An Automated Strategy for Gas Turbines Off-Design Predictions with a CFD-based Throughflow Method

TitleAn Automated Strategy for Gas Turbines Off-Design Predictions with a CFD-based Throughflow Method
Publication TypeJournal Article
Year of Publication2021
AuthorsRicci M, Pacciani R, Macelloni P, Cecchi S, Bettini C, Marconcini M
JournalApplied Thermal Engineering
Date Published03/2021
ISSN Number1359-4311
KeywordsThroughflow model; Axisymmetric Euler equation; Off-design; Turbomachinery
With the increasing importance of renewable energy sources in the power generation
scenario, traditional fossil-fuel power generation systems are subjected to relevant and
rapid load variations. Consequently, designers have become more and more interested
at predicting the transient behavior of fossil fuel power plants. Tools allowing off-design
performance predictions of turbomachines have consequently become desirable even
in the first design phases. The paper presents the development of a strategy for gas
turbines off-design analyses that exploit a novel CFD-based throughflow method, and
its application to a heavy-duty, medium size, F-Class, 4-stage gas turbine designed
and manufactured by Ansaldo Energia. The throughflow code is based on the
axisymmetric Euler equations with tangential blockage and body forces, and inherits its
numerical scheme from a state-of-the-art CFD solver (TRAF code), including real-gas
capabilities. The strategy starts from the calibration of the throughflow method in order
to match the results of 3D CFD analyses at design point, whereupon the computational
framework is frozen and used for off-design simulations.
The proposed methodology is fairly general and will be discussed in details in the
paper. The analysed operating conditions of the turbine encompass a wide range of
expansion ratios and corrected rotational speeds. The feasibility of the procedure is
assessed by a detailed comparison with 3D CFD results in terms of span-wise
distributions and performance figures.
It will be shown how the generality and reliability of the proposed method demonstrates
its feasibility for an intensive use in the design of gas turbines. In particular,
throughflow predictions can compete with the ones provided by state-of-the-art 3D
CFD approaches and can be obtained with a small fraction of the computational time.
Refereed DesignationRefereed