tube flame

[A.G.G.]

hello this my tube flame is good????????

[Johansson]

Well, that depends a bit on the size of the turbo your are using.

I can see one bad thing right away and that is the diameter of the flame tube. If you have calculated the total area of the holes correctly so the area is roughly equal to the area of the intake on the compressor housing then the flame tube diameter is way too small for good combustion. You see, the smaller the diameter of the flame tube the faster the air travels through it. Since it takes a while for the propane and air to mix into a combustable gas it is best to have a large diameter so the fuel and air can be mixed as high up in the combustor as possible, otherwise the flame zone can start just before the turbo inlet and reach all the way through the turbine and cause overheating in an instant.

If you build your flame tube according to the Jetspecs program it should work fine on propane.

//Anders

[A.G.G.]

thanks johasson I calculate the area of the compressor and I divide it in the flame tube?

[A.G.G.]

my new flame tube 3 in. diameter

[Johansson]

That looks better. A question though, just how much have you read about DIY turbines? Do you for example know about the relation between combustion air and dillution air, where the main idea is that only 20-30% of the air going through the engine is burnt and the rest is used to keep the air entering the turbine cool enough so the turbine won´t get overheated?

If your compressor inlet has an area of, lets say, 30cm2 then the area of the holes needed for burning the propane is 0.3x30=9cm2 and the dillution area would then be 21cm2. If you divide the flame tube in two and try to keep the hole area in the upper part closest to the fuel nozzle around 30-40% of the total area and the remaining area in the half closest to the turbo it should work fine.

An important thing to remember is that the holes closest to the propane nozzle should be smaller in diameter than the ones further down, big holes next to the injector could disturb the flame causing flame-outs, so use plenty of smaller holes instead. For the dillution holes you can use quite large holes for good mixing of cool and hot air in the flame tube.

By the way, when you make the propane injector you should build it so that it ejects the propane towards the sides and not straight down the tube for best result.

A link to a well-built small DIY turbine - http://www.rcdon.com/html/gr-1_turbojet ... oject.html

Best of luck with your engine!

//Anders

[A.G.G.]

I totally include/understand the operation of turbojet home made single I construct other types of combustors treating to make them but small and efficient

[A.G.G.]

thanks johasson I hope to soon put a video of the operation of my jet engine

[Johansson]

I hope that is not what the engine looks like while running... ;-)

You do have a P2 and TOT gauge on the engine, right?

//Anders

[A.G.G.]

the image is not very good I hope to put an image with but clarity my tot is 700º/900ºg

start: 800º/900º
operation: 600º/700º

[Johansson]

Is that measured with or without a nozzle added to the exhaust? It would be fun to see a video of the engine running!

//Anders

[A.G.G.]

soon it will fix a video :D