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Parson’s turbine is

A simple impulse turbine with degree of reaction R=0

An impulse-reaction turbine with degree of reaction R=0.5

An impulse-reaction turbine with degree of reaction R=0.9

A pure reaction turbine with degree of reaction R=1

For a particular reaction turbine, the enthalpy drops in the moving blade and in the fixed blade are stated to be 15kJ/kg and 25kJ/kg respectively. The degree of reaction for the turbine is

0.375

0.5

0.625

0.67

The degree of reaction is defined as the ratio of

Heat drop in moving blades to heat drop in fixed blades

Heat drop in moving blades to heat drop in the entire stage of reaction turbine

Heat drop in fixed blades to heat drop in the entire stage of reaction turbine

Heat drop in fixed blades to heat drop in moving blades

The essential merit of a reaction turbines lies in

Greater work output

High diagram efficiency

Blade speeds lie in the useful range

Capability to have expansions in stages

Which aspect is not true in the control of a reaction turbine?

Steam is only partially expanded in the nozzle, the remaining expansion takes place in the rotor blades

Reaction turbine blades use aerofoil section and are asymmetrical

Different pressures exist on the two sides of the moving blades

The number of stages required for a reaction turbine are less than those for an impulse turbine of the same power

What changes occur in the magnitude of pressure and velocity when steam flows through the fixed blades of a reaction turbine?

Velocity decreases and pressure remains constant

Both pressure and velocity decrease

Velocity increases and the pressure falls

Both pressure and velocity increase

As steam glides over the moving blades of a reaction turbine

Both pressure and velocity decrease

Both pressure and velocity increase

Pressure drops and velocity increases

Velocity decreases and pressure remains constant

The velocity here refers to the absolute velocity

Which one of the following sketches represents an impulse turbine blade

(a)

(b)

(c)

(d)

De-laval turbine has a shaft speed of about

10,000 rpm

15,000 rpm

20,000 rpm

30,000 rpm

De-laval turbine is

Single rotor impulse turbine

Velocity-compounded impulse turbine

Pressure-compounded impulse turbine

Impulse-reaction turbine

Which of the following is a pressure compounded turbine?

Parsons

Curtis

Reteau

All of three

Theoretically the work of two row Curtis wheel is………….times that of a simple wheel; blade speeds being equal in both the cases

2

4

6

8

Running speeds of steam turbines can be brought down to practical limits by which of the following method(s)? by using heavy flywheel by using a quick response governor by compounding by reducing fuel feed to the furnance Choose the correct answer using the codes given below:

3 alone

1, 2, 3 and 4

1, 2 and 4

2 and 3

Compounding of steam turbine is done to

Balance the rotor

Reduce the blade friction

Reduce the rotor speed

Connect the shaft of one turbine to that of another

A single stage impulse turbine is generally not used in practice because

It cannot generate more power

Heat energy is not utilized fully

It has very low efficiency

It needs large reduction gearing due to high speeds

Which of the following is wrong statement?

At Cb/Ca1=0, torque on the blades is minimum and no work is done

At Cb/Ca1=1, both torque and work done are zero

At Cb/Ca1=cos /2, maximum work output is obtained

At Cb/Ca1=cos /2, the diagram efficiency has a maximum value

Where is the nozzle angle, Cb is the blade speed and Ca1 is the absolute velocity of steam jet issuing from the nozzle

For a single stage impulse turbine with nozzle angle 20o, rotor diameter 2m and speed 3000 rpm, the optimum velocity of steam in m/s is

334

356

668

711

A single stage impulse turbine with a diameter of 120 cm runs at 3000 rpm. If the blade speed ratio is 0.42, then the inlet velocity will be

79 m/s

188 m/s

450 m/s

900 m/s

In single stage impulse turbine, the maximum rate of doing work per kg of steam per second is given by

0.5 Cb2

Cb2

2 Cb2

4 Cb2

Where Cb is the blade speed

For a fixed value of nozzle angle, maximum work would be produced when blade speed and absolute velocity of steam jet conform to the ratio

