Internal Flows in Pipes: Fluid Mechanics for Mechanical Engineers

Question 1

Laminar flow is characterized by:

Accepted Answer

Fluid particles moving in parallel layers without relative motion.

Answer

Fluid particles moving randomly in all directions.

Answer

Fluid particles creating eddies and vortices.

Answer

Laminar flow does not occur in pipes.

Question 2

In turbulent flow through a pipe, the friction factor is generally:

Accepted Answer

Higher than in laminar flow.

Answer

Lower than in laminar flow.

Answer

Equal to the friction factor in laminar flow.

Answer

Cannot be determined without additional information.

Question 3

Which factor does NOT influence the pressure drop in a pipe?

Accepted Answer

Fluid temperature

Answer

Pipe length

Answer

Pipe diameter

Answer

Fluid density

Question 4

In a pipe network with two parallel pipes of equal length and diameter, the total flow rate through the network is:

Accepted Answer

Twice the flow rate through each individual pipe.

Answer

Equal to the flow rate through each individual pipe.

Answer

Half the flow rate through each individual pipe.

Answer

Cannot be determined without additional information.

Question 5

Which method is NOT used for calculating the friction factor for turbulent flow in a pipe?

Accepted Answer

Reynolds number

Answer

Moody diagram

Answer

Colebrook equation

Answer

Darcy-Weisbach equation

Question 6

The Reynolds number is a dimensionless parameter that does NOT depend on:

Accepted Answer

Pipe length

Answer

Pipe diameter

Answer

Fluid velocity

Answer

Fluid viscosity

Question 7

What parameter plays the most crucial role in determining whether fluid flow is laminar or turbulent?

Accepted Answer

Reynolds Number

Answer

Pipe diameter

Answer

Fluid velocity

Question 8

The velocity profile in a circular pipe for laminar flow is:

Accepted Answer

Parabolic

Answer

Uniform

Answer

Linear

Answer

Exponential

Question 9

The Darcy-Weisbach equation for pressure drop in a pipe is:

Accepted Answer

ΔP = f * (L/D) * (ρV²/2)

Answer

ΔP = f * (L/D) * (ρgV²)

Answer

ΔP = f * (L/D) * (μV/ρ)

Answer

ΔP = f * (L/D) * (ρV²/μ)

Question 10

The Moody diagram is used to determine:

Accepted Answer

Friction factors for pipe flow

Answer

Pressure drops in pipe networks

Answer

Pump head requirements

Answer

Pipe diameters for given flow rates

Question 11

In turbulent flow, the friction factor depends on:

Accepted Answer

Reynolds number and relative roughness

Answer

Velocity and pipe diameter

Answer

Fluid viscosity and pipe length

Answer

Flow rate and pressure gradient

Question 12

The Reynolds number indicates:

Accepted Answer

The ratio of inertial forces to viscous forces

Answer

The ratio of pressure drop to pipe diameter

Answer

The ratio of flow rate to pipe cross-sectional area

Answer

The ratio of pipe length to pipe diameter

Question 13

Which characteristic is NOT true for laminar flow in a pipe?

Accepted Answer

Friction factor varies with Reynolds number

Answer

Smooth and orderly flow

Answer

Parabolic velocity profile

Answer

Pressure drop is proportional to flow rate

Question 14

The hydraulic diameter of a non-circular pipe is:

Accepted Answer

4 times the cross-sectional area divided by the wetted perimeter

Answer

The diameter of a circular pipe with the same flow rate and pressure drop

Answer

The average diameter of the pipe cross-section

Answer

The diameter of the largest inscribed circle in the pipe cross-section

Question 15

The Hardy Cross method in pipe network analysis is used to:

Accepted Answer

Solve for unknown flow rates and pressures in a network

Answer

Determine the most efficient pipe layout for a given application

Answer

Calculate the pressure drop in a single pipe

Answer

Design pumps and valves for a piping system

Question 16

Which of the following equations represents the Darcy-Weisbach formula for calculating pressure drop (ΔP) in a pipe due to friction?

