Week 2 - Converging diverging nozzle

Converging diverging nozzle

Aim: To study CD nozzle using Ansys Fluent.

Objective:

Apply given BCs

• At Inlet, Pressure = 1atm and Temperature = 300K. The outlet pressure= 0.027 atm.

• In the operating conditions, consider the reference pressure to be zero.

Plot:

1. The pressure, velocity and temperature variations across the domain
2. The variation of Mach number across the domain and at what distance from the inlet does the flow become supersonic

Theory:

A convergent nozzle is a nozzle that starts with larger cross-sectional area and gets decreases. As a fluid enters the smaller cross-section, it has to speed up due to the conservation of mass.

Procedure :

Open space claim in Ansys Fluent.

Geometry:

Mesh:

Size 10 mm

Assign names accordingly

Setup:

Solver:

Pressure based

Axisymmetric

Steady state.

Energy - On.

K -epsilon model

Inlet:

Outlet:

Results:

Pressure contour:

Velocity contour:

Temperature contour:

Mach number:

Conclusion:

If the flow is subsonic then (M < 1), increase in the area (dA > 0 ) produces decrease in the velocity (dV < 0).
For a supersonic flow (M > 1) velocity change (dV/V) is negative i.e. (1 - M^2 < 0), increase in the area (dA > 0) produces an increase in the velocity (dV > 0).