JM 50 kit engine from minijetengine.com won't run on liquid

[z28guysteve]

Upon completion of my JM50 I have not been able to make the engine sustain on liquid fuel without becoming extremely hot. The flame front will not stay in the primary zone no matter how slowly I try to meter liquid fuels. I can get a mildly hot sustaining idle on gaseous propane, but liquid propane too will run too hot.

I'm not able to form a proper recirculation zone in the basket. I have not yet had a chance to install anything to measure case pressure.

Here is a pic of the basket and some videos
photos.app.goo.gl/5yr58FCSAMUHkr1QA
photos.app.goo.gl/oQsFuDjAzhiyexNq5
photos.app.goo.gl/2E6nCtMuRRJqiWeRA

[z28guysteve]

The inner and outer basket sleeves are seen aligned on their rear edges. This is exactly how they sit in relation to one another in the assembled engine.

The vapor tubes are straight and vertical, they align with the peripheral edge of the basket. Which to me, I would think may be discouraging the formation of a toroidal vortex, the inner liner has more holes, and higher holes than the outer basket, so I would think that should encourage flow to travel outward at the top of the primary zone, and inward on the bottom of the primary zone, yet the vapor tubes being on the periphery of the basket would directly oppose this flow.

I think maybe I need to bend and aim my vapor tubes to aim more centrally and add some tubular stainless vortex jets?

[racket]

Remove the jetnozzle

[ripp]

Hi,

at first glanceI noticed three things:

firstly the turbine is leaking

second, the injectors are too long and extend too far into the sticks

third, when assembling the combustion chamber, the tertiary holes are are straight to each other?

Ralph

[z28guysteve]

The injectors. Wow, I feel really dumb for not noticing that. (They are extremely long)

The "leak" I think is just cold vapor showing from the super cold liquid propane flowing through the line. I can't detect an actual leak on the engine.

And the dilution zone holes... They are supposed to be aligned with each other inside to out? I found no reference to this anywhere. Can you explain why this should be so? I'd like to know more.

They would be impossible to change to have the inside and outsid tertiary holes to align with each other since the inner liner has 6 rows of holes and outer has 10 rows of holes.

[racket]

Before you go playing around with the flametube GET RID OF THE JET NOZZLE its restricting flow and sending your temperatures too high

[ripp]

please don't say stupid we are all human and anyone can have a Mistake in reasoning, even the greatest experts.

if you have built the combustion chamber according to a blueprint, it can mostly be due to an assembly error.

all modern combustion chambers that I know have theirs opposite the tertiary holes, which causes a better mixing of the cooler air with the hot gas.





your injector ring is not original either, is it?

the injection needle must be spring-loaded on the inside of the stick.





www.gerald-rutten.nl/turbines.htm

would you like to send me the plans of this turbine I would like to take a closer look at it.

Ralph

[z28guysteve]

Email me at [e-mail]
I'll send plans i followed to construct this engine.

[ripp]

I sent you a message in this forum

[jetjeff]

Hi Steve,

Where do these kits come from (who manufactures them)?  The only other website that sold turbines in kit form was JetJoe.

Regards

Jeff

[z28guysteve]

www.minijetengine.com/collections/jet-turbines/products/mj52-mini-jet-engine-kit

[racket]

May I suggest you start to measure a few parameters , like RPM , compressor disharge pressure , and thrust .

If this is your first build then you have no idea what to expect .

You state that you can get sustain on gaseous fuel , the switch to liquid fuel will increase your fueling by several times , you could very likely be overspeeding the engine on liquid propane being supplied at high pressure .

DO NOT START THE ENGINE UNTIL YOU KNOW MORE ABOUT WHATS REQUIRED , IF IT EXPLODES YOU COULD BE KILLED

[z28guysteve]

RPM 120,000
Compressor discharge psi 1psi
Thrust, virtually none...

The diffuser in this design I think is trash.

[racket]

With 120,000 rpm you should be producing ~10 psi of P2 , either your tach or P2 gauge is reading incorrectly .

We need a lot more information from you .

What information came with the kit ??

[dieselguy86]

The diffuser is definitely crappy. The point next to the compressor wheel should be a sharp point, the pics I seen on their site shows a very blunt point.
Also in your video, do you have any oil going to your bearings?

-Joe