1:4

1:2

2:3

1:1

If nozzle angle is 30o the De-Laval turbine will have a maximum efficiency of

0.43

0.5

0.75

0.875

If nozzle angle is 30 degree, the efficiency of an impulse turbine would be maximum when the blade speed equals

0.433 Ca1

0.5 Ca1

0.75 Ca1

0.866 Ca1

Where Ca1 is the absolute steam velocity at exit from the nozzle

The optimum value of nozzle angle lies within the range

20-25 degree

15-20 degree

10-15 degree

5-8 degree

The blade speed ratio defines the relation between

Relative velocities at outlet and inlet

Cosine of angles made by relative velocities at outlet and inlet

Blade speed and absolute steam velocity at inlet

Absolute steam velocities at inlet and outlet

Because of sonic and supersonic speeds, the time taken by steam for its passage through nozzle is of the order of

For supersaturated adiabatic flow through a nozzle, the pressure p and volume v are related by the expression

pv=c

Pv1.3=c

Pv1.135=c

Pv1.15=c

The specific volume of supersaturated steam can be worked out by using the correlation

pv=0.01(H-464.1)

pv=0.1(H-464.1)

Pv1.3=0.3(H-464.1)

pv=0.15(H+464.1)

Where v is specific volume in m3/kg, H is enthalpy of steam in kcal/kg and p is the pressure in kgf/cm2

Wilson’s line is associated with

Governing of steam engines

Supersaturated expansion through a steam nozzle

Binary vapour cycle

Condensation of steam in the later stages of a steam turbine

Which is not true regarding effect of supersaturated flow in a steam nozzle?

Reduction in heat drop

Reduction in exit velocity

Decrease in mass flow rate

Increase in entropy

All of the following statements are correct, except

When the pressure at the throat of nozzle is well above critical pressure, the flow accelerates in the convergent part and decelerates in the divergent part

With the sonic velocity attained at throat, subsequent reduction in back pressure does not affect the flow condition in the convergent part

The nozzle is said to be under expanding when it operates above the design pressure

The expansion process occurring outside the nozzle is violent and irreversible

In flow through a convergent nozzle, the ratio of back pressure to the inlet pressure is given by the relation , if the back pressure is lower than that given by the above equation, then

The flow in the nozzle is supersonic

The shock wave exists inside the nozzle

The gases expand outside the nozzle

A shock wave appears at the nozzle exit

Shock waves involving an abrupt rise of pressure and increase of entropy generally occur

At entry to nozzle

In the convergent section of the nozzle

At the nozzle throat

In the divergent section of the nozzle

At what location of a converging diverging nozzle, does the shock boundary layer interaction take place?

Converging portion

Throat

Inlet

Diverging prition

A convergent diversity nozzle is said to be choked when 1. critical pressure is attained at the throat 2. velocity at the throat becomes sonic 3. exit velocity becomes supersonic Which of these statements are correct?

1, 2 and 3

1 and 2

2 and 3

1 and 3

Which statement is not true for a steam turbine when compared to steam engines?

High thermodynamic efficiency

High power output per unit weight of machine

High power turbine units would need a heavier flywheel

Capacity to carry considerable overloads with only slight reduction in efficiency

In the steam turbine embodying impulse principle, the expansion of steam takes place in

Stationary nozzles

Moving nozzles

Blades mounted on the wheel attached to the shaft

Partly in stationary nozzles and partly in moving blades

When steam flows over moving blades of an impulse turbine

Pressure drops and velocity increases

Pressure remains constant and velocity decreases

Both pressure and velocity remain constant

Both pressure and velocity decrease

The effect of friction when steam flows across the blade passages is expressed by the ratio of relative velocities at outlet and inlet (K=Cr2/Cr1). The factor K is called

Friction factor

Blade velocity coefficient

Blade speed ratio

Utilization factor

In an impulse turbine, the blade friction reduces the relative velocity of steam on passing over the blades by about

