Free Printable STEAM TURBINES (PART

1.

The blade speed ratio of an impulse turbine is

a)

Blade velocity / Steam velocity at inlet

b)

Blade velocity / Steam velocity at outlet

c)

Air velocity / Steam velocity at inlet

d)

None of the above

2.

In general, the flow through a nozzle is regarded as

a)

Isentropic

b)

Isobaric

c)

Isothermal

d)

Isochoric

3.

In an impulse turbine, the steam is expanded in

a)

Moving blades only

b)

Nozzles only

c)

Both in fixed and moving blades

d)

None of the above

4.

The shape of blades of …………. is of half-moon geometry

a)

Reaction turbine

b)

Impulse turbine

c)

Francis turbine

d)

Propeller

5.

In case of an impulse turbine, complete pressure drop occurs in

a)

Nozzle only

b)

Moving Blades only

c)

Nozzle and Moving blades

d)

None of the above

6.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Find the blade angle in degree, assuming the steam enters the blade without shock.

a)

15.1

b)

45.2

c)

25.5

d)

10.4

7.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Calculate the tangential forces on the blades (N) for the turbine . Neglect friction effects on blades.

a)

546.36

b)

498.65

c)

660.54

d)

254.77

8.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Calculate the diagram power (kW) for the turbine. Neglect friction effects on blades.

a)

100.25

b)

76.43

c)

150.63

d)

200.36

9.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the axial thrust (N), assuming the steam enters the blade without shock.

a)

0

b)

0.01

c)

0.15

d)

1.52

10.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram efficiency (in %), assuming the steam enters the blade without shock.

a)

79.65

b)

81.52

c)

80.65

d)

91.65

11.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the axial thrust (N), if the relative velocity is reduced to 80% of that at inlet due to friction

a)

49.65

b)

41.36

c)

25.65

d)

50.65

12.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram power (kW) , if the relative velocity is reduced to 80% of that at inlet due to friction

a)

148.56

b)

179.36

c)

200.36

d)

68.77

13.

Steam enters an impulse turbine at a velocity of 500 m/s and having nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram efficiency (in %), if the relative velocity is reduced to 80% of that at inlet due to friction

a)

73.35

b)

70.65

c)

78.55

d)

79.36

14.

A partly impulsive and partly reaction force are the driving forces in case of

a)

An impulse turbine

b)

Fifty percent reaction turbine only

c)

Sixty percent reaction turbine only

d)

Any reaction turbine other than hundred & zero percent

15.

A reaction turbine follows the law of ________, as it works on the principle of impulse and reaction.

a)

Impulse momentum

b)

Angular momentum

c)

Both a. and b.

d)

None of the above

16.

Degree of reaction is defined as

a)

Enthalpy drop in the moving blades to the enthalpy drop in the stage

b)

Enthalpy drop in the moving blades to the enthalpy drop in the fixed blades

c)

Enthalpy drop in the fixed blades to the enthalpy drop in the moving blades

d)

Enthalpy drop in the fixed blades to the total enthalpy drop in the moving blades

17.

Parallel flow turbine are also called as __________ turbines.

a)

Axial flow

b)

Radial flow

c)

Both radial flow and axial flow

d)

None of the above

18.

The driving force in an 50% reaction turbine is partly impulsive force and partly reaction force

a)

True

b)

False

c)

Sometimes true

d)

True only with special attachments

19.

What is typical of a Parson’s reaction turbine?

a)

Identical moving & fixed blades

b)

Fixed & moving blades of different shape

c)

Pressure drop does not take place in moving blades

d)

Pressure drop takes place in the moving nozzle only

20.

The value of specific speed of Kaplan turbine is generally _____________ that of the Pelton turbine.

a)

Higher than

b)

Lower than

c)

Same as

d)

Unpredictable

21.

A Francis Turbine is a type of __________?

a)

Impulse Turbine

b)

Screw Turbine

c)

Turgo turbine

d)

Reaction turbine

22.

A 50% reaction turbine is rotating at 2400 rpm with a mean blade speed of 100 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area. Calculate the mass flow of steam through the turbine in kg/h.

a)

29340

b)

21147

c)

25365

d)

30285

23.

A 50% reaction turbine is rotating at 2400 rpm with a mean blade speed of 100 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area. calculate the diagram power (kW) if there are five pair of blades in the group.

a)

429.7

b)

235.8

c)

565.3

d)

691.4

24.

