Heat and Flow Technology I. ÓBUDA UNIVERSITY Heat and Flow Technology I. Use only inside Dr. Ferenc Szlivka Professor Dr. Szlivka: Heat and Flow Technology I_4

Kinematics and continuity 4. chapter

Plain flow

Streamlines around a semi sphere and bridge pillar

Streamlines around a drop

Unsteady streamlines

Streamlines around an airfoil

Hot jet flow

Streamlines around a car

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)

Kármán vortex street

Kármán vortex street in a wind tunnel

Continuity law for a steady flow

Continuity law in differential form Steady flow Constant density flow

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.

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.

Solution: First we should calculate the magnitude of free area The area of window: The free area: The volume flow rate:

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.

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:

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.

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.

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: Fluid mechanics 4. Megoldás: b./ Let’s apply the politropic state equation: The politropic power is the next: Dr. Szlivka: Fluid mechanics 4.

Vorticity and potential vortex

Potential or irrotational and vortex flows

Potential vortex

Vorticity, rotation, angular velocity

Vorticity, rotation in a 3D coordinate system

Potential vortex and G, the circulation