Editing Turbofan (section)

==Terminology==
<!--Currently unsure how to add this to here currently as my brain isn't working. Please add the engine terms: Flight Idle, Ground Idle, High Idle, TOGA (Take-Off Go-Around)-->

; [[Afterburner]]: jetpipe equipped for afterburning<ref name="auto">The Cambridge Aerospace Dictionary, Bill Gunston 2004,{{ISBN|978 0 511 33833 5}}</ref>
; Augmentor: afterburner for turbofan with burning in hot and cold flows<ref name="auto"/>
; Bypass: that part of the engine as distinct from the core in terms of components and airflow, e.g. that part of fan blading (fan outer) and stators which pass bypass air, bypass duct, bypass nozzle
; [[Bypass ratio]]: bypass air mass flow /core air mass flow<ref>Jet Propulsion, Nicholas Cumpsty 1997, {{ISBN|0 521 59674 2}}, p.65</ref>
; Core: that part of the engine as distinct from the bypass in terms of components and airflow, e.g. core cowl, core nozzle, core airflow and associated machinery,  combustor and fuel system
; Core power: also known as "available energy" or "gas horsepower". It is used to measure the theoretical (isentropic expansion) shaft work available from a gas generator or core by expanding hot, high pressure gas to ambient pressure. Since the power depends on the pressure and temperature of the gas (and the ambient pressure) a related figure of merit for thrust-producing engines is one which measures the thrust-producing potential from hot, high pressure gas and known as "stream thrust". It is obtained by calculating the velocity obtained with isentropic expansion to atmospheric pressure. The significance of the thrust obtained appears when multiplied by the aircraft velocity to give the thrust work. The thrust work which is potentially available is far less than the gas horsepower due to the increasing waste in the exhaust kinetic energy with increasing pressure and temperature before expansion to atmospheric pressure. The two are related by the propulsive efficiency,<ref>{{Cite journal |last1=Roth |first1=Bryce |last2=Mavris |first2=Dimitri |date=2000-07-24 |title=A comparison of thermodynamic loss models suitable for gas turbine propulsion - Theory and taxonomy |url=https://arc.aiaa.org/doi/10.2514/6.2000-3714 |journal=36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit |language=en |location=Las Vegas, NV, U.S.A. |publisher=American Institute of Aeronautics and Astronautics |pages=4–8 |doi=10.2514/6.2000-3714}}</ref> a measure of the energy wasted as a result of producing a force (i.e. thrust) in a fluid by increasing the speed (i.e. momentum) of the fluid.
; Dry: engine ratings/ throttle lever positions below afterburning selection
; EGT: exhaust gas temperature
; EPR: engine pressure ratio
; Fan: turbofan LP compressor
; Fanjet: turbofan or aircraft powered by turbofan (colloquial)<ref>The Cambridge Aerospace Dictionary, Bill Gunston 2004,{{ISBN| 978 0 511 33833 5}}</ref>
; Fan pressure ratio: fan outlet total pressure/fan inlet total pressure
; [[Flex temp]]: At reduced take-off weights commercial aircraft can use reduced thrust which increases engine life and reduces maintenance costs. Flex temperature is a higher than actual outside air temperature (OAT) which is input to the engine monitoring computer to achieve the required reduced thrust (also known as "assumed temperature thrust reduction").<ref>{{cite web | url=https://skybrary.aero/articles/reduced-thrust-takeoff | title=Reduced Thrust Takeoff | date=30 May 2021 }}</ref>
; Gas generator: that part of the engine core which provides the hot, high pressure gas for fan-driving turbines (turbofan), for propelling nozzles (turbojet), for propeller- and rotor-driving turbines (turboprop and turboshaft), for industrial and marine power turbines<ref>Gas Turbine Performance Second Edition, Walsh and Fletcher 2004,{{ISBN|0 632 06434 X}}, p.5</ref>
; HP: high-pressure
; Intake ram drag: Loss in momentum of engine stream tube from freestream to intake entrance, i.e. amount of energy imparted to air required to accelerate air from a stationary atmosphere to aircraft speed.
; [[IEPR]]: integrated engine pressure ratio
; IP: intermediate pressure
; LP: low-pressure
; Net thrust: nozzle thrust in stationary air (gross thrust) – engine stream tube ram drag (loss in momentum from freestream to intake entrance, i.e. amount of energy imparted to air required to accelerate air from a stationary atmosphere to aircraft speed). This is the thrust acting on the airframe.
; [[Overall pressure ratio]]: amount of times the pressure increases due to ram compression and workndone by the compressor stages
; Overall efficiency: thermal efficiency × propulsive efficiency
; [[Propulsive efficiency]]: propulsive power/rate of production of propulsive kinetic energy (maximum propulsive efficiency occurs when jet velocity equals flight velocity, which implies zero net thrust!)
; [[Thrust specific fuel consumption|Specific fuel consumption]] (SFC): total fuel flow/net thrust (proportional to flight velocity/overall thermal efficiency)
; Spooling up: increase in RPM (colloquial)
; Spooling down: decrease in RPM (colloquial)
; Stage loading: For a turbine, the purpose of which is to produce power, the loading is an indicator of power developed per lb/sec of gas (specific power). A turbine stage turns the gas from an axial direction and speeds it up (in the nozzle guide vanes) to turn the rotor most effectively ( rotor blades must produce high lift), the proviso being that this is done efficiently, i.e. with acceptable losses.<ref>Jet Engines and Propulsion Systems For Engineers, Human Resource Development, GE Aircraft Engines 1989, p.5-9</ref> For a compressor stage, the purpose of which is to produce a pressure rise, a diffusion process is used. How much diffusion may be allowed ( and pressure rise obtained) before unacceptable flow separation occurs (i.e. losses) may be regarded as a loading limit.<ref>Aerodynamic Design Of Axial Flow Compressors, N65 23345,1965, NASA SP-36, p.68</ref>
; [[Stagnation pressure]]: also known as total pressure; pressure of the fluid if all the kinetic energy were to be converted into pressure isentropically; sum of static pressure and dynamic pressure
; [[Static pressure]]: pressure of the fluid which is associated not with its motion but with its state<ref>Clancy, L.J., ''Aerodynamics'', page 21</ref> or, alternatively, pressure due to the random motion of the fluid molecules that would be felt or measured if moving with the flow<ref>Introduction To Aerospace Engineering With A Flight Test Perspective, Stephen Corda 2017,{{ISBN|9781118953389}}, p.185</ref>
; [[Specific thrust]]: net thrust/intake airflow
; [[Thermal efficiency]]: rate of production of propulsive kinetic energy/fuel power
; Total fuel flow: combustor (plus any afterburner) fuel flow rate (e.g., lb/s or g/s)
; Total pressure: also known as stagnation pressure; sum of static pressure and dynamic pressure; pressure of the fluid if all the kinetic energy were to be converted into pressure isentropically
; Turbine rotor inlet temperature: maximum cycle temperature, i.e. temperature at which work transfer takes place