Turbines (Steam, Gas and Water) Flashcards Preview

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Flashcards in Turbines (Steam, Gas and Water) Deck (94)
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1

How are gas turbines classified on combustion process ?

Constant Volume
Constant Pressure

2

How are gas turbines classified on action of expanding gases ?

Impulsive forces
Impulsive-Reactive force

3

How are gas turbines classified on working path of gases ?

Open cycle gas turbine
Closed cycles gas turbine

4

How are gas turbines classified on direction of flow ?

Axial
Radial

5

What is axial flow ?

Flow of working fluid is parallel to axis of shaft

6

What is radial flow ?

Flow of working fluid is in direction of radius

7

How are gas turbines classified on shaft configuration ?

Single shaft
Multiple Shaft

8

How are gas turbines classified on thermodynamic cycle ?

Simple cycle
Simple cycle with regenerator
Simple cycle with re-heat

9

How are gas turbines classified on basis of application ?

Aviation
Industrial

10

What are the three main components of open cycle gas turbines ?

Compressor
Combustion Chamber
Gas turbine

11

What is the function of the compressor ?

It draws air from the atmosphere and compresses it to high pressure adiabatically

12

What is an adiabatic process ?

A process that occurs without transfer of heat or matter between a system and it's surroundings.

13

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

14

What happens in the gas turbine ?

The product of the combustion chamber is expanded on the turbine blade adiabatically.

15

What happens to the thermal energy of the gas ?

It is extracted by the turbine and converted to power

16

Why are the turbine and compressor mechanically coupled via a shaft ?

Some energy is used to turn a shaft to drive the compressor

17

Why are closed cycle gas turbines smaller than open cycle gas turbines ?

High density working fluid is used

18

Which gas turbine has a greater thermal efficiency ?

Closed cycle gas turbines have a greater thermal efficiency for the same range of temperatuer

19

Why is there less corrosion in closed cycle gas turbines ?

Working fluid is not contaminated because of indirect heating.

20

How is the working fluid contaminated in open cycle gas turbines ?

Fuel combustion

21

Which turbine offers a greater output ?

Closed cycle gas turbines have a greater output per unit weight of turbine

22

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.

23

Why are closed cycle gas turbines not suitable for avionics ?

They need cooling water or a coolant to remove heat

24

Why is heat transfer efficiency lower in closed cycle gas turbines ?

Heat is transfered indirectly and higher heat transfer area is required

25

What kind of heat exchangers required in closed cycle gas turbines ?

Complicated heat exchangers

26

Why does the closed cycle gas turbine need to be perfectly sealed ?

The working medium should not leak.

27

Do gas turbines have a greater thermal efficiency than IC Engines ?

Yes, because they do not have any reciprocating component.

28

What is the reason gas turbines can be operated at a much higher speed than IC engines ?

They are better balanced.

29

Why are they better balanced ?

There is no reciprocating component.

30

Why can cheaper fuels be used in gas turbines than in IC engines ?

External combustion