Anemometer

Content
1. What is anemometer?
2. What is anemometer used for?
3. What is the principle of anemometer?
4. Anemometer type
5. Anemometer specifications and features
6. How to use anemometer?
7. Precautions for using anemometer
8. How to order anemometer?

Anemometer is an instrument for measuring the velocity of airflow. There are many types of anemometers, the most commonly used in weather stations is the wind cup anemometer, which consists of three parabolic cone cups fixed at 120° to each other on the bracket to form the induction part, the concave surface of the cups are all in one direction. The whole induction part is mounted on a vertical rotating shaft, under the action of wind, the wind cup rotates around the shaft at a speed proportional to the wind speed.

Wind anemometer is an instrument that can measure the wind speed, it can measure the speed and direction of the average flow. It can measure the pulsating velocity of the incoming flow and its spectrum. It can measure the Reynolds stress in turbulent flow and the velocity dependence and time dependence of two points. It can measure the wall shear stress (usually done by using a hot film probe placed flush with the wall, the principle is similar to that of hot wire velocimetry). Fluid temperature can also be measured (the curve of probe resistance with fluid temperature is measured in advance, and then the temperature can be determined from the measured probe resistance.
In addition to wind speed can also measure the wind temperature and air volume. Many industries need to use the anemometer, the recommended use of the industry: fishing industry, all kinds of fan manufacturing, ventilation exhaust system industry, and so on.
Anemometer different seasons and different geographical situations will make the wind direction in the atmosphere constantly changing. Wind direction can help us to predict and study climate change. The study of wind direction requires the use of an anemometer. The anemometer's portion of the arrow rotates with the wind speed. The anemometer must be installed in a place where there are no buildings or trees to obstruct the movement of the wind. The hot ball type electric anemometer, used in heating, ventilation, air conditioning, meteorology, agriculture, refrigeration and drying, labor and health investigation, etc., needs to determine the airflow speed of indoor and outdoor or model can be used, is a basic instrument to measure low wind speed.

The basic principle of the anemometer is to put a thin metal wire in the fluid, and pass a current to heat the wire so that its temperature is higher than the fluid's temperature, which is why line tachometers are called " hotline". When the fluid flows through the wire in the vertical direction, it will take away part of the heat of the wire, so that the temperature of the wire drops. According to the theory of forced convection heat exchange, a relationship exists between the heat lost by the hot wire, Q, and the velocity of the fluid, v. A standard hot wire probe, consists of two brackets tensioning a short, thin wire. The wire is usually made of metals with high melting points and good ductility such as platinum, rhodium, and tungsten. The commonly used wire diameter of 5 μm, length of 2 mm; the smallest probe diameter of only 1 μm, length of 0.2 mm. according to different purposes, the hot wire probe is also made of double wire, three wire, oblique wire and V-shaped, X-shaped, etc. To increase the strength, sometimes use metal film instead of metal wire, usually in a thermally insulated substrate sprayed with a thin metal film, called the hot film probe. The thermal line sensor must be calibrated before using. Static calibration is carried out in a special standard wind tunnel, measuring the relationship between the flow rate and output voltage and drawn into a standard curve; dynamic calibration is carried out in a known pulsating flow field, or in the anemometer heating circuit with a pulsating electrical signal, calibrate the frequency response of the hot wire anemometer, if the frequency response is not good available to improve the corresponding compensation line.
0 to 100m / s flow measurement range can be divided into three zones: low speed: 0 to 5m / s; medium speed: 5 to 40m / s; high speed: 40 to 100m / s. Anemometer thermal probe for accurate measurement of 0 to 5m / s; anemometer rotor type probe to measure 5 to 40m / s flow velocity is the most ideal; and the use of Pitot tube can be in the high-speed range to get the best results. An additional criterion for proper selection of anemometer flow probes is temperature, usually up to about +-70C for thermal sensors and up to 350C for special rotor probes, and above +350C for pitot tubes.

