Aerodynamics - Integral Form of Conservation Equation for Inviscid Flow Quiz(MCQ)

1 .

What forces are exerted on the body by a fluid flow?

A)

Lift force

B)

Shear stress

C)

Pressure force

D)

Pressure and shear stress

Correct Answer : Pressure and shear stress

Explanation : When a body is kept in a stream of fluid flowing over it, there are two forces exerted. One is the pressure distribution and the other is the shear stress distribution. This leads to formation of lift or drag.

2 .

Thrust produced by engine is due to the shear stress distribution from the fluid.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

Explanation : When the gas flows through the engine, there is a distribution of pressure and shear stress over all the components of the engine – compressor blades, turbine blades, combustion chamber and nozzle. This leads to the thrust formation.

3 .

What causes thrust of an engine?

A)

Change in momentum

B)

Difference in lift distribution

C)

Difference in drag distribution

D)

Mass flow entering the engine

Correct Answer : Change in momentum

Explanation : The thrust is caused due to the difference in momentum of the air which leaves from the exhaust and the one that enters the engine. There is a presence of pressure difference between exhaust and the inlet which causes thrust.

4 .

What happens to the integral ∫dS when the area of exhaust is less than the area of inlet?

A)

Zero

B)

Negative

C)

Positive

D)

Infinity

Correct Answer : Negative

Explaination : The sign of the integral ∫dS in the momentum equation is determined by the area of exhaust and inlet. When the exit area is less than the inlet area, the sum of negative components of pressure is more than the sum of positive components of the pressure. Thus, the sign becomes negative.

5 .

Integral form of momentum equation cannot replace the need for theoretical and experimental measurements.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

Explanation : In real life scenario, computing the thrust of the jet engine using theoretical and experimental results can be very exhaustive. The data obtained is not just extensive but also complex. Thus, to replace this, an integral form of momentum equation is used which gives the result much more accurately.

6 .

The integral form of the conservative equation is used for computing thrust of an engine.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The integral form of conservative equation finds use in many practical scenarios such as finding thrust of a jet propulsion device – engine. It can be used to find out the thrust of turbojet, turboprop, ramjet, turbofan, rocket engine and many more.

7 .

What is the thrust of an engine if the inlet and exhaust mass flow rate are 150 kg/s and 190 kg/s respectively with the pressure difference between the exhaust and ambient air is 1.85 × 10⁴? The exhaust area is 2m², the ambient and exhaust velocities are 280 m/s and 400 m/s.

A)

50 kN

B)

62 kN

C)

71 kN

D)

84 kN

Correct Answer : 71 kN

Explaination : Aerodynamics