Nozzle and Diffuser Flow: Interactive Learning Quizzes for Fluid Mechanics

Question 1

For a supersonic flow through a nozzle, the exit pressure:

Accepted Answer

Is less than the ambient pressure

Answer

Is equal to the ambient pressure

Answer

Is greater than the ambient pressure

Answer

Cannot be determined without additional information

Question 2

The maximum theoretical flow rate through a choked nozzle is:

Accepted Answer

Equal to the sonic flow rate

Answer

Greater than the sonic flow rate

Answer

Less than the sonic flow rate

Answer

Cannot be determined without additional information

Question 3

The Mach number at the throat of a converging-diverging nozzle is:

Accepted Answer

1

Answer

0

Answer

Less than 1

Answer

Greater than 1

Question 4

The efficiency of a diffuser is primarily determined by its:

Accepted Answer

Pressure recovery ratio

Answer

Mach number ratio

Answer

Area ratio

Answer

Velocity ratio

Question 5

In a converging-diverging nozzle operating in overexpanded conditions, what is likely to occur?

Accepted Answer

A shock wave forms at the nozzle exit

Answer

The pressure at the exit is higher than the ambient pressure

Answer

The flow remains entirely subsonic

Answer

The flow becomes choked

Question 6

Which of the following factors does NOT influence the mass flow rate through a nozzle?

Accepted Answer

Fluid viscosity

Answer

Nozzle geometry

Answer

Stagnation pressure

Answer

Stagnation temperature

Question 7

The isentropic flow assumption used in nozzle analysis implies that the flow is:

Accepted Answer

Adiabatic and reversible

Answer

Incompressible

Answer

Isothermal

Answer

Viscous

Question 8

The Prandtl-Meyer expansion fan is associated with:

Accepted Answer

Supersonic flow

Answer

Subsonic flow

Answer

Transonic flow

Answer

Laminar flow

Question 9

What characterizes isentropic flow in a nozzle, and why is it important for nozzle design?

Accepted Answer

Isentropic flow in a nozzle is frictionless, adiabatic, and reversible, resulting in constant entropy and maximum flow velocity.

Answer

Isentropic nozzles have perfectly circular cross-sections for uniform expansion.

Answer

Isentropic flow in nozzles is a theoretical concept with no practical applications.

Question 10

The critical pressure ratio for a converging-diverging nozzle is approximately:

Accepted Answer

0.634

Answer

0.528

Answer

0.707

Answer

0.800

Question 11

For isentropic flow, the ideal throat area of a converging-diverging nozzle is proportional to:

Accepted Answer

Mass flow rate

Answer

Stagnation pressure

Answer

Stagnation temperature

Answer

Mach number

Question 12

The shock waves that occur in a converging-diverging nozzle when the back pressure is increased are:

Accepted Answer

Normal shock waves

Answer

Oblique shock waves

Answer

Expansion waves

Answer

Compression waves

Question 13

Which of the following statements accurately describes supersonic flow in a converging-diverging nozzle?

Accepted Answer

The flow is isentropic up to the throat, and then expands supersonically in the diverging section.

Answer

The Mach number is always less than 1.

Answer

The pressure remains constant throughout the nozzle.

Answer

The flow is supersonic throughout the nozzle.

Question 14

The primary purpose of a diffuser in a fluid system is to:

Accepted Answer

Convert kinetic energy into pressure energy, thereby increasing the pressure of the fluid.

Answer

Decrease the fluid pressure.

Answer

Generate shock waves in the fluid.

Answer

Increase the Mach number of the fluid.

Question 15

The efficiency of a diffuser is typically quantified by:

Accepted Answer

The ratio of pressure rise to velocity decrease.

Answer

The ratio of inlet pressure to outlet pressure.

Answer

The ratio of velocity decrease to pressure rise.

Question 16

The function of a back pressure valve in a diffuser is to:

Accepted Answer

Control the pressure recovery by regulating the outlet pressure.

Answer

Prevent flow separation.

Answer

Reduce noise levels.

Answer

Increase the diffuser efficiency.

Question 17

For a converging-diverging nozzle operating at design conditions, what is the Mach number at the throat?

Accepted Answer

1

Answer

1.5

Answer

0.5

Question 18

What is a primary function of a diffuser?

Accepted Answer

Increase pressure

Answer

Increase velocity

Answer

Decrease temperature

Question 19

In a converging nozzle, what is the maximum achievable Mach number?

Accepted Answer

1

Answer

1.5

Answer

0.5

Question 20

Which of the following is a common application of converging-diverging nozzles?

Accepted Answer

Rocket engines

Answer

Air compressors

Answer

Heat exchangers

Answer

Water pumps

Question 21

A converging-diverging nozzle operates with a back pressure greater than the critical pressure. What type of flow regime is established within the nozzle under these conditions?

Accepted Answer

Subsonic flow throughout the nozzle

Answer

Supersonic flow throughout the nozzle

Answer

Sonic flow at the throat, followed by supersonic flow

Answer

Sonic flow at the throat only

Question 22

What is the primary function of a diffuser in a fluid flow system?

Accepted Answer

Convert kinetic energy to pressure energy

Answer

Reduce pressure drop

Answer

Increase turbulence

Answer

Increase flow velocity

Question 23

Which of the following factors most directly influences the efficiency of a diffuser?

Accepted Answer

Pressure recovery coefficient

Answer

Pipe diameter

Answer

Fluid viscosity

Answer

Flow rate

Question 24

In a subsonic diffuser, the flow velocity:

Accepted Answer

Decreases

Answer

Remains constant

Answer

Becomes supersonic

Answer

Increases

Question 25

Which type of diffuser is commonly used in supersonic flow applications?

Accepted Answer

Compression ramp diffuser

Answer

Converging diffuser

Answer

Subsonic diffuser

Answer

Parallel diffuser

Question 26

What is the relationship between the pressure recovery coefficient and the diffuser efficiency?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Not related

Answer

Quadratic

Question 27

In a converging-diverging nozzle, the point where the flow reaches sonic velocity is known as the:

Accepted Answer

Throat

Answer

Exit

Answer

Inlet

Answer

Convergent section