FABRICATION OF MULTIPLE NOZZLE SYSTEM AND
The main objective of the present study is to increase the efficiency
of laboratory model wind turbine using multiple nozzle system. The
steps involved in the manufacture of multiple nozzle system and
parameters of research are discussed in this chapter. The method of
conducting an investigation in various stages using nozzle system is
also discussed in this chapter. Experimental setup consisting wind
tunnel and lab model wind turbine are demonstrated. This chapter
also includes the specifications of instruments like Anemometer, Non-
contacting tachometer, Thermocouple, Wattmeter, Voltmeter and
Ammeter. The method used in finding the theoretical and
experimental power coefficients of wind turbine in each module of the
experiment, heat gain by air, etc, are also presented.
3.1 PROBLEM FORMULATION
The investigation is focused on enhancing the power coefficient.
The effect of various nozzle systems on power coefficient of wind
turbine is discussed in the thesis. The internal nozzle set is fabricated
and inserted inside the outer convergent nozzle. The outer convergent
nozzle is fabricated as per recommendations. If the length of the
nozzle is too short, the velocity increases in a short period along with
turbulence. Due to increase in turbulence, back flow may occur. It
reduces the coefficient of discharge. In the other case, when length of
the nozzle is large, inner wall surface increases resistance to the fluid
flow in the form of friction. Coefficient of discharge then, decreases.
Hence, proper care is to be taken in selecting the length of the nozzle.
After fabrication of the multiple nozzle system, importance is given
to vary the angle of attack. The facility of blade swivel is provided to
the wind turbine. The distance of wind turbine from wind tunnel is
found through an experiment.
Theoretically and experimentally the power coefficient is
determined under various stages of the experiment using nozzle
system. Only, by knowing the air velocity at the inlet and outlet of the
wind turbine the theoretical power coefficient can be determined. But,
another experimental setup is made ready to determine experimental
power coefficient using dynamo and inverter.
The theoretical and experimental power coefficient of the turbine is
compared in various stages of investigation at different angles of
attack. The amount of energy absorbed by air while heating is also
determined as a part of the investigation. Both driver and driven
shafts rotate at different speeds. Hence, variation in speed ratio is also
studied in various stages of the experiment.
Computational fluid dynamics is used for the validation of air
velocities from nozzle system. Computationally and experimentally air
velocities from nozzle systems are determined and compared. Variations
in fluid properties like pressure, turbulent kinetic energy, etc, along the
length of nozzle system are also studied using CFD. The drop in air
temperature for the flow through multiple nozzle system is analyzed as
part of the research.
3.2 EXPERIMENTAL SETUP AND ITS DESCRIPTION
Investigation requires a wind tunnel since it produces air at
constant velocity. Complete description of wind tunnel, wind turbine,
etc, are furnished in this section.
3.2.1 Wind Tunnel
Wind tunnel is used to supply air continuously at constant
velocity. It is driven by a blower mounted at one end. It is illustrated
in Figure 3.1. Air is sucked at the other end called inlet duct. The
equipment consists of convergent and divergent portions and, with a
test section at throat. Wind tunnel is used to analyze the lift and drag
forces on airfoil - shaped blades of aero planes, wind turbine, rotary
compressor, etc. The pressure developed on blades at different
positions can be determined using manometers. Wind tunnel is driven
by D.C blower.
Make : Kirloskar Electrical Company Limited
Phase : Three phase induction motor
Speed : 1400 RPM
Voltage : 415 volts
Current : 4.9 A
Power : 2.2 kW
Connection : Delta
Size of the inlet duct:
Length : 0.91 m;
Width : 0.91 m
Size of the test section:
Length : 0.48 m
Height : 0.29 m
Width : 0.30 m
Size of the outlet circular duct:
Diameter : 0.6 m
Total length of wind tunnel : 5.05 m
Various portions of wind tunnel and their details are stated below.
It is aerodynamically contoured section with contraction area
ratio 9:1. The square shaped duct has dimensions of 900 mm X 900
mm. For effective flow of air, the ratio of length to cell size of the
honeycomb is taken as 6, as per the recommendations of the vendor
of wind tunnel. Further, the wire mesh smoothens the air flow.
Provision is made to remove the screen for cleaning of wind tunnel.
Also, higher velocities can be obtained if the screen is removed, but it
is not of laminar. The duct is secured to the test section by
flange/bolts. The provision is made to separate test section and inlet
duct. Inlet duct is shown in Figure 3.2.
