A State-of-the-Art CFD Setup for Axial Compressors: Details and Validation

TitleA State-of-the-Art CFD Setup for Axial Compressors: Details and Validation
Publication TypeConference Paper
Year of Publication2020
AuthorsCozzi L, Rubechini F, Arnone A, Depalo S, Astrua P, Schneider A, Benvenuto M
Conference NameASME Turbo Expo 2020 Turbomachinery Technical Conference and Exposition
Date Published09/2020
PublisherASME
Conference LocationVirtual Event, September 21-25, 2020
Abstract
The overall fraction of the power produced by renewable
sources in the energy market has significantly increased in recent
years. The power output of most of these clean sources is
intrinsically variable. At present day and most likely in the upcoming
future, due to the lack of inexpensive and reliable large
energy storage systems, conventional power plants burning fossil
fuels will still be part of the energy horizon. In particular,
power generators able to promptly support the grid stability,
such as gas turbines, will retain a strategic role.
This new energy scenario is pushing gas turbine producers to
improve the flexibility of their turbomachines, increasing the
need for reliable numerical tools adopted to design and validate
the new products also in operating conditions far from the nominal
one.
Especially when dealing with axial compressors, i.e. machines
experiencing intense adverse pressure gradients, complex flow
structures and severe secondary flows, CFD modelling of offdesign
operation can be a real challenge.
In this work, a state-of-the art CFD framework for RANS analysis
of axial compressors is presented. The various aspects involved
in the whole setup are discussed, including boundary conditions,
meshing strategies, mixing planes modelling, tip clearance
treatment, shroud leakages and turbulence modelling.
Some experiences about the choice of these aspects are provided,
derived from a long-date practice on this kind of turbomachines.
Numerical results are reported for different full-scale compressors
of the Ansaldo Energia fleet, covering a wide range of operating
conditions. Furthermore, details about the capability of
the setup to predict compressor performance and surge-margin
have been added to the work.
In particular, the setup surge-margin prediction has been evaluated
in an operating condition in which the turbomachine experiences
experimental stall. Finally, thanks to several on-field
data available at different corrected speeds for operating conditions
ranging from minimum to full load, a comprehensive validation
of the presented numerical framework is also included in
the paper.
Notes

GT2020-14507

Refereed DesignationRefereed