-compress incoming air.
-expand air extracting some power to drive the compressor, with the rest producing thrust or driving a turbine to produce shaft power.
The most familiar version uses chemical fuel for the heat addition stage, but of course one could use other means for adding heat. Two other methods that come to mind are nuclear energy and electrical energy.
A nuclear-powered gas turbine, while theoretically possible, has scale and control problems that would make it just about impossible to execute.
But an electrically-powered gas turbine seems like it might be possible; it would just be a matter of installing grid heaters with high power and low flow restriction.
Question: has anyone ever made an electrically-powered gas turbine engine, even if only for research or demonstration purposes?
One issue is you would lose lots of useful energy to heat doing it that way instead of just using a electric motor to directly turn whatever you want to turn with the turbine, but it would work. In the case of thrust, using a prop would be a lot more efficient.
Actually your nuke idea is a lot more feasible, and something like it has been proposed for rocket engines over chemical combustion.
Agreed, which is why I wouldn’t expect to see anything like this in mass production; but I thought someone somewhere might have put one together for research purposes (though I’m not sure what could be learned from such a device).
if the energy addition to the system was strictly from the heater element(s,) it would be impossible to get any more energy out of the turbine than you put in to the heaters. You would be fighting a losing battle trying to keep the heaters hot while the compressor is blowing air over them.
further, I don’t think simply heating air will get you any useful expansion. The big thing about burning chemical fuels is not just the heat the reaction produces, but the massive increase in gas volume from the combustion of the fuel.
…this will depend entirely on how much electrical power is being dumped into the heaters, and whether the turbine can extract enough power to keep the compressor going. Not clear whether this is impossible with existing materials.
I gather you’re talking about the increase in gas volume as a result of the additional mass of combustion products, namely CO2[sub]2[/sub] and H[sub]2[/sub]O, which would not be present in an electrically-powered gas turbine engine. Interesting point, and it makes me wonder about how big a factor this is in combustion-driven gas turbine engines. I was under the impression that gas turbine engines typically operate with a lot of excess air; not referring to high-bypass turbofan aircraft engines, but rather to simple/basic gas turbine engines moving far more air through the combustion chamber than is strictly needed to support combustion. If that’s the case, then the ratio of exhaust mass flow rate to intake air flow rate might be fairly close to 1:1.
I’m curious to hear from someone who works on jet engines and knows real world values for air flow rates and fuel flow rates.
I was just thinking about an electric Jet Engine, funny story too! There’s a colleague in my PLC class that fly’s battery powered RC airplanes, and he asked the professor if he’d like to see him fly his electric Jet. (battery powered airplane with a rear prop that resembles a military fighter Jet) In a confused look the professor responded you have an electric Jet? :dubious:
Anyhow I got to thinking if this would be possible and I immediately starting thinking about a plasma arc as the fuel source. Ever seen an arc flash protection suit used by people working on transformers or other high voltage equipment? Supposedly the ionnized air becomes hotter than the surface of the sun! Maybe in the future such a device could power commercial Jets, and with the help of a anode rode it could intentionally attract lightning…
Now that you mention it, some very efficient plasma jets have been theorized. I don’t recall the details, but apparently the energy needed to induce and maintain a plasma in an open system is very low. It seems like ‘free energy’ but it’s taking advantage of the existing ions in the intake air and the small percentage of ions needed within a gas to reach a plasma state which releases a lot of heat.
One problem is you would reduce many useful power to warm doing it that way instead of just using a engine unit to straight convert whatever you want to convert with the generator, but it would perform. In the situation of forced, using a brace would be a lot more effective. Actually your nuke concept is a lot more possible, and something like it has been suggested for bomb Google over substance burning.