Aerodynamics – exam 20-06-2014

Basic part

1. Formulate the Kutta-Joukovsky condition. Explain the meaning of this

condition, in particular by drawing the streamlines pattern of flow past an
airfoil. Mark the location of points of the maximal pressure and provide the
value of this maximum (free-stream velocity, density and pressure are,
respectively,

,

,

V

const p









). Write the Kutta-Joukovsky formula for the

lift force and transform it to the formula for the lift force coefficient C

L

(the

airfoil chord length is equal c).

2. Define the pressure center and the aerodynamic center. How – within the

framework of the thin airfoil theory – does the airfoil camber affect the
location of these points along the airfoil’s chord.

3. Make a careful plot of the velocity profiles and the streamline pattern of the

laminar boundary layer flow near its separation point. Define the
displacement and momentum thickness. Write the von Karman equation at the
point of separation.

4. Draw a typical shape of the lift/drag polar plot for a laminar airfoil. Mark the

points of maximal lift and maximal aerodynamic efficiency. Assuming that
for some airfoil C

D

= 0.06 at C

L

=0.4, evaluate – using the results from the

lifting-line theory – the drag coefficient of an elliptic wing with the aspect
ratio equal 10.

5. Define an isentropic process. Provide the relation between pressure and

density in the isentropic process.

6. In the density/pressure plane, draw the plot of the thermodynamic process

corresponding to a shock wave. Can an expansion (rarefaction) shock wave
appear in real flows? Explain your answer.

7. Make a careful plot of velocity and temperature profiles in the laminar

compressible boundary layer at the thermally isolated wall.

8. Make a careful and precise plot of a supersonic flow past a flat plate at

nonzero angle of incidence.

Time: all problems – 70 minutes, just problems 5

th

to 8

th

– 30 minutes.