Accepted Answer

ΔP = f * (L/D) * (ρ/2) * V^2

Answer

ΔP = f * (L/D) * (μ/ρ) * V

Answer

ΔP = (ρ/2) * V^2

Answer

ΔP = μ * L * V / D

Question 17

In a pipe with laminar flow, the velocity profile across the pipe's cross-section is:

Accepted Answer

Parabolic

Answer

Linear

Answer

Exponential

Answer

Hyperbolic

Question 18

Which numerical method is used to determine the flow rates in each branch of a pipe network designed to deliver a specific flow rate to each branch?

Accepted Answer

Hardy-Cross method

Answer

Gauss-Seidel method

Answer

Euler's method

Answer

Runge-Kutta method

Question 19

A characteristic of a hydraulically smooth pipe is:

Accepted Answer

Friction factor independent of Reynolds number

Answer

Very high friction factor

Answer

Rough inner surface

Answer

Laminar flow regime

Question 20

In a turbulent flow regime, the pressure drop (ΔP) along a pipe can be estimated using:

Accepted Answer

Moody diagram

Answer

Hagen-Poiseuille equation

Answer

Bernoulli equation

Answer

Stokes equation

Question 21

The Reynolds number (Re) for flow in a pipe is a dimensionless parameter that represents the ratio of:

Accepted Answer

Inertial forces to viscous forces

Answer

Gravitational forces to inertial forces

Answer

Pressure forces to viscous forces

Answer

Surface tension forces to inertial forces

Question 22

Which equation accurately represents the Darcy-Weisbach equation for calculating pressure drop in a pipe?

Accepted Answer

ΔP = f * (L/D) * (ρV²/2g)

Answer

ΔP = f * (L/D) * (ρV²/2)

Answer

ΔP = f * (L/D) * (ρV²/g)

Answer

ΔP = f * (L/D) * (ρV)

Question 23

For laminar flow in a pipe, what is the typical range of Reynolds numbers?

Accepted Answer

0 to 2100

Answer

2100 to 4000

Answer

4000 to 10000

Answer

Above 10000

Question 24

In the Moody diagram, which parameter represents the relative roughness of a pipe?

Accepted Answer

Relative roughness

Answer

Friction factor

Answer

Reynolds number

Answer

Diameter ratio

Question 25

What is the relationship between the Darcy friction factor (f) and the friction coefficient (λ)?

Accepted Answer

f = λ/4

Answer

f = 2λ

Answer

f = λ²

Answer

f = 1/λ

Question 26

Which flow regime exhibits a parabolic velocity profile?

Accepted Answer

Laminar

Answer

Turbulent

Answer

Critical

Answer

Both laminar and turbulent

Question 27

In internal pipe flows, the critical Reynolds number signifies the:

Accepted Answer

Onset of turbulent flow

Answer

Determination of friction factor

Answer

Prediction of pressure drop

Answer

No practical significance

Question 28

In pipe networks, which of the following is NOT considered a minor loss?

Accepted Answer

Pressure head

Answer

Bends

Answer

Pipe expansions

Question 29

For fluid flow in a pipe, the Reynolds number is 10,000. Which flow regime is most likely occurring?

Accepted Answer

Turbulent flow

Answer

Laminar flow

Answer

Both laminar and turbulent flow

Answer

Neither laminar nor turbulent flow

Question 30

Which equation can be used to calculate the pressure drop due to friction in a pipe?

Accepted Answer

Darcy-Weisbach equation

Answer

Hagen-Poiseuille equation

Answer

Navier-Stokes equations

Answer

Bernoulli's equation

Question 31

What is the primary purpose of the Haaland equation?

Accepted Answer

Calculating friction factors in pipes

Answer

Determining Reynolds number

Answer

Predicting flow patterns

Answer

Analyzing fluid properties

Question 32

For a given flow rate, which pipe configuration will result in the lowest pressure drop?

Accepted Answer

Larger diameter smooth pipe

Answer

Smaller diameter smooth pipe

Answer

Smaller diameter rough pipe

Answer

Larger diameter rough pipe

Question 33

What is the main significance of the Moody diagram?

Accepted Answer

Provides friction factors for various pipe conditions

Answer

Predicts flow patterns based on Reynolds number

Answer

Calculates pressure drops in pipe networks

Answer

Determines fluid properties

Question 34

How does Reynolds number affect the flow regime of a fluid?

Accepted Answer

High Reynolds number indicates turbulent flow.

Accepted Answer

Low Reynolds number indicates laminar flow.

Answer

Reynolds number does not affect flow regime.

