When was the turbofan invented?
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Answer . A propeller is completely external and is the main source of propulsion for a airplane with a piston or turbojet engine. A turbofan is more enclosed and provides …some propulsion along with also cooling the jet engine that is the main source of propulsion.
A turbojet is one of the oldest kinds of jet engine designs.The air flow enters the jet engine at one end and is compressedwhile it travels through rows of rotating blades (…calledcompressors; sometimes referred to as stages). It is then ignitedin the combustion chamber and as the gas expands and speeds up, itcauses the turbine blades to turn, which provides the torque to thecompressor stages. The force of the exhaust gases exiting is whatprovides the forward motion of the engine and is referred to as thrust . A turbofan jet engine is the most widely used jet engine onmodern aircraft today. It uses a fan placed directly in front of aseries of compressors to compress the air. The operation is similarto the turbojet engine, except not all of the air moved by the fangoes into the engine's combustion chamber. A portion of the airflows over the engine itself, called bypass air . Bypass airalso produces thrust in conjunction with the exhaust gas pressure. Turbofan engines come in two varieties: high bypass and low bypass . With high bypass turbofans, the majority of the total engine thrust(as much as 80%) is produced by the bypass air. With low bypassturbofans, the majority of the thrust is produced by the exhaustgases. Large commercial airliners (such as the Boeing 747 JumboJet), large military cargo jets (such as the Lockheed-Martin C-5Galaxy) and some small military tactical fighters jets (such as theFairchild-Republic A-10 Thunderbolt II) use high bypass turbofansbecause they offer better subsonic efficiency at low to mediumaltitudes, are quieter, and still offer strong thrust at the costof supersonic capabilities. Low bypass turbofans are popular on small, high-performancetactical fighter aircraft (such as the Lockheed-Martin F-22ARaptor) and sacrifice fuel efficiency for improvements in thefollowing areas: high altitude performance, supersonic performance,supersonic efficiency, and afterburning fuel economy. Inafterburning engines, fuel is sprayed into the exhaust stream andproduces the famous flame trail that jet engines are known for.Activating the afterburner can increase thrust output by as much as50%. Turbofans as a whole offer better efficiency than turbojets at highsub and transonic speeds, and at low supersonic speeds with littlesacrifice in thrust performance.
it works by how the pilot operates it. Engine start on the top of the head location. the pilot pulls the switch down know as engine ignition. It would start the turbofan and i…t would be blowing fast That is completely wrong!! Whoever wrote the above knows nothing about Aerospace Engineering and needs to find something different to do in their lives. The Turbofan jet engine is the most commonly used engine on a commercial airliner such as a Boeing 747 or a 737. Basically an enormous fan sucks in lots of air, which is then separated into two groups: around 80% goes into the bypass duct, and stays cool, while the small amount that remains goes through the core. In the core, the air is pressurized first in the Low Level Compressor, then pressurized even more in the High Level Compressor. This extremely pressurized air is then forced through the Combustor, where fuel is injected into it and then ignited. This creates very hot air, and is forced through a series of Turbines. After this, the cool air from the bypass duct is mixed with the hot air from the core and is forced out of the Nozzle in an hourglass shape to create thrust. This is exactly how a Turbofan Engine works.
To understand how is the turbofan working, firsly you should know how is theturbojet working, so here you are the explanation. . A turbojet is essentially a tube with a con…striction in it with a turbine at the beginning and a turbine at the end, connected together on the same axle. Fuel burns in the combustion chamber behind the constriction in the tube, sending hot, expanding gases mostly out the back end of the tube. The hot gases push on all sides of the tube including the constriction in front, and so the sum of all the pressure forces on the tube points forwards, providing thrust, just as a rocket engine works. The turbine on the exhaust side uses a fraction of the energy of the exiting exhaust to spin the turbine blades and axle, and in turn this spins a turbine in front which compresses the air needed to burn the fuel. Compressing the input air increases the amount of expansion of the gases in the combustion chamber -- the fuel burns fast because there is plenty of oxygen, and there is a lot of expansion of the gas in the burning and decompression. A turbofan engine is just a turbojet with a big fan in front attached to the turbine axle. A fraction of the exhaust energy is used to spin the fan which blows a huge amount of air past the engine, which does not participate in the combustion but which provides quite a lot of thrust (just the total force the jet engine pushes forwards with). I suspect that this also helps the fuel effiency of the engine. Smaller airplanes put a propeller in front instead of the turbofan's big fan and air diversion assembly.
A turbofan is an Cold Air Unit that lowers the temperature of the air passing through it. The air is made to work (reducing temperature) by turning the turbine and made to wor…k even more (another drop in temperature) by turning the fan.
There are two types of turbofan engines- high bypass and low bypass engines. About 80 percent of the total engine thrust from a high bypass turbofan engine is produced by t…he bypass of air around the core. These types of engines generally have a large fan in the front to pull in large volumes of air to produce such a powerful jet stream out the back. The front fan is driven by the compression, combustion, and expulsion of the hot gases out the back of the core. About 20 percent of the air pulled in from the front fan is used to drive the core. High bypass turbofan engines are used on almost all commercial jet aircraft because they burn less fuel. A low bypass engine is exactly the opposite. The core is used to drive a smaller fan in the front which only about 20 percent of the total volume of air pulled in is bypassed. The remaining 80 percent of the air being drawn into the engines core is compressed, combusted, and the hot gasses expelled out the back to produce the necessary thrust to propel a jet forward. Low bypass turbofan engines are found on jets that require supersonic speeds. These engines are incredibly powerful but at the cost of a high fuel burn rate.