It is the center portion of the tunnel cram between the inlet duct
and the diffuser. It has a transparent window, which facilitates
visualization easy. It is illustrated in Figure 3.3. The traversing
mechanism is fixed on its top for the movement of pressure probe.
There is a provision to calibrate strain gauge for determining lift and
drag force. A few holes on all sides test section are made to keep airfoil
model tight in the test section and pressure probes. Test section is
shown in Figure 3.3.
The diffuser starts with 300 mm x 300 mm square section at the test
section end and, enlarges to diameter of 600 mm at the outlet. The length
is 2000 mm with the taper of 5 degrees. It is flanged and bolted to the test
section along with driving unit. For the smooth flow of air, the outlet of
wind tunnel is changed to round shape from square shape. The end of the
diffuser is assembled with an axial flow fan unit driven by a DC motor.
The velocity of air, lift, drag and the pressure distribution on airfoil
can be controlled using control console. Thirstier speed controller is
connected to DC motor. The digital strain indicators are connected to
the strain gauge. Twelve numbers of manometers are provided to
record pressure developed on the surface of component in the test
section. External power supply is given to smoke generator and its
accessories. The control console is energized through 3 phase, 440V,
15A, A.C supply with neutral and earth connections. All safety
precautions to take care of excessive electrical loading are provided.
The arrangement of the control console is illustrated in Figure 3.4.
(Instruction manual of Ind- lab Equipments82)
3.2.2 Laboratory Model Wind Turbine
Out of the vertical axis and horizontal axis wind turbines, a
horizontal axis wind turbine is preferred to generate electricity. In the
present investigation, a three bladed horizontal axis wind turbine is
used. Laboratory model wind turbine is shown in Figure 3.5.
Specification of wind turbine:
Weight of each blade : 500 gm
Length of each blade : 0.24 m
Height of tower : 1.45 m
Diameter of hub : 0.04 m
Type of Airfoil : Flat and symmetrical (NACA0012)
3.2.3 Fabrication Of Outer Convergent Nozzle
As a part of manufacture of multiple nozzle system, the outer
convergent nozzle is fabricated first. It is fabricated with its outlet
diameter equal to the rotor diameter and inlet diameter is made equal to
the outlet diameter of wind tunnel. The side view of outer convergent
nozzle is shown in Figure 3.6.
Specification of outer convergent Nozzle
Material : Galvanized Iron
Inlet diameter : 0.6 m
Outlet diameter : 0.45 m
Length of the nozzle : 0.6 m
18.104.22.168 Theory of Cd for a Nozzle
The flow rate of fluid from a nozzle can be determined using the
Where, Q is the rate of discharge of fluid, Cd is the coefficient of
discharge, A is the area of cross section, β is the diameter ratio
(D1/D2) and hL is the loss of head. Instead of the coefficient of
discharge, it is more convenient to use the velocity coefficient Cv. It is
represented by the equation 3.2.
From equations 3.1 and 3.2 the coefficient of discharge becomes
Where, is the pressure drop and is density of flowing fluid. Cd
can be calculated based on applicable standards like ISO 5167 or
similar ASME standards. It is represented in the equation 3.4 and is
suited for small size nozzles. (ISI 1932 Code and Similar ASME
But, if the diameter of the nozzle is large i.e, the inlet diameter lies
in the range of 50 mm to 630 mm the equation 3.5 is suitable. For
in the range of 104 to 107 and β in the range of 0.2 and 0.8, the
relation shown in equation 3.5 is best suited.
22.214.171.124 Reason for Choosing L=D1 for Outer Nozzle
According to law of continuity, air velocity is independent of the
length of the nozzle. According to Karasawa83 et al. (1992) whenever
the ratio of the length to the inlet diameter of the rounded nozzle is
50, the coefficient of discharge becomes 0.67. But, when the length of
the nozzle is made equal to the inlet diameter, the coefficient of
discharge is found to be 0.98. The rise in the coefficient of discharge is
particularly significant in the nozzle flow. The outer nozzle in the
present study is circular in shape. Hence, the length of the outer
nozzle in the present study chosen is equal to its inlet diameter.
3.2.4 Set of Internal Convergent Nozzle
In the next stage of fabrication, a set of internal convergent nozzles
is made. The fabrication of a set of internal convergent nozzles is
shown in Figure 3.7. Two circular flanges are made using galvanized
iron. Six circular holes are drilled in both circular flanges, to fit
internal nozzles. The opposite ends of holes of round flanges are joined
using circular, conical pipes. The group is named ‘Set of Internal
Convergent Nozzles’. Arc welding is used in the fabrication.
