What is Gas turbine: Definition and 67 Discussions

A gas turbine, also called a combustion turbine, is a type of continuous and internal combustion engine. The main elements common to all gas turbine engines are:

an upstream rotating gas compressor
a combustor
a downstream turbine on the same shaft as the compressor.A fourth component is often used to increase efficiency (on turboprops and turbofans), to convert power into mechanical or electric form (on turboshafts and electric generators), or to achieve greater thrust-to-weight ratio (on afterburning engines).
The basic operation of the gas turbine is a Brayton cycle with air as the working fluid: atmospheric air flows through the compressor that brings it to higher pressure; energy is then added by spraying fuel into the air and igniting it so that the combustion generates a high-temperature flow; this high-temperature pressurized gas enters a turbine, producing a shaft work output in the process, used to drive the compressor; the unused energy comes out in the exhaust gases that can be repurposed for external work, such as directly producing thrust in a turbojet engine, or rotating a second, independent turbine (known as a power turbine) that can be connected to a fan, propeller, or electrical generator. The purpose of the gas turbine determines the design so that the most desirable split of energy between the thrust and the shaft work is achieved. The fourth step of the Brayton cycle (cooling of the working fluid) is omitted, as gas turbines are open systems that do not reuse the same air.
Gas turbines are used to power aircraft, trains, ships, electrical generators, pumps, gas compressors, and tanks.

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  1. G

    Why air is compressed in Gas turbine engine ?

    i understood brayton cycle etc.. but why is air compressed in the GT engine ? iS is anything related related to following reasons ? 1. FOr better combustion of fuel, if so why ? 2 IS it to increase the temperature of air, if so why ? 3 any other reason
  2. B

    Gas turbine self sustaining point

    Hi, I want to review a turbocharger gas turbine design project. The previous problem was, the gas turbine could not sustain itself. Help me out if you can figure out what could be wrong.
  3. M

    What are some recommended resources for learning about gas turbine aero design?

    Hello gas turbine peeps, I'm going to be starting a new position doing Aero CFD for a power generation gas turbine company. While I have a good amount of theoretical and academic knowledge of CFD in general, my practical application experience is limited. I was hoping to do a little light...
  4. K

    Misc. DIY Gas Turbine Blades: Can I Make Them Using Ceramic and Carbon Fiber?

    I have been researching DIY gas turbines lately, and I have concluded that I want to make one. :smile: My only issue is that all amateur designs I have seen use turbochargers. I would like to see an axial, multi-stage compressor/turbine design. Obviously this would require one to fabricate the...
  5. J

    Isentropic efficiency vs polytropic efficiency of a gas turbine

    definition wise i got the difference between these two efficiencies. but in practice how does these two differ? i was referring to this book: Jet propulsion: a simple guide to the aerodynamics and thermodynamic design ... By N. A. Cumpsty he has mentioned this: "using polytropic...
  6. M

    Gas turbine blades Dimentions and Design of aircraft engine

    Hi I am working on gas turbine design to investigate fatigue and creep failure and i want to design gas turbine blades for aircraft engine. I need to find out the dimention for CAd design if anyone help me that what should be the dimention of these blades and how many blades attached to...
  7. L

    Gas turbine firing tempurature

    Does anyone have a spreadsheet with formulas or a set of formulas that one can use to determine the turbine inlet temperature of a gas turbine knowing measured parameters like fuel flow, compressor discharge tempuratures, LHV of fuel.
  8. P

    Calculating Gas Turbine Shaft Power

    Homework Statement I have been asked to calculate a range of values relating to a Gas Turbine engine, and while I have been able to find the majority of the values I am almost certain that the Thermal Efficiency value of 1.64% I have come up with is incorrect. This relies on Shaft power...
  9. S

    Chromium use in Gas Turbine Engines help

    Hi all, I'm hoping that someone may be able to help! I'm doing a project which has involved me looking at the use of superalloys in Gas Turbine engines (i.e. Rolls Royce, GE etc). As part of that I am looking in particular at the use of Chromium within these engines, does anybody have any...
  10. E

    Fuel injectors for gas turbine

    I am looking to find information on fuel injector vanes that can be used for fuel injection into a gas turbine. I am at the moment designing one that will be integrated into the gas turbine. However i am struggling because i need to know if there is a formula for particle spread I have a formula...
  11. T

    Question about gas turbine instrumentaion if u can

    hi everyone: i have a question about gas turbines : i am working as instrumentation engineer( beggar ) at a power station .. we use gas turbine GE ( mark V) frame 9 . i got that alarm : exhaust thermocouple # 10 fail , drop number 123 if anybody working in such a field can help me in...
  12. H

    Regenerative Air Standard Gas Turbine

    Hi there, can anyone shed some light on regenerative gas turbine cycle. How to work problems of this sort. DATA: compressor intake: 0.95 bars @ 22 `C pressure ratio 6:1 (compressor), 82% efficient turbine inlet: 1100 K. 85% efficient. regenerative effectiveness: 70% Intercooling...
  13. S

    Gas Turbine Plant: Combustion Process & Air-Fuel Ratios

    Again another homework question, all help greatly appreciated A gas turbine plant is fuelled by Methane,. After compresssion the air and fuel enter the combustion chamber at a temp of 600K and excess air is supplied in order to limit the temp of the combustion products to 1200K after steady...
  14. S

    How Do Air-Fuel Ratios Affect Gas Turbine Temperatures?

    Going to be honest this is a ibt of homework i have been set but from the note i hae it doesn't make any sense what so ever! so any help would be greatly appreciated :-) A gas turbine plant is fuelled by Methane,. After compresssion the air and fuel enter the combustion chamber at a temp of...
  15. L

    How can a student create a gas turbine engine from scratch?

    Hello guys, I'm a second year BSc aerospace student in Holland, and I'm thinking about making a gas turbine engine. I hope to specialize in powerplants eventually. You people seem knowledgeable, so I thought I'd ask my question here. Anyway, bare with me a bit... I first thought about...
  16. P

    Aero engine without gas turbine

    Is there any aero engine in the world without any rotating bodies like compressor-turbine? Other than ram jet or scramjet. Thers is a vague idea in my mind to go for an aero engine without rotating elements in it. I just wanted to confirm if it is there.
  17. S

    Optimizing Fuel Injector Orientation for Increased Thrust in Gas Turbine Engines

    Why does the pressure in the burner of a gas turbine engine drop when you are increasing the internal energy of the air?
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