wind tunnel fm ii lab manual jan2010

8/10/2019 Wind Tunnel FM II Lab Manual Jan2010

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Experiment 1Wind Tunnel Test of Symmetrical Aerofoil

Title:Aerofoil Test in Wind Tunnel at Different Anglesof Attack

Objective(s):To measure the drag and lift forces applied on a symmetrical aerofoil at different anglesof attack.

Theory:Any object that moves in air (or vice versa) is subjected to stresses.

The normal stress is pressure (P)The tangential stress is shear()

On an aerofoil:Part of the pressure and part of the shear becomes lift forcePart of the pressure and part of the shear becomes drag force

The aerofoil is designed as streamlined body to minimize the drag and maximize the lift.

The drag is characterized as DC

areaheaddynamic

forcedrag

AU

FD

221

The lift is characterized asL

C areaheaddynamic

forcelift

AU

FL

2

2

1

Where A = C x L


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Apparatus:WT04 sub-sonic wind tunnel, Pitot tube, digital micromanometer & tubing 6mm Dia OD,symmnetric aerofoil with angle adjustment model & 3 components balance

Figure 1 The WT04 sub-sonic wind tunnel

Figure 2 Aerofoil with Angle Adjustment model and The 3 Component Balance

Procedure:1. Make sure the fan is switched off.2. Install the aerofoil angle adjustment model into the test section, with bottom shaft insert

into the 3 components balance.3. Adjust the aerofoil models angle of attack to +0

o.

4. Ensure the test section glass frame is fully closed and no lost part is left in the testsection.

5. Adjust the lift and drag strain gauge amplifier reading to zero.6. Place a small screw driver to adjust the zero potentiometer until the indicator showing

zero.7. Boot up the PC, select the Main Menu screen to visualize the balance reading.8. Set the air speed at 30 m/s via PC.9. Wait for 1 minute for fan speed to reach stable condition.10. Obtain the lift and drag reading and fill in the table below.11. Repeat the above steps with different angle of attack, i.e. +3, +6, +9, +12 and +1512. Repeat the above steps with negative angle of attack, i.e. -3, -6, -9, -12 and -15


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Figure 3 Angle of Attack

Angle of Attack, (

o)

Lift Force, FL(N)

Drag Force, FD(N)

CL CD

0

3

6

9

12

15

-3

-6-9

-12

-15

Results:Plot the graphs of variation lift and drag co-efficient with angle of attack for symmetric aerofoil

Discussions and Conclusions:


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Experiment 2Compressible flow in isentropic convergent-divergent nozzle and choking in compressible

fluid flow

Title:Compressible flow in Convergent Nozzle

Objective(s):To demonstrate the effect of compressibility on the flow equations for a convergent flow.

Theory:For air flow higher than 0.3 Mach, the flow is considered compressible. It means that there is anoticeable change in density.

Mach Number, Ma)(

)(

asoundofspeed

Vvelocityflow

kRT

V

WhereTis the local temperature in Kelvin, K

From conservation of energy principle, we get:

o

oin

P

PPV

)(2 1 1.a

o

oout

P

PPV

)(2 2 1.b

Where Pg

VPo

2

2

at state 1 or 2, or (in or out)

From continuity equation

222111 AVAV 2

From 1.a and b, getting:

In theoretical form 1

2

2

12 PP

A

APP oo


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Apparatus:Armfield Compressible Flow Bench, convergent-divergent duct, two inclined tube manometers,mercury manometer.

Figure 1 The Compressible Flow Bench

Procedure:1. Connect one inclined tube manometer to read Po-P1using the 12.7mm range.2. Connect another inclined tube manometer to read Po-P2using the 25.4mm range.3. Adjust the flow to give approximately equal increments of (Po-P1).

4. For each flow rate, read both manometers.5. Repeat the above steps using the 50.8mm range of an inclined tube manometer and with

mercury monometer to measure Po-P2.


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Figure 2 The Convergent-divergent Duct

d1= 24mm; d2= 9.5mm; d3= 24mm

Results:Plot (Po-P2) against (Po-P1) for each set of readings.



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Experiment 3Pelton Water Turbine

Title:Pelton Turbine characteristics

Objective(s):To determine the characteristics of a Pelton turbine at different operating speeds. Conditions

Theory:This type of hydraulic machine is converting the head energy to mechanical energy.

The input,

g

VQg

HQP

i

in

2...

..

2

The output,

TN

rF

TPout

60

2

).(

.

The turbine efficiency,

%100in

o

P

P

Flow rate, volume flowing per time,

t

VQ

Figure 1 Impeller of Pelton Turbine


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Apparatus:

Armfield R15 Pelton (Impulse) Turbine test bench.

