ME 318: THERMOFLUIDS LAB-II (0,1)

Table of Contents

1. Introduction to the lab equipment and safety precautions

Fluid Mechanics-II

2. Impact of a water jet on a flat plat 3. Impact of a water jet on a hemispherical cup.4. Determination of torque produced using pelton wheel.5. To show the existence of laminar and turbulent flows and to complete the value of

Reynolds’s number when the flow changes from laminar to turbulent using Mercury Manometer

6. To show the existence of laminar and turbulent flows and to complete the value of Reynolds’s number when the flow changes from laminar to turbulent using Water Manometer

7. To determine the variation of friction factor with Reynolds’s number for a straight pipe.

8. To determine the relationship between total head loss and flow rate for pipe bends and other common pipe fittings (light blue circuit). Also determine the loss coefficient for each fitting

9. To determine the relationship between total head loss and flow rate for pipe bends and other common pipe fittings (dark blue circuit). Also determine the loss coefficient for each fitting.

10. To investigate the influence of bend radius on the total head loss in pipe bends.11. To find the velocity of air on Wind Tunnel using Pitot Tube.12. To find Lift, Drag force and find the Application of Bernoulli’s Equation on Air

Flow Bench.13. To find Hydraulic Jump and Laminar, Turbulent Flow etc. on Flow Channel.

Thermodynamics-II

14. To investigate the flow of steam through a convergent Nozzle.15. To investigate the flow of steam through convergent/divergent nozzle and to plot

the pressure variation along its length.16. To determine the brake power of a single cylinder steam engine with varying

load.17. To trace the PV diagram of a piston side and piston rod side with the help of

indicator unit.

18. Study of operational procedure and determination of steam flow rate of a steam turbine.

19. Experiment Practice / Viva

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List of Figures

Figure No: 1………………………………………………………………………………4 Impact of a water jet

Figure No: 2………………………………………………………………………………6Pelton wheel Apparatus.

Figure No: 3………………………………………………………………………………9Apparatus to find laminar and turbulent flows and Reynold’s No

Figure No: 4 …………………………………………………………………………… 13Pressure losses in bends and pipes.

Figure No: 5 ……………………………………………………………………………17 Nozzle Test Rig fitted with the convergent nozzle

Figure No: 6 ……………………………………………………………………………21. Nozzle Test Rig fitted with the convergent/ divergent nozzle

Figure No: 7 ……………………………………………………………………25Steam Engine with Dynamometer

Figure No: 8 …………………………………………………………………………25Steam Engine with Dynamometer

Figure No: 9 …………………………………………………………………………27Steam Engine with Dynamometer

Figure No: 10 …………………………………………………………………………28Steam Turbine Unit

Figure No: 11 ………………………………………………………………………….. 28Steam Turbine Unit

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Fluid Mechanics-II

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EXPERIMENT # 1 : Impact of a jet

INTRODUCTION:

Water turbines are widely used through the world to generate power. In the type of water turbine referred to as a Pelton wheel, one or more water jets are directed tangentially on to vanes generated to the rim of the turbine disc. The impact of the water on the vanes generates a torque on the wheel, causing it to rotate and to develop power. Such turbines can generate considerable output at high efficiency. Power in excess of 100 MW, and hydraulic efficiencies greater than 100%, are not uncommon. It may be noted that the Pelton wheel is best suited to conditions where the available head of water is great, and the flow rate is comparatively small. Objectives:

1. To measure the force produce by a water jet when it strikes two types of vane: a flat plate and a hemispherical cup.

2. To compare the results with the theoretical values calculated from the moment flux in the jet.

Apparatus

Fig No: 1

Method

1. Fit the flat plate to the apparatus.2. Set the weighing beam to its datum position. Set the jockey weight on the beam so

that datum groove is at zero on the scale. Turn the adjusting nut above the spring until the grooves on the tally are in line with the top plate.

3. Switch on the bench pump and open the bench supply valve.

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4. Fully open the supply valve and slide the jockey weight along the beam until the jockey return to its datum position. Record the reading on the scale corresponding to the grove on the jockey weight.