5-8%

10-15%

15-20%

20-30%

In an ideal impulse turbine, the

The absolute velocity at the inlet of moving blade is equal to that at the outlet

The relative velocity at the inlet of moving blade is equal to that at the outlet

Axial velocity at the inlet is equal to that at the outlet

Whirl velocity at the inlet is equal to that at the outlet

Blading efficiency is defined as the ratio of

Relative velocities at outlet and inlet

Blade speed and absolute steam velocity at inlet

Work done by steam on blades and the energy supplied to the blades

Cosine of the angles made by relative velocities at outlet and inlet

Blading efficiency is also known as

Stage efficiency

Overall efficiency

Nozzle efficiency

Diagram efficiency

In a single stage impulse turbine, the maximum blading efficiency is given by__________

When compared to stable flow, the available enthalpy drop for supersaturated flow of steam through a nozzle

Remains same

Increases

Decreases

Is unpredictable

Because of sonic and supersonic speeds, the time taken by steam for its passage through nozzle is of the order of

For supersaturated adiabatic flow through a nozzle, the pressure p and volume v are related by the expression

pv=c

Pv1.3=c

Pv1.135=c

Pv1.15=c

The specific volume of supersaturated steam can be worked out by using the correlation

pv=0.01(H-464.1)

pv=0.1(H-464.1)

Pv1.3=0.3(H-464.1)

pv=0.15(H+464.1)

Where v is specific volume in m3/kg, H is enthalpy of steam in kcal/kg and p is the pressure in kgf/cm2

Wilson’s line is associated with

Governing of steam engines

Supersaturated expansion through a steam nozzle

Binary vapour cycle

Condensation of steam in the later stages of a steam turbine

Neglecting the effect of friction and assuming blades to be symmetrical, the maximum blading efficiency of a single stage impulse turbine is given by

2 cos2

cos2

Cos2

In a single stage impulse turbine, the maximum blading efficiency is obtained when

=cos

=cos2

=

=

When is the nozzle angle and is the blade speed ratio

A simple impulse turbine with degree of reaction R=0

An impulse-reaction turbine with degree of reaction R=0.5

An impulse-reaction turbine with degree of reaction R=0.9

A pure reaction turbine with degree of reaction R=1

For a particular reaction turbine, the enthalpy drops in the moving blade and in the fixed blade are stated to be 15kJ/kg and 25kJ/kg respectively. The degree of reaction for the turbine is

0.375

0.5

0.625

0.67

The degree of reaction is defined as the ratio of

Heat drop in moving blades to heat drop in fixed blades

Heat drop in moving blades to heat drop in the entire stage of reaction turbine

Heat drop in fixed blades to heat drop in the entire stage of reaction turbine

Heat drop in fixed blades to heat drop in moving blades

The essential merit of a reaction turbines lies in

Greater work output

High diagram efficiency

Blade speeds lie in the useful range

Capability to have expansions in stages

Which aspect is not true in the control of a reaction turbine?

Steam is only partially expanded in the nozzle, the remaining expansion takes place in the rotor blades

Reaction turbine blades use aerofoil section and are asymmetrical

Different pressures exist on the two sides of the moving blades

The number of stages required for a reaction turbine are less than those for an impulse turbine of the same power

What changes occur in the magnitude of pressure and velocity when steam flows through the fixed blades of a reaction turbine?

Velocity decreases and pressure remains constant

Both pressure and velocity decrease

Velocity increases and the pressure falls

Both pressure and velocity increase

As steam glides over the moving blades of a reaction turbine

Both pressure and velocity decrease

Both pressure and velocity increase

Pressure drops and velocity increases

Velocity decreases and pressure remains constant

The velocity here refers to the absolute velocity

Which one of the following sketches represents an impulse turbine blade

(a)

(b)

(c)

(d)

De-laval turbine has a shaft speed of about

10,000 rpm

15,000 rpm

20,000 rpm

30,000 rpm

De-laval turbine is

Single rotor impulse turbine

Velocity-compounded impulse turbine

Pressure-compounded impulse turbine

Impulse-reaction turbine

Which of the following is a pressure compounded turbine?

