Combustor design and red hot turbine and turbine housing.

[racket]

For a turbo based engine with a "sore thumb" combustor can , I think the single spray nozzle is "best??" in the long term , theres a bit more work with the higher fuel pressures , but thats offset against the extra work constructing the vapourisers , plus the spray nozzle is less likely to experience failures as can happen with the tubes.

For "micro" type engines with annular flametubes the evaporator tube setup is pretty much the only way to go

Cheers
John

[smithy1]

What John said....originally mine was designed by John with "evap tubes", but they tended to burn out quite easily....so I converted it to a "modified" single spray nozzle from a Rolls-Royce C20B turbine engine, works fine thus far and requires much less maintenance/repair than the evap tubes.
Mine does start on straight fuel but can be a bit hit 'n miss and temperamental untill up to temperature, so I tend to start and "pre-heat" on propane.

Smithy.

[rickw]

what is the alternative to a 'sore thumb' haha combustor

[rickw]

Racket
do you have any photos of your combustor designs?

[racket]

Checkout my builds in jetandturbineowners.proboards.com/board/2/diy-turbine-engine-discussion-builds

[rickw]

What is going on at the top of your combustor?

[rickw]

Those tubes the are U shaped?

[racket]

Yep , they're "walking stick" vapourisers , similar to what is used in full sized aero turbine engines

[azwood]

Those are the evap tubes where the fuel gets sprayed through.because they are glowing hot the fuel turns to vapor as it travels though it which make it combust better. Hope that helps.

[azwood]

Sorry vaporisers I keep calling them evaps.

[racket]

LOL, evaps.........vapourisers , same same , technically correct to call them vapourisers , even though they evaporate the fuel , I'll still call them by both names , I think evaporators is a term more easily understood , whereas vapourisers has other connotations these days.....................neither of them fully turns the fuel into a "gas" , some liquid is still ejected from their outlets ..

I just pulled the 12/118 engines flametube apart and its "evaporators" are still fairly shiny/silvery in parts and don't appear to have been unduly scorched by the combustion process surrounding them .

[rickw]

What gallon per hour nozzle would be good for a liquid fuel application?

[rickw]

Also hollow cone solid cone spray

[racket]

One that provides adequate fuel at the fuel pressure you design for .

A 59 mm inducer will flow up to maybe 1 lb/sec of air so you'll be needing 1 lb/minute of fuel , or 60 lbs/hr , so a 10GPH with 100psi pressure drop across the nozzle , 130 psi fuel pressure if 30 psi of air pressure in the combustor , would be as big as you'd need , but probably better to start with a smaller fuel nozzle initially as its safer , you won't overfuel/overspeed with a 4 GPH nozzle , it will allow you to get a feel for liquid fueling and an indication of what size will be required .

Cheers
John

[rickw]

Thanks