5. Measure the flow rate by timing the collection of water.6. Move the jockey weight inwards by 10 to 15 mm and reduce the flow rate until

the beam is approximately level position.7. Repeat the step 6 until you have 6 sets of readings over the range of flow. For the

last set, the jockey should at about 10mm from the zero position.8. Switch off the bench pump and fit the hemispherical cup to the apparatus using

the same method as of flat plat take another set of readings.

Switch off the bench pump and record the mass m of the jockey weight, the diameter of the nozzle and the distance of the vanes from the outlet of the nozzle.

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EXPERIMENT # 2: Pelton Wheel

Objective

Determination of torque produced using a Pelton wheel.

Equipment required

1. A suitable stroboscope for measurement of rotational speed.2. Pelton Wheel apparatus.

Fig No: 2

Procedure for calibration of dynamometer scale

a) Set the quadrant arm (carrying the scale graduated 0-35) horizontal with weight hanger suspended from the pointer at the 100mm radius

b) Turn the loading knob (at the top) anti-clockwise to lower the pivot of the lever from the lever arm until the friction cord is slackened off.

c) Remove the friction cord by unhooking it from the lever arm. In this configuration the tension in the spring should be adjusted by turn the knurled nut to counterbalance the weight of the lever arm and the weight hanger (i.e. set the pointer mid way between the upper and lower stop).

d) Place a 50 g mass on the hanger. This will deflect the pointer downwards on to the lower stop. Unclamp the quadrant arm (knob at left hand side) and rotate it slowly clockwise (upwards) until the pointer lifts off the lower stop pin and reaches a central position between the stop pins.

e) In this position the torque applied to the lever by the weight at 100mm radius is counteracted by the tension in the spring. Read off the angular position of the pointer relative to the scale.

f) Add further mass in increment of 20g (10g as appropriate) and read off and record the angular deflection in the spring.

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g) Plot a graph of scale reading against mass at 100mm. The resulting graph should be straight line from which the calibration factors for the dynamometer, Kg/deg. can be determined.

h)Mass (g)

Test Procedure

a) When no mass on the hanger, and the pivot of the lever arm is lowered, reassembled the friction cord around the aluminum drum.

b) Connect the supply. Start up the pump and with the valve on the pelton wheel nozzle set position ‘4’ say, turn the supply valve to the fully open position. This setting will give app. Maximum flow.

c) Turn the loading (at the top) clockwise to raise the pivot of the lever arm and supply a resisting torque to the pelton wheel. The friction cord will move the pointer to the lower stop pin.

d) Unclamp the quadrant (by unscrewing the knob at the left hand end of the lever arm) and rotate it clockwise (upwards) to lift the pointer off the lower stop pin. The friction cord is then counteracted by the tension in the spring. Read off and record the angular deflection of the quadrant scale relative to the pointer.

e) Using the stroboscope check and record the rotational speed of the pelton wheel rotor.

f) Repeat for other values of the resisting torque (as given by different setting of the loading knob) until the rotor stalls (is at standstill).

g) Calculate power in watts at each speed.

Power = .

Where = torque in Nm , and = angular velocity in rad/s

rpm

= --------x 2

60

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h) Plot torque (Nm) and power (watts) against rotational speed (rev/min)

Results of a typical test

Scale reading

Mass at 100mm radius(from calibration graph)

Torque(nm)

Speed(rev/min)

Power(watts)

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EXPERIMENT # 3: Laminar, turbulent flow and Reynold’s no

Friction Loss Along a Pipe

Objectives:

1. To demonstrate the existence of laminar and turbulent flow and to establish the value of Reynolds number for transition from laminar to turbulent flow.

2. For the laminar flow regime, to use Poiseuille’s equation to calculate the coefficient of viscosity.

3. To determine the variation of friction factor ‘f’ in the laminar and turbulent flow regimes.

Apparatus

Fig No: 3

Method

1. Connect the bench supply hose to the inlet of the apparatus and direct the outlet flexible outlet pipe into the bench drain.

2. Open the needle valve (N) on the right of the apparatus.3. Start the bench pump and slowly open the bench supply valve so that water flows

through the apparatus.4. Open the bleed screws (B) at the top of the mercury U-tube, and then slowly

closes the needle valve so that the air is expelled from the piezometer tubes. Open the air valve (V) to release the air from the water manometer. When all air bubbles have been driven out, close the bleed screws and air valve.

