1. THERMO- AND FLUID MECHANICS LECTURE
ÓBUDA UNIVERSITY
THERMO- AND FLUID MECHANICS LECTURE
Only using inside
Dr. Ferenc Szlivka
professor
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

2. Kinematics and continuity 4. chapter
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

3. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Plain flow
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

4. Streamlines around a semi sphere and bridge pillar
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

5. Streamlines around a drop
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

6. Streamlines around a drop looked from a moving system
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

7. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Unsteady streamlines
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

8. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Streamlines around an airfoil
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

9. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Hot jet flow
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

10. Streamlines around a car
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

11. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
The path line: the way of a particle.
The streamline: the line which is tangential to the velocity in every point of it.
The streak line: the line of the particles coming from the same point of the stream (of the space)
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

12. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Kármán vortex street
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

13. Kármán vortex street in a wind tunnel
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

14. Continuity law for a steady flow
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

15. Continuity law in differential form
Steady flow
Constant density flow
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

16. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
The volume flow rate or discharge is the volume of fluid flowing past a section per unit time.
The mass flow rate is the mass of fluid flowing past a section per unit time.
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

17. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Outflow through window with grille
Calculate the volume flow rate coming out through the windows!
The velocity of air is v= 4 m/s,
The length of the square is, H=2m.
The area of grille is Agr=1m2.
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

18. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Solution:
First we should calculate the magnitude of free area
The area of window:
The free area:
The volume flow rate:
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

19. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Outflow through a rain grille
The air is flowing with v=2,6 m/s through a HELIOS type square rain grille.
The velocity vector and the normal vector of the area have an angle a=450 .
A length of the square is b=395 mm = 0,395m.
The free surface area is 80% of the whole area.
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

20. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Solution:
First we should calculate the magnitude free area
The velocity vector component projected to the normal vector of area
And the volume flow rate:
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

21. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Continuitate in compressor
The air is flowing in the suction side with velocity.
It was measured the pressure and the temperature
of the incoming and outgoing air.
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

22. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Data:
Questions:
a./ Calculate the velocity at the pressure side ( )!
b./ Calculate the power of the politropic state change between the pressure
and the suction side.
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

23. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Solution:
a./ The mass flow rate are the same in the pressure and the suction side of the compressor:
The incoming density:
The outgoing density
From the densities we can calculate the velocity on the pressure side:
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

24. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Solution:
b./ Let’s apply the politropic state equation:
The politropic power is the next:
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

25. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Vorticity and potential vortex
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

26. Dr. Szlivka: Thermo- and Fluid Mechanics 4.

27. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Potential or irrotational and vortex flows
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

28. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Potential vortex
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

29. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Vorticity, rotation, angular velocity y
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

30. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Vorticity, rotation in a 3D coordinate system
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

31. Dr. Szlivka: Thermo- and Fluid Mechanics 4.
Potential vortex and G, the circulation
Dr. Szlivka: Thermo- and Fluid Mechanics 4.

32. Dr. Szlivka: Thermo- and Fluid Mechanics 4.