Compressible Flow: Master the Fundamentals of High-Speed Gas Dynamics

Question 1

In a normal shock wave in supersonic flow, what occurs to the total pressure?

Accepted Answer

Decreases

Answer

Increases significantly

Answer

Remains unchanged

Answer

Becomes zero

Question 2

In one-dimensional compressible flow, which physical property is assumed to change with both pressure and temperature?

Accepted Answer

Density

Answer

Viscosity

Answer

Velocity

Answer

Pressure

Question 3

What is a defining characteristic of a normal shock wave in compressible flow?

Accepted Answer

A sudden increase in velocity, pressure, and temperature.

Answer

A gradual decrease in velocity, pressure, and temperature.

Answer

A change in the direction of flow.

Answer

A constant value of velocity.

Question 4

Which characteristic defines isentropic flow?

Accepted Answer

Constant entropy along a streamline

Answer

Constant temperature and velocity along a streamline

Answer

No change in flow direction

Answer

No friction

Question 5

In supersonic flow, what triggers the formation of a normal shock wave?

Accepted Answer

An increase in the local Mach number above unity

Answer

A decrease in the local Mach number below unity

Answer

A rise in static pressure

Answer

A decrease in the local temperature

Question 6

In a supersonic flow through a normal shock wave, what is the Mach number downstream of the shock?

Accepted Answer

Less than 1

Answer

Greater than 1

Answer

Equal to 1

Answer

Cannot be determined without additional information

Question 7

In a one-dimensional, constant area flow of an ideal gas with a Mach number of 2.5, what is the effect of introducing a normal shock wave?

Accepted Answer

The flow experiences an increase in entropy, resulting in a decrease in temperature and pressure.

Answer

The flow accelerates and becomes supersonic downstream of the shock wave.

Answer

The flow velocity remains constant across the shock wave.

Question 8

In an isentropic flow of an ideal gas through a converging-diverging duct, how does the Mach number (M) at a specific location relate to the cross-sectional area (A) of the duct at that location?

Accepted Answer

M is inversely proportional to A.

Answer

M is constant throughout the duct.

Answer

M is directly proportional to A.

Question 9

Which thermodynamic process involves no change in entropy?

Accepted Answer

Isentropic

Answer

Isothermal

Answer

Adiabatic

Question 10

In isentropic flow, what happens to the specific entropy of the fluid as it moves along a streamline?

Accepted Answer

Remains constant

Answer

Increases

Answer

Decreases

Answer

Varies randomly

Question 11

Which of the following phenomena is exclusively characteristic of compressible fluid flow?

Accepted Answer

Shock waves

Answer

Laminar flow

Answer

Viscous dissipation

Answer

Poiseuille flow

Question 12

In an isentropic nozzle, the flow is:

Accepted Answer

Adiabatic and reversible

Answer

Isothermal and irreversible

Answer

Adiabatic and irreversible

Answer

Isothermal and reversible

Question 13

The Mach number of a flow is defined as:

Accepted Answer

The ratio of flow velocity to sonic velocity

Answer

The ratio of pressure to density

Answer

The ratio of temperature to viscosity

Answer

The ratio of velocity to pressure

Question 14

A shock wave can be described as:

Accepted Answer

A discontinuity in the flow field

Answer

A region of supersonic flow

Answer

A region of subsonic flow

Answer

A type of expansion fan

Question 15

The normal component of velocity across a shock wave is:

Accepted Answer

Discontinuous

Answer

Continuous

Answer

Zero

Answer

Sonic

Question 16

The Prandtl-Meyer expansion fan is:

Accepted Answer

An isentropic expansion of a supersonic flow

Answer

An isentropic compression of a subsonic flow

Answer

A shock wave with a curved front

Answer

A region of viscous flow

Question 17

In an isentropic process for a perfect gas, which property remains constant?

Accepted Answer

Entropy

Answer

Temperature

Answer

Enthalpy

Answer

Volume

Question 18

What is the primary reason for the formation of a shock wave in a compressible flow?

