Gas Turbine Engine Fundamentals
How this Complex Engines made ?
What is a Gas Turbine ?
A gas turbine is a thermal machine that converts the energy contained in a flow of burnt gases to mechanical energy. The high temperature gas flow is used to produce mechanical work. Gas turbines can be used for a large number of industrial applications. For example, the work extracted from the gas flow can be used to produce electrical power in an electrical power plant.
Gas turbines are widely used in the aeronautical field because they are not only able to generate mechanical work, but also to supply a significant thrust through the acceleration of the burnt gases. Besided, and different from a recipocationg engine, a turbine does not include parts in recipocating motion, but only rotationg parts. For this reason, together with several other reasons, gas turbines are able to provide high power outputs while having relatively little weight.
Evolution
The first forms of turbines have been used since 150 B.C. by Hero, an Egyptian scientist form Alexandria, to drive turbines by the ascending gas from a fire, and directed them through to the turbine by ventilation shafts. This first rudimentary turbine is known as the “Aeolipile”. It Consisted of a boiler, two hollow bent tubes mounted to a sphere. The steam coming from the boiler enter through the two hollow tubes supporting the sphere, and then exit through the bent tubes on the sphere. This cause spinning. History reveal Hero used this invention to pull-open temple doors.
Around the year 1500 A.D., Leonardo Da Vinci designed a device called the “chimney jack”. The chimney jack was used to turn a roasting skewer. this reaction-type turbine worked on the principle of heat raising gases from the roasting tire. As the hot rose, it passed through fanlike blades. In this way, the roast could be tun through a series of gears.
In 1629, an Italian engineer, Giovanni Braca used steam to rotate a turbine which gave power to operate machinery, in an invention called stamping mill. This device was generated by a steam-powered turbine. A jet nozzle directed steam onto a horizontally mounted turbine wheel, which then turned an arrangement of gears that operated his mill.
In 1687, Isaac Newton attempted to put his newly formulated laws of motion to the test with his steam wagon. With this inventory, he tried to propel the wagon by directing steam through a nozzle pointed rearward. Steam was produced by a boiler mounted on the wagon. due to lack of power from the steam, this vehicle didn’t ever operate.
The real first Gas Turbine in the history could be considered the project of John Barber. In 1791, Barber was the first to patent a design that used the thermodynamic cycle of the modern gas turbine. His inventory design contained the vasics of the modern gas turbine, such as a compressor, a combustion chamber and a turbine. The turvine was equipped with a chain-driven recipocating type of compressor, and he intended its use for jet propulsion.
Arrival of Gas Turbine Engines
The modern Gas Turbine engine type for aircraft propulsion was developed between 1930 and 1940. In january 1930, an Englishman, Frank Whittle, submitted a patent application for a gas turbine for jet propulsion. In may 1941 the Whittle W1 engine made it’s first flight mounted in the Gloster Model E28/39 aircragt. The airplane would later achieve a speed of 370 MPH in level flight with 1000 pounds of thrust.
The German student Hans Von Ohain and Max Hahn, seemingly unaware of Whittle’s work patented a jet propulsion engine in 1936. Ernst Heinkel Aircraft Company adapted their ideas and flew the second aircraft engine of his development in an HE-178 to speeds of over 400 MPH. This engine used first centrifugal flow compressor, and in later developments, also an axial flow compressor. This turbine was used to power the ME262 jet fighter to 500 MPH. These planes were introduced in the closing stages of World War II. On September 1929, using a modified glider and Opel rockets, the Germans were the first to achieve flight using a reaction engine.
In 1940, an Italian Engineer, Secondo Campini of the Caproni Company, developed a turbine engine that used a 900-HP recipocating engine to drive it’s three-stage compressor. This turbine was installed in the Campini-Caproni CC-2, but it only achieved 205 MPH. In August 1940, the CC-2 made its first flight, with the whole project ending just eight years later. In the same period, the W. IX engine, a complete set of plans for the W.2B engine,and a group of Power Jets engineers were flown to the United States from Britain. A contract was awarded by General Electric Corporation to develop an American version of The W. IX. In Octover 1942, the Bell Xp-59A, fitted with two General Electric I-A engines made this country’s first jet propulsion flight.
Different types of Aircraft Engines
Nowadas, gas turbine is a definition often used in association with aircraft jet engines. This is not correct because gas turbines are used in several an ddifferent types of engines. The large family of aeronautical reaction engines includes : The Rocket Engines, The Ramjet Engines, The Pulse-jet Engines, The Gas Turbine Engines
Rocket engine is usually considered a jet engine, but it has one major difference in that it does not use atmospheric air as the propulsive fluid stream, It produces its own propelling fluid by the combustion of liquid or solid fuel with oxygen which it carries, thus enebling it to operate outside the atmosphere
The last three types of engines mentioned above use the oxygen contained in the air to allow combustion to start, and sustain it.
There are four different categories of gas turbine engines : The Turbojet Engines, The Turboprop Engines, The Turboshaft Engines, The Turbofan Engines.
These types of engines are commonly used in the aerospace industry nowadays.
Each type of engine exploits the same basic thermodynamic characteristics, but is different from the others because of some typical features of its construction, and in the case of turboprop engines, because it is the propeller that generates the tracrion force.
