Wind Energy Knowledge
        Principle of Wind Motor

        The rotating principle of wind wheel of wind motor is the same as that of pinwheel, but wind wheel vanes have rational shape. To reduce resistance, the section of wind motor is streamline. Its front edge has good fillet, tail has sharp rear edge and surface is smooth. It can generate upward resultant force when wind blows to drive wind wheel to rotate quickly. For high-power wind motor, speed of wind wheel is very low, while jointly worked machines have high speed requirements, so gear box should be set to improve wind wheel speed to working speed of work machinery. When wind vertically blows to rotating face of wind wheel, wind motor can exert maximum power, and due to variable direction, a device is needed to ensure that wind wheel rotates and automatically aligns wind direction when wind direction changes, which is the action of tail. Wind motor is the prime motor of various machines. Wind-driven water pump uses it to drive water pump and watercart, and wind rice mill uses it to drive rice mill, and the kind of machine is direct utilization device of wind energy. Wind driven generator drives the generator. The kind of machine consists of two parts, one is wind motor body and accessories which convert wind energy into mechanical energy, the other is electric part including generator and electric device which convert mechanical energy into electric energy and reliably provide it to users. Small wind driven generator has low capacity, power from several to thousands of watts, and advantages of simple structure and convenient carrying. It has variable speed connection and direct connection according to connection mode of wind motor and generator.

        Energy storage is an important problem of wind energy utilization, especially wind power generation, and its vitality depends on the reliability of energy storage device (such as storage battery) to a large extent. Energy storage device stores redundant energy when wind blows, and outputs energy for application when there is no wind. The research of energy storage modes is an important task of wind energy utilization.

        Wind energy is very abundant in nature. Total power of recently available wind energy is about 106-107 megawatts, which is 10 times more than utilizable waterpower resource in the world. But it needs the human to vigorously develop.

        China used wind energy at the earliest. Before 2000 years, wind-driven sailing boat has moved in the river, and in Ming Dynasty, wind waterlift was used and wind machine for agricultural product processing was discovered.

         

        Composition of Wind Motor

        The wind motor consists of five parts:
        (1) Wind wheel. Wind wheel consisting of two or more vanes is installed on the head, and a main part converting wind energy into mechanical energy.
         
        (2) Head. The head is a support bearing wind wheel axle and members (such as generator and gear system) above it, and can freely rotate round vertical shaft of tower.
         
        (3) Tail. The tail is on the rear of the head to make wind wheel over against wind direction when wind direction changes.
         
        (4) Revolved body. The revolved body is between head chassis and tower to rotate under the action of tail torque.
         
        (5) Tower. Tower, as a framework supporting wind motor body, erects wind motor in the air which is not affected by surrounding barriers.
         
        According to the number of wind wheel vanes, wind motor is divided into few vane and multi-vane types. The few vane type, with 2-4 vanes, has advantages of high speed, little average mass of unit power and compact structure, is used in areas with higher annual average wind speed and a prime motor mainly used for wind driven generator, and has the defect of difficult starting. The multi-vane type, with 4-24 vanes, is commonly used for areas with annual average wind speed below 3-4m/s, and has the advantage of easy starting, so it has high utilization rate. It is widely used for directly driving husbandry machinery because of low speed.