Specification of Internal Convergent Nozzle:
Material : Galvanized Iron
Number of nozzles : 6
Inlet diameter of each nozzle : 0.15 m
Outlet diameter of each nozzle : 0.10 m
Length of each nozzle : 0.60 m
126.96.36.199 Reason for Using Six Internal Nozzles
Ghassemieh84 et al. (2006) studied the effect of the coefficient of
discharge of fluid flow on geometry of nozzles. The effect of cone angle
in the range of 100 to 1200 is studied in the article. In the study,
Ghassemeih used the following relations.
Equation 3.6 and 3.7 are used to determine the coefficient of
discharge and Coefficient of velocity. Equation 3.8 is used to
determine the coefficient of contraction. Ghassemieh conducted
experiments by varying the pressure with the possible fluctuation of
temperature + 20C. The author concluded that nozzles with cone angle
less than 450 have a coefficient of discharge 0.89 to 0.95 and is
independent of cone angle. For, the cone angle in the range of 350 to
450, the Cd is substantially independent of supply pressure. But in
the case of low cone angles the coefficient of discharge increases
slightly as the supply pressure increases. In the analysis, m is the
mass flow rate of fluid, d1 is the inlet diameter of nozzle, P is the
supply pressure and V2 is the velocity of fluid from nozzle system.
Gassemieh also conducted experiments to identify the effect of the
coefficient of discharge on various ratios of inlet to outlet diameters. In
the study, diameter ratios are varied namely, 1.31, 1.33, 2.0, etc, up to
4.0. The author concluded that the coefficient of discharge increases
slightly as diameter ratio increases. Also, the author of the article states
that multi-hole nozzle facilitates the increase in the coefficient of
discharge through an experiment on 3, 4 and 5 number of multi-hole
The nozzle cone angle is determined from the equation 3.9.
For outer nozzle system with inlet diameter 0.6 m, outlet diameter
0.45 m and length 0.6 m the cone angle becomes 14.030. While
selecting the internal nozzle set, the diameter ratio taken is 1.5, which
is slightly more than 1.33. The geometry of single outer nozzle
provides the facility to have six number of nozzles with inlet diameter
0.15 m and outlet diameter 0.10 m. The cone angle in case of internal
nozzle thus becomes 4.760. According to Gassemieh, The decrease in
the cone angle increases the coefficient of discharge. Hence, the
multiple nozzle system is fabricated with six internal nozzles with the
cone angle 4.760.
3.2.5 Multiple Nozzle System
The assembly of outer nozzle and internal nozzle set is titled
“Multiple Nozzle System”. Perspective views of multiple nozzle system
are shown in Figure 3.8 and 3.9. Care is taken to avoid leakage loss
through joints. At the end, length of internal nozzles is projected
slightly outwards to keep air in the proper direction. The addition of
outer convergent nozzle to internal convergent nozzle set is made with
the help of bolts and nuts.
3.2.6 Electric Air Heaters
Countries like India and China are exceptionally warm, especially
in summer and temperatures range from 400C to 450C in different
zones. Electric air heaters are used to heat flowing air through
multiple nozzle system. These electric heaters heat air by 100C more
than the atmospheric conditions. But, in the open-wind farms electric
heaters are not required. Air is heated up using solar radiation. Air
heaters are available with different configurations and designs. Finned
tubular type air heaters are used in the investigation. These heaters
are shown in Figure 3.10. These are made of aluminium tube with
corrugated aluminium fins. Fins are wrapped around the tube and
Specification of Air Heaters:
Capacity : 750 W
Length : 0.43 m
Outer diameter with fins : 0.076 m
3.3 INSTRUMENTS USED IN THE INVESTIGATION
Rotating disc type anemometer is used to determine air velocity. A
Non-contacting type tachometer is used to measure speed of driver
and driven pulleys during power measurement. The temperature of air
is measured using K-type thermocouple. The instruments used in the
study are calibrated and, the error analysis of instruments is
furnished in Appendix-B.
3.3.1 Rotating Disc Type Anemometer
Rotating disc type anemometer is placed in the direction normal to
the direction of air flow. Anemometer is shown in Figure 3.11. The
circular disc of anemometer rotates when it is placed in the direction
of air flow. The number of rotations made by the disc is calibrated into
air velocity in m/s. Air velocity can also be measured in knots or
Kilometers per hour using such anemometer. It works safely even in
the range of 25-30 m/s. A digital monitor is provided to indicate wind
speed. Anemometer is calibrated in the range of 6 m/s to 29.5 m/s.
