How is the wind speed measured?

January 16, 2019 ~ arcozhang ~ Leave a comment

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.

Wind speed sensor Introduction to several wind speed measurement methods

January 16, 2019January 16, 2019 ~ arcozhang ~ Leave a comment

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

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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.

wind-speed-sensor

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.

What is the use and precautions of the wind vane?

January 16, 2019January 16, 2019 ~ arcozhang ~ Leave a comment

Wind speed and direction instrument

The working principle of the wind speed and direction indicator has been described above. The recommended FC-16025 hand-held wind speed and direction indicator is now described. It is convenient for everyone to better understand and master the use.

1, the wind direction measurement part
1) Before observing, check whether the wind direction part is vertically and firmly connected to the guard of the anemometer cup and rotate the tray nut in reverse to lower the tray supporting the table direction dial, so that the shaft tip is in contact with the prototype bearing.
2) The azimuth reading should be read when the wind direction pointer is stable during observation.

2, the wind speed measurement part

1) Confirm that the battery is installed in the instrument. This instrument uses 3 sections of 5#1.5 dry battery. Please be careful not to use rechargeable battery. Its output voltage is only 1.2V. The voltage is not enough. Open the rear cover of the instrument and it will be 3 Section 5# dry battery is installed in the battery holder. (Note that the battery electrode must be correct.) After the battery is installed, the instrument may be in a power-on state or may be in a power-off state. This is the power switch on the panel to control the power supply. On and off.
Please refer to the panel layout of the instrument. After the instrument is powered on, first perform the self-test of the display. All the strokes that may be used on the display are displayed for about 2 seconds, and then the instrument enters the measurement state.
The button functions are: A – instantaneous wind speed B – average wind speed C – instantaneous wind level D – average wind level E – corresponding waves
Instantaneous, average wind speed unit: m/s, instantaneous, average wind level unit: level, corresponding to wave height unit: m

2) When the instrument is running, measure the instantaneous wind speed, average wind speed, instantaneous wind level, average wind level, and corresponding wave height. Only one of the parameters can be displayed. The display parameters are switched by the wind speed display key and the wind level display key. Each time the wind speed key is pressed, the parameter is switched between the instantaneous wind speed and the average wind speed. Each time the wind level display key is pressed, the display parameter is at the instantaneous wind level, and the average wind level. The corresponding mark is also switched between the corresponding wave height and the sign of the unit at the same time.
Each time the wind speed button is pressed: a decimal point appears at the corresponding position when displayed. The wind speed and wave height parameters are retained after the decimal point, and the wind level displays an integer, and no decimal point is displayed.
The average wind speed, the average wind level, and the corresponding wave height require a sampling time of one minute. Therefore, within one minute after power-on, or within one minute after the latch is cancelled, the correct average value cannot be obtained. Wait until the sampling time is longer than one minute. The display will only display valid parameter values in the future.

3) After the observation, in order to protect the shaft tip and the prototype bearing, the tray nut is rotated forward, the tray is raised, and the direction dial is lifted, so that the shaft tip and the jewel bearing are separated.
The latch display button toggles the instrument between the measured state and the latched state. When the measurement status is pressed, the instrument enters the latched state. After the measured value is latched, the displayed value is locked.
When the latch key is pressed in the latched state, the latch function disappears, indicating that the instrument returns to the measurement state.
Due to the small dry battery used, the stored energy is limited, so turn off the power in time after use, and remove the battery to extend the battery life.
Due to the strict mechanical structure inside the instrument, care should be taken when using it.

Wind speed and direction meter use precautions

1, the use of the environment:

1. It is forbidden to use an anemometer in a flammable gas environment.
2. It is forbidden to place the anemometer probe in a flammable gas. Failure to do so may result in fire or even explosion.
2, note:

1. Do not disassemble or modify the anemometer. Failure to do so may result in electric shock or fire.
2. In use, if the anemometer emits an unusual smell, sound or smoke, or if liquid flows into the interior of the anemometer,
Please turn off the battery immediately to remove the battery. Otherwise, there is a danger of electric shock, fire and damage to the anemometer.

3, maintenance:

1. Do not expose the probe and anemometer body to rain. Otherwise, there may be electric shock, fire and personal injury. Do not touch the internal sensor area of the probe.
2. When the anemometer is not used for a long time, please take out the internal battery. Otherwise, the battery may leak, causing damage to the anemometer.
3. Do not place the anemometer in a place with high temperature, high humidity, dust and direct sunlight. Failure to do so may result in damage to internal components or deterioration of anemometer performance.
4. Do not wipe the anemometer with volatile liquid. Otherwise, the anemometer housing may be deformed and discolored. When the surface of the anemometer is stained, it can be wiped with a soft fabric and a neutral detergent.
5. Do not drop or press the anemometer. Failure to do so will result in malfunction or damage to the anemometer.
Instructions for use: Please use the anemometer correctly according to the requirements of the instruction manual. Improper use can result in electric shock, fire, and damage to the sensor.
6. Do not touch the sensor part of the probe while the anemometer is energized. Otherwise, it will affect the measurement results or cause damage to the internal circuit of the anemometer.