University research project topic

[Theo]

Hey folks, I'm studying mechanical engineering at university and hoping to do something pulse jet related for my senior project. I've got experience building liquid rocket engines and have wanted to try a pulse jet for a while. I'm looking for suggestions on specific topics to investigate.

I've done some looking into potentially making a quieter engine, but the literature seems hopeless. Also considering trying to scale down and attempt a micro-engine.

Anyone have thoughts/suggestions for an interesting semester-long topic? Keep in mind we'll be a team of 5 students.

[tufty]

Hello Theo.

It's an interesting field, but a fairly old one, and a lot of this stuff has already been done to death. Noise reduction has been a holy grail, but we're talking about a thermo-acoustic engine, so... There was a university team that came up with a tiny, tiny valveless jet at one point, I think you're unlikely to beat them. Subsonic to supersonic transition has been looked at too. This ins't really a lot of help, I know. Alternative fuels, maybe? Investigation of combustion chamber geometries, perhaps, there's a lot of stuff that's never been possible which is now (relatively) easy with additive manufacturing and software geometry optimisation.

Good luck in any case

Simon

[Theo]

Simon,

Thanks for the opinion. I tend to agree that lots of the noise reduction studies have been extensive enough. I recently came across this paper https://www.jstor.org/stable/44467029 from 1984 (see link) which states, among other things,

"Ignition delay could be reduced by pre-heating the fuel (13) or impinging the spray onto a hot surface (perhaps the pulsejet walls).Unfortunately time was not available to pursue these possibilities further."

Has anyone heard of a regeneratively cooled pulse-jet? Seems like an obvious way to recover the lost heat from the glowing body.

[Mark]

I remember a design where the intakes and exhausts ends were directed facing into each other with a cowling over them which collected or vented the thrust.
https://www.pulse-jets.com/phpbb3/downl ... hp?id=4342
https://www.pulse-jets.com/phpbb3/downl ... hp?id=4343

Here's this maybe of interest too.
"The analysis is extended to include systems of multiple engines and again verified by comparison to experiment. It is shown that multiple engines can be locked in phase or in antiphase predictably by selecting the proper interconnection method. The latter has important implications for noise reduction and for propulsion applications involving arrays of pulsejets."
https://arc.aiaa.org/doi/10.2514/1.B38855