Playing with gas turbines
can be exceptional fun
, although some with an over developed sense of fear
may see it as ever so slightly dangerous.
So... read on at your peril.
Gas turbines (also known as jet engines) are inherently simple devices, often with only a single moving part (the rotor shaft), this node offers a good overview. Of course, simple though they are, a conventional linear gas turbine must by nature of its harsh operating environment and use be manufactured to very exacting tolerances, using various exotic materials.
However, with a little cunning, we can take a now common piece of automotive technology, the turbocharger, and turn it into our very own jet engine. Conveniently, a turbocharger contains two of the essential components required by any gas turbine, a compressor and a turbine. Of course in normal use, the exhaust of the vehicle is directed throught the turbine chamber of the turbo which directly drives the compressor rotor, thus providing the engine with a compressed (and hence denser) combustion gas. So, if we connect the compressor chamber to the turbine chamber via a combustion chamber and add fuel, we have every chance of generating a self sustaining combustion cylcle. This type of gas turbine is known as a radial turbine, as opposed to the more conventional axial turbine.
I did just this, and after (considerable) arseing around, got the thing to ignite and sustain combustion using propane gas as the fuel.
This was not an easy thing to do and the manufacture of the combustion chamber and associated plumbing took a lot of time, but the sound of your very own jet engine firing and and spooling up can't be beaten.
So, you may ask, what's the point?....Well there isn't one really. It doesn't generate much thrust (although attaching it to a bicycle did occur to me), it doesn't have a hot wheel, so you can't take a mechanical drive off it.
But... the noise is indescribable (it still makes my spine tingle, to think of it). This, and the five foot jet of blue flame which shoots from the turbine exhaust makes one hell of a spectacle.
Sadly after a couple of runs, it burnt itself out. Turbochargers (even the hefty truck item I used) just aren't designed for the heat and rotational speeds produced.
This lead to my getting hold of a real gas turbine - an APU (auxiliary power unit) from a jet airliner. Now that is real fun (see combined heat and power node).
Don't try this. I have scars and no paint on my garage door as a direct result :-)