Parsons

Curtis

Reteau

All of three

Theoretically the work of two row Curtis wheel is………….times that of a simple wheel; blade speeds being equal in both the cases

2

4

6

8

Running speeds of steam turbines can be brought down to practical limits by which of the following method(s)? by using heavy flywheel by using a quick response governor by compounding by reducing fuel feed to the furnance Choose the correct answer using the codes given below:

3 alone

1, 2, 3 and 4

1, 2 and 4

2 and 3

Compounding of steam turbine is done to

Balance the rotor

Reduce the blade friction

Reduce the rotor speed

Connect the shaft of one turbine to that of another

A single stage impulse turbine is generally not used in practice because

It cannot generate more power

Heat energy is not utilized fully

It has very low efficiency

It needs large reduction gearing due to high speeds

Which of the following is wrong statement?

At Cb/Ca1=0, torque on the blades is minimum and no work is done

At Cb/Ca1=1, both torque and work done are zero

At Cb/Ca1=cos /2, maximum work output is obtained

At Cb/Ca1=cos /2, the diagram efficiency has a maximum value

Where is the nozzle angle, Cb is the blade speed and Ca1 is the absolute velocity of steam jet issuing from the nozzle

For a single stage impulse turbine with nozzle angle 20o, rotor diameter 2m and speed 3000 rpm, the optimum velocity of steam in m/s is

334

356

668

711

A single stage impulse turbine with a diameter of 120 cm runs at 3000 rpm. If the blade speed ratio is 0.42, then the inlet velocity will be

79 m/s

188 m/s

450 m/s

900 m/s

In single stage impulse turbine, the maximum rate of doing work per kg of steam per second is given by

0.5 Cb2

Cb2

2 Cb2

4 Cb2

Where Cb is the blade speed

For a fixed value of nozzle angle, maximum work would be produced when blade speed and absolute velocity of steam jet conform to the ratio

1:4

1:2

2:3

1:1

If nozzle angle is 30o the De-Laval turbine will have a maximum efficiency of

0.43

0.5

0.75

0.875

If nozzle angle is 30 degree, the efficiency of an impulse turbine would be maximum when the blade speed equals

0.433 Ca1

0.5 Ca1

0.75 Ca1

0.866 Ca1

Where Ca1 is the absolute steam velocity at exit from the nozzle

The optimum value of nozzle angle lies within the range

20-25 degree

15-20 degree

10-15 degree

5-8 degree

The blade speed ratio defines the relation between

Relative velocities at outlet and inlet

Cosine of angles made by relative velocities at outlet and inlet

Blade speed and absolute steam velocity at inlet

Absolute steam velocities at inlet and outlet

Because of sonic and supersonic speeds, the time taken by steam for its passage through nozzle is of the order of

For supersaturated adiabatic flow through a nozzle, the pressure p and volume v are related by the expression

pv=c

Pv1.3=c

Pv1.135=c

Pv1.15=c

The specific volume of supersaturated steam can be worked out by using the correlation

pv=0.01(H-464.1)

pv=0.1(H-464.1)

Pv1.3=0.3(H-464.1)

pv=0.15(H+464.1)

Where v is specific volume in m3/kg, H is enthalpy of steam in kcal/kg and p is the pressure in kgf/cm2

Wilson’s line is associated with

Governing of steam engines

Supersaturated expansion through a steam nozzle

Binary vapour cycle

Condensation of steam in the later stages of a steam turbine

Which is not true regarding effect of supersaturated flow in a steam nozzle?

