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The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. [1] A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core.
The engine performance deteriorates with use as parts wear, meaning the engine has to use more fuel to get the required thrust. A new engine starts with a reserve of performance which is gradually eroded. The reserve is known as its temperature margin and is seen by a pilot as the EGT margin. For a new CFM International CFM56-3 the margin is 53 ...
For example, Concorde cruised at 1354 mph, or 7.15 million feet per hour, with its engines giving an SFC of 1.195 lb/(lbf·h) (see below); this means the engines transferred 5.98 million foot pounds per pound of fuel (17.9 MJ/kg), equivalent to an SFC of 0.50 lb/(lbf·h) for a subsonic aircraft flying at 570 mph, which would be better than even ...
Research into the next generation of commercial jet engines, high-bypass ratio turbofans in the "10-ton" (20,000 lbf; 89 kN) thrust class, began in the late 1960s. Snecma (now Safran), who had mostly built military engines previously, was the first company to seek entrance into the market by searching for a partner with commercial experience to design and build an engine in this class.
Aircraft engine performance refers to factors including thrust or shaft power for fuel consumed, weight, cost, outside dimensions and life. It includes meeting regulated environmental limits which apply to emissions of noise and chemical pollutants, and regulated safety aspects which require a design that can safely tolerate environmental hazards such as birds, rain, hail and icing conditions.
A link between a gas turbine compressor and its engine can be shown with lines of constant engine temperature ratio, ie the effect of fuelling/increased turbine temperature which raises the running line as the temperature ratio increases. One manifestation of different behaviour appears in the choke region on the right-hand side of a map.
Jet engine maker CFM International said on Friday aviation regulators in the United States and Europe have certified a "more durable" high-pressure turbine kit for its LEAP-1A engines that power ...
Airplane engines are in the middle, as they only react against airflow through the engine, but some of this reaction mass (and combustion ingredients) is breathed rather than carried aboard. As such, "specific impulse" could be taken to mean either "per reaction mass", as with a rocket, or "per fuel burned" as with cars.