Crossword clues for turbofan
Wiktionary
n. A turbojet engine having a (typically ducted) fan that forces air directly into the hot exhaust and obtains a portion of the thrust from the turbojet and a portion from the turbojet section.
WordNet
n. jet engine in which a turbine drives air to the burner [syn: turbojet, turbojet engine, turbofan engine]
Wikipedia
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the turbo portion refers to a gas turbine engine which achieves mechanical energy from combustion, and the fan, a ducted fan that uses the mechanical energy from the gas turbine to accelerate air rearwards. Thus, whereas all the air taken in by a turbojet passes through the turbine (through the combustion chamber), in a turbofan some of that air bypasses the turbine. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of those contributing to the thrust. The ratio of the mass-flow of air bypassing the engine core compared to the mass-flow of air passing through the core is referred to as the bypass ratio. The engine produces thrust through a combination of these two portions working in concert; engines that use more jet thrust relative to fan thrust are known as low bypass turbofans, conversely those that have considerably more fan thrust than jet thrust are known as high bypass. Most commercial aviation jet engines in use today are of the high-bypass type, and most modern military fighter engines are low-bypass. Afterburners are not used on high-bypass turbofan engines but may be used on either low-bypass turbofan or turbojet engines.
Most of the air flow through a high-bypass turbofan is low-velocity bypass flow: even when combined with the much higher velocity engine exhaust, the average exhaust velocity is considerably lower than in a pure turbojet. Turbojet engine noise is predominately jet noise from the high exhaust velocity, therefore turbofan engines are significantly quieter than a pure-jet of the same thrust with jet noise no longer the predominant source. Other noise sources are the fan, compressor and turbine. Jet noise is reduced with chevrons, sawtooth patterns on the exhaust nozzles, on the Rolls-Royce Trent 1000 and General Electric GEnx engines used on the Boeing 787.
Since the efficiency of propulsion is a function of the relative airspeed of the exhaust to the surrounding air, propellers are most efficient for low speed, pure jets for high speeds, and ducted fans in the middle. Turbofans are thus the most efficient engines in the range of speeds from about , the speed at which most commercial aircraft operate. Turbofans retain an efficiency edge over pure jets at low supersonic speeds up to roughly Mach 1.6.
Modern turbofans have either a large single-stage fan or a smaller fan with several stages. An early configuration combined a low-pressure turbine and fan in a single rear-mounted unit.
Usage examples of "turbofan".
The thrust of her quad turbofan engines, already blazing with power, carried her into the night.
He walked inside the shelter and approached two technicians working on the left Tumanskii turbofan of his beloved Mig-29 Fulcrum.
Using the surviving turbofan and the little that remained of hydraulics, Lancaster pulled out of the spin and managed to level off just as a Mig-29 rolled behind him.
Kevin applied full throttle, but was disappointed at the sluggishness of his craft with only one turbofan providing the thrust, even in full afterburner.
Schofield looked back through his rear windshield, through the blur of his rear turbofan and saw the three hovercrafts behind him.
In the cabin, Schofield quickly jammed the big vehicle into reverse and engaged the turbofan again.
AL-31FM turbofan on either side, jointly generating almost 60,000 pounds of thrust, Hua was the master of the eternal forces of air and fire, water and earth.
Her twin turbofan engines hung like afterthoughts at the twin-rudder tail, itself a throwback to the thirties.
Whitney turbofan jet engines, providing a cruising speed of six hundred and five miles per hour.
Twice the speed of sound was achieved by the four General Electric turbofan afterburners 50,000 feet above an oil-rig colossus whose platform looked like a pinhead, 300 nautical miles east of the Bay of Fundy.
Kamil was congratulating the commander of the Amn Al-Khass unit that had finally overrun the UN assassination team when the whine of an Allison Rolls Royce AE3007H turbofan jet engine passing almost directly overhead made them all instinctively duck.
Rolls-Royce Pegasus Three turbofan that could supply 23,000 pounds of thrust, thundered to life.
Japan Air Lines as, a week later, James Bond settled into the comfortable window seat of the four-jet, turbofan Douglas DC-8 at London Airport and listened to the torrent of soft Japanese coming from the tannoy that would be saying all those things about life jackets and the flying time to Orly.
Bobbie Jo punched up her engines and dove, turbofans screaming, to the roof of a tandem-trailered truck just then sluicing down the incline and into the dark of the transitway tunnel.
Thorvin wound up his turbofans and slid forward, weaving around the ankles of Shank and Rico and advancing to the end of the passage.