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# Compressible Flow And Flow Through Open Channel - MCQ Test 2

## 30 Questions MCQ Test Mock Test Series - Mechanical Engineering (ME) for GATE 2020 | Compressible Flow And Flow Through Open Channel - MCQ Test 2

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This mock test of Compressible Flow And Flow Through Open Channel - MCQ Test 2 for Mechanical Engineering helps you for every Mechanical Engineering entrance exam. This contains 30 Multiple Choice Questions for Mechanical Engineering Compressible Flow And Flow Through Open Channel - MCQ Test 2 (mcq) to study with solutions a complete question bank. The solved questions answers in this Compressible Flow And Flow Through Open Channel - MCQ Test 2 quiz give you a good mix of easy questions and tough questions. Mechanical Engineering students definitely take this Compressible Flow And Flow Through Open Channel - MCQ Test 2 exercise for a better result in the exam. You can find other Compressible Flow And Flow Through Open Channel - MCQ Test 2 extra questions, long questions & short questions for Mechanical Engineering on EduRev as well by searching above.
QUESTION: 1

Solution:

Ans. (a)

QUESTION: 2

### A correctly designed convergent-divergent nozzle working at a designed load is:

Solution:

Ans. (b) Divergent portion will be act as nozzle only if flow is supersonic for that it must be choked.

QUESTION: 3

### The concentration of pressure pulses created by an object moving atMach number of 0.5 is:

Solution:

Ans. (a) Pressure pulses moves with sonic velocity but object moves with half of sonic velocity so concentration of pressure pulse become larger ahead of the object.

QUESTION: 4

In isentropic flow between two points, the stagnation:[

Solution:

Ans. (d) Stagnation temperature cannot vary

QUESTION: 5

For one-dimensional is entropic flow in a diverging passage, if the initial static pressure is P1 and the initial Mach number is M1 ( (M1 < 1),then for the down stream flow

Solution:

Ans. (b) For down stream flow, M2 < M1 and P2 > P1 for diverging section and
subsonic flow conditions.

QUESTION: 6

Consider the following statements:
1. De Laval nozzle is a subsonic nozzle.
2. Supersonic nozzle is a converging passage.
3. Subsonic diffuser is a diverging passage.
Which of these statements is/are correct?

Solution:

(d) Only third statement is correct, i.e. subsonic diffuser is a diverging passage.

QUESTION: 7

The critical pressure ratios for the flow of dry saturated and superheated steam through a nozzle are respectively.

Solution:

Ans. (c) Critical pressure ratio for dry saturated and superheated steam through
a nozzle are 0.577 and 0.546.

QUESTION: 8

If the cross-section of a nozzle is increasing in the direction of flow insupersonic flow, then in the down stream direction.

Solution:

Ans. (d)

QUESTION: 9

Steam pressures at the inlet and exit of a nozzle are 16 bar and 5·2 barrespectively and discharge is 0·28 m3/s. Critical pressure ratio is 0.5475.If the exit pressure is reduced to 3·2 bar then what will be the flow ratein m3/s?

Solution:

Ans. (a) Flow Ratio remains constant for chocked condition. Therefore flow rate
will remain same even when there is decrease in the pressure to 3.2 bar.
∴ Flow rate in m3 / sec = 0.280 m3 / sec

QUESTION: 10

Assertion (A): For pressure ratio greater than the critical pressure ratio, a convergent-divergent nozzle is required.
Reason (R): Divergent portion increases the flow area which increasesthe mass flow rate.

Solution:

Ans. (c) A is correct but R is wrong.

QUESTION: 11

Shear stress in a turbulent flow is due to:

Solution:

Ans. (d)

QUESTION: 12

Reynolds stress may be defined as the

Solution:

Ans. (c) Reynolds stress may be defined as additional shear stresses due to fluctuating velocity components in a turbulent flow.

QUESTION: 13

Consider the following statements regarding a hydraulic jump:
1. There occurs a transformation of super critical flow to sub-criticalflow.
2. The flow is uniform and pressure distribution is due to hydrostatic force before and after the jump.
3. There occurs a loss of energy due to eddy formation and turbulence.
Which of these statements are correct?