A 50% reaction turbine is rotating at 2400 rpm with a mean blade speed of 100 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area. Calculate the useful enthalpy drop (kJ/kg) if there are five pair of blades in the group.

a)

117.8

b)

170.2

c)

161.3

d)

198.9

25.

In case of an impulse turbine, complete pressure drop occurs in

a)

Nozzle only

b)

Moving blades only

c)

Nozzle and moving blades only

d)

None of the above

26.

The flow through a nozzle is regarded as

a)

Isothermal flow

b)

Isentropic flow

c)

Isochoric flow

d)

Isobaric flow

27.

In an impulse steam turbine, absolute velocity at the exit of the blade_____ in comparison with the inlet absolute velocity to the blade

a)

Increases

b)

Decreases

c)

Remains constant

d)

Can't comment

28.

An impulse steam turbine has a number of pressure stages with each stage having a row of nozzles and a single ring of blades. With reference to the plane of rotation, nozzle angle of first stage is 20 deg and blade exit angle is 30 deg. The velocity of steam leaving the nozzles is 350 m/s and the mean blade speed is 100 m/s. Determine the work done in a stage per kg of steam (kJ/kg). Blade friction factor is 0.8 and nozzle efficiency is 0.85.

a)

56.42

b)

45.98

c)

39.45

d)

40.79

29.

An impulse steam turbine has a number of pressure stages with each stage having a row of nozzles and a single ring of blades. With reference to the plane of rotation, nozzle angle of first stage is 20 deg and blade exit angle is 30 deg. The velocity of steam leaving the nozzles is 350 m/s and the mean blade speed is 100 m/s. Calculate the stage efficiency. Blade friction factor is 0.8 and nozzle efficiency is 0.85.

a)

91.26

b)

56.60

c)

45.26

d)

75.26

30.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Find the blade angle in degree, assuming the steam entering the blade without shock.

a)

19.5

b)

20.6

c)

33.8

d)

15.6

31.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Calculate the tangential force (N) on the blades. Neglect the friction effects on blades.

a)

532.23

b)

677.67

c)

653.58

d)

536.44

32.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Calculate the diagram power (kW)

a)

160.9

b)

220.8

c)

108.6

d)

95.3

33.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the axial thrust (N)

a)

0.93

b)

8.45

c)

0

d)

0.75

34.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram efficiency (in %)

a)

79.11

b)

87.56

c)

75.34

d)

80.26

35.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the axial thrust (N), if the relative velocity is reduced to 80% of that at inlet due to friction

a)

65.38

b)

25.45

c)

35.91

d)

41.04

36.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram power (kW) if the relative velocity is reduced to 80% of that at inlet due to friction

a)

144.84

b)

543.55

c)

232.36

d)

182.90

37.

Steam enters an impulse turbine at a velocity of 700 m/s which has nozzle angle 20 deg. The symmetrical blades have a mean peripheral velocity of 300 m/s. Consider a mass flow rate of 0.75 kg/s. Estimate the diagram efficiency (in %), if the relative velocity is reduced to 80% of that at inlet due to friction

a)

76.21

b)

79.54

c)

57.65

d)

78.82

38.

In __________ turbine pressure drop takes place in moving blades as well.

a)

Reaction Turbine

b)

Impulse Turbine

c)

Both

d)

None

39.

What is typical of a Parson’s reaction turbine?

a)

Fixed & moving blades of different shape

b)

Pressure drop does not take place in moving blades

c)

Pressure drop takes place in the moving nozzle only

d)

Identical moving & fixed blades

40.

A partly impulsive and partly reaction force are the driving forces in case of

a)

Any reaction turbine other than hundred percent one

b)

An impulse turbine

c)

Fifty percent reaction turbine only

d)

Sixty percent reaction turbine only

41.

Force obtained from the change in pressure on the moving blades helps to drive a reaction turbine

a)

True

b)

False

c)

Data insufficient

d)

Cannot say

42.

One of the characteristics of reaction turbine is

a)

Steam expansion over rotor blades & relatively low RPM

b)

Steam expansion over rotor blades & relatively high RPM

c)

Steam expansion over nozzle & relatively low RPM

d)

Steam expansion over nozzle & relatively high RPM

43.