3.3.2 Non - Contact Tachometer
A Non-contacting tachometer is shown in Figure 3.12. It is a device
used to measure speed of the rotating shaft of turbine in revolutions
per minute. It does not have any physical contact with rotating shaft.
Such tachometer is best suited in wind farms since turbine is
mounted at great heights.
A light beam from source is focused on to a target marked on the
rotating shaft. A photo receiver receives the re-reflected light beam
with the help of photo probe. Both light source and photo receiver are
housed at front side of tachometer. The time interval between the two
consecutive sensations is calibrated into R.P.M. A digital screen is
provided to indicate speed of the rotating shaft. The instrument is
calibrated in the range of 500 R.P.M to 14000 R.P.M.
3.3.3 Temperature Measurement
In the study, K – Thermocouple is used to measure temperature of
the air. A thermocouple works on See beck effect. When two dissimilar
metals are at two different temperatures and if joined together, at
junction net e.m.f is induced. (Sachdeva86, 2005)
K-type thermocouple has been made of two different materials
Nickel and Chromium. It works in the range of -2000C to 13500C. Its
sensitivity is 41µV/°C. Totally, three different thermocouples are used.
One is placed at the inlet of multiple nozzle system and, another is
placed at the outlet of multiple nozzle system. To measure
temperature of air at the inlet of turbine one more thermocouple is
used. Method of temperature sensing is shown in Figure 3.13.
Thermocouples are calibrated in the range of 00 -100 0C.
3.3.4 Wattmeter, Voltmeter and Ammeter
Wattmeter is used to determine the amount of power given to heat
air. Voltmeter and ammeter are used to determine the power produced
by wind turbine. All instruments are calibrated before use. A
voltmeter of capacity 300 V, ammeter of 1A-2A capacity and wattmeter
of capacity 1A-2A and 300 V are used in the study. Another wattmeter
of capacity 3000 W is used in the analysis of energy gain by air. The
experimental set up with these instruments is shown in Figure 3.14.
3.4 EXPERIMENTAL SETUP FOR POWER MEASUREMENT
The rotor wind turbine is coupled to power producing device
dynamo. The rotational mechanical energy of the rotor is converted
into electric energy. The ratio of power produced to the power available
in the wind is the experimental power coefficient. Details of setup
needed for determining experimental power coefficient are furnished
The dynamo uses rotating coils of wire and magnetic field to
convert mechanical rotation into a pulsing direct electric current
through Faraday’s law of induction. A dynamo machine consists a
stationary structure, called stator. It facilitates the rotation of
armature against magnetic field. The motion of armature within the
magnetic field causes the field to push on the electrons, creating an
electric current in it. In small machines, the constant magnetic field is
provided using one or two permanent magnets; larger machines have
the constant magnetic field provided by one or more electromagnets.
When an armature rotates in a magnetic field, the e.m.f is induced in
it generating direct current. The commutator is essentially a
rotary switch. It consists of a number of contacts mounted on the
machine's shaft, combined with graphite-block stationary contacts,
called "brushes". The commutator reverses the connection of the
windings to the external circuit. When the potential reverses, instead
of alternating current, a pulsing direct current is produced. (Wikipedia
of Dynamo) A dynamo of capacity 12 Volts has been used in the
investigation. The column element of wind turbine is welded with two
V type thin rods. It provides support to Dynamo. The produced D.C
power is converted into A.C power using inverter.
3.4.2 Pulley and Belt Arrangement
The rotational mechanical energy of rotor of the turbine is
transmitted to dynamo using belt and pulley arrangement. The
arrangement of belt and pulley is shown in Figure 3.15. Dynamo
produces large power when its shaft rotates at high speed. The shaft
of dynamo can be rotated at high speed by increasing the speed ratio.
Pulleys and belts have two uses; to increase or decrease speed of
driven pulleys. They are used to transmit power from one shaft to
another shaft. The dynamo may not generate power if the driver and
driven pulleys are made of the same diameter. The speed of dynamo
pulley is increased by using pulleys of different sizes. Driver pulley is
made of larger diameter than driven pulley to increase speed ratio. In
the investigation, synthetic nylon pulleys have been used. They are
machined using lathe machine to correct diameter. Nylon material
offers low resistance when compared to cast iron. Dynamo shaft
rotates at almost double the speed of rotor shaft. Hence, the speed
ratio becomes 2.0. The belt used in the transmission is of V-type.
