Engine Model Examples

In this chapter, we describe the calibration of three real engines in GasTurb performance models, using only measured data and information from the public domain. We recommend following a specific sequence of tasks and show that starting from relatively little input data the analysis evolves to make reliable performance predictions down to component level across a wide range of power settings and operating conditions. We describe in detail how to check the input data for consistency and create a Cycle Reference Point. The focus then moves to the compressor and turbine maps with advice on positioning the reference point in the map, scaling and finally modifying efficiency and speed. Equally important are the hints on how to implement information on active control items such as variable guide vanes or tip clearance systems. The engines modeled are the Pratt & Whitney J57, a two-spool turbojet run in an altitude test facility, the CFM56-3, a high bypass ratio turbofan run on a maintenance test bed and the Williams F107, a low bypass ratio turbofan with mixed exhaust and data taken from a specification.