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5. With the needle valve (N) closed, check that the mercury levels in the U–tube are in balance. If not repeat the process of expelling air. For the first part of the experiment obtain readings of head loss h along the pipe using the mercury U-tube as follows.

6. Close the water manometer isolating tap (T) and fully open the needle valve.7. Collect the flow from the outlet pipe into a measuring cylinder and measure the

time t for collection of a known quantity Q.8. Read the heights of the two columns of mercury in the U-tube.9. Reduce the flow rate by partially closing the needle valve to produce

approximately 10% reduction in differential U-tube reading, and then repeat the measuring process.

10. Repeat this procedure until you have about 10 sets of readings over the whole flow range.

11. Measure the water temperature from time to time during the experiment. Now obtain a similar set of readings over a smaller range of flow, using the constant head tank and the water manometer for measurement of head loss. To do this, proceed as follows;

12. Switch on the bench pump and adjust the bench supply valve until you obtain a steady trickle of water down the overflow pipe.

13. Open the isolating tap (T), and then pump some air into the top of the manometer to depress the water surfaces to a convenient level in the two limbs.

14. Check that the two sides balance at zero flow; If they do not, repeat the process of bleeding air from the top of the manometer.

15. Starting with a differential manometer reading of about 450mm of water again take readings of head loss and flow rate until you have about10 sets of readings over the whole range.

16. Measure the water temperature from time to time during the experiment.17. Record the length L and diameter D of the test pipe.

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Results

Length of pipe between piezometer taping, L = mm = m

Diameter of pipe D = mm = mCross-section area A = m2

Result with Mercury U-tube

Mean temperature of water = oCCoefficient of viscosity = Ns/m2 (from graph)Hydraulic gradient, i = (h1 – h2)/L Velocity, V = Qty/ t x AReynold’s number, Re = VD/Where; = 1000 Kg/m3

Plot i against V and add a scale of Re along the top of the graph. Obtained values of log i and log V and plot a graph.

Qty t h1 h2 i oC

V Re Log i Log V

Determination of critical Reynolds number

As the flow rate reduced, laminar flow first becomes established and when V has the value,

V = m/sRe =

Calculation of viscosity from experimental results

Poiseuille’s equation i = 32 V/ gD2

= gD2/ 32 x i / VFrom fig 1. the standard value of viscosity at the mean temperature is = --------------------Ns/m2

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Calculation of index n in turbulent regime

For the turbulent regime the slope of the line is

n = i V

Calculation of ‘f’ as a function of Re

The relationship between friction factor f and hydraulic gradient i is given by the equation;

i = 4f/D V2/2gf = i/4 D2g/V2

The relationship between Reynolds number Re and velocity V has been established previously in these results for the particular temperature of the tests. Read off values of i at few values of Vin each of the laminar and turbulent region. Calculate values of f and Re from the expressions. Then plot a graph between friction f and Re with the following standard equations.

Laminar: f = 16/ ReTurbulent: 1/ f = 4log (Re f) – 0.4

Conclusions

In your laboratory, write a summary what you have learned from the experiment and answer the following questions.

1. At what value of Re does turbulent flow change to laminar flow? How does this value compare with the accepted value of 2000?

2. What accuracy have you achieved in measuring the coefficient of viscosity?3. What difference in friction factor you expect if the inside surface of the pipe is

very rough?

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EXPERIMENT # 4 : Pressure losses in bends and pipes

Objectives

1. To determine the relation ship between total head loss and flow rate for pipe bends and other common fittings.

2. To determine the loss coefficient K for each fitting and to compare the results with standard data.

Apparatus

Fig No:4

Methods

1. Close the globe valve K and open the gate valve D. Switch on the bench pump and open the bench supply valve to admit water to the dark blue circuit. Allow water to flow for 2 to 3 minutes.

2. Close the gate valve D and bleed all the air into the top of the manometer tubes. Check that all the manometers show zero pressure difference.

3. Open the gate valve and then, by carefully open the bleed screws at the top of the mercury U-tube, fill each limb with water. Make sure that all air bubbles have been expelled, and then close the bleed screws.

