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block

As fluid crosses a shock wave:

Select the correct answer(s).  

(0/0)

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pressure decreases, while temperature and density increase

pressure and temperature increase, but density decreases

the pressure is constant, other quantities increase

pressure, temperature and density increase

none

When a liquid flows under pressure through a pipe, the head loss due to surface friction with the pipe is h=f(L/D)(v^2/2g). Which of the following statements is false.

Select the correct answer(s).  

(0/0)

Explanation

D stands for the diameter

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The variable D is the depth of the flow in the pipe

The friction factor f is a function of the Reynolds number

The equation is valid for laminar as well as turbulent flow

The head loss h is expressed in units of distance

none

If you were to remove the rust on a pump (but not change anything else), which of the following statements would be TRUE?

Select the correct answer(s).  

(0/0)

Explanation

The efficiency of the pump increases. Since the power is unchanged, improving the efficiency must correspond to the energy added to the fluid increasing, meaning the momentum of the water must increase

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The power used by the pump would decrease

The change in momentum of the water pumped would decrease

The power used by the pump would increase

The change in momentum of the water being pumped would increase

none

When designing a streamlined body it is important to...

Select the correct answer(s).  

(0/0)

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Choose slenderness to minimize the sum of skin friction and pressure drag

Minimize thickness-to-chord

Make the body as short as possible, to minimize surface area

Make the body as long as possible, to minimize wake width

none

Which of the following is a non-dimensional grouping where F is force, p is density, A is the area, and U is the velocity?

Select the correct answer(s).  

(0/0)

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F/(pAU^2)

F/(p^2AU)

F/(pAU)

F/(pA^2U)

none

Separation occurs when...

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(0/0)

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the flow near he wall comes to rest, such that du/dy=0 at the wall

the flow involves a liquid, rather than a gas

the boundary layer becomes turbulent

the boundary layer thickness is zero

none

Pressure drag results from...

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cavitation

shear stress variations across the body

the presence of a wake

high ambient pressure

none

An isentropic process is defined as:

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adiabatic and reversible

a process where entropy can successfully be decreased

isothermal and reversible

adiabatic and incompressible

none

In an ideal gas, the speed of sound can be written as

Select the correct answer(s).  

(0/0)

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a function of the friction coefficient

a constant in any condition

a function of temperature and a few gas constants

an integral of a function of pressure

none

The transition between laminar and turbulent pipe flow usually occurs at a Reynolds number of

Select the correct answer(s).  

(0/0)

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900

1200

2100

1500

none

The lift on a body immersed in a fluid is...

Select the correct answer(s).  

(0/0)

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in an arbitrary direction

normal to the flow velocity

at 45 degrees to the flow velocity

parallel to the flow velocity

none

The pressure increase achievable across a compressor stage is chiefly limited by...

Select the correct answer(s).  

(0/0)

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the ambient pressure

the casing material

the cavitation pressure

the development of separation and stall over the blades

none

If dp/dx is the pressure gradient in the direction of the flow, separation is more likely when...

Select the correct answer(s).  

(0/0)

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the pressure gradient is irrelevant, what matters is absolute pressure

dp/dx <0

dp/dx > 0

dp/dx=0

none

In a converging-diverging nozzle,

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(0/0)

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sonic conditions can only happen at the exit;

sonic conditions can only occur at the inlet;

sonic conditions are possible only at the throat.

sonic conditions are not possible;

none

A shock wave...

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(0/0)

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is nonadiabatic and reversible

is adiabatic and reversible

is nonadiabatic and irreversible

is adiabatic and irreversible