FJK-1 & FJK-2 Gas Turbines

[racket]

Hi Erik
Yeh, about 1.3 lbs/sec mass flow if using the "standard" 11 lbs/sq inch/minute of inducer area...............but in your cold climate maybe another 10%, so getting towards 1.5 lbs/sec, a bit will depend on the turbine stage size/restriction as to the actual mass flow.

this might be of help www.ebay.com/itm/1969-Cummins-Diesel-Engine-Manual-T-18A-Turbocharger-B-/140154273309?pt=LH_DefaultDomain_0&hash=item20a1d87e1d

Cheers
John

[nersut]

Hi John

Thanks for the eBay link, I ordered the workshop manual today & it's already shipped



1.5 lbs/sec sounds good, I think the T18 uses ordinary brass bushes & 360 degree thrust bearing instead of one piece aluminum like in the VT-50.

Cheers
Erik

[nersut]

I am having an idea or a dream of building a DIY 2-stage gas producer turbine engine with a power turbine at the end.
The idea is to use two different sized turbochargers & a power turbine. Basically a DIY 3-shaft gas turbine engine.

The goal is higher efficiency/lower fuel consumption.

Here is my schematic illustration of the engine. Next is a schematic illustration of a commercial 3-shaft gas turbine engine, a Pratt & Whitney Canada - PW100.

 

The PW100 engine is a 3-shaft turboprop engine. It has two radial compressors which is connected to its own turbine (2-shafts gas producer) + two power turbines/shaft.

My  illustration is using the same configuration as the PW100 but uses turbochargers in stead. I have collected a bunch of turbochargers in different sizes.

Any comments & ideas are very welcome.

Cheers
Erik

[racket]

Hi Erik

It is possible , but a lot of work just to save a bit of fuel and gain a few extra horsepower.............the big problem is matching up the flow capacities of the various parts , you'll also need an intercooler between the compressor wheels otherwise the small alloy comp wheel could be overheated and fail, aero 2 stage comps generally use titanium wheels to cope with the second stage high temp .

There have been DIY attempts at making two stage engines but their outputs leave a lot to be desired, to do the job properly so that the outcomes are worth all the effort will be a big job , and in a lot of cases impossible due to the non availability of the necessary turbine wheels to connect to the large first stage compressor wheel , the turb wheel needs to be small due to the higher than normal pressures/densities being processed .

Cheers
John

[gidge348]

Hi Erik, I have been doing a bit of head scratching looking at your proposed engine and think that you may actually create and engine that is "less" efficient, not more?

The main issue I feel would be that low pressure compressor limits the mass of air that the engine will in-jest, so if the air is burnt in a High pressure combustion chamber it will still only supply the same mass as if it were just going through a combustor, but with the added losses of the HP Turbine.

A couple of things to think about, maybe bypassing some of the gasses from the exhaust of the HP Turbine direct to he power turbine? look up what the largest LP compressor available is? Try and design a single shaft, multi compressor,turbine engine.

Don't let me put you off, experimentation is the mother of innovation.

Good Luck
Ian...

[racket]

Hi Ian

It is possible to produce a more powerful engine , but the actual percentage thrust increase isn't a huge amount , though if used to power a freepower turbine the percentage gains are greater.

I started making a 2 stage setup ~10 years ago using my Garrett TV84 for the low pressure stage , even purchased a huge truck intercooler to use between compressor stages , but ended up not proceeding with the build as other jobs took precedence .

The main gains from a two stage engine is better fuel economy from the higher expansion ratio , but unless we want to run our engines for hours on end its not worth all the trouble and complexity , easier to build a larger single stage unit :-)

The actual design work is similar to the multi stage turbos on tractor pulling engines .

Cheers
John

[nersut]

Hi John & Ian

I know it would take twice the effort (or more) to build this 2-stage engine than a single turbocharger gas turbine & there is no guarantee that it will successfully run.
But the biggest turbocharger I could find is the T18, and it is too expensive for me to ship heavy things up here in the far north.
Bigger is better! (gas turbines) 

So instead of a huge single turbocharger gas turbine I am interested in the 2-stage version. 

