Newbie questions on anular combustion/Schreckling design

[Bounce]

Hi

As I've done quite a lot of reading through this and the DIYGT-Yahoo forum I found pictures of engines with an anular combustion design which really draw my attention. Although searching the internet for plans and explanations I've just got the question how the combustion chamber has to be attached to the turbo and what I need to watch for, building the insides of the combustion chamber. So far I would be very thankful for some plans/links/explanations.

Greetings
Dennis

[Bounce]

Ok I've now kind of understood the funktioning of an annular type reverse flow combuster. But there's still one question: are there any progs or terms to calculate the combustor housing,flame tube and jetpipe?? Or do you just do this like you feel it could be right?

Regards
Dennis

[Johansson]

Hi Dennis!

There is a great program called JetSpecs Designer 2.0 that is very useful, you can for example calculate the maximum safe rotation speed, theoretical thrust, size of jet nozzle and be able to change parameters like outside temp and see how that will affect the performance of the engine.

The program can also design a rough combustor for propane, but since you are into annular combustors it will be of little use. The GTBA newsletters contain much info on how micro turbine combustors have developed over the past years.

//Anders

[Bounce]

Hi Anders!

I've already downloaded the JetSpecs program but, as you said, it is of very little use for designing annular type turbines. Also I thought of a new question: how should I build the ignition? For the moment I'm completely helpless with this but I'm thinking about it.
So far

Greetings
Dennis

[Fricke]

Ok I've now kind of understood the funktioning of an annular type reverse flow combuster. But there's still one question: are there any progs or terms to calculate the combustor housing,flame tube and jetpipe?? Or do you just do this like you feel it could be right?

Hi Dennis!

If your going to build an annular CC then get a copy of Thomas Kamps book. In that book there is all the info you need. It´s worth the money.

Join the DIYGasTurbine list on Yahoo http://tech.groups.yahoo.com/group/DIYGasTurbines/join There are some very clever people around who will help you out!

Take some time to read the posts (over 30,000!) And you should have a good clue on how to do it!

//Fredrik

[Fricke]

Also I thought of a new question: how should I build the ignition? For the moment I'm completely helpless with this but I'm thinking about it.

For an ignition 'box' you can use

An old weedwhacker motor with the piston, cylinder and conrod removed, spin it with an electric drill.

Build one of the many NE555 based circuits here on this forum.

Make a 'buzzbox' also presented in a few different ways here.

My favorite is to get a coil from a fairly modern car, the type that is controlled by the ECU box. And drive it with a NE555...

And don´t even think of running your GT without an tachometer to have 100% control of the GT´s speed. I know that there are some members on this forum that run without a tacho. But they are playing a dangerous game! (I know I´ve blown a few GT´s before I got wise and started to use a tacho)

A simple multimeter with a frequency input and a few cheap components and you have a reliable tacho.

PM me for some schematics and if you need more help.

//Fredrik

[Bounce]

Thanks to you Fredrik!

But my problem was not how to build the ignition circuit or how to spool the turbine up but how to place the ignition inside the tubine (imho slightly complicated with these reverse-flow-combuster thing). My fault by badly explaining my problem. I'll maybe come back to your offering of writing you.

Sincer regards
Dennis

[Johansson]

It is commonly done by fitting the spark plug to the combustor casing so the electrode reaches into it through an air hole.

I have turned away a couple of cm´s of the threads on my plug so the spark runs from the electrode to the flame tube, works just fine unless the engine is spooled up too much before ignition, then the air entering the hole pushes the fuel mist away from the spark...

//Anders

[Fricke]

Thanks to you Fredrik!

But my problem was not how to build the ignition circuit or how to spool the turbine up but how to place the ignition inside the tubine (imho slightly complicated with these reverse-flow-combuster thing). My fault by badly explaining my problem. I'll maybe come back to your offering of writing you.

Sincer regards
Dennis

Aha! =)

Put the sparkplug down stream of the fuel injection point. Straight thru the casing into the cc. It´s not more complicated then with the normal can type of CC.

[Bounce]

Thanks to all of you!

I already knew how to build an ignition but not how I should do on this type of engine until I came to realize again that complex problems deserve an easy solution. I'll go and get a copy of one of Kamps' books asap and since they're offered in german, too they will be lot easier for me to fully understand being to lazy to translate everything :wink:

So far, regards
Dennis
PS: What size of turbo would you recommend? Will a turbo out of a 2,5l car do it or will I need a bigger one? (For use in a kart or something)

[Fricke]

PS: What size of turbo would you recommend? Will a turbo out of a 2,5l car do it or will I need a bigger one? (For use in a kart or something)

The turbo I used on my kart had a 52 mm inlet, it was from a Volvo FL4 (if I recall correctly) the engine was a 4 liter.

The bigger the better! =)

Get a copy of JetSpec.exe and put in the sizes of the compressor wheel and you´ll have a good estimate of the thrust.

//Fricke