Accepted Answer

Rapid changes in pressure and density

Answer

Viscous dissipation

Answer

Expansion of the flow

Answer

Heat transfer

Question 19

Which of the following statements about expansion fans in compressible flow is accurate?

Accepted Answer

They involve a gradual expansion of the flow

Answer

They are regions of supersonic flow

Answer

They occur only in subsonic flows

Answer

They are accompanied by an increase in pressure

Question 20

The Mach number for a flow represents:

Accepted Answer

The ratio of flow velocity to the speed of sound

Answer

The ratio of pressure to density

Answer

The ratio of temperature to pressure

Answer

The ratio of density to viscosity

Question 21

What is the key difference between a normal shock and an oblique shock?

Accepted Answer

Normal shocks have straight wavefronts, while oblique shocks have curved wavefronts

Answer

Normal shocks occur in subsonic flows, while oblique shocks occur in supersonic flows

Answer

Normal shocks involve a larger pressure change than oblique shocks

Answer

Normal shocks do not occur in compressible flow, while oblique shocks do

Question 22

Which method is used to analyze the flow properties across a shock wave?

Accepted Answer

Rankine-Hugoniot relations

Answer

Bernoulli's equation

Answer

Darcy-Weisbach equation

Answer

Maxwell's equations

Question 23

For a converging-diverging nozzle, what is the Mach number at its throat?

Accepted Answer

1

Answer

0

Answer

Less than 1

Answer

Greater than 1

Question 24

Which type of expansion fan is the Prandtl-Meyer expansion?

Accepted Answer

Prandtl-Meyer expansion

Answer

Isentropic expansion

Answer

Shock wave

Answer

Vortex sheet

Question 25

The isentropic stagnation temperature is:

Accepted Answer

Higher than the flow temperature

Answer

Equal to the flow temperature

Answer

Lower than the flow temperature

Answer

Dependent on the Mach number

Question 26

In supersonic flow, the relationship between Mach number (M) and pressure coefficient (Cp) is given by:

Accepted Answer

M = sqrt((1 + Cp)/(1 - Cp))

Answer

M = sqrt((1 - Cp)/(1 + Cp))

Answer

Cp = M^2 - 1

Answer

Cp = 1 - M^2

Question 27

Which of the following dimensionless parameters is particularly relevant in the analysis of compressible fluid flow?

Accepted Answer

Mach number

Answer

Reynolds number

Answer

Prandtl number

Answer

Nusselt number

Question 28

In a compressible flow through a convergent nozzle, the area ratio at the nozzle throat is referred to as:

Accepted Answer

Critical

Answer

Subcritical

Answer

Supercritical

Answer

Mach 1

Question 29

The critical pressure ratio for a convergent-divergent nozzle in compressible flow is:

Accepted Answer

0.528

Answer

1.0

Answer

1.893

Answer

2.403

Question 30

In a Prandtl-Meyer expansion fan in compressible flow, the flow turns:

Accepted Answer

Outward

Answer

Inward

Answer

Upward

Answer

Downward

Question 31

Which of the following is the fundamental governing equation for one-dimensional, steady, inviscid, and adiabatic compressible flow?

Accepted Answer

Euler equation

Answer

Navier-Stokes equation

Answer

Bernoulli equation

Answer

isentropic flow equation

Question 32

What is the defining characteristic of isentropic flow?

Accepted Answer

Entropy remains constant

Answer

Heat transfer occurs

Answer

Flow is reversible

Answer

Velocity is constant

Question 33

What is the significance of the Prandtl-Meyer expansion fan?

Accepted Answer

It represents a region of supersonic flow expansion

Answer

It is characterized by a constant entropy change

Answer

It precedes the formation of a shock wave

Answer

It occurs exclusively in two-dimensional flows

Question 34

Define the Mach number and explain its significance.