If there is no suitable turbine wheel, could a external wastegate valve fitted to mimic a smaller turbine wheel?

If possible, which configuration is the "correct one", A or B?

A. low compressor turbine with a wastegate valve.


B. high compressor turbine with wastegate valve.


I also added a intercooler/charge-cooler in the diagram.

Cheers
Erik

[racket]

Hi Erik

I've been having a bit of a think on it and you might be able to "pad out" the low pressure turbine stage by having another combustor between the high and low turb stages to replace the temp drop ( >100 deg C ) through the high pressure turbine and perhaps have some water spray for steam generation to further fill the low pressure stage .

A lot will depend on the turbos used and their configurations , its a case of "juggling" the requirements, its not an impossible job :-)

Once you have the T18 apart and give me some dimensions I'll do so "numbers" for you .

Cheers
John

[nersut]

Hi John

It sounds a bit complicated now... Yeah, maybe I should skip it then. I have to stick to the T18 for now.

Another thing! I want to get rid of my current starting unit, it's a ~ 2 kW vacuum cleaner motor (230V) with a one way valve.
It works perfectly every time an weights about a kg? The annoying thing is I have to run a portable but heavy 230V generator just to spin up my turbine for start up.

I want to try with air impingement starting. But I have to build a high pressure air compressor first.
My plan is to use a regular household refrigerator compressor converted to a air compressor, to pump air in to a CO₂ fire extinguisher bottle.
Some refrigerator compressors can pump air up to 300-400 psi (~ 20-27 bar) I have seen several builds on the net, some coupled in series to produce even higher pressure.

Should 300 psi of air in fire extinguisher bottle be sufficient for a start up?

Cheers
Erik

[racket]

Hi Erik

300psi would be enough pressure, but that pressure and the delivery quantity needs to be maintained during most of the spoolup which could last 30 seconds , I doubt that a CO2 cylinder will hold enough quantity :-(

Have you considered using a brushless RC motor , there are some very powerful (4-5Kw) ones available at quite reasonable costs www.hobbyking.com/hobbyking/store/__516__512__Electric_Motors-39mm_and_above.html

Cheers
John

[nersut]

Hi John

Ok, if 300 psi should be sufficient with enough capacity for start up, then I want to try with that first.
Maybe with 2 bottles instead, my current turbine with vacuum cleaner motor starter reaches self sustaining after 8 to 10 sec. from fuel delivery start.

I also found another Danfoss fuel pump which will be installed soon, it has 2 solenoids one for low pressure/flow & one for full pressure/flow.
With this pump I could remove my second fuel nozzle used for start & idle, and use only one fuel nozzle for idle & full speed.
Both low & full pressure is adjustable, the fuel pump motor speed remains the same.

Cheers
Erik

[racket]

Hi Erik

If you can get a self sustain in 10 seconds then your vac starter is more than powerful enough, theres a good chance your 300 psi in a single bottle will be enough , trial and error testing required :-)

Cheers
John

[nersut]

Hi John

Sounds promising!

I have a backup plan, today I went to the local scrapyard & found this nice MIL-spec axial fan blower rated 300 CFM at 27 volts @ 42 amps.



If impingement starting fails I could replace my AC vac motor with this DC fan above and two 12 volt car batteries instead of the petrol generator.

I also collected some other items from the scrapyard.

A cast burner head with stardard Hago spray nozzle, HT sparkplug & lead0, it also have whirl/mixing vanes.



And other useful items like: MIL-spec wire connectors & plugs & two heavy duty transistors, rated 1000 V & 300 amps!



I will probably use some of the items for my turbine. It's always nice to visit a scrapyard now & then, free stuff!


Cheers
Erik

[nersut]

Look what I also found... A real JATO rocket engine!  15 KS-1000 MK 6, it's rated for 1000 lbs of thrust for 15 sec.

 

A little story of the rockets: link

I think I with sandblast the bottle & repaint it like the original ones with texts & use it as decoration. 

Cheers
Erik

[Richard OConnell]

very nice find Erik!! Dare I ask where you came across this?