From the known wind pressure at a certain height (such as the basic wind pressure at a height of 10 meters), calculate the coefficient of wind pressure at another arbitrary height. The wind pressure height variation coefficient increases with the height above the ground, and its variation pattern is directly related to the ground roughness and wind speed profile. When designing engineering structures, wind pressure values corresponding to corresponding heights should be used at different heights.
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For some high-rise buildings with obvious lateral effects, the impact of cross-wind wind vibration should be considered. "Since it is more complicated to determine whether the impact of cross wind vibration needs to be considered, it involves factors such as the height of the building, aspect ratio, structural natural vibration frequency and damping ratio. If the height of the building exceeds 150m or the aspect ratio is greater than 5 for high-rise buildings, Transverse wind vibration should be considered.
Twisting wind force is caused by the asymmetric effect of wind pressure on each facade of the building, which is related to the turbulence of the wind and the vortex in the wake of the building's leeward side. p>
It is generally believed that for most high-rise buildings, the torque caused by wind pressure is relatively small, so it can not be considered. However, for some high-rise buildings with asymmetrical planes, especially when the center of mass and rigidity of the structure deviate, the torsional wind will occur. The influence of vibration cannot be ignored.
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Some wind turbines do not have tail fins, so how do they ensure that they are consistent with the direction of the wind?
In areas with complex terrain such as mountains and canyons, due to the blocking and refraction of the terrain, the air flow is hindered and interfered with, resulting in cross winds. The pressure difference in the atmospheric circulation can also cause cross winds. >
According to the query of Xiaoyiai Education, cross winds are caused by differences in air pressure. When the air pressure on the ground is different, air will flow from high-pressure areas to low-pressure areas, forming airflow due to the influence of the earth's rotation. , the airflow will be affected by the Coriolis force, making the direction of the airflow not perpendicular to the ground, but showing a certain deflection angle, which forms a cross wind. In addition to the difference in air pressure, the generation of cross wind is also related to the terrain and the ground. It is related to factors such as the ocean. For example, in valleys or canyons, air flow is restricted due to terrain, and strong cross winds are easy to form. On the ocean, different air pressures will be formed due to different factors such as seawater temperature and salinity. Bands, also produce cross winds
Applications of cross winds: The role of cross winds in wind power generation The role of cross winds is very important in wind power generation when wind turbine blades are affected by cross winds. Torque is produced, causing the fan to rotate, and the kinetic energy generated by this rotation can be converted into electrical energy., thus providing us with clean energy. In addition, crosswinds can also change the direction of the wind turbine to better align it with the direction of the wind, thereby improving power generation efficiency.
Although today's large wind turbines do not have tail fins, they are equipped with wind direction sensors and use servo motors to drive the impellers in the direction of the incoming wind.
The principle of the tail is that the wind force (aerodynamic force) acting on it makes the tail in the downwind direction. But when the impeller is large, a large tail wing is also required. The engineering cost of making a large rear wing would also be high.
At the same time, the tail also brings a lot of vibration problems.