4. Close the gate valve, open the globe valve, and repeat the procedure for the light blue circuit.

Dark Blue Circuit

5. Open fully the bench supply valve. Then close the globe valve and open fully the gate valve to obtain the maximum flow rate through the dark blue circuit.

6. If necessary, adjust the water level in the manometers by pumping air into, or releasing air from the bleed valves at the tops of the manometers.

7. Record the readings of the manometers in the dark blue circuit. Note the reference number of each manometer and also record the type of fitting next to each pair of

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results. Also read the levels in the mercury U-tube connected between the inlet and out let of the gate valve D.

8. Measure the flow rate by timing the collection of water in bench weighing tank.9. Measure the water temperature.10. Close the gate valve to reduce the differential manometer readings by about 10%.

Again read the manometer and U-tube, and then measure the flow rate.11. Repeat this procedure until you have about 10 sets of readings over the whole

range of flow.

Light Blue Circuit Close the gate valve and open the globe valve. Then repeat (6) and (11) to obtain the sets of readings for the light blue circuit.

Result for dark blue circuit

Water temperatures:-------------- oC Mean temperatures: ---------------------oCSr.No

MKg

ts

Vm/s

V2/2gmm

Manometer readings and differential heads (mm of water)

U-tube (mm of Hg)

Elbow Bend Straight pipe Mitre bend Gate valve1 2 h’ 3 4 hf 5 6 h’ h1 h2 H

12345678910

Results for light blue circuit

Water temperature:-------------- o C Mean temperature: --------------------- o C

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Sr.

No

MKg

ts

Vm/s

V2

/2g mm

Manometer readings and differential heads (mm of water) U-tube (mm of

Hg)Expansion Contraction Bend J Bend H Bend G Globe

Valve7 8 h

’9 1

0h’

11

12

h’

13

14

h’

15

16

h’

h1

h2

H

16

Thermo-II

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EXPERIMENT # 5 : Flow Through a Convergent Nozzle

Objective

To investigate the flow of steam through a convergent nozzle.

A pparatus :

Nozzle Test Rig fitted with the convergent nozzle.

Fig No: 5

T heory :

Nozzle:- The purpose of a nozzle is to convert the internal energy of steam into kinetic energy and this is done by expanding steam from a higher to lower pressure. Since the passage of steam through the nozzle is rapid there is little time for any heat flow to the surroundings to take place and hence the expansion can be considered to be adiabatic. The shape of the nozzle must be such that the conversion from internal energy to kinetic energy is carried out with the greatest efficiency. There are two types of nozzles to be considered i.e. converging and converging- diverging nozzle and selection of one or the other depends on final discharge pressure required. Convergence tends to stabilize the flow so that the rapid changes of cross sectional area can be tolerated while divergence has the opposite effect, thus necessitating gradual increases of cross sectional area. The minimum section of a nozzle is called the THROAT, and the pressure at the throat for maximum work done is known as the CRITICAL PRESSURE. If the discharge pressure is greater than the critical pressure a convergent nozzle only is required, if it is less than the critical pressure a converging – diverging nozzle is necessaryFor any nozzle, there is a critical pressure ratio at which the flow through nozzle maximum. This ratio is given by

P

Pt

1

Adiabatic index for steam

Where Pt = throat pressure, P1 = inlet pressureThroat pressure becomes equal to Pc critical pressure

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If the throat pressure is the critical value, then velocity at the throat is the critical velocity, which is the local sonic velocity. Thus for a convergent nozzle, the maximum flow velocity is the sonic velocity. Considering the flow through the converging-diverging nozzle under varying the outlet pressure conditions, if P2 (backpressure) is greater than Pt, then the nozzle acts as a venturi. If the pressure is reduced to a value below P t the flow in the divergent section becomes supersonic and the device acts as a converging-diverging nozzle. Under these

condition the pressure at the throat Pt must be the critical pressure, that is P

pt

1 must be

critical pressure ratio, and the flow is maximum. While acting as a nozzle the backpressure is raised, the super sonic flow comes into contact with the higher density fluid and a compression shock occurs.

