Ramil C.

Salundaga Propulsion Ancillary System and Gas Turbine

BSMARE- B3A Professor/ Instructor: 2/E Oliverio Padrique

WEEK 3- ACTIVITY 3
Construction and Operating Principles of the Different Types of Gas Turbine

Answer the question properly.

1.) Give the different types of Gas turbine.

The different types of Gas Turbine are:
 Jet Engines
 Turboprop Engines
 Aeroderivative gas turbines
 Amateur gas turbines
 Auxiliary power units
 Industrial gas turbines
 Turboshaft engines
 Radial gas turbines
 Scale jet engines
 Microturbines

2.) Differentiate and discuss the different operating principles of the different
type of Gas turbine according to your understanding.

JET ENGINES
A jet engine is a type of reaction engine discharging a fast-moving jet that generates
thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid
propulsion, the term jet engine typically refers to an internal combustion airbreathing jet engine
such as a turbojet, turbofan, ramjet, or pulse jet. In general, jet engines are internal combustion
engines.
Airbreathing jet engines typically feature a rotating air compressor powered by a turbine,
with the leftover power providing thrust through the propelling nozzle, this process is known as
the Brayton thermodynamic cycle. Jet aircraft use such engines for long-distance travel. Early
jet aircraft used turbojet engines that were relatively inefficient for subsonic flight. Most
modern subsonic jet aircraft use more complex high-bypass turbofan engines. They give higher
speed and greater fuel efficiency than piston and propeller aeroengines over long distances. A
few air-breathing engines made for high- speed applications (ramjets and scramjets) use the ram
effect of the vehicle's speed instead of a mechanical compressor.

TURBOPROP ENGINES
A turboprop engine is a turbine engine that drives an aircraft propeller. A turboprop
consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling
nozzle. Air enters the intake and is compressed by the compressor. Fuel is then added to the
compressed air in the combustor, where the fuel-air mixture then combusts. The hot combustion
gases expand through the turbine stages, generating power at the point of exhaust. Some of the
power generated by the turbine is used to drive the compressor and electric generator. The gases
are then exhausted from the turbine. In contrast to a turbojet or turbofan, the engine's exhaust
gases do not provide enough energy to create significant thrust, since almost all of the engine's
power is used to drive the propeller.

GE T64 turboprop, with the propeller on the left, the gearbox with accessories in the middle, and the gas generator
(turbine) on the right
AERODERIVATIVE GAS TURBINES
The aeroderivative gas turbine is a lighter weight variation of a gas turbine. Despite being
classified as a gas turbine, the fuel source for the aeroderivative turbine is not really gas.
Actually, they are designed so that fuel and air are mixed and then ignited to achieve the desired
output. The design of gas turbines is comprised of a compression device to facilitate the taking
in of air and compressing it (the “gas” in this case) and then applying heat by means of a burner.
The resulting flow of hot air is used as the source of powering the turbine. Today, these are
typically designed to make use of a combustion process that is continuous as opposed to the
intermittent nature of automotive combustion engines.
One area of widespread use of aeroderivative gas turbine technology is in aviation where
the power harnessed by the turbine is used to power a compressor. The hot air that exits the
turbine is used for thrust by forcing the air into the atmosphere via an exhaust nozzle.

LM6000 GTG in an electrical power plant application.

AMATEUR GAS TURBINES

The simplest form of self-constructed gas turbine employs an automotive turbocharger as
the core component. A combustion chamber is fabricated and plumbed between the compressor
and turbine sections. More sophisticated turbojets are also built, where their thrust and light
weight are sufficient to power large model aircraft. The Schreckling design constructs the
entire engine from raw materials, including the fabrication of a centrifugal compressor wheel
from plywood, epoxy and wrapped carbon fibre strands.
Several small companies now manufacture small turbines and parts for the amateur. Most
turbojet-powered model aircraft are now using these commercial and semi-commercial
microturbines, rather than a Schreckling-like home-build.
AUXILIARY POWER UNITS
Small gas turbines are used as auxiliary power units (APUs) to supply auxiliary power to
larger, mobile, machines such as an aircraft. They supply:
 compressed air for air conditioning and ventilation,
 compressed air start-up power for larger jet engines,
 mechanical (shaft) power to a gearbox to drive shafted accessories or to start large
jet engines, and
 electrical, hydraulic and other power-transmission sources to consuming devices
remote from the APU
.

The Riedel APU installed on a preserved BMW 003 jet engine, with what appears to be an electric starter for the Riedel
APU.

