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I often read that turbine engines can run on almost any fuel source. I understand that turbine engines are less "picky" in terms of the fuel source that they can use, but surely there would still be some limitations as to which fuel source can be used e.g. a certain range for flash point, auto-ignition temperature etc.?

Likewise, could a turbine engine be built from scratch to run on a fuel not normally suitable for turbine engines? And if so, would this engine be less efficient?

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  • $\begingroup$ The starting system will be designed for the fuel or range of fuels to be used. $\endgroup$
    – Solar Mike
    Apr 28 '19 at 18:48
  • $\begingroup$ @SolarMike, so could a turbine engine be designed to run optimally on almost any hydrocarbon, from gasoline to sunflower oil? Or would there be some fuels outside of the range of what could be used in a turbine engine? $\endgroup$ Apr 28 '19 at 18:58
  • $\begingroup$ Flame speed is an issue. Typical fuels have about a factor of 100 difference in laminar flame speed. So we try not to have to worry about that by making pretty darn sure we only need to consider turbulent flame speed. Turbulence is something that can be designed in. But combustion also takes time. Droplets have to be vaporized by the nearby combustion before that fuel will burn. So you need to provide enough turbulence and volume for the combustion to take place. This varies by fuel. $\endgroup$
    – Phil Sweet
    May 28 '19 at 22:26
  • $\begingroup$ You also need to make sure that conditions that trigger a flameout with one fuel don;t cause a back burn with a different fuel. The range of safe operating conditions and operating loads may vary. $\endgroup$
    – Phil Sweet
    May 28 '19 at 22:27
  • $\begingroup$ Corrosion and erosion would be significant parameters aside from fuel characteristics. $\endgroup$ May 29 '19 at 16:19
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Your range of "gasoline to sunflower oil" (in a comment) is too small. Turbine engines run very well on natural gas, when used for gas pumping applications.

Combustion is continuous, so auto-ignition and flash point are not very relevant except for light-up, and you can use a different fuel for that if need be.

The only real limitation is clean burning. A burnt-on deposit of "crud" covering everything can seriously screw up the heat transfer of the hot end cooling system, and even the blade aerodynamics.

The efficiency is mainly driven by the combustion temperature, and therefore by the chemical reactions involved. Hydrocarbons are all pretty similar in that respect, but (as a theoretical concept only!) a turbine fueled by say carbon monoxide, or by acetylene gas, or more practically by hydrogen, would be somewhat different.

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  • $\begingroup$ Thanks for your answer. Of course, that makes sense to extend it to gas, I was just using that range for liquid fuels. Also, what fuels would be more likely to lead to unclean burning and produce this "crud"? $\endgroup$ Apr 28 '19 at 19:52
  • $\begingroup$ Anything which doesn't burn completely. For example if "dirty" fuel contained suspended sand particles (too small to efficiently filter out) you would soon have a combustion chamber covered with a layer of glass. That is a real problem with aircraft engines operating in desert conditions. Combustion gas temperatures can be higher than the melting point of the combustion chamber, which is cooled by a thin film of relatively cold gas (but still at say 800C!) flowing over the metal walls. It doesn't take much buildup of debris to stop a system like that from working properly. $\endgroup$
    – alephzero
    Apr 28 '19 at 20:05
  • $\begingroup$ thanks for explaining this. So, assuming the fuels are "clean" from these particles, would there be any reason why some fuels wouldn't burn as completely as others i.e. would gasoline be more/less likely to burn completely than diesel? Or is it merely to do with external particles? $\endgroup$ Apr 28 '19 at 20:32
  • $\begingroup$ @PhysicsGuy123 for a fuel that's really different to gasoline or sunflower oil, and does tend to have a lot of "crud", look up heavy fuel oil :-) (I've no idea whether a gas turbine could be designed to run on HFO, given suitable pre-heating (to lower viscosity) and filtering of solids, but I imagine it would be different) $\endgroup$
    – Flyto
    May 28 '19 at 23:00

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