bypass ratio


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bypass ratio

n
(Aeronautics) aeronautics the ratio of the amount of air that bypasses the combustion chambers of an aircraft gas turbine to that passing through them
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[W.sub.a] is the total airflow of the ACE, [T.sub.t4] is the HPT inlet total temperature, nt is the total compression ratio, [[pi].sub.FAN] is the compression ratio of the fan stage, [[pi].sub.FFAN] is the compression ratio of FFAN, [[pi].sub.RFAN] is the compression ratio of RFAN, [[pi].sub.HPC] is the compression ratio of HPC, [D.sub.F] is the diameter of the engine at fan entry, [B.sub.t] is the total bypass ratio, [B.sub.1] is the first bypass split ratio and [B.sub.2] is the second bypass split ratio, and [N.sub.1] is the relative rotating speed of LPR.
The main advantage of this model was the consideration of the bypass ratio. Contrary to the previous models, the one proposed by Rodriguez included the bypass ratio in its equations.
The bypass ratio [K.sub.F.E1] for classical engine is defined as ratio between [M.sub.a.II.E.1] and [M.sub.a.I.E.1].
At the same time, the current engine architecture used by the major engine manufacturers is reaching its limit, as bypass ratios are pushed higher, and the consequential diameter of the fan becomes larger--and one primary limiting factor comes in to play.
The new engine has internal variable geometry features that allow the system to vary the bypass ratio and fan pressure ratio, optimizing engine operation for varying flight conditions.
The TFE731 gear box resulted in a gear reduction of 1.8:1, to power the fan for a 2.5 bypass ratio, which was very high for the 1960s.
Consequently, noise reduction strategies are aimed at increasing the bypass ratio to lower nozzle exit velocities and designing bypass and core flows to improve mixing with each other and the atmosphere.
At the design point, the bypass ratio (x = [the bypass flow rate] / [the circulating flow]), and the pre-expansion ratio (y = [pressure difference of pre-expansion] / [pressure difference between the gas cooler outlet and the evaporator inlet]) become ~ 0 because the volumetric EXP/C2 ratio ([sigma][v.sub.EC]) has been defined from the state of the cycle without either bypass or pre-expansion.
Europe's environmental engine targets for 2020 can be met using engines with a bypass ratio of 14, according to an analysis tool developed for the European Union's Environmentally Friendly Aero-engine (Vital) project.
Bypass ratio: Substituting the mass equations into the ratio of equations [7] to [6] gives:
fan, 2.8 bypass ratio, 3500 hour TBO PW610 engine will be supplied to Eclipse Aviation, Albuquerque, N.M., for its Eclipse 500 aircraft.
He concluded: "The aim is to achieve a very high bypass ratio engine that can meet the noise and specific fuel consumption goals on ACARE without the penalties of drag and weight normally associated with low specific thrust engine".