Aerodynamic

Question 1

Size of a fluid particle

Answer 1

1 μm

Question 2

2D Body Definition

Answer 2

d/dxi = 0

Question 3

Vorticity in 2D

Answer 3

ω = (δv/dx - δu/dy)k

Question 4

Definition:

Streamline
Vortex Line
Smokeline/Streakline

Answer 4

Streamline tangent to velocity
Vortex Line tangent to vorticity
Smokeline/Streakline: line formed by particels that passed a certain point

Question 5

Drag is..

Answer 5

A component of the aerodynamic force

Question 6

parts of aerodynamic drag

Answer 6

Friction
Form drag
Wave drag (only for compressible flows)

Question 7

Definition Reynolds number

Answer 7

L*U/ν

Question 8

Main consequence on the flow due to the pressure of turbulence

Answer 8

diffusion is greatly increased

Question 9

Mach number

Answer 9

M² =v²/a²

Question 10

dimensionless coefficients c_l, c_d

Answer 10

= l/(0.5 ρU²c)

= d/(0.5 ρU²c)

Question 11

Aspect Ratio R

Answer 11

AR = b²/S
if rectangular: AR = b/c
Delta Wing: R = 2 tan(Δ/2)

Question 12

pressure and friction coefficient

Answer 12

= (p-p_infinity)/(0.5 ρU²c)
incrompressible, irrotational => 1

= τ/(0.5 ρU²c)

Question 13

Airfoil nomenclature

Answer 13

LE leading edge
TE trailing edge 
Chord (tangent LE-TE)
Meanline 
Curvature t/c
Maximum thickness d/c

Question 14

Lift coefficient in thin airfoil theory

Answer 14

C_l = 2π (α-α0)