Chapter 9 - 3D Flow Flashcards
Looking from behind which way do wing tip vortices rotate on the left?
Clockwise
Looking from behind which way do wing tip vortices rotate on the right?
Anti- Clockwise
tip vortex reduces if Wing aspect ratio, Aircraft speed and Amount of lift generated do what?
Wing Aspect ratio increases
Aircraft speed increase
Amount of life being generated decreases
What creates a vortex
High pressure from under the wing coming round and having no where else to go
Which x2 factors affect vortices intensity the most
The Px differential
The velocity the wing is travelling at. fast = less vortices created
Downwash is created by vortices doing what
Each vortex rotates sharply downwards behind the trailing edge because of the airs viscosity this causes downward component of air to leave the trailing edge
What other component is created by Vortices
Drag
Pan wise flow goes from
root to tip under the wing
tip to root over the wing
How are trailing edge vortices created
When x2 airflows (one H and one L) traveling in slightly different directions meet and cause a vortices
Key point vortices give a velocity to downward air leaving the TE
Yes key for EAF
In 3D flow what happens to down wash compared to 2D
becomes greater than the upwash
Greatest downwash happens at the on a rectangle wing?
Tip of the wing
The main difference between 2D and 3D flow is the EAF which is created by downwash and effects our?
wing aero dynamic forces
The induced AOA is
The angle between the EAF and RAF
Because the vector perpendicular to the EAF is rewards this creates?
induced drag
The angle of attack using 3D flow is
Angle between the RAF and the longitudinal axis
The induced AOA is larger when
Flying at a lower TAS
Or the vortices are larger due to to higher AOA or higher camber
What is effective AOA
The angle between EAF and the chord line
AOA is the sum of
Induced and Effective
Small vortices = what effective AOA
shallow EAF which means large effective AOA which means small induced drag
On rectangular wing how does the EAF change from root to tip
Root has a small angle for EAF - therefore large effective AOA and is produce most life per square area.
Tip has a large angle for the EAF - therefore small effective AOA and large induced AOA = induced drag
