PD-01 Jet Engine

[racket]

Hi Patty

26 psi P2 , you're getting there :-)

Temperatures were slowly climbing with the P2 pressure, as would be expected .

All in all a pretty good run ................except for the last few seconds , cracks can't be tolerated .

Hopefully theres not too much damage inside

Cheers
John

[smithy1]

Hi Patty....You mean to tell us you knew the turbine was cracked and still ran it at 26psi P2..?? Hmmmmm...food for thought right there. We must remember these compressor and turbine wheels are under tremendous stress at the speeds we run them....add a bunch of heat to the turbine wheel and these stresses become very high indeed. Some of the blades have unimaginable loads at high rpm.

Cheers,
Smithy.

[madpatty]

Hi Guys,
LOL... I am sorry if i am conveying wrong messages but that blade had been cracked since last few test runs so i just decided let go with it....

What else is a better way to destroy an otherwise crap turbine wheel.

I haven't taken apart the engine yet but hopefully some new bushes and a shaft is all that is needed.....i dont want my shaft tunnel to be damaged, though it is standard OEM piece but still a lot of work to make a new shaft housing to fit my setup.

Cheers,
Patty

[madpatty]

Hi Racket,
Its just the fuel supply now that is preventing me now to get to 3 PR....

Can you tell me how good are my temperatures and turbine blade colour.....

Can we directly relate the TOT with the turbine colour we are seeing as the colour of the blades is near the the turbine inducer which is obviously at a good deal higher temperature than the exducer....
What is coming to mind is for the TOT vs colour comparison it is the HUB colour which is most near to the TOT.
What you think?

Cheers,
Patty

[racket]

Hi Patty

Your turb wheel temps look OK , they're only red.

I did notice that at 5.27 on your video there was some orangey yellow appearing at the 3-4 o'clock position , I thought your rpm might have been falling, lowering airflow , whilst fuel flow remained the same , but your P2 was still steady , so maybe something was amiss inside the engine .

You still shouldn't have the temperatures you do considering theres no jet nozzle or restriction downstream , they should be in the 500s at most , I'd guess that your excessive compressor wheel clearances are contributing , I'd suggest doing something about them when you have the engine apart .

The most you should be able to "tilt" the comp nut is ~0.025" - 0.6mm total from one extreme to the other , the clearance between the comp blades and the shroud should be ~0.010 - 0.012", 0.25-0.3mm radially , double that diametrically .

Bearing clearances should be only ~0.002" - 0.05mm diametrically (0.001" radially) between bearing ID and shaft journal , and maybe ~ 0.003 - 0.075mm diametrically ( 0.0015" radially) between bearing OD and ID of shaft tunnel.

By tightening up the comp clearance your compressor will work more efficiently and require less horsepower from the turbine wheel allowing you to lower temperatures .

Cheers
John

[madpatty]

Hi Racket,
What are the optimum measurements for Length of the NGVs and distance between NGV trailing edge and turbine inducer??

I opened up the engine today and found that some NGV blades were damaged due to contact with turbine inducer tips....
So i have decided to weld on new NGVs.

NGV length:- 20mm (earlier it was 26mm)
Number of vanes:- 21

Radial distance between turbine inducer and NGV trailing edge:- 8mm(earlier it was 3mm)

Cheers,
Patty

[racket]

Hi Patty

I'd cut back on the number of vanes to maybe 13 or 15 , it'll depend on how it looks once you draw it up , as long as the vanes are nicely tapered and the throat area and gas angles are correct it'll work OK , try to "copy" a ready made turbocharger design with regards shapes , length etc ..................stick with the 8mm gap, but no larger as there'll be gas velocity changes as they spiral in

Cheers
John

[madpatty]

Hi Guys,
The last test run left a considerable amount of damage but obviously nothing that cannot be cured.

NGV and shaft tunnel were both damaged with bushes seized inside the tunnel. I never thought the turbine inducer could touch the NGVs trailing edge as there was a good amount of distance between turbine inducer and NGVs but surely things go unexpected when the rotor rotating at >100000 RPM comes to a halt instantly.

So this gave me an opportunity to make new NGVs with slightly lesser throat area of ~968 sq.mm compensating 1 NGV blocked area reduction. I also left some vaneless gap between NGV and turbine inducer. The vaneless space was selected according to information posted by Chris(finiteparts) in "information on small gas turbines" thread.
This vaneless gap will provide me an added benefit and will protect the turbine blades from reaching the NGVs and destroying them again.

And the Test RUN.




The test was a success with max. P2 of 27.5 Psi and even lesser TOTs with max of 556 degrees. C at 27 psi.


P2(psi)                   TOT(deg.C)             RPM


7                           550                        64300

10                         519                        73300

14                         513                        81700

20                         521                        

24                         540                        A9690 

26                         548                        

27                         556                        L0410


Cheers,
Patty

[racket]

Hi Patty

Getting ever closer :-)

Temperatures are good though still a tad high for no backpressure , I'd say its from the comp clearances .

No video , on the video :-(

Development progressing nicely

Cheers
John

[madpatty]

Oops....youtube didn process that video completely.

i have repaired that though.

[madpatty]

A random video of the gauges at full throttle.



Cheers,
Patty

[racket]

Hi Patty

Did I see a 499C at 0.58 secs on the video , thats a first time , into the 400s , excellent :-)

Cheers
John

[madpatty]

Hi Racket,
Yup the engine idles at lower temperatures....that was at about 10 Psi P2.

Cheers,
Patty

[pitciblackscotland]

Hi Mad Patty,
I have been watching your build thread from the start. I'm am very impressed with your work and ongoing R&D. Keep up the good work

Cheers,
Mark.

[finiteparts]

Patty,

That's looking good. I got to give you credit for the fastest turn-around time! I am glad those spacing and solidity numbers worked out for you so well.

~ Chris