1 - Basic Aerodynamic Theory

Question 1

what are the conditions required for the use of the continuity equation for mass flow rate?

Answer 1

streamline flow

Question 2

what are the conditions required for the use of the continuity equation for volumetric flow rate?

Answer 2

streamline flow
incompressible (fluid’s density constant)

Question 3

streamline

Answer 3

line which shows the direction of the flow of a fluid at any particular moment

when the streamlines are close together it indicates the speed of the fluid flow is relatively high, when they are far apart it indicates the speed is relatively low

Question 4

streamline flow

Answer 4

the fluids flow in parallel layers such that there is no intermixing or disruption of the streamlines or separation

Question 5

Conservation of mass

Answer 5

States that mass in a defined system cannot be destroyed, created if there is not a source (supply of mass) or a sink (consumption of mass) within the system

Total change of mass within the system = 0

Question 6

Bernoulli’s theorem

Answer 6

in a flow of an ideal (incompressible) fluid along a streamline, the sum of the potential energy (gρh), kinetic energy (ρ(v²/2), and the capability (ρ) to produce work due to pressure at any point on the streamline, remains constant

Question 7

what are the conditions for using Bernoulli’s theorem?

Answer 7

incompressible (below 250kts)
streamline
steady state
no friction
level flow*

Question 8

Stagnation point

Answer 8

When the airspeed decreases to 0, static pressure reaches its highest value. Where airspeed = 0 is the stagnation point.

Question 9

Venturi effect

Answer 9

Reduction in static pressure caused by decreasing the cross sectional area of the flow path

Question 10

What is stagnation pressure?

Answer 10

Same as total pressure (for a level fluid flow)

Question 11

What does a pitot tube measure? What is its output?

Answer 11

(Stagnation) total pressure
The difference of total-static (dynamic)