A device for measuring wind speed and determining the direction of its blow is known as an observer, or an anemometer. Such devices are used if necessary, control over the parameters of the movement of air masses.
Principle of operation
Despite the variety of anemometers, which differ structurally, most of them work on the principle of determining the nature of the action of air flow on moving rotating elements.
Devices in this category are able to determine the maximum current wind speed when blowing a stream in a certain direction. Separate models give indicators of air volumetric flow rate, flow temperature, humidity. Thus, a functional instrument for measuring wind speed turns into a portable weather station.
Types
There are several separate varieties of devices capable of calculating wind speed. Currently, the following types of devices for this purpose are distinguished:
- rotational;
- vortex;
- thermal;
- dynamometric;
- optical;
- ultrasound.
Let's take a closer look at the devices of each type, determine their capabilities, methods of operation.
Rotational anemometers
The meteorological device can be equipped with cups or blades, which 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 captures the number of revolutions over a certain time period. Visual information is provided by a wind speed scale or digital display.
Designs of this type were invented for a long time. However, despite the advent of more advanced instruments, rotational anemometers still continue to be successfully operated by meteorologists around the world.
Vortex Anemometers
In such devices, the measurement of wind speed and
direction occurs due to the impact of air currents on a light impeller located in a vertical plane. As in the previous case, the rotation of the impeller by acting on the system of
gears transfers data to the counting mechanism.
Currently, manual vortex anemometers are the most common. The latter are used to measure the speed of air flows in ventilation systems and pipelines, are installed in the ducts of industrial and residential facilities.
Thermal Anemometers
Thermal appliances are not in great demand. Most often, the need for their application arises when measuring indicators of slow air flow.
A thermal wind speed sensor functions according to the principle of measuring the temperature of a filament or a special plate on which air pressure is applied. At various flow indicators, a certain amount of energy is released, which allows one or another temperature of a thermal element to be maintained. In such a 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 a L-shaped tube sealed on one side. Data is obtained by comparing the excess air pressure outside and inside the element.
A dynamometer for measuring wind speed is used not only in meteorology. Similar devices are installed for 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 determining the speed of sound at the receiver, depending on the flow of air masses. Here are the most high-precision, modern devices that also allow you to fix the direction of wind flows.
Three-dimensional and two-dimensional ultrasonic devices are distinguished. The first ones make it possible to obtain indicators of the direction of movement of flows in three components. In turn, a two-dimensional meteorological device allows you to measure the direction and speed of the wind only in the horizontal plane. Some ultrasound systems calculate airflow temperatures.
Optical Anemometers
Physicists, engineers involved in space programs often resort to the use of laser optical devices to measure the speed and direction of movement of air flows. Similar devices work according to the definition of the dependence of the light scattered or reflected by a moving object on its speed. This method does not imply a direct effect of gaseous, solid or liquid substances on the elements of the measuring device.
The scope of application 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 with high accuracy to calculate 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 technology.
Selection tips
What should I look for when choosing a device for measuring the speed and direction of movement of air flows? The list of tasks that are set before the user is of decisive importance. Depending on this, the following technical characteristics of the device are important:
- maximum measuring range;
- error margin;
- the possibility of use in certain temperature conditions;
- safety level for the user when 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 of the device and the method of generating data;
- dimensions of the device;
- the ability to calculate indicators at night (the presence of backlight).
Currently, meteorological instruments with heaters are possible for operation in extremely low temperatures. For mines and mines, specialized anemometers are used, which are able to function smoothly with high dustiness of the surrounding space and in explosive atmospheres. Such functional devices tolerate the effects of high humidity and remain operational at significant temperature differences.
Eventually
As you can see, depending on personal needs, it is possible to choose the most suitable device for fixing air flow indicators. However, there are some difficulties. Since all anemometers are measuring instruments, they are subject to certification and attestation in the relevant state institutions.