By:

Name: Pooja Dubey

Course: EEE

Roll No:120104026

Measurement of speed of wind Anemometer

Hot wire anemometer

Wind mill anemometer

Laser doppler anemometer

Ultrasonic anemometer

Time of flight

Measurement of Wind Speed

Wind speed is the magnitude of the wind velocity vector.

The wind velocity is a vector, which includes both speed and direction.

Wind Speed is measured with a device called a wind anemometer.

The term “anemometer” strictly refers to a general fluid speed measuring device.

For example “hot wire anemometers” are used to measure turbulence levels in fluid flows..

An anemometer is a device to measure the wind

speed and direction. Wind measurement is

significant for detecting wind in industrial field.

Besides, wind measurement can be applied in

environment monitoring and controlling systems,

air conditioning systems and so on .

Hot wire anemometers use a very fine wire (mm) electrically

heated up to some temperature above the ambient.

Air flowing past the wire has a cooling effect on the wire.

Hot Wire Anemometer allows accurate monitoring for very low air

velocity measurements.

1) Hot Wire / Film Anemometer

The other form of mechanical velocity

anemometer is windmill type or propeller

anemometer.

An aerovane combines a propeller and a tail

on the same axis to obtain accurate and

precise wind speed and direction

measurements from the same instrument.

where the direction of the air motion is always

the same, as in the ventilating shafts of mines

and buildings,air meters are employed, which

give most satisfactory results.

Some pictures showing

usage of

WINDMILL

ANEMOMETER

The Laser Doppler Anemometer is a very high-

tech anemometer, so it is usually more accurate.

Laser Doppler anemometers use a beam of light from a

laser that is divided into two beams, with one propagated

out of the anemometer. The air particles caught in the

beam are reflected back into the anemometer

where it’s measured.

When the particles are in great motion, they produce a

Doppler shift for measuring wind speed in the laser light,

which is used to calculate the speed of the particles, and

therefore the air around the anemometer.

Some pictures showing

usage of

LASER

DOPPLER

ANEMOMETER

The anemometers described above use the wind kinetic energy to

support the measurement. They do not need any extra source to

provide parameters.

There are some other types of anemometer which introduce extra

sources as parameters to wind speed, for example the speed of

sound.

One of such anemometer is ultrasonic anemometer.

It uses ultrasonic propagation time as the

parameter to wind speed. The ultrasonic is

generated from an ultrasonic source and

received by an ultrasonic receiver.

The propagation time is really short. By

measuring the propagation time, the wind speed

can be determine.

. In order to do this, there are some objectives

which need to achieve

1. Construct the test bed which consists of

ultrasonic transmitter and receiver.

2. Measure the different wind velocity.

.

FIG 1. TEST BED

Dash rectangle box is the test bed where the

measurement is done, the dotted line is the propagation

distance over which time is measured.

The generator provides power to the ultrasonic source

which transmits ultrasound

Digital oscilloscope is used to measure the time

difference between transmit and receive which is the

propagation time. Filter is used to eliminate the

frequency which is not equal to the transmitted signal.

The reason to choose the ultrasound instead of audio

sound is that ultrasonic has much higher frequency than

audio sound.

In the last slide, there is a setup showing the

wave speed in two cases.

The role of the transmitter and receiver can be

changed.

In the first case, path 1 to 2,1 is the left point and

2 is the right point, the wave travels at a speed of

c minus V.

Therefore time of flight is distance traveled

divided by the velocity, L by c minus V for the

In the second case, path 2 to 1,1 is the left point

and 2 is the right point, the wave travels at a

speed of c plus V.

Therefore time of flight is distance traveled

divided by the velocity, L by c plus V for the

backward path.

Ultrasonic anemometers require less

maintenance, respond better to rapid wind gusts.

Accuracy is high.

New high-tech ultrasonic instruments used to

measure wind speed and direction and are

reliable .

Well suited for turbulence measurements.

This study produced a basic one-dimensional

ultrasonic anemometer using the theory of

Time of flight (TOF).The transducers used in

this experiment are cheap and simple

functional. Sonic anemometers can take

measurements with very fine temporal

resolution, 20 Hz or better, which makes

them well suited even

for turbulence measurements

D. Han, S. Kim and S. Park, “One-dimensional

ultrasonic anemometer using the directivity angle of

an ultrasonic sensor, volume 39 , October 2008.

D. Han and S. Park, “A Study on Characteristics of

Continuous Wave Ultrasonic Anemometer,”

Sensors Applications Symposium ,February 2011.

M.P. del Valle, J.A.U. Castelan, Y. Matsumoto and

R.C. Mateos, “Low Cost Ultrasonic Anemometer,”

Electrical and Electronics Engineering, 2007.

http://www.slideshare.net/snesajid/anemometer-

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