Core size is a parameter used in aeroengine performance engineering to enable a size comparison between jet engine (e.g. turbofan) cores. A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... CFM56-3 turbofan, lower half, side view. ...

The alternative core power parameter is more difficult to compute, but has the advantage that it takes into account not only the basic flow size of the device, but also the impact of core supercharging and turbine rotor inlet temperature.

There are several definitions of core size in use, but the following definition is fairly popular:

where:

~ compressor entry mass flow

~ compressor exit total pressure

~ compressor exit total temperature

Compressor entry rather exit conditions are used in the calculation, because core size is then unaffected by changes in interstage bleed flows during engine development.