Between grooves of two pulleys the belt slides.
3.4.3 Dynamo Testing
The working of dynamo is tested with 6 V and 12 V D.C bulbs. The
bulbs glow bright as shown in Figure 3.16. Wind turbine rotates at
more speed when it is not connected with belt and pulley. Figure 3.17
shows the operation of wind turbine without dynamo. It runs at high
speed in the absence of dynamo. The arrangement of turbine with
dynamo using belt and pulley arrangement is shown in Figure 3.18.
Figure 3.1 Wind Tunnel
Figure 3.2 Inlet Duct of Wind Tunnel
Figure 3.3 Test Section
Figure 3.4 Control Console
Figure 3.5 Laboratory Model Horizontal Axis Wind Turbine
Figure 3.6 Side View of Outer Convergent Nozzle
Figure 3.7 Set of Internal Convergent Nozzles
Figure 3.8 Rear Front View of Multiple Nozzle System
Figure 3.9 Perspective View of Multiple Nozzle System
Figure 3.10 Corrugated Aluminium Fin Electric Air Heaters
Figure 3.11 Rotating Disc Type Anemometer
Figure 3.12 Non – contacting Tachometer
Figure 3.13 Temperature Detection Using Thermocouple
Figure 3.14 Use of Wattmeter, Voltmeter and Ammeter
Figure 3.15 Belt and Pulley Arrangement
Figure 3.16 Test of Dynamo
Figure 3.17 Wind Turbine without Pulley Arrangement
Figure 3.18 Wind Turbine with Pulley Arrangement
3.5 RESEARCH METHODOLOGY
In this section, the method of carrying research has been
3.5.1 Practical Difficulties of Multiple Nozzle System
Figure 3.19 Thematic Representation of Wind turbine with Multiple Nozzle System
The addition of multiple nozzle system to rotor of wind turbine is
shown in Figure 3.19. The rotor of turbine and tower may suffer due
to excessive stress produced by multiple nozzle system. Yaw
mechanism helps to keep the rotor of wind turbine in the direction of
the wind. Multiple nozzle system if, is mounted on rotor, also follow
the path of the rotor. This causes additional stresses. These practical
difficulties can be overcome using innovative design of “High Wind
Power Generator” as shown in Appendix.
3.5.2 Experiment Modules of Investigation
The research is aimed at high power coefficient of the wind turbine.
Nozzle system is assembled to wind tunnel instead of wind turbine to
overcome the practical difficulties. It releases tension on wind turbine.
Enhancement in power coefficient of wind turbine is estimated in the
following modules of the experiment. Totally experiment is conducted
in four stages namely,
Module Mo : Study of laboratory model wind turbine without any
nozzle system. It is shown in Figure 3.20.
Module M1 : Study using outer Convergent nozzle. It is shown in
Module M2 : Study with multiple nozzle system without electric
heaters. It is shown in Figure 3.22.
Module M3 : Study with multiple nozzle system with electric
heaters. It is shown in Figure 3.23.
Figure 3.20 Module Mo (Without Nozzle System)
Figure 3.21 Module M1 (With Outer Convergent Nozzle)
Figure 3.22 Module M2
(Multiple Nozzle System without Electric Heaters)
Figure 3.23 Indicating Position of Heaters in Module M3
3.5.3 Heat Gain by Air
Electric power is supplied to heaters to heat air. Hundred percent
of heat may not be transferred to air. A part of energy has been wasted
in the form of heat losses. The power given to electric heaters (Qi) is
measured using wattmeter. Heat is supplied to air which is flowing
through multiple nozzle system. Heat absorbed by air is estimated
using the following relation.
is the mass flow rate of air at the inlet of multiple nozzle
system, is total inlet area of multiple nozzle system, Cp is the
specific heat at constant pressure of air, and dT is the rise in
temperature due to heating. The total heat absorbed by air is
determined in the presence of one, two and all three heaters.
3.5.4 Blade Orientation
Figure 3.24 Blade Swivel in the Quarter Segment of a Circle
The angle at which the wind faces the chord of an airfoil is the
angle of attack. Wind tunnel produces wind in the fixed direction. But,
a facility has been provided to change the location of blade of wind
turbine by varying the orientation of airfoil. The blades can be
swiveled at 00, 300, 450, 600 and 900 in quarter segment of a circle. All
three blades of wind turbine are swiveled to the same inclination
during the experiment. The blade orientation in a quarter segments of
a circle is illustrated in Figure 3.24.
