Simcenter STAR-CCM+ Example and how a supersonic rocket nozzle exhaust works - part 1

INTRODUCTION

A rocket nozzle is used to expand and accelerate the combustion products of rocket engines to high supersonic speeds. The form are normally based on the de Laval nozzle [1], which is a convergent-divergent nozzle (CD Nozzle). The CD Nozzle decreases (converges) its diameter from the begin till the middle (throat), forcing the subsonic flow to accelerate till Mach 1 on the throat and downstream of the throat, the diameter increases again (diverges), allowing the gases to expand isentropically to a supersonic flow. [2]

NOZZLE SHAPES
The nozzle main shapes are convergent (where the diameter decreases), used mainly in jet engines; divergent (where the diameter increases) used mostly in scramjets, and the convergent-divergent nozzle (CD Nozzle), where the diameter decreases till a point (throat) and afterwards increases again, used in rocket engines.

In this first part, this is an Example is a 2D generic nozzle showing the shock (diamond) pattern formation at supersonic exhaust conditions. No reactions are modelled.







A comparison between different nozzle types is made in the second part of this article.

The example sim file attached is a demonstration and not an endorsement of a best practice. It is provided to showcase the use of simulation features in a given application.. 
Open the file in a software version equal to or newer than the one specified in the Version Applicable field.

See also:. 

• How do I prescribe the supersonic static pressure?
• Transonic/Supersonic Wing Simulation Tutorial and Best Practices

[1] https://en.wikipedia.org/wiki/De_Laval_nozzle
[2] https://www.grc.nasa.gov/www/k-12/airplane/nozzled.html
[3] https://en.wikipedia.org/wiki/Propelling_nozzle
[4] https://aerospaceweb.org/design/aerospike/shapes.shtml