Rocket Nozzles

[1]

Propelling a rocket works just like newtons' third law in that every action produces an equal and opposite reaction. This means that by burning fuel and or shooting fuel out of the end of the rocket it is pushed with an equal force in the opposite direction causing it to move through the air and or space.

In order to propel the rocket nozzles are used to direct and increase the thrust generated by the engine.  

The combusting fuel creates high pressure in the engine which causes the gases to exit the nozzle at insanely high speeds propelling the rocket in the desired direction.

[2]

The diagram above shows a basic view of a rocket engine with the nozzle at the base. The thrust output can be varied by changing the nozzle dimeter, and the throat diameter. This works as when the gas expands the pressure drops but in order to keep the total energy constant the kinetic energy must increase which means a greater exit velocity for the gas. 

The article below [3] looks into how using Computational Fluid Dynamics (CFDs) can lead to optimised rocket nozzles. This is done through computer simulation software where nozzle size and shape can be varied. 

Have a go at doing your own rocket nozzle simulations at home with this awesome free software from our friends at NASA. All it requires is an understanding of Java. Now to most mechanical engineer or other courses this could be a problem but luckily us general engineers are all coding experts. Take a look at the    

NASA Rocket Nozzle Simulator by clicking the link.

[1] https://giphy.com/gifs/animative-animation-cartoon-dJezVlwfVulTykjRQj

[2] https://www.mpoweruk.com/rockets.htm

[3] Yumuşak, M. and Eyi, S. (2012). Design optimization of rocket nozzles in chemically reacting flows. Computers & Fluids, 65, pp.25-34.