Abstract:
The
ability to accurately extract steady state performance information from transient
engine test data has the potential to significantly reduce test bed time and cost,
depending upon the accuracy with which engine phenomena such as heat soakage and
transient
tip clearance changes can be modelled within the context of a whole
engine
performance code.
This thesis describes
improvements to the GTTrans generic Whole engine
performance code thermo mechanical heat
soakage and tip clearance methods. This
thesis describes the streams method in which a collection of definite volumes are used
to
represent engine component hardware and perform transient heat transfer
calculations
accounting for both conduction and convection to and from non-trivial
engine component geometries. Transient metal and gas temperature profiles are then
used to estimate transient blade
tip clearances. The streams method has been
incorporated into a Rolls-Royce Trent 500 engine performance code. Accounting for
heat
soakage, tip clearances, and bleed temperature Variations within the engine code
affected the
predicted steady state operation as well as making spool accelerations
more
sluggish and raising compressor working lines during transient manoeuvres.
Although all three effects were significant, heat soakage appeared to have the largest
effect on transient
performance, particularly during the hot reslam manoeuvre.
Rolls-Royce PLC sponsored this EngD project laying down 5 project requirements
that enhanced heat
soakage and tip clearance methods should meet, i.e. handle both
heat
soakage and tip clearances, be physics based, run at or near to real time, meet
given accuracy targets, and be capable of being calibrated. The streams method met
the first three of these
requirements, although with further development it might be
possible to meet all five.
This thesis also contains analysis and recommendations regarding the process of
technology transfer from the Cranfield University Technology Centre in Gas Turbine
Performance to within
Rolls-Royce.
