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High and low temperature measurements of wind speed
High and low temperature measurements of wind speed there are several ways, including:
One of the oldest instruments is cup anemometer, mostly used in the field of meteorology, the wind cup cross arm, wind blowing in different places under different rotation speed to determine wind speed, the available range of cup anemometer very wide, and now many dimensions cup anemometer, Lee without small anemometer can be in the chamber in such a small volume of air velocity measurements.
2, cata thermometer is a special type of glass thermometers, flow of the cooling effect is based on the design, the measurement principle is based on the use of cata first heated to a certain temperature thermometer cooling (e.g., cooling from 38 ° to 35 °) of the desired time to determine the size of the wind speed at that point, but the thermometer when measured after each measurement must be re-heated, so this method is cumbersome.
Thermal anemometer hot wire anemometer and the measurement principle is based on the design of the cooling effect of convection, the two anemometers to measure the components in the quantitative measurement of electric power, the measurement assembly reaches a predetermined standard temperature, when the air flows through the component, component temperatures drop, the decrease of the component of air velocity can be determined, the measurement unit is a hot platinum wire wound into, and the thermal anemometer measurement component in many cases a negative temperature coefficient resistance, as has been small size and small heat capacity of the components, the thermal time constant of the measured components that can be made very small, while the cross-sectional area can be measured on a small flow rate, which is particularly useful in the case of low wind speed, has applied temperature range -30 degrees to 100 degrees, in the hot wire anemometer, the hot components of the cooling effect depends on the bobbins and the angle between the flow direction, when the hot air is equal to the direction of the worst cooling effect, by turning the hot anemometer components that can accurately determine the air flow.
Cup anemometer and thermometer cata only be used to tolerating into the large test chamber, hot-wire anemometer and a hot bulb anemometer can be used for small, high-temperature chamber.