aerodynamics Flashcards
What is the difference between rotational and irrotational flow?
In rotational flow, fluid particles rotate about their own axes (non-zero vorticity). In irrotational flow, particles do not rotate (zero vorticity).
What is the condition of irrotationality for 2D flow?
The curl of the velocity field must be zero
What is the relationship between vorticity and circulation?
Vorticity is local rotation, while circulation is the line integral of velocity around a loop. In 2D, vorticity equals circulation per unit area.
ow are flows around semi-infinite bodies, oval bodies, and cylinders synthesized?
By combining uniform flow, sources/sinks, vortices, and doublets to model complex geometries.
What are the four elementary flows for inviscid incompressible flow?
Uniform flow, source/sink flow, vortex flow, and doublet flow.
Why is the Laplace equation the governing equation of 2D, irrotational, incompressible flow?
It ensures potential flow, where velocity potential
đ satisfies continuity in a non-divergent field.
What is the Magnus effect?
lift generated on a rotating body in a fluid stream due to pressure differences, causing force perpendicular to the flow.
What is the Kutta-Joukowski theorem?
It states that lift per unit length is proportional to circulation around the aerofoil:
đżâ=đđÎ
What is the philosophy of classical thin aerofoil theory?
It simplifies lift prediction by modeling the camber line as a vortex sheet and using the Kutta condition in potential flow.
What is the Kutta condition?
Ensures smooth flow at the trailing edge, requiring finite, continuous velocity and vortex sheet strength.
What condition must be satisfied for the camber line of an aerofoil to be a streamline?
Pressure along the camber line must align with the flow direction to avoid separation
Where is the aerodynamic center of a flat plate or thin aerofoil located?
At the quarter chord point (25% of the chord from the leading edge).
What are the types of low-speed aerofoil stall?
Leading-edge stall, trailing-edge stall, and thin aerofoil stall, each affecting
đśL and CP due to flow separation.
How does aerofoil thickness affect the type of stall?
Thicker aerofoils often experience trailing-edge stall, while thinner aerofoils exhibit abrupt leading-edge stall.
What are high-lift system configurations, and how do they increase CL,max?
High-lift systems (like flaps and slats) enhance lift by modifying flow, critical for takeoff and landing.