3.6 EXPERIMENTAL PROCEDURE
In various modules of experiments stated above, the power
coefficient of wind turbine is determined at various blade orientations.
The distance of the wind turbine is determined by changing its
position at different distances from wind tunnel. Power coefficient is
determined theoretically and experimentally. In every module of
investigation the chord of all blades, is oriented at angles of 00, 300,
450, 600 and 900. The air at high speed from wind tunnel is focused on
to rotor of the turbine. In these modules, the efficiency of the lab
model wind turbine is determined with and without using the nozzle
system at different positions of blade. The horizontal shaft of the wind
turbine rotates freely in bearings. Initially, the rotor is allowed to
rotate without connecting dynamo. Power coefficient is determined
theoretically by knowing wind speed at the inlet and outlet of wind
turbine. Later, experimental power coefficient is determined when the
shaft of the turbine is coupled with shaft of dynamo, using belt and
3.6.1 Determining Theoretical Power Coefficient
Rotating disc anemometer is placed in a direction normal to the
flow of air to determine air velocity at the inlet and outlet of the wind
turbine. The equation 3.12 is used to determine the power in the
wind. For a wind turbine rotor with swept area ‘A’ and, air density ‘ρ’
the power available in wind becomes
The theoretical power of wind turbine can be determined using the
equation 3.13. Thus, theoretical power coefficient, which is the ratio of
theoretical power to power in the wind, is determined in various
In module M1, under the first change in the experiment, the
fabricated outer/single nozzle is assembled to wind tunnel. The high
velocity of air rotates the rotor of turbine at high speeds. Theoretical
power coefficient is determined at different positions of blade.
As part of the next evolution in conducting the investigation i.e,
under module M2, multiple nozzles system is joined to wind tunnel.
The multiple nozzle system produces air at a high speed and kinetic
energy due to increased coefficient of discharge. The theoretical power
coefficient is then, determined.
To study the effect of conversion of heat energy into kinetic energy
electric heaters are used. These heaters are placed at the inlet of
multiple nozzle system. The air is heated almost 100C more than
ambient conditions. Three heaters each of 750 W is used to heat air.
Energy gain from heaters is also determined using the equation 3.1.
The hot air is allowed to pass through multiple nozzle system. The
change in revision is named as module M3, and the theoretical power
coefficient is determined.
No rotating parts are used in raising kinetic energy in all modules.
In all the modules of experiments, wind turbine is placed at same
distance from wind tunnel.
3.6.2 Determining Experimental Power Coefficient
The dynamo is connected to inverter to convert produced D.C
current into A.C current. Then experimental power coefficient of wind
turbine becomes the ratio of power produced to the power available in
the wind. It is determined in all stages of the experiment as discussed
above. All instruments are calibrated in recording the data. The
equivalence of kW and kVA is shown below. (Mukharjee87, 2001)
3.6.3 Comparing Air Velocities from Nozzle System
The blower fan produces air at 8.5 m/s of velocity. Air at this
velocity enters into nozzle system (V1). At the outlet of nozzle system,
velocity of air (V2) is recorded using rotating disc type anemometer.
Anemometer is placed at three defined positions, horizontally and
then vertically. The average of all these velocities is considered to
determine the experimental velocity of air from nozzle system. The
rise in velocity of air at the outlet of multiple nozzle system is verified
computationally, using computational fluid dynamics (CFD). The
temperature of air at the inlet of nozzle system (T1), outlet of the nozzle
system (T2), and at the inlet of wind turbine (Ti) is recorded using
3.6.4 Speed Ratio
The ratio of speed of driver pulley to driven pulley is speed ratio.
Driver pulley is made twice the diameter of the driven pulley.
Theoretically, driven pulley should rotate twice the speed of driver
pulley. But, practically it would not happen. Belt between grooves of
pulley may offer some resistance. Hence, actual speed ratio may be
reduced. The speeds of both the pulley of rotor (Nrp) and pulley of
dynamo (Ndp) are measured using non-contacting tachometer.
3.7 SUMMARY AND CONCLUSIONS
The problem is formulated based on determining experimental and
theoretical power coefficients of the wind turbine. Under research
methodology, various modules of experiment are discussed. Various
instruments like rotating disc type anemometer, non-contacting
tachometer etc, are demonstrated. The research methodology in
carrying out the investigation is also discussed. After the conduct of
the experiment, the results are discussed in chapter 4.