Reduction in heat drop

Reduction in exit velocity

Decrease in mass flow rate

Increase in entropy

All of the following statements are correct, except

When the pressure at the throat of nozzle is well above critical pressure, the flow accelerates in the convergent part and decelerates in the divergent part

With the sonic velocity attained at throat, subsequent reduction in back pressure does not affect the flow condition in the convergent part

The nozzle is said to be under expanding when it operates above the design pressure

The expansion process occurring outside the nozzle is violent and irreversible

In flow through a convergent nozzle, the ratio of back pressure to the inlet pressure is given by the relation , if the back pressure is lower than that given by the above equation, then

The flow in the nozzle is supersonic

The shock wave exists inside the nozzle

The gases expand outside the nozzle

A shock wave appears at the nozzle exit

Shock waves involving an abrupt rise of pressure and increase of entropy generally occur

At entry to nozzle

In the convergent section of the nozzle

At the nozzle throat

In the divergent section of the nozzle

At what location of a converging diverging nozzle, does the shock boundary layer interaction take place?

Converging portion

Throat

Inlet

Diverging prition

A convergent diversity nozzle is said to be choked when 1. critical pressure is attained at the throat 2. velocity at the throat becomes sonic 3. exit velocity becomes supersonic Which of these statements are correct?

1, 2 and 3

1 and 2

2 and 3

1 and 3

Which statement is not true for a steam turbine when compared to steam engines?

High thermodynamic efficiency

High power output per unit weight of machine

High power turbine units would need a heavier flywheel

Capacity to carry considerable overloads with only slight reduction in efficiency

In the steam turbine embodying impulse principle, the expansion of steam takes place in

Stationary nozzles

Moving nozzles

Blades mounted on the wheel attached to the shaft

Partly in stationary nozzles and partly in moving blades

When steam flows over moving blades of an impulse turbine

Pressure drops and velocity increases

Pressure remains constant and velocity decreases

Both pressure and velocity remain constant

Both pressure and velocity decrease

The effect of friction when steam flows across the blade passages is expressed by the ratio of relative velocities at outlet and inlet (K=Cr2/Cr1). The factor K is called

Friction factor

Blade velocity coefficient

Blade speed ratio

Utilization factor

In an impulse turbine, the blade friction reduces the relative velocity of steam on passing over the blades by about

5-8%

10-15%

15-20%

20-30%

In an ideal impulse turbine, the

The absolute velocity at the inlet of moving blade is equal to that at the outlet

The relative velocity at the inlet of moving blade is equal to that at the outlet

Axial velocity at the inlet is equal to that at the outlet

Whirl velocity at the inlet is equal to that at the outlet

Blading efficiency is defined as the ratio of

Relative velocities at outlet and inlet

Blade speed and absolute steam velocity at inlet

Work done by steam on blades and the energy supplied to the blades

Cosine of the angles made by relative velocities at outlet and inlet

Blading efficiency is also known as

Stage efficiency

Overall efficiency

Nozzle efficiency

Diagram efficiency

In a single stage impulse turbine, the maximum blading efficiency is given by__________

When compared to stable flow, the available enthalpy drop for supersaturated flow of steam through a nozzle

Remains same

Increases

Decreases

Is unpredictable

Because of sonic and supersonic speeds, the time taken by steam for its passage through nozzle is of the order of

For supersaturated adiabatic flow through a nozzle, the pressure p and volume v are related by the expression

pv=c

Pv1.3=c

Pv1.135=c

Pv1.15=c

The specific volume of supersaturated steam can be worked out by using the correlation

pv=0.01(H-464.1)

pv=0.1(H-464.1)

Pv1.3=0.3(H-464.1)

pv=0.15(H+464.1)

Where v is specific volume in m3/kg, H is enthalpy of steam in kcal/kg and p is the pressure in kgf/cm2

Wilson’s line is associated with

Governing of steam engines

Supersaturated expansion through a steam nozzle

Binary vapour cycle

Condensation of steam in the later stages of a steam turbine

Neglecting the effect of friction and assuming blades to be symmetrical, the maximum blading efficiency of a single stage impulse turbine is given by

2 cos2

cos2

Cos2

In a single stage impulse turbine, the maximum blading efficiency is obtained when

=cos

=cos2

=

=

When is the nozzle angle and is the blade speed ratio

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