Flashcards in Turbines (Steam, Gas and Water) Deck (94)
How are gas turbines classified on combustion process ?
How are gas turbines classified on action of expanding gases ?
How are gas turbines classified on working path of gases ?
Open cycle gas turbine
Closed cycles gas turbine
How are gas turbines classified on direction of flow ?
What is axial flow ?
Flow of working fluid is parallel to axis of shaft
What is radial flow ?
Flow of working fluid is in direction of radius
How are gas turbines classified on shaft configuration ?
How are gas turbines classified on thermodynamic cycle ?
Simple cycle with regenerator
Simple cycle with re-heat
How are gas turbines classified on basis of application ?
What are the three main components of open cycle gas turbines ?
What is the function of the compressor ?
It draws air from the atmosphere and compresses it to high pressure adiabatically
What is an adiabatic process ?
A process that occurs without transfer of heat or matter between a system and it's surroundings.
What happens in the combustion chamber ?
Fuel is injected into the high pressure air and combustion takes place. The temperature of the air increases at constant pressure
What happens in the gas turbine ?
The product of the combustion chamber is expanded on the turbine blade adiabatically.
What happens to the thermal energy of the gas ?
It is extracted by the turbine and converted to power
Why are the turbine and compressor mechanically coupled via a shaft ?
Some energy is used to turn a shaft to drive the compressor
Why are closed cycle gas turbines smaller than open cycle gas turbines ?
High density working fluid is used
Which gas turbine has a greater thermal efficiency ?
Closed cycle gas turbines have a greater thermal efficiency for the same range of temperatuer
Why is there less corrosion in closed cycle gas turbines ?
Working fluid is not contaminated because of indirect heating.
How is the working fluid contaminated in open cycle gas turbines ?
Which turbine offers a greater output ?
Closed cycle gas turbines have a greater output per unit weight of turbine
What is the reason expensive fuels are used in open cycle gas turbines ?
Fuel comes in contact with working medium and should not contaminate it.
Why are closed cycle gas turbines not suitable for avionics ?
They need cooling water or a coolant to remove heat
Why is heat transfer efficiency lower in closed cycle gas turbines ?
Heat is transfered indirectly and higher heat transfer area is required
What kind of heat exchangers required in closed cycle gas turbines ?
Complicated heat exchangers
Why does the closed cycle gas turbine need to be perfectly sealed ?
The working medium should not leak.
Do gas turbines have a greater thermal efficiency than IC Engines ?
Yes, because they do not have any reciprocating component.
What is the reason gas turbines can be operated at a much higher speed than IC engines ?
They are better balanced.
Why are they better balanced ?
There is no reciprocating component.