400LB Thrust Ambitious Project

[madpatty]

Hi Guys.
You read it right.

I thought, in order to keep myself motivated, I should start a build thread of this Overly ambitious but not impossible project.
I have acquired this titanium compressor impeller (170/230mm).

My preliminary calculations show, this impeller is good for ~400lb thrust at modest 3.5PR.
But finding a suitable turbine is a challenge.
I need something in the ballpark of a 215mm axial turbine or a (215/170mm radial turbine)
The turbine that I have is slightly too big at 270/185mm.
If any of you have any suggestions and comments please let me know.

But sure this pair looks too good together.



Cheers.

[racket]

Hi Patty

Just grind down the inducer of the turbine wheel to your 215 mm , its exducer area is the right area size ratio to the comp inducer area ..

Cheers
John

[wannabebuilderuk]

I don't even want to think how much that must cost.... Even as titanium!

[monty]

Patty,

This should be FUN! ;-)

Monty

[ripp]

Hi Patty,

This runner belongs to which engine?

Cheers
Ralph

[madpatty]

Nov 25, 2021 2:29:05 GMT -5 ripp said:

Hi Patty,

This runner belongs to which engine?

Cheers
Ralph

Hi Ralph.
Not completely sure.
Only know that the Turbine belongs to GTCP-100 apu.

Regards

[madpatty]

Hi All.

I have been contemplating the basic design and how each component will be joined.
Which kind of bearings to use(brass or balls) and bearings placement.

The turbine has this extra long extension on the exhaust side which will cause too much of an overhang if I’ll use bearings between the compressor and turbine.



The turbine has a through bore with a shaft extension press fitted through(maybe acting as tie shaft or bearings support in the apu).

Any ideas are welcome.

Thanks

[madpatty]

There are more pictures and the X section of the APU which uses this turbine wheel.

jetandturbineowners.proboards.com/post/31381/thread

Thanks

[finiteparts]

Patty,

That compressor looks a lot like my TPE331 first stage impellers, but mine do not have any curvic coupling on the forward end of the shaft.   The dimensions are roughly the same.  Do you have any part numbers on the impeller that you can google?

To get a rough idea of the original design turbine inlet flow conditions, I dug up an old paper and found some numbers on the compressor design for the GTCP105.

The design point conditions for the GTCP105 1st stage compressor have it at a corrected flow(W*(theta^0.5) / delta ) of 623.2 lbm/min at a corrected rpm (N/(theta^0.5)) of 33,719 and a total to total PR of 2.65.  The second stage compressor flows a corrected flow of 278.0 lbm/min, corrected rpm of 28,400  at a t-t PR of 2.075.

where:

theta = Absolute inlet temperature (R)/519  -  corrected temperature
delta = Inlet pressure (psia) /14.7               -  corrected pressure

Reference:
Dallenbach, F., "The aerodynamic Design and Performance of Centrifugal and Mixed-Flow Compressors", SAE Technical Progress Series Vol.3, Centrifugal Compressors, 1961.)

So, on a standard day, the flow out of the compressor system is roughly 10.39 lbm/s at a t-t PR of 10.4 lbm/s.  

I would start with these numbers as rough estimates of a design point for the turbine and back-calculate the compressor performance at these flows.  Since you are going to be operating this turbine way-off design point, I am not sure what to say on how it will perform, but at least you have an idea of the flow capabilities. Using that turbine, you will set the flow through the engine with the NGV throat area and the turbine will have to perform with whatever comes it's way.

Quick hand calc of the original design NGV throat area if we assume the turbine inlet temperature is 1700 degF and the combustor pressure loss is 5%, gives a NGV throat effective area of 12.05 in^2 at choked conditions.  If you can get the 7.7 lbm/s that the TPE331 flows at roughly a t-t PR of 3.0, you would need a NGV throat effective area of around 16.4 in^2 at choke assuming that you are also firing at 1700 F, which puts you at roughly 478 lbf thrust, dry (assumes compressor and turb eff ~ 80%).

At that compressor physical size, it is usually lighter and easier to use an axial turbine. TPE331 turbine wheels show up on ebay now and then and would likely already be matched.

This will be a monumental task, with lots of challenges.  
Good luck!
Chris

[racket]

Hi Chris

Yep , very similar comp to the TPE 331 first stage I was going to use in my build jetandturbineowners.proboards.com/thread/371/skuld-666 .

The TPE second stage turb wheel is a reasonable match for it, or use a cutdown third stage if easier to source .

I think the radial wheel Patty has will be OK if he simply cuts down the inducer diameter to keep tip speed under control , the exducer area isn't too big

Cheers
John

[madpatty]

Hello All.
Been thinking about how to use this turbine.

The turbine is made of two separate sections (joined together I don't know how)as you can see in the pictures.



The long shaft is a press fit "through" the turbine and I think it can be removed out probably by using a hydraulic press or something.

If anyone knows more details about how these impellers are assembled or disassembled then please share.

Thanks.

[stevie]

Cool shaft side with Ln2? I believe some shaft assemblies are done this way AKA the old time NYE squirt bearing shaft fitment.
nyethermodynamics.com/squirt_1/index.html
Steve

[racket]

Hi Patty

Why do you need to disassemble the unit ??

Cheers
John

[madpatty]

Dec 11, 2021 17:02:16 GMT -5 racket said:

Hi Patty

Why do you need to disassemble the unit ??

Cheers
John

Hi Racket.
Because all that extra weight on the exhaust side of the turbine is of no use and is a huge cantilever load for any turbine side bearing.
Also it would be harder for me to make external spline and also install a rear bearing at that location.

It would be best if I could make my own shaft and just use a usual two bearing design we all use here.

Thanks

[racket]

Hi Patty

That makes sense :-)

Is there any indication of alignment components between exducer piece and main section ?

Cheers
John