EG-293 Aerodynamics key definitions Flashcards
What is Geometric similarity?
States that the prototype and model must be identical in shape and in size. The ratio of the corresponding linear dimensions in the model and the prototype must be the same.
What is kinematic similarity?
Flow fields in the prototype and model must have geometrically the same set of streamlines.
What is Dynamic similarity?
Implies that the force distribution between the two flow fields is such that the types of forces are parallel and have the same ratio of magnitudes.
What is the Centre of Pressure?
Xcp, the location where resultant of a distributed load effectively acts on a body.
What is the Aerodynamic centre?
The point at which the pitching moment of the aerofoil does not vary with angle of attack.
What is the Mean free path?
The average distance a molecule travels before it collides with another molecule.
What is a continuum?
A fluid (gas or liquid) that is continuously distributed along the region of interest.
What is fluid particle?
A relatively small mass of a fluid, containing a large number of molecules that will provide meaningful statistical averages.
What is pressure and it’s units?
Force per unit area acting in the normal direction.
Units: Pa or N/m^2
What is Shear stress?
The stress component that acts tangential to an area.
What is Normal stress?
The stress component that acts normal to an area or perpendicular to the shear stress.
What is the definition of Eularian?
Fixed in the flow field and you observe the variation of properties at the point (spatial description).
What is the definition of Lagrangian?
Identified fluid particles are followed in the course of time.
What is density?
It is the mass per unit volume.
What is viscous flow?
If the viscosity (frictional effects) is important.
