Course contain

• Introduction
• Theory of operation (thermo-dynamics)
• Classification & application
• Component parts
• Systems
• Operation &maintenance
• Control & codes
What is gas turbine ?

The gas turbine is an internal combustion,

constant flow engine designed to convert the
energy of fuel into useful power. The fuel is
burned to add heat to a gas ( usually
compressed air ) .
Mars Engine Cutaway
Boyle's Law
Charles' Law
Atmospheric Factors Affect Performance

Atmospheric factors affect the performance of gas turbines.

Some of these factors are:
· air density · contaminants

Temperature and water content affect the density of the air.

Because cold air is more dense than hot air, it has more mass.
The more air in the gas turbine, the more force created.

On a very cold day, a gas turbine can exceed its peak load. On
a very hot day, a gas turbine will produce much less power.

The atmosphere also contains foreign matter that is harmful to

gas turbines, such as pollen and dust. The contaminants reduce
the efficiency of the turbine and damage internal parts.
 Brayton Cycle

The Brayton Cycle is unique among engine cycles

because all the events in the cycle take place at the
same time without interruption.
The exhaust event is the only part of the cycle that
does not take place in the engine.
• Mass Moment of Inertia (Moment of Inertia) - I - is a
measure of an object's resistance to change in rotation
direction. Moment of Inertia has the same relationship
to angular acceleration as mass has to linear
acceleration.

• that determines the torque needed for a desired angular

acceleration about a rotational axis
• To accelerate the engine, the fuel flow will increase rapidly,
while, due to the inertia of the gas producer (in a two-shaft
engine), the airflow will lag behind, thus, creating a very rich
mixture.

• Control systems, therefore, usually limit the rate of change of

fuel flow, not only to avoid flame-out, but also to avoid high
transient temperatures in the turbine.

• The reverse situation occurs during deceleration. The fuel flow is

reduced very quickly, while the airflow remains high for a short
period of time, thus creating a very lean mixture at
thecontinuously high air velocity of the combustor.
Turbine (Brayton) Energy Transfer Cycle
Brayton Cycle
Simplified Engine Airflow Diagram
Temperature and Pressure Relationships at
100% Ngp
Air Flow Across Stator and Rotor Blades
Turbine Operation
Engine Main Subassemblies
Radial Tilt Pad Bearing
Radial Tilt-Pad Bearing
Compressor
Assembly
For small engine
Variable Vane Assemblies
Thrust Bearing
Turbine Nozzle Effect
Combustion
Reduction Drive Assembly
Speed Reduction
Reduction Gear Unit
Mars Engine Mounted Accessory Gear Box
Mars Free Standing Accessory Gear Box
Shear Coupling (with coupling guard removed)
View of Engine External Components
Temperature Stations
Engine Oil Pressurizing Airflow Diagram
Labyrinth Seal
Rotor Seals
Number 1 Bearing Support Housing
Number 1 Bearing Seal Air Flow
Number 2/3 Bearing Seal Air Flow
11th Stage Bleed Air Tap
Cooling Air Flow
Cooling Air Flow
Turbine Cooling Air Flow Diagram
Bleed Air System Components
Variable Vane Electric Actuator
Compressor Variable Vane Assembly
(Internal)
Bleed Air System Components
Typical Bleed Air Trunnion Valve
Mars Engine
Specification
Engine Support Systems
 Systems
• Engine Case – Air Inlet
• Lubrication & Lube Oil
• Hydraulic Oil System
• Fuel System
• Control system
Air inlet system
• The purpose of the air inlet system is to carry clean,
dry air to the compressor with minimum turbulence
and energy loss.
• The air inlet system controls the air quality and
directs a steady flow of air to the compressor air inlet.
The amount and quality of air affects engine
performance and reliability.
The inlet silencer is a baffle
arrangement intended to quiet the
noise vibration of the compressor
blading.

The trash screens are the next

component in the inlet ducting
assembly. Trash screens prevent
foreign objects from entering the
compressor inlet.

Trash screens are installed

downstream in the ducting before
the compressor inlet.
Access doors are provided to allow cleaning and
servicing of the trash screens.

Trash screens are constructed of stainless steel and

should not require maintenance other than periodic
cleaning and inspection.
 Starting

purpose

• Pneumatic Starting
• Hydraulic Starting
• Diesel Starting
• Ac direct starting
Air starter
- High torque to weight ration

video
. A typical pneumatic starting system
requires approximately 2600 scfm.
 Hydraulic starting

A typical 55 gpm hydraulic

starting system that operates
at 5000 psig uses a 200
horsepower electric motor.

The motor normally operates

on 480 volt, 3-phase AC and
rotates at 1800 rpm on 60 hz
or at 1500 rpm on 50 Hz.

The hydraulic pump is an

axial-pisto
The fluid discharges
from the starter to
the low pressure side
of the system and
returns through a
filter to the supply
pump inlet.
Video
 Diesel starting

The diesel starting

engine for G.E. Frame
5 gas turbines is a 12
cylinder, two-cycle
engine rated at 2300
rpm.
AC Direct Drive Start System Components
Magnetic Speed Probe
Lube oil
Fuel
system
General Operational Sequence
30 General Operational Sequence