The wind speed of one-way flow is basically stable, and the direction of air flow is basically the same. There is little difference between the wind speed near the intake and that of the working face, and the uniformity of the wind speed in the whole dust-free workshop is good. Generally, the uniformity of the wind speed can not be considered.
The wind speed and direction of each part of non-unidirectional flow are different. The uniformity of wind speed in the whole dust-free workshop is poor. It is necessary to consider the uniformity of wind speed. Sometimes it is necessary to measure the wind speed of each part separately.
When measuring wind speed, it is necessary to judge the direction of wind beforehand, because the probe of general anemometer has directivity, so it is necessary to recognize the direction when measuring wind speed. Since the air flow at the intake is divergent, it is usually necessary to add a wind shield to determine the wind speed at the inlet.
(1) a common method is to measure wind speed with hot sphere anemometer and to measure wind speed with hot ball anemometer. The general thermo ball anemometer has high sensitivity but poor stability. Therefore, the drugstore should pay attention to the wind speed measured by Hot-bulb anemometer: check whether the appearance and working state of anemometer are normal; correct the zero position of anemometer before measuring; correct the zero position when the probe should be in the windless state; measure the wind speed of dust-free workshop when the windward side of the anemometer probe should be vertical to the wind direction; wait for the display to be stable. After reading, care should be taken to prevent the anemometer probe from touching other objects.
(2) wind speed is determined by rotor anemometer. Rotor anemometers have friction on their spindles, so the sensitivity of early rotors is low and people don't like to use them very much. With the neck of technology, the sensitivity of rotorcraft anemometer is getting higher and higher, and more and more people use rotorcraft anemometer.
When measuring wind speed with rotorcraft anemometer, we should pay attention to the following points: checking whether the appearance and working state of the anemometer are normal; checking whether the friction force of the rotating shaft is normal; recognizing the direction of the air flow when measuring the wind speed; the rotorcraft's rotating plane should be vertical to the direction of the wind; the rotorcraft should be all in the wind channel; waiting for the display of stability before starting reading. Number.
(3) wind speed is measured with a pitot tube and a micro pressure gauge. The static pressure and total pressure were measured by standard pitot tube combined with micromanometer. The dynamic pressure was calculated by static pressure and total pressure, and then the wind speed was calculated by dynamic pressure.
In general, the wind speed measured by standard pitot tube is more reliable. The standard wind speed in the wind tunnel is measured by the standard pitot tube combined with the micro pressure gauge. However, the operation of this method is rather troublesome, and it is sensitive and accurate to the micro pressure gauge.
When measuring the wind speed of dust-free workshop with pitot tube, the following points should be noticed: check whether the inlet of standard pitot tube is damaged; check whether the standard pitot tube is blocked; check whether the pipeline connecting the pitot tube is unobstructed; check whether the display of micro-pressure gauge is normal; and the direction of the standard pitot tube should be accurate.