A gas turbine engine uses a pressurized gas to spin a turbine and compressor. Inside the engine, fuel is ignited to increase the gas’s temperature and pressure. This causes the gas to act on the turbine at a higher velocity. Gas turbine engines are used to power many aircraft and boats and have recently been used in some battle tanks.
A turbine uses the energy of a flowing fluid to rotate a wheel. The concept of a turbine has existed for many years; windmills and water wheels are simple examples. Moving air passes over a windmill’s slanted blades, causing the wheel to spin. Turbines can also be used with steam, as in the case of many power plants. The turbine in a gas turbine engine, however, uses highly pressurized air to rotate.
Norwegian engineer Aegidius Elling was granted a patent for a gas turbine in 1884. His first turbine model that produced more power than it consumed was unveiled in 1903. Elling’s design locked a spinning air compressor to the turbine, a feature widely used today. He believed that if more heat-resistant materials could be found, the gas turbine engine could be used to power airplanes.
The main parts of a gas turbine engine are the compressor, the combustion area and the turbine. Air enters the compressor at normal pressure and then gets compressed. In the combustion area, some type of fuel is burned to increase the temperature and energy content of the air. The high-temperature, high-pressure gas is then forced to exit the engine, turning the turbine on its way out. A solid shaft connects the compressor and turbine—the rotation of the turbine is used to spin the compressor, which makes the engine as a whole more efficient.
The shaft that connects the compressor to the turbine may or may not be used to power additional devices. In a jet engine, the method of obtaining thrust is expelling the exhaust gas at a high velocity, which causes the aircraft to be pushed forward. In vehicles that are not powered by thrust, the spinning shaft can be used to do mechanical work. The M1 Abrams tank of the United States Army uses a gas turbine engine for this purpose. In this case, the flow of gas is used to rotate a shaft that powers the tank’s treads.
A gas turbine engine has several advantages over the type of engine found in most automobiles. First of all, it has a better power-to-weight ratio. Gas turbine engines are also smaller than their automobile counterparts for a given amount of power. These reasons explain why many helicopters and airplanes use this type of engine.