CONTENT • INTRODUCTION • THEORY OF OPERATION • BRAYTON CYCLE • TYPES OF GAS TURBINE • SCALE JET ENGINE • MICROTURBINES • GAS TURBINE IN SURFACE VEHICLE • MARINE APPLICATION • NON-MILITARY MARITIME • TURBOFAN • TURBOPROP • ADVANTAGE & DISADVANTAGE • CONCLUSION
INTRODUCTION A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between. A typical axial-flow gas turbine turbojet, the J85
THEORY OF OPERATION • Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbine's blades, spinning the turbine which powers the compressor and, for some turbines, drives their mechanical output. The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas.
BRAYTON CYCLE • The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the airbreathing jet engine and others.
TYPES OF GAS TURBINE • Jet engines • Turboprop engines • Aeroderivative gas turbines • Amateur gas turbines • Auxiliary power units • Industrial gas turbines for power generation • Compressed air energy storage • Turboshaft engines • Radial gas turbines • Scale jet engines (micro-jets)
MICROTURBINES Also known as: • Turbo alternators • Turbogenerator
GAS TURBINES IN SURFACE VEHICLES • Gas turbines are often used on ships, locomotives, helicopters, tanks, and to a lesser extent, on cars, buses, and motorcycles. • A key advantage of jets and turboprops for aeroplane propulsion - their superior performance at high altitude compared to piston engines, particularly naturally aspirated ones - is irrelevant in automobile applications. Their power-to-weight advantage, though less critical than for aircraft, is still important.
PASSENGER ROAD VEHICLES More recently, there has been some interest in the use of turbine engines for hybrid electric cars. For instance, a consortium led by micro gas turbine company Bladon Jets has secured investment from the Technology Strategy Board to develop an Ultra Lightweight Range Extender (ULRE) for next generation electric vehicles.
CONCEPT CARS • Jaguar C-X75 concept car. This electrically powered supercar has a top speed of 204 mph (328 km/h) and can go from 0 to 62 mph (0 to 100 km/h) in 3.4 seconds. It uses Lithium-ion batteries to power 4 electric motors which combine to produce some 780 bhp. It will do around 100 miles on a single charge of the batteries but in addition it uses a pair of Bladon Micro Gas Turbines to re-charge the batteries extending the range to some 560 miles
RACING CARS • Rover and the BRM Formula One team joined forces to produce the Rover-BRM, a gas turbine powered coupe, which entered the 1963 24 Hours of Le Mans, driven by Graham Hill and Richie. It averaged 107.8 mph (173 km/h) and had a top speed of 142 mph (229 km/h). Rover-BRM
MOTORCYCLES MTT Turbine SUPERBIKE appeared in 2000 (hence the designation of Y2K Superbike by MTT) and is the first production motorcycle powered by a turbine engine - specifically, a Rolls-Royce Allison model 250 turbo shaft engine, producing about 283 kW (380 bhp). Speed-tested to 365 km/h or 227 mph. Y2K MTT
MARINE APPLICATIONS Naval Gas turbines are used in many naval vessels, where they are valued for their high power-to-weight ratio and their ships' resulting acceleration and ability to get underway quickly. The first gas-turbine-powered naval vessel was the Royal Navy's Motor Gun Boat MGB 2009 (formerly MGB 509) converted in 1947. The Gas turbine from MGB 2009
NON-MILITARY MARITIME • Gas turbines have been used experimentally to power seagoing commercial vessels since about 1949 (Anglo Saxon Petroleum oil tanker "Auris"). • In July 2000 the Millennium became the first cruise ship to be propelled by gas turbines, in a Combined Gas and Steam Turbine configuration. The liner RMS Queen Mary 2 uses a Combined Diesel and Gas Turbine configuration.
TURBOFAN • Large jetliners use what are known asturbofan engines, which are nothing more than gas turbines combined with a large fan at the front of the engine. • The turbofan is basically the combination of two engines, the turbo portion which is a conventional gas turbine engine. • The low specific thrust/high bypass ratio turbofans used in today's civil jetliners (and some military transport aircraft) evolved from the high specific thrust/low bypass ratio turbofans used in such [production] aircraft back in the 1960s.
Animation of a 2-spool, high-bypass turbofan. A. Low pressure spool B. High pressure spool C. Stationary components1. Nacelle2. Fan3. Low pressure compressor4. High pressure compressor5. Combustion chamber6. High pressure turbine7. Low pressure turbine8. Core nozzle9. Fan nozzle
TURBOPROP • A turboprop engine is similar to a turbofan, but instead of a fan there is a conventional propeller at the front of the engine. The output shaft connects to a gearbox to reduce the speed, and the output of the gearbox turns the propeller. A turboprop engine in operation
ADVANTAGES OF GAS TURBINE ENGINES • Very high power-to-weight ratio, compared to reciprocating engines; • Smaller than most reciprocating engines of the same power rating. • Moves in one direction only, with far less vibration than a reciprocating engine. • Fewer moving parts than reciprocating engines. • Low operating pressures. • High operation speeds. • Low lubricating oil cost and consumption. • Can run on a wide variety of fuels.
DISADVANTAGES OF GAS TURBINE ENGINES • Cost is very high • Less efficient than reciprocating engines at idle speed • Longer startup than reciprocating engines • Less responsive to changes in power demand compared to reciprocating engines