The engine pressure ratio (EPR) is the total pressure ratio across a
jet engine
A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...
, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor.
Jet engines use either EPR or compressor/fan RPM as an indicator of thrust. When EPR is used, the pressures are measured in front of the compressor and behind the turbine.
Integrated engine pressure ratio
The integrated engine pressure ratio (IEPR) is a ratio used on some
turbofan
A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the add ...
s to include fan discharge total pressure and compressor inlet total pressure. If compressor inlet pressure is P0 and fan discharge total pressure is P1, then the integrated engine pressure ratio will be P1 /P0.
The IEPR is an engine indicator system unique to the
Rolls-Royce RB211
The Rolls-Royce RB211 is a British family of high-bypass turbofan engines made by Rolls-Royce Holdings, Rolls-Royce. The engines are capable of generating of thrust. The RB211 engine was the first production turbofan#Three-spool, three-spool e ...
.
See also
*
Jet engine performance
A jet engine converts fuel into thrust. One key metric of performance is the thermal efficiency; how much of the chemical energy (fuel) is turned into useful work (thrust propelling the aircraft at high speeds). Like a lot of heat engines, jet engi ...
*
Turbofan
A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the add ...
References
* The Boeing Company '' Engine thrust control system '
US Patent 4248042Includes
Boeing
The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
's discussion on EPR or IEPR being a better indicator of thrust.
External links
Pressure Variation EPR - NASA Animation
Engineering ratios
Aircraft engines
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