Outlet Velocity of Nozzle:

Flow energy equation:-

mo (u1 + p1v1+ z1g + c12 / 2) + Q = mo (u2 + p2v2 +z2g +c2

2 / 2) + W

Where,mo = mass flow rate kg / sU1= internal energy at inlet kJ / kgP1 =Inlet pressure barV1 = Inlet specific volume m3 / kgZ1 =Elevation of Inlet mC1= Inlet velocity of flow m / sQ = Heat kJ/s = kWW = work kJ / sh1 = u1 + p1v1 = enthalpy at inleth2 = u2 + p2 v2 =enthalpy at outlet

For a very small duration of flow through nozzle, the heat rejected to the surroundings is nearly zero therefore Q = 0As nozzle is open duct there is no work done so W = 0. The elevation difference i.e. Δz = 0 The inlet velocity comparing with the outlet velocity is nearly negligible so c1 = 0Thus flow energy equation reduced tou1 + p1v1 = u2 + p2 v2 + c2

2 / 2As h = u + pv Thus c2 = √ (h1 – h2) x2 ______ I

Equation I give the final velocity of the steam flowing out of the nozzle

Nozzle Efficiency. The nozzle efficiency is defined by the ratio of the actual enthalpy drop to the isentropic enthalpy drop between the same pressures

Nozzle Efficiency = h1 – h2 / h1 - h2 s

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h1 = Enthalpy at inlet pressure p1

h2 = Enthalpy at outlet pressure p2

h 2 s = found from steam table at constant entropy s1 = s2

If a correctly shaped divergent section is fitted after the throat, the flow is directed and controlled so that the velocity is increased and it becomes supersonic. In order to keep the out let velocity from the divergent passage is greater than at the throat, the pressure at outlet must be less than that at the throat.Considering the flow through the nozzle under varying the outlet pressure conditions, if p2 is greater than pt , then the nozzle acts as a Venturi, the divergent passage acting as a diffuser which slows and regains pressure .If the pressure is reduced to a value below p t

the flow in the divergent section becomes supersonic and the device acts as a nozzle. Under these conditions the pressure at the throat pt must be the flow critical pressure, that

is P

pt

1 must be critical pressure ratio, and the flow is maximum. While acting as a

nozzle the backpressure is raised, the super sonic flow comes into contact with the higher density fluid and a compression shock occurs.

Procedure

1. Traverse the search tube to the exhaust side limit.2. Select and fit the convergent nozzle, taking care not to damage the nozzle profile.3. Open the cooling water inlet and outlet valves to give reasonable quantity of flow.4. Open the backpressure valve.5. Open the steam inlet valve on the apparatus and allow the steam to flow for ten

minutes to warm up the equipment.6. Set the inlet pressure (P1) to 7 bars by throttling the steam inlet valve.7. Set the exhaust pressure to 6.5 bars by adjusting the back pressure regulating valve.8. The time and mass of water collected in this time found by measuring.9. Repeat step "7" & "8" for a series of down steam pressure (P2), reduce pressure in

steps of 0.5 bar .

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Observations

S/No. Pressure (P1) Back Pressure (P2) Distance Nozzle Pressure / Throat Pressure (Pt)

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EXPERIMENT # 6 : Flow through a Convergent /Divergent Nozzle

Objective

To investigate the flow of steam through a convergent / divergent nozzle and to plot the pressure variation along its length.

A pparatus : Nozzle Test Rig fitted with a convergent divergent nozzle.

Fig No: 6

T heory :

Nozzle:- The purpose of a nozzle is to convert the internal energy of steam into kinetic energy and this is done by expanding steam from a higher to lower pressure. Since the passage of steam through the nozzle is rapid there is little time for any heat flow to the surroundings to take place and hence the expansion can be considered to be adiabatic. The shape of the nozzle must be such that the conversion from internal energy to kinetic energy is carried out with the greatest efficiency. There are two types of nozzles to be considered i.e. converging and converging- diverging nozzle and selection of one or the other depends on final discharge pressure required. Convergence tends to stabilize the flow so that the rapid changes of cross sectional area can be tolerated while divergence has the opposite effect, thus necessitating gradual increases of cross sectional area. The minimum section of a nozzle is called the THROAT, and the pressure at the throat for maximum work done is known as the CRITICAL PRESSURE. If the discharge pressure is greater than the critical pressure a convergent nozzle only is required, if it is less than the critical pressure a converging – diverging nozzle is necessaryFor any nozzle, there is a critical pressure ratio at which the flow through nozzle maximum. This ratio is given by

