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Anemometry
We are Group5 Weather station
The team Members
Saran Jackson
Robert Howard
Robert Garvey
Gene Fitzgerald
Introduction
• Wind measurements are usually related to the horizontal
component.
• It is a vector, requiring both a magnitude (speed) and direction
(the direction from which the wind is blowing)
• Wind velocity is turbulent; it is often reported as a mean and
variation about the mean (gustiness)
Construction
• Ideal (perfect) wind instrument
– Respond to slight breezes
– Rugged enough to withstand hurricane-force winds
– Respond rapidly to turbulence
– Have linear output
– Exhibit simple dynamic performance characteristics
Conditions in Ireland
Wind over Ireland
The wind at a particular location can be influenced by a number of factors such as
obstruction by buildings or trees, the nature of the terrain and deflection by nearby
mountains or hills. For example, the rather low frequency of southerly winds at Dublin
Airport is due to the sheltering effect of the mountains to the south. The prevailing wind
direction is between south and west. Average annual wind speeds range from 11 Km/h in
parts of south Leinster to over 29 Km/h in the extreme north. On average there are
less than 2 days with gales each year at some inland places like Kilkenny but more than
50 a year at northern coastal locations such as Malin Head. Indeed the north and west
coasts of Ireland are two of the windiest areas in Europe and have considerable potential
for the generation of wind energy.
Notable Storms
"The night of the Big Wind" on the 6th-7th January 1839 It was during this storm that a
gust of 200 Km/h was recorded at Kilkeel in County Down, making it the highest sea-level
wind speed recorded in Ireland.
Slope of the line
m
Calculations
y2  y1 0.132  0.010


x2  x1
30.7  2.6
0.00434
V
Km / h
Offset = 0
Max non linearity (furthest point from line)
y = mx+c
Y = Vout,
m = 0.00434
x = 0.093 [V]
c=0
0.93 = (.00434) x (18)
Measured value
Difference
Max non linearity
Sensitivity
0.078
0.093
0.015
0.015
0.00434
V
Km / h
Block Diagram
Wind
Speed
0 to 30.7
[km/h]
DC
Generator
K1 = 0.0434 V/kmh
0 to 132
[mV]
K2 = 38.06 dB
AMP
0 to 9.6
[V]
PLC
(12 BIT)
K3 = 197 counts/V
Results
Our next step was to calibrate our anemometer. We used a mobile hand held weather
station that was provided by the college. We set up a hair dryer which was plugged into a
variable resistor and turned the resister in increments of 5 volts , we checked the speed
using the hand held weather station and the moved the fan across onto the anemometer
this gave us an output voltage. We used these results to tabulate
V in (V)
Speed (Km/h)
V out (mV)
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
2.6
4
6.5
8.5
10.5
12.5
13.5
15
16.5
18
20.3
21
22
23
25
26
26.4
27.9
29
30.7
10
18.5
28
41
50
63
66
75
75
93
99
105
105
107
120
125
127
127
130
132
Wind Speed Versus Output Voltage Graph
180
Output Voltage (mV)
160
140
120
100
80
60
40
20
0
0
5
10
15
20
Wind Speed (Km/h)
25
30
35
Generating a useful voltage.
The DC motor running as a generator has given us the linear output which is needed to give us an
accurate picture of wind speed versus output voltage. While the output is linear, the voltage been
supplied is to small for the PLC to read so the mill volt output needs a non inverting operational
amplifier to increase the Voltage from 0 – 132mV range to a 0 – 9.6 volt range, or as close as can be
built.
Non inverting Op Amp Calculations
The Range = 0 mV and 132 mV
10  0.12  83.3 Is the approximate Gain
Gain =
Av  1 
R2
R1
 80  1 
R2
R2
 79 
R1
R1
R1  79  R2 ,
R1  10 R2  790