Week 2 - Converging diverging nozzle

Aim

To plot the pressure, velocity, temperature & the variation of Mach number across the domain .

Introduction

A de Laval nozzle or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube which is pinched in the middle, making a carefully balanced, asymmetric hourglass shape. It is used to accelerate a compressible fluid to supersonic speeds in the axial (thrust) direction, by converting the thermal energy of the flow into kinetic energy.De Laval nozzles are widely used in some types of steam turbines and rocket engine nozzle. It also sees use in supersonic jet engines.

A de Laval nozzle will only choke at the throat if the pressure and mass flow through the nozzle is sufficient to reach sonic speeds, otherwise no supersonic flow is achieved, and it will act as a venturi tube; this requires the entry pressure to the nozzle to be significantly above ambient at all times (equivalently, the stagnation pressure of the jet must be above ambient).

Procedure

1.A 2d figure of the nozzle was created in spaceclaim with exact dimensions given above.

2.The diagram was meshed

Number of nodes = 3924

Number of elements = 3780

3.The simulation was done in FLUENT

Solver Type = Pressure - Based

Velocity Formulation = Absolute

Time = Steady

2D Space = Planar

Result

From the plot we can conclude that mack number increases when the fluid is flowing through the throat region. i.e mack number is highest when fluid is the throat.