P

Pt

1

Adiabatic index for steam

Where Pt = throat pressure, P1 = inlet pressure

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Throat pressure becomes equal to Pc critical pressure

If the throat pressure is the critical value, then velocity at the throat is the critical velocity, which is the local sonic velocity. Thus for a convergent nozzle, the maximum flow velocity is the sonic velocity. Considering the flow through the converging-diverging nozzle under varying the outlet pressure conditions, if P2 (backpressure) is greater than Pt, then the nozzle acts as a Venturi. If the pressure is reduced to a value below P t the flow in the divergent section becomes supersonic and the device acts as a converging-diverging nozzle. Under these

condition the pressure at the throat Pt must be the critical pressure, that is P

pt

1 must be

critical pressure ratio, and the flow is maximum. While acting as a nozzle the backpressure is raised, the super sonic flow comes into contact with the higher density fluid and a compression shock occurs.

Outlet Velocity of Nozzle:

Flow energy equation:-

mo (u1 + p1v1+ z1g + c12 / 2) + Q = mo (u2 + p2v2 +z2g +c2

2 / 2) + W

Where,mo = mass flow rate kg / sU1= internal energy at inlet kJ / kgP1 =Inlet pressure barV1 = Inlet specific volume m3 / kgZ1 =Elevation of Inlet mC1= Inlet velocity of flow m / sQ = Heat kJ/s = kWW = work kJ / sh1 = u1 + p1v1 = enthalpy at inleth2 = u2 + p2 v2 =enthalpy at outlet

For a very small duration of flow through nozzle, the heat rejected to the surroundings is nearly zero therefore Q = 0As nozzle is open duct there is no work done so W = 0. The elevation difference i.e Δz = 0 The inlet velocity comparing with the outlet velocity is nearly negligible so c1 = 0Thus flow energy equation reduced tou1 + p1v1 = u2 + p2 v2 + c2

2 / 2As h = u + pv Thus c2 = √ (h1 – h2) x2 ______ I

Equation I give the final velocity of the steam flowing out of the nozzle

Nozzle Efficiency. The nozzle efficiency is defined by the ratio of the actual enthalpy drop to the isentropic enthalpy drop between the same pressures

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Nozzle Efficiency = h1 – h2 / h1 - h2 s

h1 = Enthalpy at inlet pressure p1

h2 = Enthalpy at outlet pressure p2

h 2 s = found from steam table at constant entropy s1 = s2

If a correctly shaped divergent section is fitted after the throat, the flow is directed and controlled so that the velocity is increased and it becomes supersonic. In order to keep the out let velocity from the divergent passage is greater than at the throat, the pressure at outlet must be less than that at the throat.Considering the flow through the nozzle under varying the outlet pressure conditions, if p2 is greater than pt , then the nozzle acts as a Venturi, the divergent passage acting as a diffuser which slows and regains pressure .If the pressure is reduced to a value below p t

the flow in the divergent section becomes supersonic and the device acts as a nozzle. Under these condition the pressure at the throat pt must be the flow critical pressure, that

is P

pt

1 must be critical pressure ratio, and the flow is maximum. While acting as a

nozzle the backpressure is raised, the super sonic flow comes into contact with the higher density fluid and a compression shock occurs.

Procedure

1. Set up the experiment in the same manner to that for the convergent nozzle. With inlet pressure 7 bars and an outlet pressure at various positions along the axis of the nozzle using the pressure probe.

2. Repeat the procedure for several values of outlet pressure, maintaining the inlet pressure constant.

Conclusion

1. Plot a graph betweenP

pt

1 and mass flow rate mo and from the graph find the

critical pressure ratio.

2. Plot P

pt

1 to a base of "x" a diagram of nozzle passage should be drawn

beneath the graph, to illustrate the passage section at each value of "x" a curve should be plotted for each value of pb. Comment on these curves.

