The process, which causes the air to enter the impeller blades of a centrifugal compressor at ________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

Which of the following statements are correct? 1) Velocity compounded impulse turbine gives less speed and less efficiency. 2) For an ideal centrifugal compressor, the pressure produced depends on impeller velocity and diameter. 3) While flowing through the rotor blades in a gas turbine, the relative velocity of gas continuously decreases. 4) While flowing through the rotor blades in an axial flow compressor, the relative velocity of air continuously decreases.

A

1 and 3

B

2 and 3

C

1 and 4

D

2 and 4

Consider the following statements pertaining to centrifugal pumps: 1. The inlet to the impeller of a centrifugal pump is always axial, while the outlet may be radial or inclined. 2. The impeller may be shrouded on both sides with an eye at the center and vanes curved backward. 3. Impeller of double-entry type has a balanced radial thrust. 4. Un-shrouded and part-shrouded impeller are used only where high efficiency is unimportant. Which of these statements are correct?

A

1, 2, 3 and 4

B

1, 2 and 3 only

C

1, 2 and 4 only

D

2, 3 and 4 only

The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades.

A

Inlet tip of a blade curves in a direction opposite to that

B

Outlet tip of a blade curves in a direction opposite to that

C

Inlet tip of a blade is towards the direction

D

Outlet tip of a blade is towards the direction

Statement (I): The term surge indicates a phenomenon of instability which takes place at low flow values and which involves an entire system including not only the centrifugal compressor, but also the group of components traversed by the fluid upstream and downstream of it. Statement(II): Choking is defined as separation of fluid from the rotor blades of centrifugal compressor.

A

Both statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

B

Both Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of Statement (I)

C

Statement (I) is true but Statement (II) is false

D

Statement (I) is false but Statement (II) is true

In a reaction turbine, the fixed blades and moving blades are of the same shape but reversed in direction. The angle of the discharging tip is 20°. The mean blade velocity is 200 m/s. The axial velocity of flow of steam is half of the mean blade velocity. Determine the inlet angles of blades.

A

45°

B

53°

C

63°

D

71°

What is the monoisotopic and average mass of valine? Given data: Mass of the most abundant isotope of Carbon (C°)=12.0000, Mass of most abundant isotope of Hydrogen (H°)=1.0078, Mass of most abundant isotope of Oxygen (O°)=15.9949, Mass of most abundant isotope of Nitrogen (N°)=14.0031, The average mass of Carbon (C)=12.011, The average mass of Hydrogen (H)=1.008, The average mass of Oxygen (O)=15.999, The average mass of Nitrogen (N)=14.007.

A

99.068 and 99.2361

B

99.216 and 99.326

C

99.111 and 99.321

D

99.068 and 99.132

Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet, and Vf = Velocity of flow at inlet)

A

Q = π.D.Vf

B

Q = π.b.Vf

C

Q = π.D.bf.V

D

Q = D.b.Vf

Discharge (Q) of a centrifugal pump is given by (where D = Diameter of impeller at inlet, b = Width of impeller at inlet and V_f = Velocity of flow at inlet)

A

$${\text{Q}} = \pi {\text{D}}{{\text{V}}_{\text{f}}}$$

B

$${\text{Q}} = \pi {\text{b}}{{\text{V}}_{\text{f}}}$$

C

$${\text{Q}} = \pi {\text{Db}}{{\text{V}}_{\text{f}}}$$

D

$${\text{Q}} = {\text{Db}}{{\text{V}}_{\text{f}}}$$

Under which of the following condition(s) are the occluded fronts created? 1. When the front remains stationary 2. When cold air mass moves to warm air mass 3. When warm air mass moves to cold air mass 4. When an air mass is fully lifted above the land surface Select the correct answer using the code given below :

A

1 and 2

B

2 and 3

C

3 and 4

D

4 only

Steam issues from the nozzle with a velocity of 1000 m/s in a De Laval turbine. The nozzle angle is 20°, mean blade velocity is 350 m/s. The inlet and outlet angles of the blades are equal. The mass of the steam flowing through the turbine per second is 0.3 kg. Calculate the tangential force on the blades. Take blade velocity coefficient as 0.8.

A

451 N

B

256 N

C

318 N

D

196 N

The process, which causes the air to enter the impeller blades of a centrifugal compressor at ________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

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