Week 2 - Converging diverging nozzle

WEEK 2 - CONVERGING DIVERGING NOZZLE

AIM:

• To create a 2-d nozzle by using the dimensions given.
• To use the following boundary conditions.

1. Inlet Pressure = 1atm and Inlet temperature = 300K.
2. Outlet pressure= 0.027 atm.
3. Operating conditions, reference pressure = 0.

• To plot the pressure, velocity and temperature variations across the domain.
• To plot the variation of Mach number across the domain.
• To find at what distance from the inlet does the flow become supersonic.
• To explain the variation of change in area on mach number on the given geometry in a few words.

Spaceclaim:

Mesh:

• Quad elements are used for meshing

Post processing:

Contours:

Plots:

Conclusion:

• From the above plots and contours we can say that velocity and mach number increases along the nozzle from the inlet to outlet.
• From the above plots and contours we can say that Pressure, density and temperature decreases along the nozzle from inlet to outlet.
• From the above mach number plot we can say that, slightly above 0.05 and approximately near to 0.055, flow is at mach 1, which is the throat of the c-d nozzle.
• The phenomenon behind this is venturi effect, this applicable for subsonic flows and here it is valid till the throat region from inlet, for the subsonic flow (M<1), a decrease in area results in incresae in velocity. Therefore velocity increases in a convergent duct and decreases in a diverging duct.
• For supersonic flow (M>1), increase in area results in increse in velocity. Therefore velocity increases in diverging duct and velocity decreases in converging duct. This is directly opposite to the behaviour of subsonic flow in converging and diverging ducts.