Accepted Answer

The ratio of flow velocity to the speed of sound

Answer

The ratio of density to viscosity

Answer

The ratio of pressure to temperature

Answer

The ratio of entropy to enthalpy

Question 35

Distinguish between a normal shock and an oblique shock wave in terms of their orientation relative to the flow direction.

Accepted Answer

Normal shock: perpendicular to flow; Oblique shock: not perpendicular

Answer

Normal shock: not perpendicular to flow; Oblique shock: perpendicular

Answer

Normal shock: strong shock; Oblique shock: weak shock

Answer

Normal shock: weak shock; Oblique shock: strong shock

Question 36

In supersonic flow applications, how does boundary layer control contribute to enhanced performance?

Accepted Answer

Reduces skin friction and prevents flow separation

Answer

Increases skin friction and promotes flow separation

Answer

Enhances stability and weakens shock waves

Answer

Improves heat transfer and reduces thermal stresses

Question 37

What is the purpose of the Laval nozzle in compressible flow?

Accepted Answer

To accelerate the flow to supersonic speeds

Answer

To decelerate the flow to subsonic speeds

Answer

To maintain constant flow velocity

Answer

To increase the flow temperature

Question 38

Which method is used to solve the conservation equations for compressible flow?

Accepted Answer

Method of characteristics

Answer

Finite element method

Answer

Boundary layer theory

Answer

Reynolds averaging

Question 39

What causes shock wave formation in compressible flow?

Accepted Answer

Rapid deceleration of the flow

Answer

Rapid acceleration of the flow

Answer

Heat addition to the flow

Answer

Boundary layer separation

Question 40

Which of the following is the primary governing equation system for compressible flow?

Accepted Answer

The Euler equations

Answer

The Navier-Stokes equations

Answer

The continuity equation and the energy equation

Answer

The Navier-Stokes equations and the energy equation

Question 41

In isentropic flow, what is the critical assumption made?

Accepted Answer

Negligible heat transfer

Answer

Constant velocity

Answer

Steady-state flow

Answer

Incompressible fluid

Question 42

Which characteristic is unique to a shock wave?

Accepted Answer

Irreversible entropy increase

Answer

Continuous velocity gradient

Answer

Adiabatic process

Answer

Predictable temperature jump

Question 43

What is the significance of the Prandtl-Meyer expansion fan?

Accepted Answer

Describes the expansion of supersonic flow around a corner

Answer

Predicts shock wave formation

Answer

Calculates pressure drop in a convergent-divergent nozzle

Answer

Represents an isentropic flow condition

Question 44

Which dimensionless parameter is used to characterize the compressibility of a fluid?

Accepted Answer

Mach number

Answer

Reynolds number

Answer

Prandtl number

Answer

Grashof number

Question 45

What is the primary distinction between subsonic, transonic, and supersonic flows?

Accepted Answer

Mach number

Answer

Reynolds number

Answer

Prandtl number

Answer

Grashof number

Question 46

In a supersonic nozzle, the flow is converging-diverging. Under what condition does a normal shock wave occur?

Accepted Answer

When the back pressure exceeds the critical pressure

Answer

When the flow is choked at the throat

Answer

When the back pressure is less than the critical pressure

Question 47

In a converging-diverging nozzle, at what Mach number does the flow become choked at the throat?

Accepted Answer

Ma = 1

Answer

Ma = 0

Answer

Ma = 2

Answer

Ma = 0.5

Question 48

What is the critical pressure ratio for a supersonic nozzle?

Accepted Answer

Pr = (2 / (gamma + 1))^((gamma) / (gamma - 1))

Answer

Pr = ((gamma - 1) / (2 * gamma))

Answer

Pr = 1

Answer

Pr = ((gamma + 1) / (2 * gamma))

Question 49

Which of the following is the correct expression for the area ratio of a Laval nozzle?

