FJK-1 & FJK-2 Gas Turbines

[nersut]

Hi my name is Erik & I am from Greenland.

I build my first gas turbine in about a month & I called it FJK-1
"FJK" stands for "Fordi Jeg Kan" no. 1 (in danish) an it means "Because I Can"

I tried 2 different types of flame holders:
The first one was a straight tube & holes calculated with JetSpecs. It ran fine on propane but was very unstable using liquid fuel. Probable because I didn't build in a evaporator unit.

The second one was a kind of toroidal vortex flame holder. I surfed on the internet an found the long-lived Rolls Royce Dart turboprop engine with can type flame holders with swirl vanes & no evaporators.
I made a miniature version of the Rolls Royce flame holder. An it runs much much better with liquid fuel. TIG welded 304 stainless steel.

My next problem was controlling the fuel. I used the fuel pump, solenoid valve & the nozzle holder from a Reillo 40 G20S residential oil burner. This unit is small an runs on 230V AC an draws 90 watts. Fuel pressure is controlled with a needle valve, 0-12 bar (0-175 psi)

I tried different nozzle sizes & makes:

• Danfoss 0.5 gph - Starts but too small and dies out.
  
• Danfoss 2.0 gph - Runs, but just above self sustain, P2 just about 0.2 bar
  
• Danfoss 4.5 gph - Runs, P2 about 0.8 bar, will only run with almost full fuel pressure. When throttling down it runs rough with black sod/smoke.
  
• Monarch 7.5 gph - Runs perfect, full control, no smoke or sod. Smooth from 0 to 1.4 bar P2 pressure.
  

Info:

• Garrett T04E10 Turbocharger (from a Volvo L120 Wheel Loader)
  
• Liquid Fuel for start & run (Kerosene or #2 Diesel)
  
• 7,5 gph @ 100 psi Fuel Nozzle (Max 9,91 GPH)
  
• No evaporator tubes
  
• Toroidal vortex combustion chamber
  
• P2 pressure 1,4 bar (20 psi)
  
• No TOT/EGT sensor Automotive EGT sensor ordered.
  
• Vacuum cleaner motor as Starter
  
• 2 meter (6,5 feet) Dinghy sails about 10 km/t (5,5 knots)
  

Okey my first gas turbine build was running! Now what? I took my FJK-1 & my friends tiny dinghy an sailed on the open sea without lifejacket or fire extinguisher...
Yes, stupid, but I am still alive!



My next move will be fitting a Power Turbine on my FJK-1.
My plan is a fairly large diameter single stage axial turbine that will spin about N2: 10.000-15.000 rpm. The reason is I want a "slow" running power turbine is I want a simple transmission & more torque. Final output shaft 5.000-8.000 rpm.

Do you have any idea what diameter, blade height, angles for the NGV & turbine blades???


Please comment & throw me some ideas/examples
And maybe some ideas what it can generate in hp/torque???


I also ordred a Arduino Uno R3 board & a LCD display and I am planning to program it to act as a fuel regulator.

A servo will be linked to the needle valve. And the EGT sensor connected to the Arduino. The Arduino will maintain a constant EGT temperature by controlling the servo/fuel delivery.

Later I can add:

• MAP sensor to display P2 & auto shut-off fuel if P2 drops below (X) P2 (flameout)
  
• Auto shut-off fuel if P2 exceeds (X) P2
  
• Display 0-100 % throttle position
  
• An maybe a simple auto startup & maintain constant EGT
  

Here is a screenshot from JetSpecs:





And some random pictures.
Hot startup



Jet Dinghy



Night run - Red Hot





T04E10 Turbine Wheel & Straightening Vanes



T04E10 Compressor Wheel



Flame Holder - 304 Stainless Steel



Flame holder Illustration - "Toroidal vortex" flame stabilization

[GrantB]

Looks like alot of fun!

[nersut]

Small update

My new Arduino Uno R3 or "Open Source Electronics Prototyping Platform" arrived yesterday an I tested the LCD display right away.



The board is easy to program just plug in the USB-cable and upload programs.

[racket]

Hi Erik

It looks like I missed your earlier posting about fitting a power turbine wheel to your engine , sorry about that .

Are you going to be powering a boat with it ??

Will you be constructing the turbine wheel yourself ??

Or will you be looking for a professionally produced turbocharger wheel ??

Do you have a thrust reading from your engine ??

If so , what thrust and what sized jet nozzle ??

These "numbers" will give me an idea of the available energy and mass flow you have available for processing by the freepower wheel .

Cheers
John

[Richard OConnell]

Looks awesome! Have you considered moving the engine closer to the water level? I'm not sure what constraints you have to work with, but I think that it would increase its performance a little bit.

Best of Luck

[nersut]

Hi John thank you for your reply.

I was testing my FJK-1 when it began to spit liquid metal out!
The fuel regulating needle valve was acting weird and I didn't noticing the fuel pressure was way off the scale, about 14bar+

The tips of the turbine wheel melted...



The FJK-1 can still start and run with 1 bar P2 with no problems.

BUT I was lucky too! I got a "new" & BIGGER turbocharger today for free.

It's a Garrett TA5101 from a Volvo 12 Liter truck engine.

I took it apart for inspection.




The turbocharger is in very good condition.

I am planning to replace the current turbo on the FJK-1 with this turbo as soon as possible (this week maybe).
It has the same oil inlet/outlet flanges but the turbine inlet is different. I think it is a T6-flange.
Just a quick modification on the turbine inlet.

A quick calculation on JetSpecs says 45lb's! of thrust at 2 bar P2 pressure



OK back to your questions.

