# Aerodynamics Questions and Answers – Incompressible Flow in Duct

This set of Aerodynamics Questions and Answers for Aptitude test focuses on “Incompressible Flow in Duct”.

1. The below figure shows which of the following wind tunnel? a) Convergent duct
b) Divergent duct
c) Convergent-divergent duct
d) Simple duct

Explanation: The velocity in the convergent duct (V1) increases until it reaches V2 near the throat, where the pressure is at its lowest. The velocity drops and the pressure begins to rise in the diverging portion.

2. In a venturi duct, the pressure at throat is __________
a) lower than ambient pressure
b) equal to ambient pressure
c) greater than ambient pressure
d) 0

Explanation: The pressure at the throat is lower than the pressure at the intake, which is one of the venturi duct’s properties (ambient pressure). It has a wide range of uses in aerodynamics as a result of this property.

3. The carburetor of an automobile engine makes use of _____
a) venturi duct
b) convergent duct
c) divergent duct
d) wind tunnel

Explanation: The pressure at the neck (p2) in the venturi duct is lower than the pressure at the intake (p1). The p2-p1 pressure difference aids in forcing fuel into the airstream and mixing it with the airstream downstream of the throat.

4. Which of the following parameter can be measured using venturi?
a) temperature
b) velocity
c) volume
d) density

Explanation: The velocity of a fluid can be measured using a venturi. Using a venturi, we can compute the pressure differential. We can instal a pressure gauge in the duct to immediately measure the pressure differential (p2-p1). Bernoulli’s equation may be used to link this pressure differential to velocity, and therefore the velocity can be computed.

5. Which of the following is an application of incompressible flow in a duct?
a) High speed wind tunnel
b) Low speed wind tunnel
c) Flow in air
d) Cannot be said

Explanation: A low-speed wind tunnel is a huge venturi in which the airfoil is propelled by a fan attached to a motor. The wind tunnel fan, which looks like an aeroplane propeller, is used to draw air through the tunnel circuit.

6. The open circuit wind tunnel is similar to venturi duct ______
a) True
b) False

Explanation: In an open circuit wind tunnel, the air is pulled straight from the atmosphere and then returned to it. In addition, the velocity at the inlet is higher than the velocity at the exhaust, thus the pressure at the exhaust is higher.

7. Inside a wind tunnel, the area further decreases from A2 to A3, that section is called as _______
a) Converging section
b) Divergent section
c) Throat section
d) Nozzle

Explanation: The diffuser’s aim is to lower the velocity. The wind tunnel is structured in such a way that the area in the divergent portion reduces and the pressure in this part grows further in order to reduce velocity.

8. The flows in which all the flow parameters are the function of ‘x’ is called as _________

a) 3D flow
b) 2D flow
c) Quasi 1D flow
d) Quasi 2D flow

Explanation: The flow field parameters are generally uniform throughout any cross section, and so only vary in the x-direction. x is supposed to be the function of all flow parameters. A=A(x), V=V(x), and p=p(x) are known as pseudo 1D flow since they only vary in one direction.

9. Incompressible flow is the one in which density is ___________
a) 0
b) constant
c) varies from point to point
d) negligible

Explanation: Because the density of incompressible flow remains constant, the fluids cannot be compressed and are referred to as incompressible fluids. Incompressible fluids are best represented by water. However, we can compress water to some amount.

10. In a wind tunnel, the section with minimum area is called as __________
a) exit
b) nozzle
c) inlet
d) throat

Explanation: When the flow enters the wind tunnel (convergent-divergent) with a velocity V1 and a pressure P1, it is called a convergent-divergent flow. At the throat, where the smallest area portion is located, the velocity increases while the pressure falls. At the throat, there is very little pressure.

The term “incompressible flow” refers to fluid flow in which the density of the fluid remains constant. At constant temperature, all liquids are incompressible. A compressible flow is one that has a significant fluctuation in density with increasing pressure. When the divergence of the flow velocity is zero, a flow is considered incompressible in fluid dynamics. However, depending on the flow system being represented, comparable formulations may be utilised. The velocity in the convergent duct (V1) increases until it reaches V2 near the throat, where the pressure is at its lowest. The velocity drops and the pressure begins to rise in the diverging portion.