The size of the wind energy captured by the wind wheel of a wind turbine is proportional to the vertical windward area of the wind wheel. That is to say, for a certain wind wheel, when it is in the vertical wind direction (front windward), it captures more wind energy; and when it is not frontal When facing the wind, the captured wind energy is relatively small; when the wind wheel is parallel to the wind direction, no wind energy is captured. In order to use wind energy more effectively, all horizontal-axis wind turbines must be able to adjust according to the wind direction, so that the wind wheel can be kept upwind to the greatest extent, so as to obtain as much wind energy as possible, thereby outputting larger electric energy. For small wind turbines, the tail wing steering mechanism is generally used. The principle of its direction adjustment is that within the rated wind speed, the tail plate and the rotating surface of the wind wheel are kept perpendicular, and the tail plate and the wind direction are kept parallel, thus ensuring the positive wind of the wind wheel. When the wind direction changes, the empennage plate also rotates, but it is always parallel to the wind direction, so the rotating surface of the wind wheel always faces the wind direction.
The greater the angle between the wind direction and the main axis, the greater the loss of wind energy. In the case of high wind speed, this loss can be used to adjust the power of the wind turbine, but this method is generally only applied to small wind turbines. The wind-facing mechanism of a small wind turbine mainly relies on the tail fin. As long as the tail wing is designed reasonably, its wind performance can fully meet the technical requirements.
The tail of a small wind turbine is composed of a tail beam, a tail plate, etc., and is generally installed behind the main wind wheel and perpendicular to the main wind wheel rotation surface. The principle of the direction adjustment is: when the wind generator is working, the tail plate always follows the wind direction, that is, parallel to the wind direction. This is determined by the length of the empennage beam and the downwind area of the empennage panel. When the wind direction deflects, the moment the empennage panel is subjected to wind pressure is sufficient to make the rotor rotate so that the wind wheel is in the windward position.
The shape of the tail plate is shown in Figure 1. Figure 1 (a) is the form used by the old wind turbine, Figure 1 (b) is an improved version of Figure 1 (a), and the form shown in Figure 1 (c) is opposite to the wind direction. The most sensitive to changes, good sensitivity, is the best shape. Figure 1(c) The tail wing has the largest wingspan to chord length ratio. The design of this tail wing is the same as that of a glider wing, which can make full use of the rising airflow. In fact, the ratio of wingspan to chord length of the tail is between 2 and 5. The height of a typical tail should be about 5 times the width.
The tail wing is generally installed in the wake area of the wind turbine rotor, but in order to avoid the wake area of the wind wheel, the tail wing is also installed at a high position, as shown in Figure 2. The length of the tail wing support arm is roughly the same as the diameter of the wind wheel as the standard, and the area of the tail wing is 1/8 of the rotation area of the wind turbine.
At present, the best small wind turbines only retain two moving parts (the fewer moving parts, the more reliable). One is that the wind wheel drives the main shaft of the generator to rotate, and the other is that the tail drives the nose of the wind turbine to yaw. Moving parts are indispensable, which is also the basis of wind turbines. In practice, the failure rate of these two moving parts is not high.