• Maybe a dinghy or on the side of my bicycle! ;D
  
• Yes I am planning to construct the power turbine my self.
  
• With the Garrett T04E the FJK-1 was making about 15-20lb's measured by a fish-scale but the frame was not completely level.
  
• The jet nozzle is about 1.8in with 4 straightening vanes
  

I will post detailed test results as soon as the "new" turbocharger is mounted.
IF it starts & runs... Fingers crossed.


Cheers
Erik

[nersut]

Hi Richard

I don't think I can lower the jet nozzle more than the current position. This is because the radiant heat is a bit strong & I think it will melt & blow/sink the dinghy if i tried. hehe!

Does thrust augmentors used on pulse jets have any positive effects when used on gas turbines?

If it does, I could modify my "thrust vectoring nozzle" or rudder to act as a thrust augmentor too.


Cheers
Erik

[Johansson]

Hi Erik!

I think you should slow down a notch and figure out why the first turbocharger melted before you fit a new one and destroy that one too.

You say that the fuel pressure regulation was acting wierd, was the gasturbine over-revving from this or was it just the fuel pressure that was unusually high?

Cheers!
/Anders

[wolfdragon]

Also, you need to install a temperature probe to monitor the turbine out temperature, there are some good guidelines for maximum numbers in the rules of thumb over at the yahoo group

[nersut]

Hi Anders & wolfdragon

I think I know why the turbine melted.

When it happened the fuel pressure was 14+ bar (the gauge needle was off the scale) & the fuel flow would have been about 11-12 gph.

Normally I set the max fuel pressure to about 10 bar & about 9 gph. I think the FJK-1 was over-fueled & probably over-revving too, because the compressor housing was very hot (almost burned my fingers).

I have been running my FJK-1 for some time now & burned maybe over 30 gallons of diesel without any problems.

As I wrote earlier I have ordered a Automotive EGT sensor with a meter. And I am planning to program the Arduino board to automatically adjust the fuel flow by monitoring the EGT temperature.
The EGT meter I ordered can measure temperatures from 200 to 1350 degree C.

Is 550 degree C okay as a max & as a fixed temperature or should it be lower/a bit higher


Cheers
Erik

[racket]

Hi Erik

650 C as a TOT should keep you out of trouble .

Please don't run your engine without an accurate TOT gauge and P2 gauge , turbine engines generally run close to their maximum temps and tip speeds to produce their power , its easy to exceed the limits with the usual result being a dead engine , you were lucky that it was only turb tips that went missing .

Get your new engine running and sorted so that its safe and then we'll think about freepower turbine wheels :-)

You'll need to reconfigure your flametube/combustor for the larger mass flow .

Cheers
John

[nersut]

Hi John

Thank you for replying.

Okay if I am going to modify the flame tube, what dimensions & hole sizes are recommended ?

I like my current flame tube design with the "toroidal vortex" like in the Rolls Royce Dart combustors.
This makes the flame tube very compact & no need for evaporator tubes.

The current flame tube is tiny:

• Length: 7.5 in
  
• Diameter: 2.5 in
  
  It is much smaller that the JetSpecs calculations which was:
  
• Length: 11.5 in
  
• Diameter: 5 in
  

This is about the ½ size of the recommended.

It ran fine until the over fueling/over speeding accident.

I took a quick calculation with JetSpecs using data from the "new" Garrett TA5101 turbocharger. It say:

• Length: 15.2 in
  
• Diameter: 5.1 in
  

If I multiply the above results with 0.5, it will be almost identical to the current flame tube if I take the elbow in the equation?

Maybe I should try the current setup first with the "new" turbocharger without modifications to the combustor?



Cheers
Erik

[racket]

Hi Eric

Your current flametube diameter is too small even for your old turbo when using kero/diesel , no wonder you had combustion stability problems initially .

Work on having the flametube crossectional area as 3 times comp inducer area .

Your old turbo was 1.9" dia inducer therefore 2.83 sq ins , multiply by 3 = 8.5 sq ins or a 3.23" dia flametube required ...................Your new turbo at 2.5" dia - 4.9 sq ins inducer your new flametube needs to be at least 4.3 inch diameter .

If the flametube area is too small the axial air velocities are too high to sustain combustion of atomised fuel , you end up with flames either going out or combustion continuing into/through the turbine wheel .................sound familiar :-((

Jetspecs recommendations are for a good reason , to stop guys building engines with undersized flametubes that WILL give nothing but problems .

Do you have pics of the flametube as it came out of the "dead" engine ??

Cheers
John

[nersut]

Hi John

And thank you for your fast replies.

Okay my current flame tube is too small...

Here is a sketch I made in 3D studio on the current combustion chamber.



Maybe I could use the current combustor housing as the new flame tube? The diameter is 4 in & the length is 10 in without the elbow.
I could make a new combustor housing maybe 6 in diameter?

Here is a sketch of the modified combustion chamber.



I also made some sketches in 3D studio for the Power Turbine including the NGV.



Please comment


Cheers
Erik

[racket]

Hi Eric

I think you should start with a fresh bit of metal and make a combustor that is big enough to do the job , as I said in my last email , your new turbo requires a flametube at least 4.3" ID , there will then be a need for at least 0.5" clearance between FT and outer can wall so a 6" tube would be OK for it .

The Dart type flametube has ~15% of the air going through the swirl vanes surrounding the spray nozzle with another ~15% going to holes in the primary zone , say 20% to the secondary holes further down the flametube and the remaining ~50% through the tertiary dilution holes , so simply split up your inducer area into the holes required at each of these stations .

Cheers
John