Accepted Answer

Ae/At = (1 / Ma2) * sqrt(((gamma + 1) / 2) * (1 + ((gamma - 1) / 2) * Ma2^2))

Answer

Ae/At = Ma2 * sqrt(((gamma + 1) / 2) * (1 + ((gamma - 1) / 2) * Ma2^2))

Answer

Ae/At = (1 / Ma1) * sqrt(((gamma + 1) / 2) * (1 + ((gamma - 1) / 2) * Ma1^2))

Question 50

Which of the following is the equation of state for an ideal gas?

Accepted Answer

PV = RT

Answer

P^2V = RT

Answer

PV/T = R

Answer

PV^2 = RT

Question 51

What is the Mach number of a flow?

Accepted Answer

The ratio of flow velocity to the local speed of sound

Answer

The Reynolds number of the flow

Answer

The square of the flow velocity

Question 52

Which of the following is an isentropic process?

Accepted Answer

A process in which entropy remains constant

Answer

A process in which temperature remains constant

Answer

A process in which density remains constant

Answer

A process in which pressure remains constant

Question 53

Which of the following is a governing equation for compressible flow?

Accepted Answer

The conservation of mass, momentum, and energy equations

Answer

The Navier-Stokes equations

Answer

The Bernoulli equation

Question 54

What is the effect of compressibility on the flow of a gas?

Accepted Answer

It introduces non-linearity into the governing equations and affects the flow characteristics.

Answer

It makes the flow more viscous.

Answer

It has no effect on the flow of a gas.

Question 55

What is the critical Mach number for a nozzle?

Accepted Answer

The Mach number at which the flow becomes choked at the nozzle exit

Answer

The Mach number at which the flow becomes subsonic

Answer

The Mach number at which the flow becomes turbulent

Answer

The Mach number at which the flow becomes supersonic

Question 56

What is the relationship between the stagnation temperature and the static temperature?

Accepted Answer

Stagnation temperature is always greater than or equal to static temperature for a compressible flow.

Answer

Stagnation temperature is always less than static temperature for a compressible flow.

Answer

Stagnation temperature is equal to static temperature for a compressible flow.

Question 57

What are the fundamental governing equations for compressible flow?

Accepted Answer

Conservation of mass, momentum, and energy

Answer

Conservation of mass and entropy only

Answer

Conservation of momentum and energy only

Answer

Conservation of mass and momentum only

Question 58

Which of the following is a characteristic of isentropic flow?

Accepted Answer

Entropy remains constant throughout the flow

Answer

Pressure remains constant

Answer

Temperature remains constant

Answer

Velocity remains constant

Question 59

What is the relationship between Mach number and flow regime?

Accepted Answer

Subsonic: Ma < 1; Supersonic: Ma > 1

Answer

Transonic: Ma > 1; Subsonic: Ma < 1

Answer

Subsonic: Ma > 1; Supersonic: Ma < 1

Answer

Transonic: Ma < 1: Supersonic: Ma > 1

Question 60

What is the primary cause of shock wave formation?

Accepted Answer

Sudden change in flow velocity

Answer

High pressure gradient

Answer

Large viscosity

Answer

Low temperature gradient

Question 61

Which of the following is a type of expansion wave?

Accepted Answer

Prandtl-Meyer expansion fan

Answer

Shock wave

Answer

Contact discontinuity

Answer

Compression wave

Question 62

What is the significance of the Rayleigh line in compressible flow?

Accepted Answer

Divides the flow regime into subsonic and supersonic regions

Answer

Indicates the onset of shock waves

Answer

Represents the stagnation point

Question 63

Which of the following is a common application of compressible flow principles?

Accepted Answer

Design of supersonic aircraft

Answer

Design of wind turbines

Answer

Design of water pumps

Answer

Design of hydraulic systems

Question 64

What is the fundamental assumption made in the derivation of the isentropic relations?

Accepted Answer

Flow is adiabatic and reversible

Answer

Flow is isothermal and irreversible

Answer

Flow is isothermal and reversible

Answer

Flow is adiabatic and irreversible