Degree of reaction is defined as

a)

Enthalpy drop in the moving blades to the enthalpy drop in the stage

b)

Enthalpy drop in the fixed blades to the enthalpy drop in the stage

c)

Enthalpy drop in the fixed blades to the enthalpy drop in the moving blades

d)

Enthalpy drop in the fixed blades to the total enthalpy drop in the moving blades

44.

A 50% reaction turbine is rotating at 2600 rpm with a mean blade speed of 120 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. Calculate the mass flow of steam through the turbine in kg/h. The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area.

a)

28044

b)

25365

c)

35236

d)

20365

45.

A 50% reaction turbine is rotating at 2600 rpm with a mean blade speed of 120 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. Calculate the diagram power (kW) if there are five pair of blades in the group.. The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area.

a)

1324.3

b)

1635.8

c)

1864.2

d)

1565.3

46.

A 50% reaction turbine is rotating at 2600 rpm with a mean blade speed of 120 m/s. The exit angle of blades is 20 deg. and the velocity ratio is 0.56. Calculate the useful enthalpy drop (kJ/kg). The mean specific volume of steam is 0.65 cub.m/kg and the mean height of blade is 25 mm. Neglect effect of blade thickness on the annulus area.

a)

161

b)

132

c)

170

d)

198

47.

A steam turbine is to operate between 150 bar, 600 deg.Celcius and 0.1 bar. The bucket velocity is limited to 250 m/s and the average nozzle efficiency is expected to be 95% for impulse and 90% for reaction turbine. All stages operate close to the speed corresponding to maximum efficiency. Nozzle angles can be assumed as 20 deg. for impulse and reaction stages. Estimate the number of stages required if all the stages are simple impulse stage.

a)

15

b)

10

c)

5

d)

20

48.

A steam turbine is to operate between 150 bar, 600 deg.Celcius and 0.1 bar. The bucket velocity is limited to 250 m/s and the average nozzle efficiency is expected to be 95% for impulse and 90% for reaction turbine. All stages operate close to the speed corresponding to maximum efficiency. Nozzle angles can be assumed as 20 deg. for impulse and reaction stages. Estimate the number of stages required if all the stages are 50% reaction stages.

a)

19

b)

5

c)

30

d)

11

49.

Single stage impulse turbine has equal blade angles and nozzle angle of 18o. If the blade velocity coefficient is 0.82, then the maximum possible blade efficiency, %

a)

82

b)

84

c)

86

d)

88

50.

A single stage impulse turbine is provided with a steam at mass flow rate of 5 kg/s. Take following data of this turbine:

Rotor diameter: 1.5 m

Rotor speed: 3500 rpm

Nozzle angle 15o

Blade speed ratio: 0.35

Velocity coefficient: 0.86

Assume that outlet blade angle is 2o less than inlet blade angle.

Find the respective inlet and exit blade angles, degrees

a)

28.8 and 26.8

b)

25.8 and 23.8

c)

22.8 and 20.8

d)

19.8 and 17.8

51.

A single stage impulse turbine is provided with a steam at mass flow rate of 5 kg/s. Take following data of this turbine:

Rotor diameter: 1.5 m

Rotor speed: 3500 rpm

Nozzle angle 15o

Blade speed ratio: 0.35

Velocity coefficient: 0.86

Assume that outlet blade angle is 2o less than inlet blade angle.

Find Absolute velocity of whirl at exit of moving blade, m/s

a)

147

b)

524

c)

483

d)

785

52.

A single stage impulse turbine is provided with a steam at mass flow rate of 5 kg/s. Take following data of this turbine:

Rotor diameter: 1.5 m

Rotor speed: 3500 rpm

Nozzle angle 15o

Blade speed ratio: 0.35

Velocity coefficient: 0.86

Assume that outlet blade angle is 2o less than inlet blade angle.

Find the Power developed, MW

a)

1.99

b)

1.79

c)

1.59

d)

1.39

53.

A single stage impulse turbine is provided with a steam at mass flow rate of 5 kg/s. Take following data of this turbine:

Rotor diameter: 1.5 m

Rotor speed: 3500 rpm

Nozzle angle 15o

Blade speed ratio: 0.35

Velocity coefficient: 0.86

Assume that outlet blade angle is 2o less than inlet blade angle.

Find Blade efficiency, %

a)

80

b)

84

c)

86

d)

88

54.