Solution:

Ans. (a)

QUESTION: 14

A convergent divergent nozzle is designed for a throat pressure 2.2MPa. If the pressure at the exit is 2.3 MPa, then the nature of the flow at the exit will be:

Solution:

Ans. (c)

QUESTION: 15

Consider the following statements for compressible flow through avarying area passage:
1. For a convergent nozzle, if the exit pressure is less than critical,external flow will not be isentropic.
2. Supersonic-subsonic diffuser would appear similar to nozzle and works without irreversibility.
Which of the statements given above is/are correct?

Solution:

Ans. (c)

QUESTION: 16

Which one of the following is proper for a normal shock wave?

Solution:

Ans. (b)

QUESTION: 17

Which of the following parameters decrease across a normal shock wave?
1. Mach number
2. Static pressure
3. Stagnation pressure
4. Static temperature
Select the correct answer using the codes given below:

Solution:

Ans. (a)

QUESTION: 18

Assertion (A): A convergent-divergent nozzle may give supersonic orsubsonic flow at the exit even if the throat is choked.
Reason (R): Depending on the back pressure ratio Pb/Po the divergent part of the nozzle may act as a supersonic nozzle or a subsonic diffuser.

Solution:

Ans. (a)

QUESTION: 19

In a normal shock in a gas, the:

Solution:

Ans. (a)

QUESTION: 20

Across a normal shock wave in a converging-diverging nozzle foradiabatic flow, which of the following relations are valid?

Solution:

Ans. (d)

QUESTION: 21

In a normal shock in a gas:

Solution:

Ans. (c)

QUESTION: 22

The fluid property that remains unchanged across a normal shockwave is:

Solution:

Ans. (a)

QUESTION: 23

A normal shock:

Solution:

Ans. (b)

QUESTION: 24

Consider the following statements pertaining to one-dimensional isentropic flow in a convergent-divergent passage
1. A convergent-divergent passage may function as a supersonicnozzle or a venturi depending on the back pressure.
2. At the throat, sonic conditions exits for subsonic or supersonic flowat the outlet.
3. A supersonic nozzle discharges fluid at constant rate even if the exit pressure is lower than the design pressure.
4. A normal shock appears in the diverging section of the nozzle if the back pressure is above the design pressure but below a certain minimum pressure for venturi operation.
Which of these statements are correct?

Solution:

Ans. (a) At the throat, sonic conditions not exits for subsonic flow when it is venture.

QUESTION: 25

Consider the following statements:
Across the normal shock, the fluid properties change in such a mannerthat the
1. Velocity of flow is subsonic
2. Pressure increases
3. Specific volume decreases
4. Temperature decreasesOf these correct statements are

Solution:

Ans. (d)

QUESTION: 26

Which one of the following is correct?
In a normal shock wave in one dimensional flow,

Solution:

Ans. (b) Entropy increases across a shock with consequent decrease in stagnation
pressure and stagnation density across the shock.

QUESTION: 27

Assertion (A): A normal shock wave can occur at any section in aconvergent-divergent nozzle.
Reason (R): A normal shock wave occurs only when the flow of the fluidis supersonic and the subsequent flow after the shock is subsonic.

Solution:

Ans. (d) A shock wave takes place in the diverging section of a nozzle, in a diffuser, throat of a supersonic wind tunnel, in front of sharp-nosed bodies.

QUESTION: 28

Assertion (A): A normal shock always makes a supersonic flow of acompressible fluid subsonic, but an oblique shock may not ensure subsonic flow after the shock.
Reason (R): A normal shock reduces the stagnation pressure and stagnation enthalpy considerably whereas the loss at oblique shock isminimized.

Solution:

Ans. (c)

QUESTION: 29

A converging diverging nozzle is connected to a gas pipeline.
At the inlet of the nozzle (converging section) the Mach number is
2. Itis observed that there is a shock in the diverging section.
What is thevalue of the Mach number at the throat?

Solution:

Ans. (b)

QUESTION: 30

Introduction of a Pitot tube in a supersonic flow would produce

Solution:

Ans. (a)