During the 18th Century, Sir Isaac Newton theorized that a rearward-channeled explosion could propel an object/machine forward at a great rate of speed. This theory, which is now physical fact, stands as the main reason for our ability to fly an airplane. Following Newton’s theory, several men and women gave flying a shot, yet the first manned flight didn’t take place until over a century later when the Wright brothers took flight in 1903 with their gas powered plane, “the Flyer.” The first-time event spurred a gas powered aircraft revolution that lasted until the late 1930s when the first jet airplane took flight with an engine designed in 1930 by British Pilot, Frank Whittle. The first American jet engine was produced by General Electric (GE) and took flight in a plane constructed by Bell Aircraft in the latter half of 1942. As a result, the US, Germany, and Great Britain all used jet-powered fighter planes by the end of WWII.
Today’s commercial engines, which can be as large as eleven feet in diameter and twelve feet in length, can weigh more than 10,000 pounds apiece and are capable of producing more than 100,000 pounds of thrust.
Though there are several different kinds of jet engines in production and in use today, such as the Turboshaft, Ramjet, Turboprop, and Turbojet, the core mechanics remain the relatively the same across the board.
All jet engines, which are also called gas turbines, work on the same principle of physics. The engine draws in air at the front with a fan. From there, a compressor raises the pressure of the air. The compressor is made up of fans with many turbines/blades that are attached to a shaft. The blades compress the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine. As the jets of gas shoot backward, the engine and the aircraft are thrust forward.
A description of each of the main components in a jet engine is as follows:
FAN: The fan is the first component in a turbofan, which is one of the modern jet engine’s vital systems. The large spinning fan sucks in large quantities of air. Most blades of the fan are made of a extremely tolerant titanium alloy. It then speeds this air up and splits it into two parts. One part continues through the "core" or center of the engine, where it is acted upon by the other engine components. The second part "bypasses" the core of the engine. It goes through a duct that surrounds the core to the back of the engine where it produces much of the force that propels the airplane forward. This cooler air helps to quiet the engine as well as adding thrust to the engine.
COMPRESSOR: The compressor is the first component in the engine core. The compressor is made up of fans with many blades and attached to a shaft. The compressor squeezes the air that enters it into progressively smaller areas, resulting in an increase in the air pressure. This results in an increase in the energy potential of the air. The squashed air is forced into the combustion chamber.
COMBUSTER: In the combustor the air is mixed with fuel and then ignited. There are as many as 20 nozzles to spray fuel into the airstream. The mixture of air and fuel catches fire. This provides a high temperature, high-energy airflow. The fuel burns with the oxygen in the compressed air, producing hot expanding gases. The inside of the combustor is often made of ceramic materials to provide a heat-resistant chamber. The heat can reach 2700°.
TURBINES: The high-energy airflow coming out of the combustor goes into the turbine, causing the turbine blades to rotate. The turbines are linked by a shaft to turn the blades in the compressor and to spin the intake fan at the front. This rotation takes some energy from the high-energy flow that is used to drive the fan and the compressor. The gases produced in the combustion chamber move through the turbine and spin its blades. The turbines of the jet spin around thousands of times. They are fixed on shafts which have several sets of ball-bearings between them. Several technological advancements have been incorporated into the area of modern turbine production as well, such as the use of thermal coating and high tolerance super-alloys. In fact, our local GE Aviation is one of the few US plants that produces what are commonly know as High Pressure Turbines (HPT) blades, which are built to handle extreme heats and pressures. These blades undergo rigorous testing and federal inspection before being placed within engines as their correct construction and high heat tolerances are integral to successful flight.
NOZZLE: The nozzle is the exhaust duct of the engine. This is the engine part which actually produces the thrust for the plane. The energy depleted airflow that passed the turbine, in addition to the colder air that bypassed the engine core, produces a force when exiting the nozzle that acts to propel the engine, and therefore the airplane, forward. The combination of the hot air and cold air are expelled and produce an exhaust, which causes a forward thrust. The nozzle may be preceded by a mixer, which combines the high temperature air coming from the engine core with the lower temperature air that was bypassed in the fan. The mixer helps to make the engine quieter.
Overall, the way a modern jet engine functions is similar to many other turbine-based energy production sites such as hydroelectric plants and wind farms. In fact, turbine produced energy accounts for nearly 40 percent of the world’s mass produced power today.
So the next time you look overhead and see that shiny dot of metal hurdling through the atmosphere, remember that it took hundreds of years and the production of many exacting pieces to make it possible.
Information provided by NASA
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