Gas Turbine Engine - Prelims

Jet propulsion

The force which is generated in the opposite direction to that of a discharge of fluid under pressure, escaping through an opening

Reaction engine

Device utilizing jet propulsion which operates on sir isaac newton's third law of motion

Hero's engine

Consisted of a sphere into which steam was introduced under pressure

Campini Camproni CC-2

One of the first attempts in developing jet powered aircraft resulted in the development of a hybrid design

Heinkel 178

Year earlier then CC-2, the germans had flown their version of a jet powered aircraft with an engine developed by a young german scientist Hans von Ohain

Hans von Ohain

German scientist who designed the engine used for the germans' version of a jet powered aircraft

Sir Frank Whittle

Submitted patents for his jet engine in 1930, but it was not until 1939 that sufficient financial and technical backing was found to enable him to manufacture a flyable version of his engine

Gloster meteor F8

This is powered by later versions of the 'Derwent' engine capable of 3600 lb of thrust

Nene engine

rolls royce culminated this engine which at the time was the most powerful engine in the world, with 5000 lb of thrust

Air breathing and rockets

Two types of propulsion devices

Air breathing

Uses atmospheric air and some fuel as main propellant

Rockets

Carries the entire propellant composed of liquid or solid fuel and the oxygen

Increase the speed of exhaust gases

Increase the quantity of exhaust gases

Jet engine can be increased in two ways

Gas turbine engine

the most practical form of jet engine in use today.

Ramjet

An athodyd which has no rotating parts and consists of a duct with a divergent entry and a convergent or convergent-divergent exit.

aero-thermodynamic-duct

Athodyd

Pulse jet

Unstable as a powerplant due to high fuel consumption and cannot match performance of modern gas turbine engines

Pulse jet

Can be run at static conditions unlike the ram jet and is constructed with a robust construction

Scram jet

is a variant of a ramjet air breathing jet engine in which combustion takes place in a supersonic airflow

Scram jet

Relies on high vehicle speed to compress the incoming air forcefully before combustion with airflow at supersonic throughout the entire engine

Rocket engine

A jet engine that does not use atmospheric air as a propulsive fluid stream (non-air breathing)

Rocket engine

Uses propellants thus enabling outside atmosphere operations

Constant pressure

In gas turbine engines, combustion occurs at

Brayton cycle

Combustion in the gas turbine occurs at a constant pressure because of the continuous process of the

engine pressure ratio

ratio of turbine discharge pressure to the inlet air pressure

spool

a compressor and turbine are joined on one shaft

turboprop

gas turbine engine that delivers power to a propeller

reduction gearing

necessary in turboprop engines because optimum propeller performance is achieved at much slower speeds that the engine's operating rpm

turboprop engines

used extensively in business and commuter type aircraft because the combination of jet power and propeller efficiency provides good performance characteristics at speeds between 300 and 400 miles per hour

equivalent shaft horsepower

output from a turboprop engine is the sum of the shaft horsepower developed at the turbine, and the residual jet thrust

turboshaft

gas turbine engine that delivers power to a shaft that can drive something else

turboshaft engines

widely used as auxiliary power units and industrial applications to drive electrical generators and surface transportation systems

turbofan engine

consists of a multi-bladed ducted propeller driven by a gas turbine engine

turbofans

were developed to provide a compromise between the best features of the turbojet and the turboprop

turbofan engine's thrust ratio

a comparison of the thrust produced by the fan to the thrust

turbofan bypass ratio

ratio of incoming air that bypasses the core to the amount of air that passes through the engine core

fan pressure ratio

pressure leaving the fan to the pressure entering the fan