3. Point out any possible sources of error in the experiment

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Observation

S/No. Pressure (P1) Back Pressure (P2) Distance Nozzle Pressure

Condensate collected in 3 mins

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EXPERIMENT # 7: Single Cylinder Steam Engine

Objective

To determine the brake power for a single cylinder steam engine with varying load.

Apparatus

Steam Engine with Dynamometer.

Fig No: 7 Fig No: 8

Theory:

The function of the engine is to convert the heat energy contained in the steam in to rotational energy at the shaft. The steam expands in the engine cylinder, doing work on the engine piston. The engine is double acting, i.e. steam is admitted to both sides of the piston. Steam admission is controlled by a slide valve which covers and uncovers the port openings.

Procedure

1. Set the valve gear to a cut -off value of 50%, and adjust the governor to maintain a constant speed through out the test.

2. Vary the brake load from zero to maximum value.3. For each load take at least three readings at every five minutes intervals, for the

parameters listed in the result. The experiment can then be repeated for different values of cut-off

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4. Results Value of cut off 50%

Observation Units 1 2 3 4 5

Engine Speed rpm

Brake Load N

Torque Nm

Brake Power kW

Conclusion

1. Plot two graphs for each of the table above against a base of rpm on x-axis and torque and brake power on y-axis.

2. Comment on the shape of the curve.3. Comments on the effect of changing the value of cut off.

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EXPERIMENT # 8: PV Diagram of Steam Engine

Objective

To trace the PV diagram of piston side and piston rod side with the help of indicator unit.

Apparatus

Steam Engine and Indicator unit

Fig No: 9Procedure

1. Set the indicator unit to the on/off valve. 2. Open selector valve to piston side of cylinder.3. Fit paper to indicator drum.4. Connect the indicator drum drive cord to drive arm.5. Ensure that when piston is at BDC, indicator drum is fully turned against spring.6. Open indicator valve.7. Push pen against paper to complete trace.8. Close indicator valve.9. Remove cord hook from operating arm.10. Remove paper with trace from drum.11. Reverse position of selector valve to piston rod side of cylinder.12. Repeat steps 1 to 8 .13. Remove indicator.

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EXPERIMENT # 9: Study of Steam turbine

Objective

Study of operational procedure and determination of steam flow rate of steam turbine.

Apparatus

Steam Turbine Unit.

Fig No: 10 Steam Turbine Fig No: 11 Steam Turbine Units

To start up steam turbine

1. Start boiler and super heater.2. Close steam valve at inlet to turbine.3. Allow steam to discharge through steam trap valve at end of line until all condensate

has been removed from steam line.4. Ensured water is present in the cooling tower sump and also that the isolating valve to

the cooling tower ball valve is open. The cooling tower drain valve should be closed and the overflow runs to a suitable drainage point.

5. Open all valves on cooling tower / condenser circuit.6. Ensure the cooling water circulating pump is primed by opening the de-airing screw

on the pump. 7. Switch on the electric, press start push button on cooling tower fan starter. Press

starter push button on circulating pump starter. 8. Control flow of water through condenser by closing slowly the valve on the outlet of

the condenser. (A), this valve is used to ensure that water is always present in the condenser.

9. Open steam inlet drain valve (B).10. Open steam turbine exhaust drain valve (D).11. Open condenser drain valve (E).12. Close steam turbine gland sealing valves (G, H, I).13. Close vacuum pump valve (J).

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14. Ensure dynamometer-loading switch on front of turbine control panel is to the OFF position.

15. Close hand nozzle valves on the turbine rotor ring.16. Check the level of the oil in the turbine oil gauges. Fill to gauge mark if required.17. Ensure that the turbine safety trip horizontal lever is engaged. 18. Slowly open turbine steam inlet valve to allow a small quantity of steam to enter the

turbine casing. This is to ensure that the turbine is warmed through.19. Close turbine steam inlet valve.20. Ensure no load on dynamometer.21. Open a hand nozzle valve on the turbine rotor ring for condensing conditions.22. Slowly open turbine steam inlet valve and allow turbine to slowly move, turn back

valve so that turbine stops but steam still passes through the turbine and condenser and is discharged through condenser drain valve (E).

