Treleaven2019_Article_AnEfficientMethodToReproduceTh.pdf (4.73 MB)
An efficient method to reproduce the effects of acoustic forcing on gas turbine fuel injectors in incompressible simulations
journal contribution
posted on 2019-04-02, 09:11 authored by Nick Treleaven, Jialin Su, Andrew GarmoryAndrew Garmory, Gary PageGary PagePrevious studies have highlighted the importance of both air mass flow rate and swirl fluctuations on the unsteady heat release of a swirl stabilised gas turbine combustor. The ability
of a simulation to correctly resolve the heat release fluctuations or the flame transfer function (FTF), important for thermoacoustic analysis, is therefore dependent on the ability of
the method to correctly include both the swirl number and mass flow rate fluctuations which
emerge from the multiple air passages of a typical lean-burn fuel injector. The fuel injector used in this study is industry representative and has a much more complicated geometry
than typical premixed, lab-scale burners and the interaction between each flow passage
must be captured correctly. This paper compares compressible, acoustically forced, CFD
(computational fluid dynamics) simulations with incompressible, mass flow rate forced simulations. Incompressible mass flow rate forcing of the injector, which is an attractive method
due to larger timesteps, reduced computational cost and flexibility of choice of combustion model, is shown to be incapable of reproducing the swirl and mass flow fluctuations
of the air passages given by the compressible simulation as well as the downstream flow
development. This would have significant consequences for any FTF calculated by this
method. However, accurate incompressible simulations are shown to be possible through
use of a truncated domain with appropriate boundary conditions using data extracted from
a donor compressible simulation. A new model is introduced based on the Proper Orthogonal Decomposition and Fourier Series (PODFS) that alleviates several weaknesses of
the strong recycling method. The simulation using this method is seen to be significantly
computationally cheaper than the compressible simulations. This suggests a methodology
where a non-reacting compressible simulation is used to generate PODFS based boundary
conditions which can be used in cheaper incompressible reacting FTF calculations. In an industrial context, this improved computational efficiency allows for greater exploration of
the design space and improved combustor design.
Funding
This work is financially supported by Rolls-Royce plc and the EPSRC (Engineering and Physical Sciences Research Council) through the Centre for Doctoral Training in Gas Turbine Aerodynamics (grant ref. EP/L015943/1) and EPSRC grant ref EP/M023893/1. Some of the calculations were performed on HPC-Midlands funded by the EPSRC, Grant ref EP/K000063/1.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Aeronautical and Automotive Engineering
Published in
Flow, Turbulence and CombustionVolume
103Issue
2Pages
417 - 437Citation
TRELEAVEN, N.C.W. ... et al., 2019. An efficient method to reproduce the effects of acoustic forcing on gas turbine fuel injectors in incompressible simulations. Flow, Turbulence and Combustion, 103 (2), pp.417-437.Publisher
© The Authors. Published by Springer VerlagVersion
- VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Acceptance date
2019-03-06Publication date
2019-03-30Notes
This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/ISSN
1386-6184eISSN
1573-1987Publisher version
Language
- en