Turbojet heat issues

[richardm]

OOPS Make a "Cone" Bacon is from my text corrector Im using french software here ...

[sharky]

Ok, I’m not sure if you saw earlier that the compressor inducer is actually larger than the turbine exducer, are you saying it should diverge at the end?

[richardm]

Yes I saw that. It s a mismatch. But I just gave you a general rule of thumb to start with your tail cone. The jet pipe is not going to correct for the mismatch. So a convergent jet pipe with an outlet about the same diameter as your compressor inducer is a starting point. I you feel it chokes your engine then enlarge the outlet end by cutting it a bit shorter til it runs fine and yields optimum thrust .

Make you cone so that its diameter fits the v band wich should be somewhat larger than the compressor inducer. Not ideal but in your situation I dont see how to manage otherwise.



That s just my idea Maybe someone has a better idea

[Jetman]

For heat measurement, I have this egt gauge located after the turbine and it has been functioning well enough. www.amazon.com/HOTSYSTEM-Pyrometer-Exhaust-Temperature-Readouts/dp/B07T2ZQFY2/ref=mp_s_a_1_10?dib=eyJ2IjoiMSJ9.SKfcAPT-HQioXolXLmLvZ_3NIy377KXiaafiIef257iX5JnwujUOuY5Ia51ocfBab7xfyVYUj_CO_sFboIHEuNnX_OnhfKtGd5ZjXxvETHC7_rFtuzRpjUgKu3Zm5jkF92_tla7ds0kWamFqcOueTXzX7YOZ5crvJSB3e28Gane17kDTPYN5gyUKak1u7NRU8hQuSwaOFa_bDlXftyymxw.rH5jjrSSJTAaJEt5noWgUC3YUsXbrK7gOdLuhDMWxKQ&dib_tag=se&keywords=turbo+egt+gauge&qid=1712947697&sr=8-10

[richardm]

I ve tried on of those The gauge works fine but i have replaced the thermocouple with a more sensitive one wich has an exposed suction for a faster response.

Like this one www.amazon.ca/Response-Thermocouple-Adjustable-Temperature-Controllers/dp/B0CNRTMDTH

If tou thermocouple is too slow to respond you may cook your turbine before the actual temp shows on te gauge

[racket]

Yep , they're the thermocouples I use , very fast response :-)

[sharky]

Ok thanks everyone! Do you think an after burner’s a possibility for this engine or would there be too much back pressure?

[richardm]

I dont know It is hard to say if a jet pipe will do any good in the first place given your turbine/ compressor inducer /exducer mismatch. Try a jet pipe first and add a burner later. Dont go chasing two rabbits, the jet pipe itself might be enough of a challenge with a lot of rework.

[racket]

An "afterburner" is possible as long as theres no nozzle on the end of it , you could still end up with thermal choking of a straight tube if its not large enough , this would probably send your comp into surge and/or your turb temps to be excessive

[stoffe64]

Hello ,what you see here is the inlet to my HOLSET HX60 turbine housing
This would have to be portmatched with a grinder to make a smoothe transition Into the turbine
Othervise it could be overtemp problems with this engine because of that disturbed flow from combustor AND it could also melt the edges of the ports and cause turbine wheel damage.

[racket]

Lotsa turbulence from those edges :-(

Restricting flow, and PROBLEMS

[stoffe64]

YES it sure would be problem there, thats why i showed it ,one of problem that might occur building these engines

[richardm]

I had the same on my turbo Gave it on smoother transition on the milling machine and made it so that my flame tube fits snuggly in the milled cavity.
I was first planning to give that middle partition a sharp edge to help the flow but change my mind because too sharp an edge would "concentrate" the heat So i just rounded it up a little

[sharky]

I don’t believe I’m having that problem, the transition is pretty smooth and it now appears to be running cool enough.
Thanks.
I do have another question though about my oil pump, it started leaking out the back where the wires exit and the front where the gears are. I’ve tried to fix it to no avail and am thinking I should probably just get a new one. Can anyone recommend an oil pump for my size of engine that’s pretty good quality and high flow rate. Probably less than $100 price range?
Thanks everyone for all your help,
Sharky

[richardm]

Hi I dont have much info about your oil system beside what I can see on your videos. From what I see your pump is sucking oil directly from the turbo oil drain port Am I right?

About the pump you re using : I would say the seals are not oil resistant and are busted What type of pump is it ? Fuel transfer pump? Hopefully not intended for water ? Maybe try to obtain oil resistant seals for the same pump from the retailer or manufacturer

In any case and if you're pumping oil directly from the turbo return port , know that you're pumping some very hot oil and gases Turbo oil seals work in part with some of the gases and compressed air pushing the oil back in the core And theses gasses must be vented to atmosphere wich precludes a direct return to the pump.