Hot air anemometer
Parameter
Tested object: Clean air at normal temperature and humidity
Measuring range: Air speed: 0.5 ~ 3M / sec; 0.5 ~ 40M / sec
Air temperature: 0 ~ 60 ° C, 60 ~ 120 ° C
Atmospheric pressure: 0 ~ 500pa, 500 ~ 4500pa
Error: Air speed: ± 5% F. S, ±0.1m/s (18～28°C)
Air temperature: ±0.5°C Dimensions: Probe: φ11～φ18.7 mm×200～690(L) mm
Line: φ6mm × 2M (L)
Instrument body: 220 
× 175 (H) × 135 (D) mm
Standard configuration: box, six “C” batteries, calibration report
Tag: Wind Speed Sensor
How does the digital anemometer operate?
1. Zero adjustment: Zero before each use: Retract the probe lever. Turn on the power switch, after 1 minute warm-up, the instrument is stable, the display is 0.00. If it is not at 0, you can adjust the zero potentiometer on the front panel of the instrument until the display is 0.00.
2. Measurement: Pull the probe lever to expose the probe and read. Turn off the power switch at any time after use and return the probe lever to the sleeve.
3. Hold: Press the hold button and the wind speed value is displayed on the meter head stably.
At the same time, when the battery voltage is lower than the working voltage, “LOBAT” appears in the upper left corner of the display, indicating that it needs to be charged, and it can be continuously charged for 8~16 hours.
How is the wind speed measured?
Determination of wind speed Commonly used instruments are cup anemometer, wing anemometer, catastat thermometer and hot bulb anemometer. The wing and cup anemometers are easy to use, but have a high inertia and mechanical friction resistance and are only suitable for measuring large wind speeds.
Hot ball electric anemometer
1. Construction principle It is an instrument capable of measuring low wind speed, and its measurement range is 0.05-10m/s. It consists of two parts: a hot ball type probe and a measuring instrument. The probe has a glass ball of 0.6 mm in diameter surrounded by a nickel-chromium wire loop for heating the glass ball and two thermocouples connected in series. The cold end of the thermocouple is attached to the phosphor bronze pillar and is directly exposed to the gas stream. When a certain amount of current passes through the heating coil, the temperature of the glass ball rises. The degree of elevation is related to the wind speed, and the degree of increase in wind speed is large; on the contrary, the degree of elevation is small. The degree of elevation is indicated on the meter by a thermocouple. According to the reading of the meter, check the calibration curve to find out the wind speed (m/s).
2. How to use
1 Before using, observe whether the pointer of the meter points to zero. If there is any offset, you can gently adjust the mechanical adjustment screw of the meter to return the pointer to zero point;
2 Place the calibration switch in the off position;
3 Insert the measuring rod plug into the socket, the measuring rod is placed vertically upwards, the screw plug is pressed tightly to seal the probe, the “correction switch” is placed at the full position, and the “full adjustment” knob is slowly adjusted to make the meter pointer Full position
4 Put the “correction switch” in “zero position”, and slowly adjust the “coarse adjustment” and “fine adjustment” two knobs to make the meter pointer point at the zero point;
5 After the above steps, gently pull the screw plug to expose the probe (the length can be selected as needed), and make the red dot on the probe face the wind direction. According to the meter reading, check the calibration curve. The measured wind speed;
6 After measuring a few points (about 10 minutes), the above steps 3 and 4 must be repeated to standardize the current in the meter; 7 After the measurement, the “correction switch” should be placed in the off position.
3. Precautions
1 This instrument is a relatively precise instrument, which is strictly resistant to collision vibration and should not be used in places with excessive dust or corrosiveness.
2 The instrument is equipped with 4 batteries, which are divided into two groups and are connected in series, and one group is single-section. When adjusting the “Full Degree Adjustment” knob, if the meter cannot reach full scale, it means that the single battery has been exhausted; when adjusting the “coarse adjustment” and “fine adjustment” knob, if the meter pointer cannot return to zero, the explanation The three batteries have been exhausted; when replacing the battery, open the small door at the bottom of the instrument and connect it in the correct direction.
3 After the instrument is repaired, it must be recalibrated.
What is the purpose of the anemometer?
Anemometer
1. Measure the speed and direction of the average flow.
2. The pulsation velocity of the incoming stream and its spectrum are measured.
3. The Reynolds stress in the turbulent flow and the velocity dependence and time dependence of the two points are measured.
4. The wall shear stress is measured (usually using a hot film probe placed flush with the wall, the principle is similar to hot wire speed measurement).