Question 35

In laminar flow through a pipe, the velocity profile is best described as:

Accepted Answer

Parabolic

Answer

Linear

Answer

Uniform

Answer

Exponential

Question 36

Which of the following fluids is generally considered to have the highest viscosity?

Accepted Answer

Honey

Answer

Water

Answer

Air

Answer

Gasoline

Question 37

How does increasing the pipe roughness typically affect the friction factor?

Accepted Answer

Increases

Answer

Decreases

Answer

No change

Answer

Depends on the flow regime

Question 38

Which of the following dimensionless parameters is specifically used to quantify pressure drop in pipe flow?

Accepted Answer

Darcy friction factor

Answer

Stanton number

Answer

Euler number

Answer

Froude number

Question 39

The pressure drop in a pipe is predominantly influenced by:

Accepted Answer

Fluid velocity, pipe diameter, and pipe length

Answer

Fluid density and viscosity

Answer

Pipe wall roughness

Answer

Entrance and exit effects

Question 40

The Moody diagram is commonly used to determine:

Accepted Answer

Friction factor for pipe flow

Answer

Velocity profile for laminar flow

Answer

Reynolds number for flow transition

Answer

Pressure drop for open channel flow

Question 41

Which of the following devices is primarily used to measure the flow rate in a pipe?

Accepted Answer

Venturi meter

Answer

Accelerometer

Answer

Thermocouple

Answer

Strain gauge

Question 42

In a circular pipe, the velocity profile for laminar flow is best described as:

Accepted Answer

Parabolic

Answer

Exponential

Answer

Uniform

Answer

Hyperbolic

Question 43

Which of the following is NOT a parameter influencing the Darcy friction factor for pipe flow?

Accepted Answer

Fluid density

Answer

Pipe diameter

Answer

Reynolds number

Answer

Surface roughness

Question 44

The Darcy-Weisbach equation is primarily used to calculate:

Accepted Answer

Pressure drop in a pipe

Answer

Reynolds number for a flow

Answer

Friction factor for a pipe

Answer

Velocity profile in a pipe

Question 45

A characteristic of a fully developed flow in a pipe is:

Accepted Answer

Constant velocity profile

Answer

Velocity gradients near the pipe walls

Answer

Entrance effects present

Answer

Time-varying velocity field

Question 46

A practical application of internal flow analysis is found in the design of:

Accepted Answer

Water distribution systems

Answer

Aerodynamic analysis of aircraft

Answer

Weather forecasting

Answer

Stock market prediction

Question 47

In a branched pipe network, a common method to control flow rate through a specific branch is to:

Accepted Answer

Install a valve

Answer

Adjust the fluid viscosity

Answer

Change the pipe material

Answer

Alter the fluid temperature

Question 48

The Reynolds number is a dimensionless parameter primarily used for:

Accepted Answer

Classifying flow regimes

Answer

Calculating pressure drop

Answer

Determining pipe roughness

Answer

Predicting flow stability

Question 49

In laminar flow, the velocity profile within a circular pipe is:

Accepted Answer

Parabolic

Answer

Linear

Answer

Exponential

Answer

Uniform

Question 50

The Darcy-Weisbach equation is mathematically represented as:

Accepted Answer

h_f = f * (L/D) * (v^2/2g)

Answer

v = (d^2 * g * h_f)/(8 * f * L)

Answer

f = (64/Re) * (L/D)

Answer

Re = (rho * v * D)/mu

Question 51

The purpose of the Moody diagram is to:

Accepted Answer

Determine the friction factor in turbulent flow.

Answer

Calculate the entrance length of a pipe.

Answer

Design pipe networks with specific flow rates.

Answer

Predict the onset of cavitation in a pipe.

Question 52

In a pipe network, the configuration that results in the lowest pressure drop is:

Accepted Answer

Parallel

Answer

Loop

Answer

Tee

Answer

Series

Question 53

When designing pipe networks, which factors are critical to consider?

Accepted Answer

Flow rate and pressure requirements

Answer

Pipe diameter only

Answer

Pipe material only

Answer

Pump type only

Question 54

The energy equation for pipe flow includes which energy components?

Accepted Answer

Potential energy, pressure energy, and kinetic energy

Answer

Thermal energy only

Answer

Potential energy only

Answer

Kinetic energy only