Hypergolic fuel?

[5150DSM]

It's just a random though.
Would a production block stand up to the combustion pressures of a hypergolic reaction? No fu(king way, right? Anyway, staged injectors, 2 per cylinder; 2 fuel tanks with completelt isolated plumbing(1 for the binary, 1 for the catalyst) Time the injector pulses like spark events... Well, I'm not an engineer or a chemist so I'm sure the specifics escape me but it sure would be interesting if there were a practical way to harness a hypergolic reaction in a small combustion engine.
Like I said, just a random though but if anyone has anything scientific to offer, please chime in with an opinion or assesment.
Aloha

 

[psychlow]

It would depend on the type of hypergolic reactants used. Hypergolic reactions tend to be deflagation-type events (burning) rather than detonation-type events (exploding), so if you could keep the combustion in an acceptable heat range and expansion rate, sure, your engine could handle it.

The questions I would have about designing an internal combustion engine for hypergolic reactants are:
1) Purpose
a) Why not just use a spark plug (or compression) to ignite an A/F mixture?
b) What benefits are there to it?

2) The reactants
a) How much do they weigh at outside temperature?
b) What type of range and reactant (gas) mileage can you expect?
c) How much would these reactants cost?
d) At what temperature do the reactants burn?
e) Any way to quench the reaction temperature (similar to running rich on a gasoline engine, or lean on a diesel engine)?
f) If either or both of the reactants are gaseous at normal temperatures/pressures, are there going to be any issues with fuel delivery on hot days vs. cold days?
i) Can this be solved by pressurizing the fuel into liquid form, similar to N20?

3) Timing
a) How do you plan on controlling ignition timing?
b) With the reactants used, what ignition point is optimal at what engine speed/load/airflow (knock vs. power, based on the expansion rate, cylinder pressures, etc etc.)?

4) Safety
a) In the event of an accident, how are you going to isolate both reactants from each other?
i) If gas leaks, it needs a spark or heat to ignite. If these two leak together, you're screwed!

I know I over-analyzed this, but hey, maybe it'll spark some intelligent discussion.

 

[5150DSM]

Uh oh, I think I stepped into one here. Anyway, I did have some constructive ideas but being generally unfamiliar with the technical aspects of hypergolic fuels, I don't actually know if they are applicable in the least.

First, the specific fuel type I am talking about is ICBM fuel. I came across some material once regarding the dismantlement of the Titan missle and how the military had all kinds of storage problems with the fuel because it was so volatile and of course had to be stored completely seperate. This made me curious about hypergolics and binary substances in general so I started looking shit up. I'm certainly no expert, in fact I wouldn't even say I have a basic understanding of the chemistry of the stuff but I am interested and trying to learn more.

Hmm, questions...
1. (A,B) The benefits as I see them are many. The combustion pressures are much higher and the combustion temps much hotter(around 3000*F) which would melt an aluminum or iron block for sure so...
If the reaction IS controllable and you could build an engine to stand the mechanical stresses(?) then I think you would have a far more efficient and far more powerful engine. I wonder if you can spin an internal combustion engine at 20-30,000 rpm?

2. I don't know the weight of the fuel in it's liquid state but I believe you could store enough fuel on-board for a "reasonable" range.(as long as you don't mind driving a bomb) If you could obtain the proper liscensing to use the fuels I think you might be able to buy them in small quantities from the military, they have vast storages of the decommisioned fuels; hell, you may be able to make your own with the right lab. Expenses are probably on the extreme side, at least you would use far less of the stuff. It's all liquid and as far as I understand, the ambient outside temperature would matter very little in the atomization of these fuels.

3. Timing
I was thinking you might be able to time the injector pulses like a staged nitrous set-up; you could deliver both reactants simultaneously at timed intervals. Of course there would have to be a tremendous amount of testing to figure out exactly to deliver the fuel but I would try to target a specific rpm range, say 5500-6500 and then burst fire the reactants at intervals that would maintain that rpm range. For example, and these are just hypothetical numbers... Deliver 5cc's of each reactant to spin the engine up to speed as the engine spins back down to 3500rpm you shift and fire the injectores again at maybe 3cc each to spin the engine back up and so on until you are in the top gear at peak rpm. I don't even know where to begin on the math to determine all the pressure, expansion rates, speed, load, etc..

4. Safety :laugh: :laugh: :laugh:
Who are we kidding, if the containment systems fail you will be part of a large purple fireball.

Feel free to discuss.
Aloha