Has anyone tried adding Nitrous

[ernie wrenn]

to the DIY's to build extra thrust through afterburner?

How about it RACKET?

[Deleted]

LoL having problems with not melting Afterburners now, think adding Nitrous, would be fun, but think i would end up with a molten mess :-)

[racket]

Hi Ernie

Mmmmmm............a few thoughts on the subject :-)

Probably get best results from compressor inlet injection chilling the ingoing air and getting a big mass flow increase rather than injecting the nitrous into the A/B,

If the engine was running "steady state" with the A/B already alight , and nitrous was then injected into the comp inlet airflow , the increased oxygen in the combustor from the nitrous wouldn't be a problem as theres already an excess to requirements , the increased mass flow of air would lower T I Ts as the A/F ratio would be increased , this in turn would allow a greater mass flow through the turb stage , pressure ratio across the turb stage shouldn't change much as the cooler inlet air/nitrous will require less horsepower/pound to compress which will offset the slightly lowered temperature drop across the turb stage from the lowered T I T .

With more oxygen in the A/B from the nitrous it would be possible to burn more fuel and get a higher temperature but as Andy indicated temps are already at levels where the wall temps are getting marginal , a possible solution would be a water spray onto the internal wall of the A/B to produce a "steam blanket" between combustion products and the metal, the steam would add to the mass flow and increase thrust .

Yep , nitrous would give a boost to a DIY engine :-)

Cheers
John

[racket]

Hi Andy

You could try CO2 injection into the inlet .................LOL, yeh yeh , I know its a fire extinguisher, but the sudden vapourisation from a liquid state will see its temp drop to ~minus 80 C , and its pretty dense at ~1.5 times air , so the mass flow goes up substantially , and its mass flow that produces most of our thrust rather than the velocity which is much harder to increase .

Lets think about this a little further, your A/B is burning combustion products with ~30% less oxygen than the combustor , lets make the combustor burn at the same ratio of oxygen by adding a third CO2 to the inlet , now your normal inlet is at say 288 deg K ( 15 deg C) ,lets add one third CO2 at 208 K , temp drops to 261 K , or ~minus 12 C average , thats a 10% increase in mass flow , actually it'll be more due to the CO2 having a higher density.

Horsepower required to compress a pound of air at 15 deg C vs minus 12 C at say 72% effic up to a 3.5 pressure ratio ...............172.3 deg rise for the 15 C or ~105.3 hp/lb , 156.2 deg C for the minus 12 C or ~95.4 hp/lb , say 10 hp /lb , so for your HX82 that'll be a saving of 20-25 hp during compression .

So far we've got 10% more mass flow , saved 20 plus hp during compression which will mean more pressure in the jetpipe , and we haven't even mentioned pressure ratio "correction" for the lowered inlet temp , thats probably worth a few more psi to P2 at the same max tip speed . .

It'd be an interesting experiment , also the track officials might be a bit happier if you've got, ...... heh heh ...... a "fire extinguisher" system onboard ;-)

Cheers
John

[ernie wrenn]

But you would be using it to run/// That was a interesting thought.

ernie

[enginewhisperer]

then you can add this idea to the CO2 injection system
www.wickmanspacecraft.com/marsjet.html

[racket]

LOL.......magnesium powder in the A/B .............now that would provide a great light show .............New Years Eve special :-)

[wolfdragon]

IF the particle size were small enough, theoretically any needle type injector could allow for a fuel and magnesium powder mix into the AB... Just when you thought Chris couldn't get more lights and sparkles coming out of the jet van...

[ernie wrenn]

I like that idea... How can I carry 2000 pounds of magnesium powder on the Hearse.....

[wolfdragon]

As much as I hate to say it, I think it would be safer to have the power premixed into the fuel rather than a dry hopper of the powder... so that might make things easier...

From that point on it's probably a matter of:
1. Will the fuel pump tolerate the magnesium power in suspension?
2. Will the injectors get clogged by the mixture?

The other side of this coin is, what is an "ideal" mixture ratio and is that still a low viscosity fluid or more of a sludge? Which will lead to a repeat of questions 1 and 2

[syler]

Why not reinforce your AB with an array of aluminum plates with a circle cut out of the middles. These would of course be heat sinks and would add strength. I'm not sure I would spray cryogenic liquid into a really hot turbo compressor. But adding O2 + fuel = more energy. I would do it for sure.