# Numerical Analysis of Pulse Detonation Combustors

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## Introduction: Numerical Analysis of Pulse Detonation Combustors

Note: This is just the simulated results done in Ansys fluent 14.0. I may not be able to post a live tutorial for doing this due to some restrictions (research about pulse detonation engines) in some countries. But i would like to share my results with you all since i have done many experimental works in pulsejet engines and many of my subscribers may be eager to know about my future research in pulse combustors. If my video violates any of the rules in instructables moderators can DELETE this instructable. Thank you very much for reading this.

Edit: Sorry everyone previously i didnt give an clear explanation of my research i would like to present it now. The main reason for doing this simulation is to understand the basic physics and applying it to design a real pulse detonation engine. The simulation is done to see how the engine would work. The detonation combustors are the EXTENSION of pulsejet engine HOW??? because both are hollow in nature, deflagration (or just explosion) in pulsejets but detonation (a violent explosion with high temp and pressure) in detonation combustors. This is just the beginning of my project still i i will be simulating more models over this and will update here.

Hello everyone, here is an numerical analysis done by me over the pulse detontaion combustors. The analysis is done to have an clear understanding over the physics behind the working of pulse detonation engines. The video contains the working of a single tube combustor with 2inches dia and 1m length. The simulation is done in ansys fluent 14.0. The convergence of the solution is about e-05 i think globally accepted solution is about e-03 so my solution is an converged solution. The results were validated with the NASA CEA (Chemical equilibrium access code) which gives the detonation properties.

The video shows the three conditions they are the initial peak condition Von Neumann spike followed by detonation and finally the rarefaction condition. The results are done for two criteria with con-di nozzle and without nozzle. In case of with nozzle you can see another shockwave travelling backwards which gives an disadvantage for refilling process.

If anyone have further questions about the working of pulse detonation engines please dont hesitate to ask me. Thank you

Regards
ganesh

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## 7 Discussions

dear ganesh

greetings!!!

can you please guide me that how can you get detonation using gases as fuel. i'm working on pulse detonation engine but i'm not able to get detonation in simulation even after using restrictions ( spiral). please guide me if there is any command or specific input that can lead to detonation. i'll be very thankful to you.

regards

sanjeev

I'm glad to see that people are still doing research to take the pulsejet concept further. It seems that it is mainly ignored for modern aircraft.

One question I have is how do you achieve a detonation? Do you just select a propellant mixture that is naturally capable of DDT like oxyhydrogen? Or is there some initiator, like a high power "spark plug" to act as a an initiator? Or .....???

You can initiate detonation from combustion sensitive mixture like h2-o2 to less sensitive mixture fuel. But the method of initiation differs. There are mainly three types of detonation initiation pre detonation method, DDT and shockwave induced detonation. In DDT method initially deflagration is accelerated to detonation by using spirals, or create blockages to create turbulence. In shockwave induced detonation a high pressure and temp region is created so that first a shockwave is created and this shockwave travels through the reactive mixture and energises the reaction rates and finally initiates detonation. For a less sensitive reactive mixture first a detonation wave is created using high sensitive mixture and this is transferred to low sensitive mixture to create another detonation wave. This method is often called as pre detonator method or detonation - detonation initiation method.

If you have further questions you can ask me.

Hi Ganesh, I think it would be worth your while to include a paragraph about what you are doing here more in layman's terms and how it applies to pulsejet builds as the majority of people will pass this over. After all, you're the guy who build the pulsejet powered bicycle!

Yes sure, sorry for not giving a clear explanation. Thanks for referring my instructable.

That's better.
Did you take the pulsejet powered bike any further; It would be great to see a video of it on a long straight road. (Or is your local law enforcement too hot on that kind of thing to risk it #;¬)

I thought to make the project more better, but i got admission in UK university for MSc so i was in a situation to stop continuing with the project.