5. The fluid temperature is measured (the probe resistance is measured in advance with the temperature of the fluid, and then the temperature is determined based on the measured probe resistance.
Wind speed sensor Introduction to several wind speed measurement methods
1. The thermal anemometer is a meter used to measure the airflow speed. It is widely used because of its high measurement accuracy, ease of use, wide measuring range and high sensitivity. The thermal anemometer uses the calorimetric principle to measure the wind speed, and is mainly composed of a wind speed probe and a measuring indicating instrument. As the structure has a hot ball type and a hot line type, the display form has various types such as pointer type and digital type, but there are only two types according to the working principle, that is, constant current type and constant temperature type. The constant current type is a constant current for the wind speed sensitive component. After heating to a certain temperature, the degree of cooling with the change of the air flow is a function of the wind speed. The constant te
mperature type is adjustable for the current of the wind speed sensitive component. The operating temperature of the wind sp
eed sensitive component in different thermal equilibrium states is basically inconvenient at different wind speeds, that is, the resistance value is substantially constant, and the power consumed by the sensitive component is a function of the wind speed.
2. Working principle of constant current anemometer: The wind speed probe is a sensitive component. When a constant current passes through its heating coil, the temperature inside the sensitive component rises and reaches a certain value in the still air. At this time, the thermocouple of the measuring component therein generates a corresponding thermoelectric potential, and is transmitted to the measurement indicating system, and the thermoelectric potential and the reference back electromotive force generated in the circuit cancel each other out, so that the output signal is zero, and the meter pointer can also refer to Zero or zero value. If the heat sensitive component at the end of the wind speed probe is exposed to the external air flow, due to the heat exchange, the thermocouple thermoelectric potential will be changed at this time, and compared with the reference back electromotive force, a weak difference signal is generated, which is measured by the measuring instrument. The system amplifies and pushes the meter pointer change to indicate the current wind speed or the current wind speed value through the display after being processed by the microcontroller.
3. The constant temperature anemometer uses a feedback circuit to keep the temperature and resistance of the wind speed sensitive component constant. When the wind speed changes, the temperature of the heat sensitive component changes, and the resistance also changes, causing the voltage across the heat sensitive component to change. At this time, the feedback circuit plays a role, causing the current flowing through the heat sensitive component to change accordingly, and the system Restore balance. The above process occurs instantaneously, so the increase in speed is like an increase in the output voltage of the bridge, and the decrease in speed is also equal to the decrease in the output voltage of the bridge.
4. Three cups of eddy current sensor: The rotating shaft of the wind cup is a metal toothed turntable, and the induction head is composed of a
coil. The coil is connected to a high-frequency alternating current, and an alternating magnetic flux is generated around the coil. The metal tooth forms a closed circuit, and the metal tooth generates an eddy current. The metal tooth generates an alternating magnetic flux in addition to the heat dissipation, resulting in an alternating magnetic flux in the opposite direction. The inductance of the coil is reduced and a change in impedance is caused. When the rotating shaft rotates, a change of the magnetic flux of the coil is caused to output a continuous pulse signal, and the pulse signal is counted to calculate the rotational speed of the rotating shaft.
5. Three cups of optocoupler sensor type sensor
, when the wind cup rotates, the multi-tooth turntable is rotated by the main shaft, so that the lower photo transistor receives the light irradiated by the upper LED, and is turned on or off, forming a speed with the cup. The proportional frequency signal is counted by the counter and converted to the actual wind speed value.
Three-cup wind anemometer measures the average wind speed within a few seconds
Wind direction and are often used with anemometers, which measure wind speed.Most of our wind sensors are modified slightly from the manufacturers’ stock items so that they may be used with our data loggers in research, air quality, and general purpose meteorological applications.
•Accuracy：±1m/s
•Start Wind：0.2-0.4 m/s
▲Voltage output type
Range：0~32. 4 m/s
Supply voltage：7V~24 V DC
Output signals：0.4~2V or 0~5 V 、1~5 V
Wind speed values =（output voltage -0.4）/1.6*32.4
▲current output type
Range：0~32. 4 m/s
Supply voltagec：12V~24V DC
Output signals：4~20 mA
Load capacity：≤200Ω
Wind speed values =（output current -4）/16*32.4
▲Pulse Output type
Range：0~60 m/s
Output signals：pulse( 0.88m/s / pulse)
Supply voltage：5V~24V DC
▲ 485 type
Range：0~32. 4 m/s
Supply voltage：7V~24V DC
Communication protocol：Modbus-RTU
Wind Sensor 