Glossary
What are transonic airfoils, and what is the active clearance control? Check out our technical dictionary and find out more about engine technology terms – from active clearance control to velocity triangle.
Phosphate treatment
Plastic media blasting
Powder metal (PM) components
Pollutants
Precipitation hardening
Pressure ratio
Principle of energy transfer
Propfan
Propulsion efficiency
Pressure ratio
The pressure ratio indicates the difference between the pressure of the air entering the engine and the pressure of the air leaving the compressor. A pressure ratio of 30:1 (1 being the pressure of the inlet air) or just 30 thus means that the air pressure at the compressor exit (just upstream of the combustion chamber inlet) is 30 times the pressure value at the compressor inlet (first compressor stage or, in most engines, fan).
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