Building The First Turbine

[racket]

Yep , I'll second the BW , not ideal having the twin entry to the turb scroll, but of the choices available its probably got best chances

[aquaticharpy]

Sweet

[aquaticharpy]

Do you think it possible to run the turbine on hydrogen gas? How easily, what would need to be done?

Thanks
John

[racket]

Yes

A very large cylinder required along with the necessary plumbing and controls

[aquaticharpy]

How do I calculate hole size for flame tube. Jet Spec doesn't calculate it, how do I find what diameter they should be to put into jet spec. Thanks
John

[racket]

Hi John

Hole sizes/number , especially for the Primary Zone , will vary depending on fuel and fueling method as well as actual flametube design used , there are a huge number of variables making it impossible for any Program to compute , Jetspecs is a simple , some might say crude device , but it has helped a lot of guys getting an engine to work .

So what fuel will you be using , how will it be injected , at what pressures , at what "angles/shapes", and into what design of flametube ?? ...........these are all your choices ...............if you don't like , or can't cope with so many choices then you need to simply copy a design someone has already built and sorted .

Cheers
John

[aquaticharpy]

I thought the cylinder flametube was the only flametube.

What else is there?

[racket]

Hi John

Nope , there are annular flametubes, but you'll only need to concentrate on the "sore thumb" combustor with its cylindrical flametube .

But there are variations of the basic design which has the outer can end cap as the end of the flametube , others have a hemispherical cap on the flametube that has a gap between it and the outer can to allow air to enter at swirl vanes and/or holes in the end cap , this design will have less air going through the sidewall in the Primary Zone and a cooler running outer can end .

Then some designs use spray nozzles whilst others evap/vapourising tubes , both will have different configurations of holes .

Then the various fuel types , gasious or liquid will have different requirement for flametube hole numbers and positions

John , there are a huge amount of variables available when building an engine , we need to settle on a few basics before designing the flametube if we want it to work with any degree of efficiency.

Cheers
John

[aquaticharpy]

Would it be unwise to make a can style jet engine? Perhaps can-annular? I'd like to run it off of diesel.

~John

[racket]

You're wasting my time , end of contribution !!

[aquaticharpy]

I've found fogging injectors~ What gph and psi would you reccomend for injecting diesel into the combustion chamber, also, what's the max gph and psi I should set a limit for top turbine speed to avoid overspeed. I'm looking to begin easy. So a Borg Warner S471, or S478

Thank you so much
I'm almost ready to start ordering

~John

[miuge]

If you're referring to water mist nozzles they might have rubber/plastic/brass/other less heat resistant materials inside, better use oil burner nozzles instead preferably stainless steel ones to avoid meltdown.
Calculate your fuel requirements per turbo compressor map, oil burner nozzles are usually rated at 100psi, the bigger the pressure the better the atomization. EFI fuel pump pressure capabilities are limited, go for something else, small hydraulic pump for example.

[aquaticharpy]

www.mcmaster.com/4759t22

I was hoping to use a nozzle from this line, as they were the highest pressure and, sadly, the highest temperature from the line. I'm sure there has to be something out there that's high pressure, lower flow rate, and high temperature.. The search goes on.

By the way. How would I go about using the compressor map to calculate fuel requirement? A link to where that information will be found would be crucial. I've found a decent pump, as well as flow bypass control valve. All I need are some nozzles before I get to move on.

Thanks
John

[aquaticharpy]

Then there was this guy; www.mcmaster.com/33925k61
Although it's a square spray with a max pressure of 150 psi. What do you think my combustion chamber psi is going to be so I can overcome it? Nozzle choices are getting slim

[miuge]

Just stick with the hollow cone stainless steel oil burner nozzle.

What kind of pump did you find?

Jul 24, 2018 2:20:12 GMT 2 racket said:
Hi

An "average??" turbo will flow ~12 lbs/min/square inch of inducer area , and if we use "safe" turbine inlet temperatures we use an overall ~60 :1 air/fuel ratio , so for every square inch of inducer area we'll burn ~12 lbs of fuel per hour .

eg , a 3" dia inducered comp has ~7 sq ins of inlet , so ~ 84 lbs of air per minute , so ~84 lbs/hr of fuel , now depending on how your fuel nozzle is calibrated , either in US or Imperial GPH and the pressure at which it is calibrated ( generally 100 psi) the required nozzle size will vary.

Kero weighs in at ~6.7 lbs/US gallon , so our 84 lbs/hr is ~12.5 US gallons , so a 12.5 US GPH nozzle if used and calibrated at the same pressure will do the job if there wasn't any combustor air pressure , if run at 100 psi delivery pressure with 40 psi combustor air pressure we effectively are flowing at only 60 psi .

We generally need more than 100 psi , so if we went to 500 psi for good atomisation , then the sq root of 500 is 22.36 , sq root 100 psi is 10 , so we divide our 12.5 GPH nozzle by 22.36/10 and use a ~5.6 GPH nozzle , again neglecting the P2 pressure.

Its better to start with a smallish fuel nozzle rather than a large one as the atomisation will be better and theres less chance of inadvertently over fuelling the engine in those first few spoolup whilst getting to know the engine, I'd aim for ~50% of theoretical max fuel flow to start with , more than enough to get a good high idle , plus a bit more , but not get into trouble.

Cheers
John