The differences between horizontal axis and vertical axis wind turbines lie in the following aspects:
1. Different Design Methods
Horizontal axis wind turbine blade design, Momentum-foil element theory is commonly used and 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 wind wheel blades is also very strong, and the entire flowis very complex. 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 of the conc methodeption itself, the accuracy of the wind energy use thus calculated is very 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. Startup wind speed
There is consensus that performancestart-up of horizontal axis wind turbines are good. However, depending on the wind speed of small horizontal axis wind turbines driven. the China Aerodynamic Research and Development Center According to tunnel experiments, the starting wind speed is generally between 4-5m/s, and the maximum reaches 5.9m/s. Such startup performance is obviously unsatisfactory. 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 the author's research, as long as the aerodynamic profile and installation angle are correctly selected, quite goodStart-up performance can be achieved by JDX twin turbine vertical axis wind turbine, JDX-H vertical axis wind turbine and JDX squirrel cage. According to the wind tunnel experiments of the vertical axis wind turbine, the starting wind speed of this Darrieus type H-shaped wind turbine only needs 2m/s, which is better than the vertical axis wind turbine. horizontal mentioned above. Current generator.
4. Structural characteristics
During rotation, the blades of the horizontal axis wind turbine are affected 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 for installation, maintenance.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.
The wind-solar hybrid street light is a public lighting system that uses wind energy to produce electricity. It combines wind turbines with street lights and uses the electricity generated by the wind turbine to power the system. street lights, achieving sustainable use of energy. When choosing the axial direction of a wind turbine, the vertical axis and horizontal axis have their own advantages and application scenarios.bles.
First of all, vertical axis wind turbines have the following advantages:
1. Strong adaptability: Vertical axis wind turbines can operate in various wind directions and are not limited by wind. directions. This means it can work in complex urban environments, such as high-rise buildings, trees and other places that affect wind direction.
2. Simple structure: The structure of the vertical axis wind turbine is relatively simple. Due to the symmetry of its design, it does not need to follow the direction of the wind, so it can reduce complexity and breakdowns. rate of mechanical components.
3. Good silence: The blades of vertical axis wind turbines produce relatively little noise when rotating, which can reduce interference to the environment.
However, horizontal axis wind turbines also have their unique advantages:
1. Haute efficiency: The blades of horizontal axis wind turbines can be adjusted according to the wind direction to achieve the best wind energy utilization efficiency. This gives horizontal axis wind turbines an advantage in terms of wind energy conversion efficiency.
2. High stability: The structure of the horizontal axis wind turbine is relatively stable and can better withstand the impact and changes in wind force. This makes horizontal axis wind turbines more reliable in adverse weather conditions.
3. Easy Maintenance: The mechanical components of horizontal axis wind turbines are relatively easy to maintain and replace because they are usually located on the ground and do not require climbing for maintenance.
In summary, both vertical axis and horizontal axis wind turbines have their own advantages in different scenarios. For wind-solar hybrid public lighting systems, if thevironment around street lights is complex and the wind direction is variable, vertical axis wind turbines are more suitable if the wind direction where the street lights are located is relatively stable and the wind energy is high; efficiency of use is required, horizontal axis wind turbines are more suitable. Therefore, when selecting the axial direction of a wind turbine, overall considerations should be taken into account based on specific application scenarios and needs.