What are the functions and applications of anemometer?

2019-07-09
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Esky Purify

What are the functions and applications of anemometers?

There are many different types of anemometers, among which the hot wire anemometer is commonly used in factory clean workshops. The principle is that a thin metal wire (called a hot wire) that is heated by electricity is placed in the airflow. The heat dissipation of the hot wire in the airflow is related to the flow rate, and the heat dissipation causes the temperature of the hot wire to change, causing the resistance to change, and the flow rate signal is converted into an electrical signal. It has two working modes:① Constant current type. The current passing through the hot wire remains unchanged. When the temperature changes, the resistance of the hot wire changes, so the voltage at both ends changes, thereby measuring the flow rate;② Constant temperature type. The temperature of the hot wire remains unchanged, such as 150℃, and the flow rate can be measured according to the current required to be applied. The constant temperature type is more widely used than the constant current type.

The main uses of the hot wire anemometer are as follows:

1. Measure the average flow speed and direction.

2. Measure the pulsating speed of the incoming flow and its spectrum.

3. Measure the Reynolds stress in turbulent flow and the velocity correlation and time correlation between two points.

4. Measure the wall shear stress (usually using a hot film probe placed flush with the wall, the principle is similar to hot wire velocity measurement).

5. Measure the fluid temperature (pre-measure the curve of the probe resistance changing with the fluid temperature, and then determine the temperature based on the measured probe resistance). In addition, many professional uses have been developed.

The ceramic base RTD thermal anemometer sensor (including temperature compensation) of the TSI 9500 anemometer series is more rugged and more sensitive

The thermal anemometer requires that the probe be perpendicular to the air outlet during the test. If the air outlet is on the side of the wall, a retractable straight probe can be selected. If the air outlet is vertically overhead, it is recommended to choose a retractable and bendable probe.

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