Figure 2 Armfield R15 Pelton Turbine

No. Part Name

1 Pump assembly3 Diaphragm valve

4 Delivery pipes

7 Glass vessel

8 Vernier height gauge

9 Sump tank

10 Turbine assembly

11 Spear valve


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Procedure:

1. Check that the sump tank is filled to the correct leveljust below the V-notch.2. If necessary, add water to the upstream side of the V-notch plate until the water level

coincides with the apex of the V- notch.3. Check that the valve at the pump discharge is closed and close the spear valve.4. Release any load on the disc brake by unscrewing the hand wheel and check that the

dial gauge reads zero. Adjust if necessary.5. Switch on the pump and slowly open the valve at the pump discharge to the fully open

position. This valve is to be kept opened throughout the test.Note: Gradually open the spear valve by three full turns of the hand wheel. 1 turn =1.75mm travel of spear.

6. Allow the speed of turbine to stabilize, then take readings of:-a. turbine speed (read on Tachometer, RPM)b. Inlet head (read on Bourdon gauge, m head)c. Flow rate (read on flow meter, m

3/hr)

d. brake force (read on brake spring balance, kg)7. Slowly apply load to the disc brake by turning the hand wheel in a clockwise direction

until the speed of the turbine reduces by approximately 100RPM.8. Keeping the speed steady (by re-adjusting the brake load if necessary), repeat the

readings in step 6.9. Repeat steps 7-8 until turbine stalls (0 RPM)10. On completion if the test:-

a. Close the guide vanesb. Release the load on the brakec. Switch off the pumpd. Close the valve at the pump discharge

Brake arm radius (r) = 0.25mTurbineSpeed,

N(RPM)

InletHead, H

(m)

Flowmeter

Reading(m

3/hr)

VolumeFlowrate,

Q(m

3/s)

BrakeReading

(kg)

BrakeForce,

F(N)

BrakeTorque, T

(Nm)

MechanicalPower, PM

(W)

WaterPower,

PW(W)

TurbineEfficiency,

Results:Plot graph of Torque against turbine speedPlot graph of mechanical power against turbine speedPlot graph of turbine efficiency to turbine speed



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Experiment 4Multi-pump Test Rig

Title:Multi-pump

Objective(s):To investigate the relationship between pressure head, flow rate, power consumed and efficiencyfor a pump.To compare the performance curves of different pumps.

Theory:The pump is a delivery system. It rises up the head of fluid by energy conversion. The inputpower usually is electrical power (P in). The output power is (Po) and is dependent on the pumpefficiency ( )

in

o

P

P

HQgPo ...

Whereis fluid density

gis gravity (=9.81)

Q is flow rate

H is delivery head

TN

TPin60

2

Figure 1 A Centrifugal Pump Figure 2 An Axial Flow Pump

Figure 3 A Gear Pump Figure 4 A Turbine Pump


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Reading Pressure

(m.H2O)Vacuum(m.H2O)

PumpHead

(m.H2O)

Volume(ltr)

Time(s)

FlowRate

(m3/s)

Torque(N.m)

InputPower

(W)

HydraulicPower

(W)

Efficiency(%)

1

2

3

4

5

6

Results:Construct a graph of Pump Pressure Head (vertical axis) against Pump Flow Rate (horizontal

Axis).Construct a graph of Efficiency (vertical axis) against Flow Rate (horizontal axis)Categorize the pumps into i. high flow/low pressure or ii. Low flow/high pressure types



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Experiment 5Francis Water Turbine

Title:Francis Turbine characteristics

Objective(s):To determine the characteristics of a Francis turbine at different operating conditions

Theory:This type of hydraulic machine is converting the head energy to mechanical energy.

The input,

g

VQg

HQP

i

in

2...

..

2

The output,

TN

rF

TPout

60

2

).(

.

The turbine efficiency,

%100in

o

P

P

Flow rate,

t

VQ

Figure 1 Francis Turbine Impeller


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h. brake force (read on brake spring balance, kg)7. Slowly apply load to the disc brake by turning the hand wheel in a clockwise direction

until the speed of the turbine reduces by approximately 100RPM.8. Keeping the speed steady (by re-adjusting the brake load if necessary), repeat the

readings in step 6.9. Repeat steps 7-8 until turbine stalls (0 RPM)10. On completion if the test:-

i. Close the guide vanesj. Release the load on the brakek. Switch off the pumpl. Close the valve at the pump discharge

Brake arm radius (r) = 0.25mTurbineSpeed,

N(RPM)

InletHead, H

(m)

Flowmeter

Reading(m3/hr)

VolumeFlowrate,

Q(m3/s)

BrakeReading

(kg)

BrakeForce,

F(N)

BrakeTorque, T

(Nm)

MechanicalPower, PM

(W)

WaterPower,

PW(W)

TurbineEfficiency,

Results:Plot graph of Torque against turbine speedPlot graph of mechanical power against turbine speedPlot graph of turbine efficiency to turbine speed


wind tunnel fm ii lab manual jan2010

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