This set of Aerodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Turbulent Flow – 1”.
1. Is turbulent flow is characterized by chaotic changes in pressure and flow velocity?
a) True
b) False
View Answer
Explanation: Turbulent flow is a flow regime in fluid dynamics characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow regime, which occurs when a fluid flows in parallel layers, with no disruption between those layers.
2. Is turbulence is observed in the surf?
a) False
b) True
View Answer
Explanation: Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds from a chimney and most fluid flows occurring in nature and created in engineering applications are turbulent.
3. Is turbulence is caused by excessive kinetic energy?
a) True
b) False
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Explanation: Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid’s viscosity. For this reason, turbulence is easier to create in low viscosity fluids but more difficult in highly viscous fluids.
4. Is unsteady vortices appears at turbulent flow?
a) True
b) False
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Explanation: In turbulent flow, unsteady vortices appears of many sizes which interact with each other, consequently drag due to friction effects increases. This would increase the energy needed to pump fluid through a pipe, for instance.
5. Is laminar flow is used to increase the drag and reduce the lift?
a) True
b) False
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Explanation: The effect can also be exploited by devices such as aerodynamic spoilers on aircraft, which deliberately spoil the laminar flow to increase the drag and reduce the lift on the aircraft, which also used as a break to stop the aircraft.
6. Is Reynolds number is used to predict the turbulence?
a) True
b) False
View Answer
Explanation: The turbulence can be predicted by a dimensionless constant called Reynolds number, which calculates the balance between kinetic energy and viscous damping in a fluid flow. However, turbulence has long resisted detailed physical analysis, and the interactions within turbulence create a very complex situation.
7. Example of turbulent flow?
a) Smoking rises from cigarette
b) Flow on a symmetric airfoil
c) Laminar flow
d) Turbulent flow on the airfoil
View Answer
Explanation: Smoke rising from a cigarette is mostly turbulent flow. However, for the first few centimeters, the flow is laminar. The smoke plume becomes turbulent as its Reynolds number increases, due to its flow velocity and the characteristic length.
8. Is flow over a golf ball is stationary?
a) True
b) False
View Answer
Explanation: Flow over a golf ball, considering the golf ball to be stationary, with air flowing over it. If the golf ball to be stationary, with air flowing over it. If the golf ball were smooth, the boundary layer flow over the front sphere would be laminar at the typical condition.
9. Is surface is perturb the boundary layer and promote turbulence?
a) True
b) False
View Answer
Explanation: The surface is dimpled to perturb the boundary layer and promote a transition to turbulence. This results in higher skin friction, but moves the point of boundary layer separation further along, resulting in lower form drag and lower overall drag.
10. Is turbulence flow is irregular?
a) False
b) True
View Answer
Explanation: Turbulent flows are always highly irregular. For this reason, turbulence problems are normally treated statistically rather than deterministically. Turbulent flow is chaotic however, not all chaotic flows are turbulent.
Sanfoundry Global Education & Learning Series – Aerodynamics.
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