Anemometer is the device that we use to measure the speed of the air. An Anemometer can measure both contained flow (airflow through ducts or vents) and free flow of air (atmospheric air). Anemometers can be of different types such as hot wire Anemometers, venturi meters, cup Anemometer, etc. While hot wire Anemometers work best for low-velocity clean air, venturi meters work best for liquid flow applications.
Due to this reason, it is very important to choose the right airflow meter for the right purpose. This post will tell you about different types of Anemometer and their functions so that you choose the right one and get the most of it.
Types of Anemometers:
On the basis of frequency response rate, electrical noise and zero-flow reading stability, Anemometers are mainly divided into two sections; constant temperature Anemometers and constant power Anemometers.
Constant temperature Anemometers: They are well-known because they provide a high-frequency response, low electrical noise, and better zero-flow reading stability. They also save the sensor from sudden burnouts if the airflow falls abruptly. You can use constant temperature Anemometers for both gas and liquid flow.
Constant power Anemometers: These Anemometers don’t come with a feedback system. Here, the temperature and the airflow are proportional to each other. Constant power Anemometers are not as popular as constant temperature Anemometers as they don’t provide a steady and credible zero-flow reading. They also have a slower temperature and velocity response than constant temperature Anemometers.
Choosing the right Anemometer:
Vane Anemometer: The Anemometers that generate rotating mechanical velocity, fall under the propeller or vane class. The axis of rotation for these Anemometers are always paraller with the airflow direction and this is the reason they are generally horizontal. Vane Anemometers work best where the direction of the wind is more or less constant (ex: ventilating shafts or ducts). They also come with added features such as dew point, temperature, humidity computing systems.
Thermal Anemometer: These types of Anemometers consist of microwires with a slightly high temperature as per the ambient. So, when air flows through, it creates a cooling effect. Thus, it creates a relationship between the airflow speed and the resistence of the wire. Thermal Anemometers can be divided into categories such as;
- Constant Voltage Anemometer (CVA)
- Constant Current Anemometer (CCA)
- Constant Temperature Anemometer (CTA)
Thermal Anemometers should be used with great care as they are very much sophisticated. They offer a high-frequency response and excellent spatial resolution than other types of measurement techniques.
Cup Anemometer: The construction of cup Anemometers is very simple and they contain a three-cups configuration where three cups are strategically placed to measure the wind flow from any direction. Cup Anemometers have gone through a lot of modifications, which eventually enhanced its accuracy and effectivity. Cup Anemometers with three-cups configuration are the industry standard for wind resource evaluation.
Thermal Anemometer with velocity or temperature profiling: These types of Anemometers use miniature sensors and compute both wind temperature and wind velocity. They are mainly used in wind tunnels to analyze heat sink and circuit boards.