The wind and determining the direction of its blow is known as an observator, or anemometer. Such a device is used if it is necessary to control the parameters of the movement of air masses.
Operating principle
Despite the variety of anemometers, which differ in design, most of them work on the principle of determining the nature of the action of the air flow on moving rotating elements.
Devices of this category are able to determine the maximum current when the flow is blowing in a certain direction. Some models give indicators of volumetric air flow, flow temperature, humidity. Thus, a functional instrument for measuring wind speed turns into a portable weather station.
Types
There are several separate types of devices capable of calculating wind speed. Currently, the following types of devices for this purpose are distinguished:
- rotational;
- vortex;
- thermal;
- dynamometric;
- optical;
- ultrasonic.
Let's take a closer look at devices of each type, determine their capabilities, methods of operation.
Rotary anemometers
The meteorological device can be equipped with cups or blades that play the role of a sensitive element. The latter are movably fixed on a vertical rod and connected to the meter. The movement of air currents causes such turntables to rotate around an axis. As you move, the measuring mechanism records the number of revolutions during a certain time period. Visual information is provided by a wind speed scale or a digital display.
Designs of this type have been invented for a long time. However, despite the advent of more advanced instruments, rotary anemometers still continue to be successfully used by meteorologists around the world.
Vortex anemometers
In such devices, the measurement of speed occurs due to the action of air flows on a light impeller located in a vertical plane. As in the previous case, the rotation of the impeller through the impact on the system transmits data to the counting mechanism.
Hand-held vortex anemometers are currently the most common. The latter are used to measure the speed of air flows in ventilation systems and pipelines, and are installed in the air ducts of industrial and residential facilities.
Thermal anemometers
Thermal appliances are not in great demand. Most often, the need for their use arises when measuring indicators of slow air flows.
The thermal wind operates on the principle of measuring the temperature of an incandescent filament or a special plate on which air pressure is applied. At different flow rates, a certain amount of energy is released, which allows maintaining one or another temperature of the thermal element. In this simple way, the wind speed is determined.
Torque anemometers
A device for measuring wind speed can also function by determining the pressure indicators of the wind flow in the middle of an L-shaped tube sealed on one side. The data is obtained by comparing the excess air pressure outside and inside the element.
A dynamometric device for measuring wind speed is used not only in meteorology. Similar devices are installed in ventilation systems and gas ducts, where the volumetric flow rate and their speed are calculated.
Ultrasonic anemometers
The principle of operation of devices of this category is based on the determination at the receiver, depending on the indicators of the flow of air masses. Here are the most high-precision, modern devices that also allow you to fix the direction of wind flows.
There are three-dimensional and two-dimensional ultrasonic devices. The former make it possible to obtain indicators of the direction of movement of flows in three components. In turn, a two-dimensional meteorological instrument makes it possible to measure the direction and speed of the wind only in the horizontal plane. Some ultrasonic systems calculate the temperature of the air streams.
Optical anemometers
Physicists and engineers involved in space programs often resort to the use of laser optical devices to measure the speed and direction of air flows. Such devices work according to the definition of the dependence of light scattered or reflected by a moving object on its speed. This method does not involve the direct impact of gaseous, solid or liquid substances on the elements of the measuring device.
The scope of optical anemometers is extremely wide, starting with determining the directions of movement of substances in living cells and capillaries and ending with the calculation of the velocity of gases in the atmosphere.
The operation of laser devices helps to calculate with high accuracy the speed of air flows around moving objects, in particular, vehicles, aircraft, space bodies. The obtained calculations enable researchers, engineers and mechanics to develop the most aerodynamic forms in the design of equipment.
What should I pay attention to when choosing a device for measuring the speed and direction of air flow? Of decisive importance here is the list of tasks that are set for the user. Depending on this, the following technical characteristics of the device are important:
- maximum measuring range;
- the magnitude of the errors;
- possibility of application in certain temperature conditions;
- the level of safety for the user when the device is exposed to aggressive environmental factors;
- type: stationary or portable device;
- the degree of protection of the mechanism from the effects of precipitation;
- the nature of the power supply of the device and the method of data generation;
- device dimensions;
- the ability to calculate indicators at night (the presence of backlight).
At present, for operation in conditions of extremely low temperatures, it is possible to use meteorological instruments with heaters. For mines and shafts, specialized anemometers are used, which are able to function properly in high dustiness of the environment and in an explosive environment. Such functional devices tolerate exposure to high humidity and remain operational with significant temperature changes.
Eventually
As you can see, depending on personal needs, it is possible to choose the most suitable device for recording air flow indicators. However, there are difficulties here. Since all anemometers are measuring instruments, they are subject to certification and attestation by the relevant government agencies.
