Francis Turbine Experiment

8/10/2019 Francis Turbine Experiment

1/7

.g

.

N

.(

.T

r

1

Abstract.

A turbine extracts energy from fluid or air flow to generate power and converts it into

useful work.The blade attached on the shaft will react to the flow so that it will move and

cause rotational energy to the rotor.Francis turbine may be designed for a wide ranged

heads and flows.Francis turbines widely used in the world because their high efficiency.The ouput power varies from just few kilowatts to one gigawatt covering a head range

from 20 meter to 700 meter.The francis turbine can be used for pumped storage where it

will acting as pump during low power demand and then reversed and used to generate

power during peak demand.

Theory:

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

The input,

Pi

n

Q.H

2

.Q. i

2g

The output,

Pout

F )

2T

60

The turbine efficiency,

Po

Pin00%

Flow rate,

QV

t


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Figure 1 Francis Turbine Impel

Apparatus:

Armfield R16 Francis (Reaction) Turbine

Figure 2 Armfield R16 Francis Turbine


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Procedure:

1. Check that the sump tank is filled.

2. Check that the valve at the pump discharge is closed and set the guide vaneson the turbine to the closed position.

3. Release any load on the disc brake by unscrewing the handwheel and check that

the dial gauge reads zero. Adjust if necessary.

4. Switch on the pump and slowly open the valve at the pump discharge to thefully open position. This valve is to be kept opened throughout the test.

5. Gradually open the guide vanes to approximately mid-position, typically15o on the indicator, then clamp in position.

6. Allow the speed of turbine to stabilize, then take readings of:-

e. turbine speed (read on Tachometer, RPM)

f. Inlet head (read on Bourdon gauge, m head)

g. Flow rate (read on flow meter, m3/hr

h. brake force (read on brake spring balance, kg)

7. Slowly apply load to the disc brake by turning the hand wheel in aclockwise direction until the speed of the turbine reduces byapproximately 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 vanes

j. Release the load on thebrake k. Switch off thepump

l. Close the valve at the pump discharge

No. Part1 Sump Tank2 Pump assembly3 Centrifugal pump4 Suction pipe

5 Valve6 Delivery pipe7 Electromagnetic flow meter


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Turbine

Speed,

N

Inlet

Head, H

(m)

Flowmeter

Reading

Volume

Flowrate,

Q

Brake

Reading

Brake

Force,

F

Brake

Torque, T

(Nm)

MechanicalPower, PM

(W)

Water

Power,

PW (W)

Turbine

Efficiency,%

2000 10.8 72.05 0.02 0 0 0 0 2118.9

0

1800 10 90.50 0.0251 2.6 25.506 6.3765 1269.8 2462.3

51.54

1600 9.8 98.00 0.02722 4.3 42.183 10.545 1766.83 2616.9 67.52

1400 9.6 100 0.02777 5.0 49.05 12.26 1797.40 2615.3 68.73

1100 9.5 108 0.03 6.2 60.822 15.20 1750.9 2795.9 62.62

1000 9.4 110 0.0305 6.6 64 16 1675.52 2812.5 59.57

Result.

Brake arm radius (r) = 0.25m

Calculation.

From the data taken,we calculate;

Volume flow rate,Q(

Brake Force,F(N)

Brake Torque,T(Nm)

Mechanical Power,Pm(W)

Water Power,Pw(W) Turbine Efficiency,(%)

Example calculation step with turbine speed ,N=1925RPM

1) Volume flow rate,Q(=72.05

=0.02

2)Brake Force,F(N)=mg

=Brake reading x9.81

=2.6x9.81

=25.506 N

3)Brake Torque,T(Nm)=Fxr

=25.506x0.25

=6.3765 N/m

4)Mechanical Power=XT

=

T


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=

(

=1269.8

5) Water Power,Pw(W)=pgQH

=1000(9.81)(0.02)(10.8)=5297.4 W

6)Turbine Efficiency

(Pout/Pin)x100

=1410.9/5297.4

=26.63 %

Graph

Figure 1

0

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7

Torque(Nm) Vs Turbine Speed(N)


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Figure 2

Figure 3

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 500 1000 1500 2000 2500

Mechanical Power(W) Vs Turbine Speed(N)

0

10

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500

Turbine Efficiency(%) Vs Turbine Speed(N)


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Discussion

Based on the graph plotted from our result,Some information had been extract.We can

see that the trend for all of the graphs is the same,as it inversely proportional to each

other.For the first graph which is the torque against turbine speed,we found out that when

the turbine speed increases,the brake torque increase,the brake torque decreases.This is

because we keep increasing the force ,the friction is higher and thus it makes the fluid

velocity decrease.

For the second graph which is the mechanical power against turbine speed,we can see

that when the turbine speed increases,the mechanical power decreases as well.The

Francis turbine is a reaction turbine,which means that the working fluid changes pressure

as it moves through the turbine,giving up the energy .From the pressure formula,we knew

that as we increases the load,the pressure increases.As the turbine speed increase,the load

also increases and pressure increase.As the turbine speed increasemthe load alos

increases and pressure increases.Thus,the mechanical power increases with the pressureincrease

For the third graph,we cannot get 100% efficiency because the machine is now well

calibrated.besides that,this might experience wear since it has been used for a long

time,resulting an error in data recorded.

Conclusion

In Conclusion, we found that the brake torque, mechanical power and turbine efficiencyare all inversely proportional to turbine speed. Hence,in reality we can apply this

knowledge by keeping the turbine speed as low as possible but still economical.There are

some errors in the experiment which causes inaccurate readings however we still get the

correct patterns that suit the predicted results.

Documents

Francis Turbine Experiment