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Eurojet EJ200 Low Bypass Augmented Turbofan

The Eurojet EJ200 is a state of the art low bypass ratio augmented turbofan engine, which was designed for use on Europe's all new front line fighter aircraft, the Eurofighter EF2000 Typhoon. The EJ200 gives the Typhoon the a unity (1:1) power to weight ratio even at maximum take off weight, and allows the sleek fighter to supercruise up to speeds of Mach 1.3; supercruise being the ability to cruise at supersonic speed without the use of the afterburner.

EUROJET Turbo GmhH is the company created to develop the EJ200, and it is actually a partnership between 4 major european companies. Rolls Royce represents the United Kingdom, DaimlerChrysler MTU of Germany, FiatAvio of Italy, and ITP of Spain. MTU is involved in the development of the low and high pressure compressors, and electronic engine controls, as well as some work on the high pressure turbine. MTU will also be responsible for some of the engine assembly and engine testing. Avio will develop the low pressure turbine, accessory gearbox, and the afterburner, while Rolls Royce and ITP will develop the combustor, jet nozzle, and turbines.

The Eurojet EJ200 features many state of the art design elements, including integrated blade/disk construction, (blisks) wide chord fan airfoils without a need for inlet guide vanes, single crystal turbine blades, an airspray fuel delivery system, and an advanced FADEC system for engine control and onboard diagnostic systems. The engine is classified as a low bypass ratio augmented turbofan engine, because its low pressure compressor feeds some of the airflow to a bypass duct, and the augmentation refers to its afterburning capability. A low bypass engine such as this is very well suited to a modern fighter; it is a perfect compromise between a turbofan engine, which provides high engine efficiency, low heat signature, and great engine response and low speed performance, and a turbojet, which provides low engine profile and compact size, and great high speed peformance and efficiency.

The engine is fed by a variable geometry inlet duct on the Eurofighter, making it difficult for enemy radar to home in on its spinning fan blades, while tailoring the airflow for varying inlet conditions. The air is drawn into the compressor inlet, which features no inlet guide vanes. The three stage wide chord low pressure compressor is classified as a fan, because apart from feeding the high pressure compressor in the engine core, it also feeds the bypass duct, which bypasses air around the engine core, surrounding it in a cooling blanket, which allows for higher combustion temperatures and turbine inlet temperatures. The engine features a bypass ratio of .4:1. The high pressure compressor has five axial stages and brings the pressure ratio to a staggering 26:1. Compressor discharge air is fed to an annular through-flow burner which utilizes air spray injectors to distribute fuel into the burner. Discharge air is injected into the fuel vaporizing nozzles which aids in the atomization of the fuel, allowing for more complete fuel distribution and more complete combustion, which of course leads to better fuel efficiency. Maximum turbine inlet temperature is a metal-melting 2,700 degrees fahrenheit, so the high pressure turbine nozzle and the turbine stages must be air cooled with bleed air, and they must be single crystal formed of exotic metal alloy compositions, with a ceramic thermal barrier coating to further protect the blades from meldown. The high turbine inlet temperature leads to tremendous efficiency and specific power. There are only two turbine stages on this engine. A single stage axial high pressure turbine drives the high pressure compressor and the accessory gearbox, and the single stage axial low pressure compressor drives the fan. After the gas has been expanded through the turbines, the remaining gas energy is available to provide thrust. The hot gas is expelled into the afterburner or augmeter, which is a tapered jet pipe with a fuel manifold and combustor integrated. It is here that the hot combustion gas is mixed with the cool air from the bypass duct. The availability of uncombined oxygen from the bypass duct makes the afterburner even more effective than in a pure turbojet. When the pilot moves the power lever into the afterburning region, fuel is distributed to the afterburner fuel manifold, and the afterburner igniter is triggered, providing a marked increase in thrust along with fuel consumption. The pilot can vary the amount of afterburner by modulating the power lever within the afterburning range. The end of the jet pipe forms a throat which accelerates the gas flow before it enters the variable geometry divergent jet nozzle. The convergent/divergent nozzle system effectively accelerates the gas flow to supersonic speed, and then allows it to expand smoothly with the outside airflow for maximum efficiency and thrust. The variable geometry nozzle varies nozzle area to optimize gas flow for a given engine regime. At low power, the nozzle is wide open, to minimize residual thrust and improve low speed engine response. As power increases, the nozzle area closes down to accelerate the gases at a higher velocity. When the afterburner is in use, the nozzle once again opens to accomodate the greater mass flow out of the tailpipe. The accessories are driven off the high pressure shaft. Accesories include oil pressure and scavenge pumps, high and low pressure fuel pumps, a DC generator, a hydraulic pump, an air turbine starter, and spare drives. Engine control is by an advanced FADEC system, which provides precise power control, ultra rapid response, and diagnostic services.

The EJ200 is a lightweight, efficient and powerful state of the art military engine which emphasizes the advantages of a simple design combined with cutting edge materials and electronic technology.

Eurojet EJ200 Low Bypass Augmented Turbofan

  • Type: Dual shaft turbofan with low bypass ratio and afterburning
  • Bypass Ratio: 0.4:1
  • Low Pressure Compressor: Three stage fan
  • Fan Pressure Ratio: 4.2:1
  • High Pressure Compressor: 5 stage axial flow compressor
  • Burner: Annular, through flow burner with airspray injectors
  • Turbine: Dual spool, single stage axial high pressure turbine, single stage axial low pressure turbine
  • Exhaust: Converging afterburning jet pipe, variable area divergent secondary nozzle.
  • Thrust Rating: 20,000 lbs. of thrust with afterburner
  • Maximum military power (no afterburner): 13,500 lbs. of thrust
  • Weight: 2,286 lbs.
  • Thrust/weight: 8.7:1
  • Air mass flow: 170 lbs/sec
  • Overall Pressure Ratio: 26:1
  • Maximum Turbine Inlet Temperature: 2,700F
  • Specific Fuel Consumption: .81 lb/lbt/hr (dry), 1.74 lb/lbt/hr (with afterburner)

 
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