How is the wind speed measured?

Commonly used instruments for measuring wind speed include cup anemometer, airfoil anemometer, thermometer and hot-ball electric anemometer. Wing anemometers and cup anemometers are easy to use, but the inertia and mechanical friction resistance are large, so they are only suitable for measuring large wind speed.

Hot-ball electric anemometer

The structure principle of 1. is an instrument that can measure low wind speed. The measuring range is 0.05- 10m/s, which consists of a hot bat probe and a measuring instrument. The probe has a glass ball with a diameter of 0.6 mm, and a nickel-chromium coil and two thermocouples connected in series are wound in the glass ball for heating the glass ball. The cold end of the thermocouple is connected to the copper column and directly exposed to the airflow. When a certain amount of current passes through the heating ring, the temperature of the glass ball rises. The degree of increase is related to the wind speed, and the degree of increase is large when the wind speed is small; On the contrary, the degree of increase is small. The magnitude of the rise is displayed on the electric meter through the thermocouple. The wind speed (m/s) can be determined by checking the calibration curve according to the reading of the electric meter.

2. Method of use

(1) before use, observe whether the meter pointer points to zero. If there is any deviation, gently adjust the mechanical adjustment screw of the electric meter to make the pointer return to zero;

(2) Put the calibration switch in the off position;

③ Insert the plug of the measuring rod into the socket, place the measuring rod vertically upward, press the plug to seal the probe, turn the "correction switch" to the full-scale position, and slowly adjust the "full-scale adjustment" knob to make the pointer of the electric meter point to the full-scale position;

④ Turn the "calibration switch" to "zero" and slowly adjust the two knobs of "coarse adjustment" and "fine adjustment" to make the pointer of the electric meter point to zero;

⑤ After completing the above steps, gently pull the plug to expose the probe of the measuring rod (the length can be selected as required) and make the red dot on the probe face the wind direction. According to the reading of ammeter, consult the calibration curve to find out the measured wind speed;

⑥ After measuring for a few minutes (about 10 minute), the above steps ③ and ④ must be repeated once to standardize the current in the instrument; ⑦ After measurement, the "calibration switch" should be placed in the closed position.

3. Preventive measures

① This instrument is a relatively precise instrument, in order to prevent collision and vibration. It should not be used in places with high dust content or corrosiveness.

② The instrument has four batteries, which are divided into two groups, one is three batteries in series, and the other is a single battery. When adjusting the "Full Scale Adjustment" button, if the instrument fails to reach full scale, it means that a single battery has been exhausted; When adjusting the "coarse adjustment" and "fine adjustment" buttons, if the ammeter pointer cannot return to zero, it means that three batteries have been exhausted; When replacing the battery, open the small door at the bottom of the instrument and connect it in the right direction.

(3) After the instrument is repaired, it must be recalibrated.