Anemometer is more, the kinds of commonly used for the wind cup anemometer zui, meteorological offices and stations, it is composed of three to 120 & deg; Fixed on the bracket of the parabolic taper part of induction, the empty cup empty cup of concave forward a direction. The induction part installed on a vertical axis, in under the action of wind, the wind cup axis is proportional to the speed of the wind speed to rotate. Anemometer its basic principle is a thin metal wire in a fluid, the flow of electricity heating wire, make its temperature is higher than the temperature of the fluid, so called wire anemometer. When the fluid flows through the wire along the vertical direction, will take away part of the metal wire heat, temperature drops make wire. Derived according to the theory of forced convection heat transfer, the retention of heat Q and the relation between velocity v of the fluid. Two supporting tension standard probe by a short, thin metal wire. Wire normally with platinum, rhodium, high melting point, good ductility, such as tungsten metal. The commonly used wire diameter of 5 & mu; M, to 2 mm long; Zui small probe diameter only 1 & mu; M, length is zero. 2毫米。 According to different purposes, the probe is made double wire, three wire, wire and V, X, etc. In order to increase the strength, sometimes with a metal film instead of metal wire, usually on a thermal insulating substrate coating a layer of thin metal film, called the hot film probe. The probe must be calibrated before use. Static calibration was conducted in the specialized standard wind tunnel, measuring the velocity and the relationship between the output voltage and drawing standard curve; Dynamic calibration is done in pulsating flow field known, or in the anemometer heated circuit and a pulse signal, to verify the frequency response of the anemometer, if poor frequency response available corresponding compensation circuit to improve them. Anemometer has many advantages, here are a few of the more important: 1, small volume, little interference flow field; 2, wide applicable scope. Not only can be used in the gas can also be used for liquid, gas in subsonic, transonic and supersonic flow in all can use; 3, high measurement precision and the repeatability is good. Anemometer disadvantage is that the probe flow field have certain interference, easy to fracture. 4, in addition to measure average speed, can also be measured fluctuating value and amount of turbulence; In addition to the measurement of single direction can also be measured simultaneously multiple directions velocity component.