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KSP inspired me to design a liquid-fueled rocket engine

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Today I did first test runs. Difficulties having ignition but third time was success.

I fuelled gasoline for only a couple of seconds run becouse this is non-cooled rocket engine.

So much happened in a such short time so I looked afterwards from three different camera angle.

Iginition yes but what happened after that? First I thought there was no combustion but why did those metal plates moved on surface? There was some kind of thrust, those plates weights about 300 grams each. Estimated thrust was 3,5 kg (about 35 N).

Was the flame transparent?

What do you think?

But I am smiling here. Good feeling!

 

look and discuss please

 

 

Edited by totalitor

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Looks to me like the gasenous oxygen supply was way to much (to high pressure) so it simply blew out the flame and came out the nozzle with qute high speed on its own...

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Both gaseous oxygen and nitrogen pressure was 10 bar. Estimated chamber pressure is 6,9 bar.

Tomorrow I will try oxygen and nitrogen 10 bar but no ignition and no gasoline inside. Have to check what it will look like.

And after that a new try but this time I put more fuel. More time to react.

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I tried today only with oxygen and nitrogen gases, they didn't move those plates so something happened on yesterday test run.

So I fuelled more fuel and tried again with same pressures. There was combustion for a short time and then a hole melted to the engine.

So it seems this design don't work. Estimated heat on nozzle is 3000 Celsius.

I have spark ignition (without spark plug). I have now learned how to ignite. Today I needed only one ignition button push.

Look yourself and analyse please.

 

 

Edited by totalitor

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THIS is rocket science! :) 

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from what it looks like, you A: need better cooling , or, you can increase the fuel to oxy ratio, which reduces the temp of the flame, which should mitigate the problem. And B: the flame of keralox should be orange-ish, for complete combustion, what it looks like is that the gox is either blowing out the flame, or preventing the kerosene from lighting off. 

For the cooling, I recommend you look into the method called "vortex cooling"

Edit: looking at the combustion instability, you need to adjust the mixture anyways 

Edited by RoadRunnerAerospace

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Definetly I need cooling for an engine. And better design, this one do not work. Back to the drawing board.

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But it did work, apparently too well!  Did it actually melt through to make the hole, or did it burn through? Running oxy-rich will make metals burn, perhaps reducing the oxygen or increasing the fuel will cool the flame (as @RoadRunnerAerospace said) and keep the metal from actually burning

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Complete ignorant here (the hottest fire I can manage to make is from my oven): how feasible would be to use abrasive resistant termal coating?

https://www.asbindustries.com/coating-materials/abrasion-resistant-coatings

(first thing I thought it's reasonable from the google search - I don't have a clue about the feasibility of the product above for the task).

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Next I try to design showerhead injector and regenerative cooling. More complicated but there is a reason for that. Now I know.

Suggestions are welcome!

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9 hours ago, Lisias said:

Complete ignorant here (the hottest fire I can manage to make is from my oven): how feasible would be to use abrasive resistant termal coating?

https://www.asbindustries.com/coating-materials/abrasion-resistant-coatings

(first thing I thought it's reasonable from the google search - I don't have a clue about the feasibility of the product above for the task).

I think you mean ablasive coating. It should work, but your engine can only be fired for a limited time. Plus it is expensive. 

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9 hours ago, totalitor said:

Next I try to design showerhead injector and regenerative cooling. More complicated but there is a reason for that. Now I know.

Suggestions are welcome!

I've heard that oil burner sprayers that are commercially available work well as injectors.

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Engine is small, Injector should be small too. Everything must go inside 16 mm circle. I plan to use outer shell 22 mm copper tube and inner shell 18 mm tube. Cooling gap is 1 mm, maybe too much but maybe it doesn't melt so soon.

Edited by totalitor

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34 minutes ago, RoadRunnerAerospace said:

AWESOME

Never seen a exhaust plume like that though

I'd hazard a guess that it's very fuel rich exhaust which is why it's so flamey

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Cooling worked so well that there is still unburn paper tape which I used to hold ignition wire on engine. And every pen marks I made to engine are still visible.

Fuel rich maybe or is combustion chamber too short?

 

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1 hour ago, totalitor said:

Cooling worked so well that there is still unburn paper tape which I used to hold ignition wire on engine. And every pen marks I made to engine are still visible.

Fuel rich maybe or is combustion chamber too short?

If I had to guess, I'd say fuel-rich. The propellant appears to be exiting the chamber before it ignites, which might be a sign of either fuel-rich combustion, excessive chamber pressure, or poor mixing of propellant and oxidizer. What pressure is your fuel and oxidizer? Your injector orifices look fairly large, and don't taper much, so the pressure drop may be lower than expected. I'm far from being an expert (or even an amateur) in rocket engines, so take this with a grain of salt. :) 

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I guess poor mixing (showerhead injector) and fuel-rich combustion.

Pressure for both propellants are 10 bar, calculated chamber pressure is 6,9 bar.

Injector orifices for oxygen: three 1,5 mm

Injector orifice for fuel: one 0,8 mm

It was designed for 0,7 mm orifice but I used 0,8 mm drill becouse I hadn't smaller. So there is 20% more area for orifice. This may explain something.

This engine has done its work and shall not be ignited no more. I will design a better one with better injector.

 

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