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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.
Turbofan engines with a bypass ratio of at least 4. Pages in category "High-bypass turbofan engines" The following 49 pages are in this category, out of 49 total.
In 2010, Pratt & Whitney launched the development of an ultra high-bypass version, with a ratio significantly higher than the PW1100G's 12.2:1 for the A320neo, to improve fuel consumption by 20% compared to a CFM56-7 and reduced noise relative to the FAA's Stage 4 by 25 dB. In 2012, wind tunnel tests were completed on an earlier version of the ...
These sizes achieve the desired high bypass ratios of over 30, but they are approximately twice the diameter of turbofan engines of equivalent capability. [67] For this reason, airframers usually design the empennage with a T-tail configuration in order to avoid the turbulent propwash adversely influencing the elevators and causing vibration ...
Schematic diagram illustrating a 2-spool, high-bypass turbofan engine with an unmixed exhaust. The low-pressure spool is coloured green and the high-pressure one purple. Again, the fan (and booster stages) are driven by the low-pressure turbine, but more stages are required. A mixed exhaust is often employed.
A turbofan typically has extra turbine stages to turn the fan. Turbofans were among the first engines to use multiple spools—concentric shafts that are free to rotate at their own speed—to let the engine react more quickly to changing power requirements. Turbofans are coarsely split into low-bypass and high-bypass categories.
The CFM International LEAP ("Leading Edge Aviation Propulsion") is a high-bypass turbofan engine produced by CFM International, a 50–50 joint venture between American GE Aerospace and French Safran Aircraft Engines. It is the successor of the CFM56 and competes with the Pratt & Whitney PW1000G to power narrow-body aircraft.
A low pressure ratio fan (such as that used on a high bypass ratio turbofan) has a range of working lines. At high flight speeds, the ram pressure ratio factors up the cold nozzle pressure ratio, causing the nozzle to choke. Above the choking condition, the working lines tend to coalesce into a unique steep straight line.