Airflow Flashcards
What are the 4 properties of an ideal fluid?
- Homogeneous;
- Continuous;
- Incompressible; and
- Non-Viscous
What prevents air from being an ideal fluid?
- It HAS viscosity
2. It IS compressible
When considering Two Dimensional flow we assume the wing span to be:
a) Finite; or
b) Infinite.
b) Infinite
In two dimensional flow:
a) Upwash is greater than downwash;
b) Upwash is equal to downwash; or
c) Upwash is less than downwash.
b) Upwash is considered equal to downwash when considering two dimensional flow.
What is the vortex direction from the right wing tip and the left wing tip?
Right: Anti Clock Wise
Left: Clock Wise
*As viewed from behind
What does the Equation of Continuity tell us about the mass flow of a fluid?
When a fluid flows through a pipe (or a stream tube) its mass flow remains constant.
What is the Equation of Continuity?
pA(1)V(1) = pA(2)V(2) = pA(3)V(3)
When applying the equation of continuity to CT4 style ops, why can we consider the density to remain constant?
At velocities below Mach 0.4 air is considered to be incompressible and density remains constant.
For subsonic flow, when fluid flows through a pipe, its mass flow must remain constant. Therefore its velocity is ____ to the cross sectional area.
a) Directly Proportional
b) Inversely Proportional
b) Inversely Proportional
If area decreases, the velocity must increase to maintain the same mass flow.
What is Bernoulli’s Principle?
The sum total of all energies in the stream of fluid remains constant (I.e, any increase in the Kinetic energy in the fluid will cause a corresponding decrease in the pressure energy of the fluid).
p1 + q1 = p2 + q2 = p3 + q3
In a venturi, when the area becomes smaller what will happen to the pressure according to Bernoulli’s principle?
Because the kinetic energy (q) will increase, there must be a corresponding pressure decrease.
In a Venturi at the throat, where the area is lesser, the velocity would:
a) Increase; or
b) Decrease
a) Increase
In a Venturi at the throat, where the speed increases, the pressure would:
a) Increase; or
b) Decrease
b) Decrease
During flight, on the upper surfaces of the wing the local speed of the airflow would ___ and the pressure would ___, also the flow would drift ___.
a) Decrease, Decrease, in-ward;
b) Increase, Increase, out-ward
c) Increase, Decrease, in-ward
d) Decrease, Increase, outward
c) During flight, on the upper surfaces of the wing the local speed of the airflow would INCREASE and the pressure would DECREASE, also the flow would drift IN-WARD.
During flight, on the LOWER surfaces of the wing the local speed of the airflow would ___ and the pressure would ___, also the flow would drift ___.
a) Decrease, Decrease, in-ward;
b) Increase, Increase, out-ward
c) Increase, Decrease, in-ward
d) Decrease, Increase, outward
d) During flight, on the LOWER surfaces of the wing the local speed of the airflow would DECREASE and the pressure would INCREASE, also the flow would drift OUT-WARD.