Which of the following statement is incorrect about the impulse turbine

a)

Impulse turbine diaphragm has nozzles mounted on it.

b)

Impulse turbine has fixed blade ring attached to the casing.

c)

Impulse turbine has pressure drop occurring only in nozzles.

d)

Impulse turbine have incomplete admission of steam.

55.

The blades of impulse turbine are of_________________.

a)

profile type and has converging area between consecutive blades

b)

airfoil type and has constant area between consecutive blades

c)

profile type and has constant area between consecutive blades

d)

airfoil type and has converging area between consecutive blades

56.

The maximum diagram efficiency of an impulse steam turbine is given by

a)

b)

c)

d)

57.

Which of the following pair(s) is/are correct

a)

Velocity compounded steam turbine : Rateau turbine

b)

Pressure compounded steam turbine: Rateau turbine

c)

Velocity compounded steam turbine: Curtis turbine

d)

Pressure compounded steam turbine: Curtis turbine

58.

The optimum value of blade speed ratio of an impulse turbine for maximum work is_______

Where α is nozzle angle and n is no of moving blades rows.

a)

b)

c)

d)

59.

A dry saturated steam enters the nozzle of a simple impulse turbine at 15 bar and 150 m/s. The steam then leaves the nozzle and enters the blades at 8 bar. Take velocity coefficient as 0.90. Also, assume that blades are equiangular and take nozzle angle as 20o. The values of the steam properties are mentioned below:

Pr (bar) hf(kJ/kg) hg (kJ/kg) sf (kJ/kg-K) sg (kJ/kg-K)

15 844.64 2792.2 2.4968 6.4448

8 721.11 2769.11 2.0462 6.6628

Find the Velocity at the exit of the nozzle, m/s

a)

518

b)

488

c)

458

d)

428

60.

A dry saturated steam enters the nozzle of a simple impulse turbine at 15 bar and 150 m/s. The steam then leaves the nozzle and enters the blades at 8 bar. Take velocity coefficient as 0.90. Also, assume that blades are equiangular and take nozzle angle as 20o. The values of the steam properties are mentioned below:

Pr (bar) hf (kJ/kg) hg (kJ/kg) sf (kJ/kg-K) sg (kJ/kg-K)

15 844.64 2792.2 2.4968 6.4448

8 721.11 2769.11 2.0462 6.6628

Find Blade angle at exit, degree

a)

30

b)

33

c)

36

d)

39

61.

A dry saturated steam enters the nozzle of a simple impulse turbine at 15 bar and 150 m/s. The steam then leaves the nozzle and enters the blades at 8 bar. Take velocity coefficient as 0.90. Also, assume that blades are equiangular and take nozzle angle as 20o. The values of the steam properties are mentioned below:

Pr (bar) hf (kJ/kg) hg (kJ/kg) sf (kJ/kg-K) sg (kJ/kg-K)

15 844.64 2792.2 2.4968 6.4448

8 721.11 2769.11 2.0462 6.6628

Find the Blade Efficiency, %

a)

88

b)

91

c)

93

d)

95

62.

A dry saturated steam enters the nozzle of a simple impulse turbine at 15 bar and 150 m/s. The steam then leaves the nozzle and enters the blades at 8 bar. Take velocity coefficient as 0.90. Also, assume that blades are equiangular and take nozzle angle as 20o. The values of the steam properties are mentioned below:

Pr (bar) hf (kJ/kg) hg (kJ/kg) sf (kJ/kg-K) sg (kJ/kg-K)

15 844.64 2792.2 2.4968 6.4448

8 721.11 2769.11 2.0462 6.6628

Find the Stage Efficiency, %

a)

89

b)

86

c)

83

d)

80

63.

A dry saturated steam enters the nozzle of a simple impulse turbine at 15 bar and 150 m/s. The steam then leaves the nozzle and enters the blades at 8 bar. Take velocity coefficient as 0.90. Also, assume that blades are equiangular and take nozzle angle as 20o. The values of the steam properties are mentioned below:

Pr (bar) hf (kJ/kg) hg (kJ/kg) sf (kJ/kg-K) sg (kJ/kg-K)

15 844.64 2792.2 2.4968 6.4448

8 721.11 2769.11 2.0462 6.6628

Find Blade velocity for maximum diagram efficiency, m/s

a)

220

b)

230

c)

240

d)

250

STEAM TURBINES (PART - B)

Total questions: 63

Worksheet time: 32mins

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