INDUSTRIAL GAS TURBINES

 For Power Generation
 Industrial gas turbines for power generation are operated in either simple
cycle, where the gas turbine alone is used to drive the generator, or in
combined cycle where the gas turbine generates power in combination with
a steam turbine. Combined cycle power plants are more efficient than either
simple cycle gas turbine plants or steam turbine plants operating without a
gas turbine. In simple cycle operation the exhaust gases from the gas turbine
exit the exhaust duct to atmosphere, whereas in combined cycle the exhaust
gas is fed into a heat recovery steam generator (HRSG). As the name
suggests, the HRSG recovers heat from the exhaust gas of the gas turbine
and uses this heat to generate steam to power a steam turbine.
  For Mechanical Drive
 Industrial gas turbines that are used solely for mechanical drive or used in
collaboration with a recovery steam generator differ from power generating
sets in that they are often smaller and feature a dual shaft design as opposed
to a single shaft. The power range varies from 1 megawatt up to 50
megawatts. These engines are connected directly or via a gearbox to either a
pump or compressor assembly. The majority of installations are used within
the oil and gas industries. Mechanical drive applications increase efficiency
by around 2%. Oil and gas platforms require these engines to drive
compressors to inject gas into the wells to force oil up via another bore, or to
compress the gas for transportation. They are also often used to provide
power for the platform. These platforms do not need to use the engine in
collaboration with a CHP system due to getting the gas at an extremely
reduced cost (often free from burn off gas). The same companies use pump
sets to drive the fluids to land and across pipelines in various intervals.

TURBOSHAFT ENGINES
A turboshaft engine is a form of gas turbine that is optimized to produce shaft power
rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional
turbine expansion to extract heat energy from the exhaust and convert it into output shaft power.
They are even more similar to turboprops, with only minor differences, and a single engine is
often sold in both forms. Turboshaft engines are commonly used in applications that require a
sustained high-power output, high reliability, small size, and light weight. These include
helicopters, auxiliary power units, boats and ships, tanks, hovercraft, and stationary equipment.
A turboshaft engine may be made up of two major parts assemblies: the 'gas generator'
and the 'power section'. The gas generator consists of the compressor, combustion chambers
with ignitors and fuel nozzles, and one or more stages of turbine. The power section consists of
additional stages of turbines, a gear reduction system, and the shaft output. The gas generator
creates the hot expanding gases to drive the power section. Depending on the design, the engine
accessories may be driven either by the gas generator or by the power section.
RADIAL GAS TURBINES
In 1963, Jan Mowill initiated the development at Kongsberg Våpenfabrikk in Norway.
Various successors have made good progress in the refinement of this mechanism. Owing to a
configuration that keeps heat away from certain bearings, the durability of the machine is
improved while the radial turbine is well matched in speed requirement.
Modern small gas turbines are technically complicated machines, including many
rotating parts, bearings, seals, lubrication systems, and advanced electronic controls. Most gas
turbine designs are optimized for maximum efficiency but generally are not portable and cannot
manage severe environmental conditions; As a result, ruggedness is usually sacrificed for
efficiency. Although this is desirable for most large power plant applications, it is not feasible
for small, portable power generation purposes. Compared to axial flow turbines, radial turbines
can work with relatively higher -pressure ratios per stage with lower flow rates. Therefore, these
machines are in the lower ranges of specific speed and power. For high-temperature purposes,
cooling the rotor blade in radial stages is not as simple as in axial turbine stages. Changeable
angle nozzle blades, even in off-design conditions, allow higher stage efficiencies in a radial
turbine stage.

SCALE JET ENGINES

Scale jet engines are scaled down versions of this early full scale engine Also known as
miniature gas turbines or micro-jets.
With this in mind the pioneer of modern Micro-Jets, Kurt Schreckling, produced one of
the world’s first Micro-Turbines, the FD3/67.This engine can produce up to 22 newtons of
thrust, and can be built by most mechanically minded people with basic engineering tools, such
as a metal lathe.
MICROTURBINES
Microturbines are small combustion turbines approximately the size of a refrigerator with
outputs of 25 kW to 500 kW. They evolved from automotive and truck turbochargers, auxiliary
power units (APUs) for airplanes, and small jet engines. Most microturbines are comprised of a
compressor, combustor, turbine, alternator, recuperator (a device that captures waste heat to
improve the efficiency of the compressor stage), and generator. The figure below illustrates
how a microturbine works.