A turboprop aircraft, such as a Cessna, cannot fly as fast as a turbofan aircraft, such as a Boeing. Because of this, lift cannot be maintained at high altitudes. As you go hi…gher, you can go faster because there's less air to slow you down. But if you don't go fast enough, then the plane will stall and keep falling until it reaches an altitude at which lift can be maintained at its current speed.
Geared turbofans have planetary reduction gearboxes to allow the fan (which pulls the airplane through the sky) will run slower than the compressor shaft. This does two things… for you. It lets the shaft turn faster, and more efficiently, than the fan can safely turn, and it increases the horsepower available to the fan. Say you have a shaft that produces 1000 horsepower at 100,000 rpm. If you turn a three-foot-diameter fan 100,000 RPM it will explode like a grenade. Installing a 10:1 reduction gear will allow the fan to run at 10,000 RPM but it will have 10,000 horsepower. (Every time the compressor shaft turns it puts out 1000hp; if it turns 10 times to make the fan turn once, it puts 10,000hp out.)
The difference between the low and high bypass turbofans is simply in the amount of air which goes into the engine versus the remainder that goes around (bypasses) the engine.… In high bypass engines ( an engine on any large commercial jet) only 20% around 20% of air goes into the engine with 80% bypassing it. (The 80% generates most of the engine thrust) In low bypass engines, this ratio is much lower
Most turbofan engines have parts running at more than one speed. The inner most compressor stages and the first turbine stages usually turn faster than the outer stages. The m…ore popular engines seen on airliners use three stages, and three different speeds at any given time. Watch a modern airliner engine during engine start and you can hear the inner stages begin to spin up before you will see the outer fan stage begin to rotate. It depends on the engine, but the largest fan stage which is seen in the intake will be less than 10k rpm, often less than 5k.
A turbofan engine is the most modern variation of the basic gas turbine engine. As with other gas turbines, there is a core engine, whose parts and operation are discussed on …a separate page. In the turbofan engine, the core engine is surrounded by a fan in the front and an additional turbine at the rear. The fan and fan turbine are composed of many blades, like the core compressor and core turbine, and are connected to an additional shaft. All of this additional turbomachinery is colored green on the schematic. As with the core compressor and turbine, some of the fan blades turn with the shaft and some blades remain stationary. The fan shaft passes through the core shaft for mechanical reasons. This type of arrangement is called a two spool engine (one "spool" for the fan, one "spool" for the core.) Some advanced engines have additional spools for even higher efficiency. How does a turbofan engine work? The incoming air is captured by the engine inlet. Some of the incoming air passes through the fan and continues on into the core compressor and then the burner, where it is mixed with fuel and combustion occurs. The hot exhaust passes through the core and fan turbines and then out the nozzle, as in a basic turbojet. The rest of the incoming air passes through the fan and bypasses , or goes around the engine, just like the air through a propeller. The air that goes through the fan has a velocity that is slightly increased from free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan. The ratio of the air that goes around the engine to the air that goes through the core is called the bypass ratio . Because the fuel flow rate for the core is changed only a small amount by the addition of the fan, a turbofan generates more thrust for nearly the same amount of fuel used by the core. This means that a turbofan is very fuel efficient. In fact, high bypass ratio turbofans are nearly as fuel efficient as turboprops. Because the fan is enclosed by the inlet and is composed of many blades, it can operate efficiently at higher speeds than a simple propeller. That is why turbofans are found on high speed transports and propellers are used on low speed transports. Low bypass ratio turbofans are still more fuel efficient than basic turbojets. Many modern fighter planes actually use low bypass ratio turbofans equipped with afterburners. They can then cruise efficiently but still have high thrust when dogfighting. Even though the fighter plane can fly much faster than the speed of sound, the air going into the engine must travel less than the speed of sound for high efficiency. Therefore, the airplane inlet slows the air down from supersonic speeds.
The Turbofan jet engine is the most commonly used engine on a commercial airliner such as a Boeing 747 or a 737. Basically an enormous fan sucks in lots of air, which is then …separated into two groups: around 80% goes into the bypass duct, and stays cool, while the small amount that remains goes through the core. In the core, the air is pressurized first in the Low Level Compressor, then pressurized even more in the High Level Compressor. This extremely pressurized air is then forced through the Combustor, where fuel is injected into it and then ignited. This creates very hot air, and is forced through a series of Turbines. After this, the cool air from the bypass duct is mixed with the hot air from the core and is forced out of the Nozzle in an hourglass shape to create thrust. I hope this helps.
No. There are not "spark plugs" on turbofan engines. There are ignitors, which help to ignite the fuel during start, but unlike spark plugs, ignitors do not run constantly.
It might sound like a good idea, but think about the incandescent light bulbs people replace on a continuous basis. If you apply this to an ignition system, you will be replac…ing some parts constantly. To add on top of that tungsten will burn out faster when more heat is applied. There are spark plugs that have metals combined with tungsten because of its rapid heat conduction.
What is the best for the inventor to protect his or her investment if the invention of a new composite material for turbofan blades is susceptible to reverse engineering?
A turbofan is used in modern aviation. Modern jetplanes use turbofans because they can save a lot of kerosine and give a lot of boost to make the airplane move through the air….