Anemometers

GAOTek offers a wide range of high-quality, affordable and accurate anemometers. An anemometer is a device used for measuring the speed and pressure of wind.

Technologies

There are two common types of anemometers - velocity anemometers and pressure anemometers. Furthermore, there are six types of velocity anemometers and three types of pressure anemometers.

Types of velocity anemometers - cup anemometers, vane anemometers, hot-wire anemometers, laser doppler anemometers, ultrasonic anemometers and ping-pong ball anemometers.

A cup anemometer has three or four cups attached to its horizontal arm, and the arm is attached to a vertical rod. As the wind blows, it rotates the cup, which in turn makes the rod spin. The stronger the wind blows, the faster the rod spins. The anemometer counts the number of rotations. This reading is used to calculate wind speed.

A vane anemometer is made up of a propeller and a tail on an axis parallel to the direction of the wind. This is important to obtain an accurate and precise wind speed direction measurement. The speed of the fan is measured by a rev counter, and converted to wind speed by an electronic chip. Volumetric flow rate can be calculated if the cross-section dimensions are known. For situations where the direction of air motion is consistent, as in ventilating shafts of mines and buildings, wind vanes known as air meters are used.

A hot-wire anemometer is a very fine wire heated electrically to a certain temperature above its ambient temperature. Air flows past the wire and cools the electrically heated wire. Since electrical resistance of metals depends on the temperature of the metal, a relationship can be established between resistance of the wire and flow speed. Hot-wire devices can be classified as - Constant Current Anemometers (CCA), Constant Voltage Anemometers (CVA) and Constant Temperature Anemometers (CTA). The voltage output from these anemometers is the result of a circuit within the device that maintains a specific variable constant, in accordance with Ohm’s law. Pulse -Width Modulation (PWM) anemometers are used in cases where velocity can be determined by the time length of a repeating pulse of current. This repeating pulse brings the wire up to specified resistance and stops when a threshold is reached. At this time a pulse is sent again. A hot-wire anemometer is delicate, and has an extremely high frequency response. It has fine spatial resolution as compared to other measurement methods. It is universally employed for detailed study of flow in case of rapid velocity fluctuations. The industrial version of fine-wire anemometer is thermal flow meter, which operates on the same principle.

Laser Doppler anemometer uses a beam of light from a laser and divides it into two beams. One of these beams is propagated out of the anemometer. The particulates flowing along with air molecules near the exit, reflect the light back into a detector, where it is measured relative to the original laser beam. When the particles are in great motion, they produce a Doppler shift. Wind speed thus measured in laser light, is used to calculate the speed of particles, and hence the air around the anemometer.

An ultrasonic anemometer measures wind speed based on the time of flight of sonic pulses between pairs of transducers. The results are then combined to yield a measurement of velocity in a 1, 2 or 3-dimensional flow. Spatial resolution is given by the path length between transducers. International standard, ‘ISO 16622 Meteorology— Ultrasonic anemometers/thermometers— Acceptance test methods for mean wind measurements is generally followed for this process.

A ping-pong ball anemometer has a ping-pong ball attached to a string. When the wind blows horizontally, it moves the ball. The angle between the string-ball apparatus and the vertical is measured to calculate the estimated wind speed.

Three types of pressure anemometers are - plate anemometer, tube anemometer, and pitot tube anemometer.

A plate anemometer consists of a square or circular flat plate suspended in the air for the wind to deflect it. The plate is kept normal to the wind by a wind vane. The pressure of the wind on the face of the plate is balanced by a spring. The compression of the spring determines the actual force exerted by the wind on the plate. This is recorded using a suitable gauge. This instrument does not respond to light winds, and it is inaccurate for high wind readings.

A tube anemometer is made up of a glass tube containing a pressure gauge. One part of the tube is bent horizontally to face the wind, and the vertical end is kept parallel to the wind flow. Wind blowing into the mouth of the tube causes an increase in pressure on one side of the manometer. The wind over the open end of a vertical tube causes little change in pressure on the other side of the manometer. The exposed part can be mounted on a high pole and requires no oiling or attention for years.

Pitot static anemometers consist of a tube with two ports, pitot and static. The pitot port measures dynamic pressure at the open mouth of the tube with the pointed head facing the wind, and the static port measures static pressure along the sides. The measurement devices can be manometers, pressure transducers, or analog chart recorders.

Features

GAOTek anemometers offer a great set of features:

Measurement: Celsius and Fahrenheit

Temperature: 0-50C

Power Supply: 110 -120V with a built in power supply

Response time: Fast and take just up to two seconds

Multi-functions for measurement: m/s, km/h, ft/min, knots, mile/h, CMM (732/733), CFM (732/733)

Our anemometers come with a high-quality analog display and an inbuilt rest transmitter. Intelligent signal processing ensures maximum measurement reliability and stability while using the device.

Applications

Cup anemometer is the industry standard for wind resource assessment studies and practice.

Ultrasonic anemometer is used at weather stations, ship navigation sites, wind turbine sites, and in aviation and weather buoys to measure gas emissions and ecosystem fluxes.

Ping-pong anemometer is used in middle-school level experiments.

Plate anemometer is used to trigger high wind alarms on bridges.

Pitot static anemometer is used for measuring airspeed of air crafts.

Showing all 24 results

Products