to efficiently generate electricity at low wind speeds, and high-quality materials can extend the life of wind turbines.
The parameters required for wind energy calculation can be provided by the Xihe Energy big data platform (xihe-energy) .