Thermal anemometer approach measures the change in electrical resistance as the sensor is cooled by the wind while energized to test the wind velocity. Wind direction information cannot be obtained.
It is easy to carry and has a high cost performance ratio, so it is widely used as a standard product for anemometers.
Thermal anemometers are possible using a platinum wire, an electric heat couple and a semi-conductor.

Ultrasonic anemometer tests the wind speed by measuring the time of ultrasonic wave transmission over a certain distance and the arrival time is delayed due to the effect of wind.
The wind direction can be known by applying the 3rd power.
Since the sensor section is large, turbulence may occur around the test section, making the flow irregular. The use is limited and the popularity is low.

Impeller type anemometer is the application of the principle of windmill, by testing the rotation of the impeller, test the wind speed, can be used for meteorological observation, etc..
The principle is relatively simple and cheap, but the test accuracy is low, so it is not suitable for micro wind speed test and small wind speed change test.

The front side of the flow surface has small holes oriented at right angles to it, and the inside contains thin tubes that extract pressure from each hole. By testing the pressure difference (the former is full pressure and the latter is static pressure), the wind speed can be known.
The principle is relatively simple and inexpensive, but it must be set at right angles to the flow surface, otherwise a proper test cannot be performed. Not suitable for general use.
The skin dragging tube type anemometer is not used as an anemometer, but as a wind speed correction for high speed domain.

Feature:
1. Handheld anemometer adopts a one-piece molding design, which is easy to carry and easy to operate.
2. Built-in sensor, that can measure wind speed and temperature.
3. The wind speed can be selected in metric and imperial units.
4. Maximum and minimum values can be displayed.
5. Equipped with backlight function, easy to use in dark areas.

1. Anemometer before use to observe whether the meter pointer refers to the zero point, such as offset, can gently adjust the mechanical adjustment screw of the meter so that the pointer is back to zero.

2. Anemometer correction switch will be placed in the off position.

3. Plug the measuring rod in the socket, the measuring rod placed vertically upward, the screw plug pressure to make the probe sealed, "correction switch" placed in the full position, slowly adjust the "full adjustment" knob, so that the meter pointer points to the full position.

4. Place the "calibration switch" in the "zero position", and slowly adjust the "coarse adjustment" and "fine adjustment" knobs to make the meter pointer point at the full position. The gauge pointer is pointing to the 0 spot position.

5. After the above steps, gently pull the screw plug, so that the probe rod is exposed (length can be selected according to needs), and make the probe on the red dot face to face with the wind direction, according to the meter reading, consult the calibration curve, you can find out the measured wind speed.

6. After measuring for several minutes (about 10min), must repeat the above 3, or 4 steps once, so that the current in the instrument is standardized.

7. After measurement, the "calibration switch" should be placed in the off position.

The following matters need to be noted during the use of the anemometer.

a. It is forbidden to use the anemometer in a combustible gas environment.

b. It is prohibited to place the anemometer probe in a combustible gas. Otherwise, it may lead to fire or even an explosion.

c. Do not disassemble or modify the anemometer. Otherwise, electrical shock or flame may occur.

d. During use, the anemometer emits an abnormal odor, sound, or smoke, or if liquid flows into the anemometer, immediately turn off the unit and remove the battery. Otherwise, there will be the risk of electric shock, fire, and damage to the anemometer.

e. Do not touch the internal sensor part of the probe.

f. When the anemometer is not used for a long time, please remove the internal battery. Otherwise, the battery may leak liquid, resulting in anemometer damage.

g. Do not place the anemometer in a high temperature, high humidity, dusty, and direct sunlight area. Otherwise, it will lead to damage to internal devices or anemometer performance deterioration.

h. Do not wipe the anemometer with volatile liquids. Otherwise, it may lead to anemometer case distortion and discoloration. When the surface of the anemometer is stained, use a soft fabric and neutral detergent to wipe.

i. Do not drop or heavily press the anemometer. Otherwise, it will lead to anemometer failure or damage.

j. Do not touch the sensor part of the probe while the anemometer is charged. If not, it will impair the measurement results or cause damage to the anemometer's internal circuitry.

If you are interested in our anemometer or have any questions, please write an e-mail to [email protected], we will reply to you as soon as possible.