A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the additional fan stage. It consists of a gas turbine engine which achieves mechanical energy from combustion, and a ducted fan that uses the mechanical energy from the gas turbine to force air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust.
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. 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 Pratt & Whitney PW6000 is a high-bypass turbofan jet engine designed for the Airbus A318 with a design thrust range of 18,000–24,000 lbf (80–107 kN).
The IAE V2500 is a two-shaft high-bypass turbofan engine built by International Aero Engines (IAE) which powers the Airbus A320 family, the McDonnell Douglas MD-90, and the Embraer C-390 Millennium.
The Europrop International TP400-D6 is an 11,000 shp (8,200 kW) powerplant, developed and produced by Europrop International for the Airbus A400M Atlas military transport aircraft. The TP400 is the most powerful turboprop in service using a single propeller; only the Kuznetsov NK-12 from Russia and Progress D-27 from Ukraine, using contra-rotating propellers, is larger.
The Rolls-Royce BR700 is a family of turbofan engines for regional jets and corporate jets. It is manufactured in Dahlewitz, Germany, by Rolls-Royce Deutschland: this was initially a joint venture of BMW and Rolls-Royce plc established in 1990 to develop this engine. The BR710 first ran in 1995. The United States military designation for the BR725 variant is F130.
The Rolls-Royce RB.183 Tay is a medium-bypass turbofan engine, developed from the RB.183 Mk 555 Spey core and using a fan scaled directly from the Rolls-Royce RB.211-535E4 to produce versions with a bypass ratio of 3.1:1 or greater. The IP compressor and LP turbine were designed using technology from the RB.211 programme. The engine was first run in August 1984. The Tay 650 had a new HP turbine which incorporated new technology which had been proven with the RB.211-535E4. This engine also had a new combustor for improved durability. The Tay family is used on a number of airliners and larger business jets, including the Gulfstream IV family, Fokker 70 and Fokker 100, with a later version being used to re-engine Boeing 727-100s.
IAE International Aero Engines AG is a Zürich-registered joint venture aeroengine manufacturing company.
A jet engine performs by converting fuel into thrust. How well it performs is an indication of what proportion of its fuel goes to waste. It transfers heat from burning fuel to air passing through the engine. In doing so it produces thrust work when propelling a vehicle but a lot of the fuel is wasted and only appears as heat. Propulsion engineers aim to minimize the degradation of fuel energy into unusable thermal energy. Increased emphasis on performance improvements for commercial airliners came in the 1970s from the rising cost of fuel.
The Rolls-Royce/SNECMA M45H is an Anglo-French medium bypass ratio turbofan produced specifically for the twin-engined VFW-Fokker 614 aircraft in the early 1970s.
The Garrett TFE731 is a family of geared turbofan engines commonly used on business jet aircraft. Garrett AiResearch originally designed and built the engine, which due to mergers was later produced by AlliedSignal and now Honeywell Aerospace.
The Pratt & Whitney PW1000G family, also known as the GTF, is a family of high-bypass geared turbofan produced by Pratt & Whitney. Following years of development and testing on various demonstrators, the program officially launched in 2008 with the PW1200G destined for the Mitsubishi SpaceJet. The first successful flight test occurred later that year. The PW1500G variant, designed for the Airbus A220, became the first certified engine in 2013. The program cost is estimated at $10 billion.
The Lycoming ALF 502/LF 507 is a geared turbofan engine produced by Lycoming Engines, AlliedSignal, and then Honeywell Aerospace. The U.S. military designation for the ALF 502 is YF102.
The Pratt & Whitney Canada PW800 is a series of turbofan engines in the 10,000–20,000 lbf (44–89 kN) thrust class, manufactured by Pratt & Whitney Canada. Intended for the regional jet and business jet market, the gear-less PW800 shares a common core with the larger, geared PW1000G. The first variants were certified on February 15, 2015, to power the new Gulfstream G500/G600. After that it has been certified also for the Dassault Falcon 6X in 2021.
The accessory drive is a gearbox that forms part of a gas turbine engine. Although not part of the engine's core, it drives the accessories – such as generators, pumps for fuel and lubrication oil, air compressors, hydraulic pumps and engine starters – that are otherwise essential for the operation of the engine or the aircraft on which it is mounted. Accessory drives on large engines handle between 400–500 hp.
The Rolls-Royce RB.203 Trent was a British medium-bypass turbofan engine of around 10,000lb thrust designed for production in the late 1960s, bearing no relation to the earlier Rolls-Royce RB.50 Trent turboprop or the later high-bypass Rolls-Royce Trent turbofan.
The Turbomeca Aspin was a small French turbofan engine produced by Turbomeca in the early 1950s. This geared turbofan design was the first turbofan to fly, powering the Fouga Gemeaux test-bed aircraft on 2 January 1952.
The IAE V2500SF SuperFan was a design study for a high-bypass geared turbofan derived from the IAE V2500. It was offered as the primary engine option for the Airbus A340-200 and 300 in January 1987. Although several customers signed preliminary contracts for this variant, the International Aero Engines board decided in April 1987 to stop the development of the SuperFan, which forced Airbus to partly re-design the A340.
A variable pitch fan is similar in concept to that of a variable-pitch propeller and involves progressively reducing the pitch of the fan on a turbofan as the engine is throttled. Although variable pitch fans are used in some industrial applications, the focus of this article is on their use in turbofan engines. No production engine uses such a feature; however, it will likely be required on at least some of the next generation of high bypass ratio turbofans.
Advanced technology engine is a turbine engine that allows different turbines to spin at different, individually optimum speeds, instead of at one speed for all. It became common in the 21st century. It emerged on larger airplanes, before finding other applications.
