Basic turbojet design

[minotron]

I’m trying to make a turbojet for a sort of science project, so I’m not tying to make anything insane, just something that can self sustain itself.

I’ve been doing some research but I still can’t seem to figure out everything. I know I’ll need a compressor rotor/impeller and a diffuser, but for example, I don’t know the angle I’ll need on the impeller’s blades or how to design the diffuser, same with the turbine rotor and stator. I’m gonna be using steel and butane, since I think those are the most appropriate and accessible materials, but I could be wrong. Any help on where to start with the design would be appreciated.
I’ve got access to some basic tools for cutting/drilling/bending metal but not any advanced machinery, is it still possible?

[racket]

NO NO NO , don't make your own bits , you'll spend years trying to get it to work , use ready made turbo bits, that way theres less chance of failure .

The amount of work required in designing an engine is rather large , better to simply buy a new cheap turbo and fit a combustor to it , you'll still need to construct ancillories like oil and fuel systems , ignition etc etc .

[minotron]

Nov 16, 2022 18:17:10 GMT -5 racket said:

NO NO NO , don't make your own bits , you'll spend years trying to get it to work , use ready made turbo bits, that way theres less chance of failure .

The amount of work required in designing an engine is rather large , better to simply buy a new cheap turbo and fit a combustor to it , you'll still need to construct ancillories like oil and fuel systems , ignition etc etc .

Hmm, I’m just trying to get it to self sustain, just to show that I can make an engine, no thrust is necessary. Is it really essential to buy pre-made items? I was hoping I could at least make the majority of the items at home and have it still “work”

[racket]

Go ahead and try if you want to , but first ,have a look on Youtube for an example you can show me

[minotron]

youtu.be/qsvpU7G5IJg

I intend to copy the dimensions of the models he’s made on metal, but if I really have to I can find a way to 3d print

[racket]

LOL.............that is not a simple build :-(

I know he makes it look simple by playing the buffoon , but that isn't the case .

All the best with your build :-)

[minotron]

Thanks, I think I’ve got a good enough basic design down on paper after watching more videos but I just want to clarify some things if that’s all right.

The diffuser blade angle should oppose the angle of the impeller/compressor, and the chamber after the diffuser should be larger than after the compressor? Also is there a “best angle” for these or is it all size dependant?

For the combustion chamber, do you want to have a small inner tube with holes to suck in air/fuel, with the outside containing the fuel injection ring and the airflow from the compressor, before being sucked into the small inner tube and lighting?
I think the combustion chamber design is the part I’m still wrapping my head around.

Finally the combusted fuel gasses/hot air should run through the turbine stator and turbine itself, before being constricted as it leaves the engine?

Thanks in advance, you clearly know your stuff on this

[racket]

Hi

The diffuser vane leading edge is set at the air angle at that radial position , determining the angle with a homemade compressor wheel at an unknown mass flow and pressure, travelling through a duct of unknown width, is impossible , ..........................as I said in my previous email , that guy made it look easy , BUT it is anything but simple, there are numerous Scientific Papers written on the subject of matching comp and diffuser .

You need to find a design and simply copy it down to the last minute detail if you want it to work , purchase this book www.abebooks.com/servlet/BookDetailsPL?bi=31212742256&searchurl=an%3Dthomas%2Bkamps%26sortby%3D17%26tn%3Dmodel%2Bjet%2Bengines&cm_sp=snippet-_-srp1-_-title1 and read it several times

Cheers
John