PD-01 Jet Engine

[madpatty]

Hi Chris,
Yea the air leakages are near the oil fuel inlet/outlet pipes in the front case......near the fuel inlet there is some big one as i can feel a proper stream of air coming out that can be felt from about a feets distance.....

I am measuring the P2 just near the diffuser discharge downstream of the compressor plate.....Near the point highlighted in this photo...



Yea i used the larger impeller......

cheers,
Patty

[madpatty]

Hi Guys,

Can anybody show me a possible method how to stop those front case leakages near the oil/fuel pipes......

Cheers,
Patty

[finiteparts]

Patty,

I would chamfer the inside of the forward casing...



Then fill the area with a bead of high temp silicone/RTV and let it set up really well...maybe a day. You don't want it to be soft at all. Then when you "clamp" it between the diffuser and the forward case it will get squeezed and form two sealing surfaces. Additionally, the air pressure that leaks in from the tube gap  acts on the inner face, that pressure just forces the sealing faces tighter. Think about in a free body diagram sort of way....



You could probably do this with a thick o-ring instead of RTV....just make sure that the chamfer is smaller than the o-ring diameter so that you get a positive amount of "squeeze" in the o-ring.

I wonder if you measure the P2 down farther, like off of the combustor case if you would get much of a difference in pressure, since where you are measuring, the diffuser discharge still has some area to expand into...

Good Luck!

Chris

[madpatty]

Hi Chris,
I today did sort of same thing.....but i am using a cork gasket sheet instead that which i was already having......i had ground some seat for that sheet in the upper case so that the upper case gets properly seated with that sheet in between......

I will test it with that packing sheet and if it doesn't work then i can add some RTV to fill the small gaps.....O-ring of appropriate size will take some time to find....

Cheers,
Patty

[madpatty]

Hi Guys,
Today i ran the engine with a new gas cylinder....and astonishingly the engine started without any trouble....the spoolup was a very easy and fast one....the engine throttle was also very responsive...the Max P2 reached was 17 Psi....This was by far the maximum P2 i have ever reached on this engine.


Here are some of the numbers that i collected:-

P2(Psi)    Temp.(degrees celsius)

11            615
12            660
15            748
17            780


i will post the video of the run soon.....


Cheers,
Patty

[madpatty]

Hi Guys,

Here is the video of today's run....The Thermocouple was being pushed away due to the jet thrust so i had to push it again and again so as to get the readings at various P2s....



Cheers
Patty

[Johansson]

Congratulations! Chase down the leaks and fix the generous clearances and you will be rewarded with much lower temps.

[mitch]

Nice run! I love the look of the engine

[madpatty]

Thanks Mitch.....

[madpatty]

Another quick spoolup of the engine....The temperatures were even lower than before as i smoothened the flow the path of the air from diffuser towards the combustion chamber....
And the data:-
P2(Psi)        Temp.(celsius)
11                664
12                669
15                730
17.5             750


I don't know what came to my mind earlier before the last test run that i coloured the diffuser with black spray paint....but as soon as the engine started making some pressure all the paint from the diffuser channels got ripped off and small dust like particles went upto the turbine and out of it...those appeared as sparks in the earlier video...i got scared thoroughly as i saw the sparks but later on opening the engine found out that it was all paint particles which got ripped off because of the high velocity air.....all the NGVs and turbine blades were intact and OK.

So i cleaned the whole diffuser, removed the paint, made the paths more smooth and spooled it up today.
Max. temperature 750 degrees at 17.5 Psi P2.

Cheers,
Patty

[madpatty]

Hi Guys,
A very basic question i wanted to ask...

I have recently got some K-type thermocouples....i want to check if the thermocouples are measuring the proper temperature....i need some reference point to calibrate with...

I checked by dipping it in boiling water(tap water)and the temperature was 111 deg. Celsius.....are they all rubbish or these are normal discrepancies.....
Is there any other standard method that can be followed to check them?

Cheers,
Patty

[Johansson]

I´ve had the same problem with automotive EGT probes, I have always assumed that every K-probe measures correctly within 1% or so but that is not the case at all unfortunately.

[madpatty]

So what are you using now to accurately measure the TOTs??....and you meant to say that thermocouple is a bad one??
Is there some correction factor which can be used to interpolate the temperature from that thermocouple...

[sven]

Fluke thermocouples can be accurate.

[smithy1]

The thermocouples John, (Racket), had fitted to the 6041 go kart are actually quite accurate, I have access to aviation spec calibrated instruments and I did a quick comparison/check last year....both of the readings were well within 1% of the officially calibrated units. I did a spread between 0c-500c and they were both well within the required 1% error.

The go kart has two probes opposite each other, 3 & 9 0'clock, one fine sunny day I noticed a difference of over 10c between them when cold ....then I realized one was in full sun and the other in shade ....once the engine was started, they read within 2c of each other at a stable idle....that's plenty good enough for me..!

Cheers,
Smithy.