Jet Engine Project

[lukenz]

Mar 14, 2020 16:38:43 GMT -5 racket said:

Bar might impact the turbine wheel if it breaks.

You need a spring loaded pressure relief valve on the oil supply as flow through a coldturbo with cold oil is minimal whereas with hot components theres vastly more flow , a fixed oriface bypass won't work no matter what pump you use .

Thanks John, on the hunt for a pressure relief valve now. I flow tested the maximum spray volume of my current spray nozzle, it resulted in an embarrassing 80ml/min! Have now ordered a nozzle that flows up to 600ml/min at around the max pressure my fuel pump runs so looking forward to trying this out. I am also looking at an alternative way to ignite the engine.

[racket]

Yep , a bigger spray nozzle required :-)

[lukenz]

Mar 18, 2020 19:29:51 GMT -5 racket said:

Yep , a bigger spray nozzle required :-)

And that bigger spray nozzle was the formula my friend + the addition of the bosses 1000CCA battery out of his funny car 😂



Have never seen another DIY turbine glow as hot as this did at the top end of the chamber, once I have sorted the ignition out (which actually melted off inside the combustion chamber and thankfully did not strike the turbine!!!) I’ll be wiring up the thermocouples and adding pressure readouts to know her behaviour. Only then will I move on to exhaust nozzle and afterburner.

Is there anything in this video that some of you more experienced builders can learn and share about my engine running?

Some technical info:

- Fuel pressure: 114psi (full throttle)
- Sustained combustion: ~14psi fuel pressure
- Oil supply pressure 40psi

[racket]

Hi Luke

Thats more like it :-)

Yep , the endcap is glowing a bit , you may need to get a bit more airflow across its under surface to create an air blanket .

Time to get some gauges on it so that its safe to run up to full speed , no glow from the turb wheel which is good at this stage of development so it'll be interesting to know what TOT jetpipe temps you have and that'll determine how much jet nozzle backpressure we can put on the engine

Cheers
John

[lukenz]

May 15, 2020 17:15:59 GMT -5 racket said:

Hi Luke

Thats more like it :-)

Yep , the endcap is glowing a bit , you may need to get a bit more airflow across its under surface to create an air blanket .

Time to get some gauges on it so that its safe to run up to full speed , no glow from the turb wheel which is good at this stage of development so it'll be interesting to know what TOT jetpipe temps you have and that'll determine how much jet nozzle backpressure we can put on the engine

Cheers
John

Cheers John, such a buzz and good way to end a Friday afternoon at work 😎

I already have ~12mm holes to cool the end plate basically 10mm along the flame tube at 12, 3, 6 & 9 o’clock, more holes or larger holes or both?

Yep, I’ll sort the ignition this week, probably replace bbq ignitor with spark plug, will the spark plug handle internal temperatures without breaking up?

Then onto some logging 👍

Cheers,

Luke

[racket]

Hi Luke

Looking at your endcap glow it looks fairly even right around which makes me think the 4 large holes aren't doing their job as I'd expect 4 "segments" seperated by the 4 air jets each cooling a radial segment .

What sort of fuel nozzle are you using , spray angle etc , it might be contributing to the heat getting back to the lid depending on how it might influence the airflow pattern within the Primary Zone.

The 4 large holes are displaced a fair way from the lid , you may need to blank them off and drill 20 smaller holes with the same total area , hard up against the weld bead , with the holes "angled" towards the endcap to get the flow onto the surface.

Sparkplugs survive OK , I have mine positioned in the sidewall between Primary and Secondary lines of holes with just the electrodes projecting inside the flametube

Looking forward to some Data :-)

Cheers
John

[lukenz]

Hi John,

I’m using a diesel burner nozzle, solid cone spray pattern at 80deg spray pattern with a maximum flow of 10 lph at 100psi.

I will try what you have suggested as far as blanking holes and drilling new ones as described.

Cool, my igniter is also located in the same place so will swap it out for a spark plug.

Will hopefully get this all done this week and try to provide some data 😎👍

[racket]

Hi Luke

Just been having another look at your flametube ..................could you please verify your hole sizes and number please , they sorta look a lot of holes/area for a 68 mm inducer .

Thanks for the nozzle data , at that 10 liters per hour - 166ml/min its still going to be only providing enough fuel for modest P2s

Cheers
John

[lukenz]

May 16, 2020 1:50:40 GMT -5 racket said:

Hi Luke

Just been having another look at your flametube ..................could you please verify your hole sizes and number please , they sorta look a lot of holes/area for a 68 mm inducer .

Thanks for the nozzle data , at that 10 liters per hour - 166ml/min its still going to be only providing enough fuel for modest P2s

Cheers
John

Hi John the below blue print is my flame tube hole config, except the primary holes are now bigger (10mm I believe) matching the total area of the drawings smaller primary holes:

ibb.co/nzfjXgX

Apologies! The spray nozzle provides 37.9 lph which = 631ml/m

Cheers, Luke

[racket]

Hi Luke

Thanks for the clarification , that eases my concerns :-)

Yep, blank off those 4 big holes at the top, at 15mm down they are too far from the endcap for the air to contact it , 20 small holes of the same total area, positioned at the edge of the weld bead and orientated to eject onto the end cap should help cool it , the next test run will show if there needs to be extra holes added or changes made.

Cheers
John

[lukenz]

May 16, 2020 18:19:56 GMT -5 racket said:

Hi Luke

Thanks for the clarification , that eases my concerns :-)

Yep, blank off those 4 big holes at the top, at 15mm down they are too far from the endcap for the air to contact it , 20 small holes of the same total area, positioned at the edge of the weld bead and orientated to eject onto the end cap should help cool it , the next test run will show if there needs to be extra holes added or changes made.

Cheers
John

Awesome mate, cheers! Will modify and test this week. What coil setup are you using for spark plug?

Cheers,

Luke

[racket]

Hi Luke

I'm using a set of points/condensor and a homemade cam on a small 12V electric motor shaft to get an auto coil sparking , I've also used an auto flasher unit in place of the points to activate the coil , some pretty crude devices have been used by us guys to get a spark going, thankfully it doesn't take much of a spark to ignite a propane pilot light :-)

Cheers
John

[lukenz]

May 17, 2020 3:48:12 GMT -5 racket said:

Hi Luke

I'm using a set of points/condensor and a homemade cam on a small 12V electric motor shaft to get an auto coil sparking , I've also used an auto flasher unit in place of the points to activate the coil , some pretty crude devices have been used by us guys to get a spark going, thankfully it doesn't take much of a spark to ignite a propane pilot light :-)

Cheers
John

Hi John,

I tried a spark plug using my ignitor already setup in the engine and works perfect so got that sorted 😎

I have drilled 12x 4.5mm holes up against the front plate on a slight angle (see pics). I have also attached a pic to show you the colours of the flame tube after last Friday’s more successful run.

[racket]

Hi Luke

All looking good for the next testrun :-)

Cheers
John

[lukenz]

May 19, 2020 4:15:08 GMT -5 racket said:

Hi Luke

All looking good for the next testrun :-)

Cheers
John

Hi John,

Fingers crossed she runs a little cooler 🙏 Would you mind explaining again the correct positions for TIT, P1 & P2? Just wasn’t 100% clear from research here and how it was explained earlier in this thread. TOT is clearly obvious 😂

Cheers,

Luke