23. Close condensate tank drain (F).24. Open condensate discharge valve (L) to drain.25. Turn on external electric to steam turbine, turn on the electric switch on the sidewall

of steam turbine panel.26. Open water valve (K) to vacuum pump.27. Press main supply and vacuum pump push button on front of steam turbine control

panel. Note care must be taken to ensure the pump does not become water locked, the time elapsed between opening water valve (K) and pressing the starter push button must be minimal. Note; do not press the START push button before water is admitted as the water acts as a lubricant and serious damage may result.

28. Close condenser drain valve (E).29. Control flow of water to vacuum pump by adjusting valve (K).30. Close exhaust line drain valve (D).31. Close steam inlet drain valve (B).32. Fully open turbine steam inlet valve. Turbine should now come up to speed. The

governor should control the turbine speed between 50-55 rps. Turn the governor speed adjusting screw (located at the end of the governor) counter-clockwise to decrease the turbine speed, or clockwise to increase the turbine speed. The correct running speed is 50 rps. If governor has not assumed speed control by the time rated speed is reached, shut down immediately and inform your demonstrator.

33. Slowly open turbine gland sealing valve (I) and throttle steam so that approximately 2 bar pressure shows on pressure gauge.

34. Open turbine gland sealing valves (G) and (H) and set these so that steam is just escaping through the glands. (Note: if steam is escaping, air cannot be drawn in through the glands and reduce the vacuum)

35. Allow the turbine to run with no load to enable whole of the system to be run-in.36. To add a load to the turbine ensures the steam inlet valve is fully open. Turn the

variable autotransformer on the front of the control panel, and adjust the turbine speed to give a constant 50 rps. Each load to be increased in turn using the same procedure. As the load increases it will be necessary to increase the steam area by opening the hand valves on the steam inlet nozzles. (Note: on the turbine unit there are nozzles for condensing conditions and one nozzle for backpressure conditions).

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37. Variation in backpressure can be achieved by closing the backpressure. (Note: this valve must never be completely closed, as this will stall the turbine).

38. To measure the amount of steam used by the turbine during a test, close vacuum pump water inlet valve (K) (the condensate extracted from the condenser is sufficient to form the water seal) Alternatively, take a note of the water flow to the vacuum pump on the water meter at the commencement of the test, and deduct this amount from the total condensate make up water collected. Press timer reset button on front of control panel. When condensate in the measuring tank actuates the middle float, switch the digital timer ON, the panel will start. When condensate reaches the top, this stops the timer. The digital display indicates the time for a fixed amount of condensate, which can be set adjustment of the top float switch position.

39. To discharge the condensate to the boiler feed water tank, alter the position of the valve (L) so that the condensate is extracted from the measuring tank and pumped to the boiler feed water tank.

To Shut Down Steam Turbine Unit

1. Turn the variable autotransformer anti-clockwise to reduce load. As the load decreases, adjust the governor so that the steam turbine does not increase its speed. Turn until no load is present.

2. Close steam inlet valve. Alternatively, release safety trip horizontal lever then close steam inlet valve.

3. Close vacuum pump water supply valve (K).4. Open condenser drain valve (E).5. Press push button for vacuum pump to release and stop vacuum pump.6. Close gland sealing valve (I).7. Open exhaust drain valve (D).8. Open steam line drain valve (B).9. Open all hand nozzle valves.10. Switch off electrics on side of turbine control panel.11. Open condensate drain valve (F).12. When the condenser cooling water has absorbed all residual heat, press the STOP

push button on the circulating pump. 13. Close isolating valve (A) on the circulating water circuit.14. Press the STOP push button on the cooling tower fan.15. Turn off the boiler.16. Switch off electrics.

Note

The valve numbers and items referred to in the following sections are detailed on drawing attached. Unless otherwise stated, all valves should be either fully opened or fully closed. It is recommended that when steam valves are opened or closed to their fullest extent, the hand wheel is turned back 1\4 of turn to prevent the spindle and seat locking when heat is supplied. Always ensure that cooling water is turned on and flowing before any steam is admitted.

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