An Advanced Unstructured-Grid Finite-Volume Design System for Gas Turbine Combustion Analysis

Anand, M. S.; Eggels, Ruud; Staufer, Max; Zedda, Marco; Zhu, Jiang

doi:10.1115/gtindia2013-3537

Cited by 42 publications

(36 citation statements)

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“…Reacting, incompressible (density-varying) Navier-Stokes equations are solved using PRECISE-UNS [28], which employs the finite volume approach to discretise the transport equations for mass, momentum and energy, along with the four equations specific for the combustion model, presented in section II.B.1. Using…”

Section: Computational Detailsmentioning

confidence: 99%

Entropy and Vorticity Wave Generation in Realistic Gas Turbine Combustors

Semlitsch¹,

Hynes²,

Langella

et al. 2019

Journal of Propulsion and Power

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Understanding the nature of the unsteady flow at the combustor exit is required to accurately simulate time dependent phenomena in the turbine entry, such as indirect noise generation. Using Large Eddy Simulations of the combustion process in a realistic geometry, we analyse the flow at its exit. Two realistic, near-ground certification operating conditions are considered. Different mechanisms for large-scale flow and thermal structure generation are described, which are ejected into the turbine. Modal decomposition methods are used to extract the spatial and temporal scales at the turbine entry. We find that, depending on the operating condition, the entropy waves convect as elongated streaks in the core of the combustor annulus or the proximity of the walls. The dominant unsteady character of the fluctuations exhibits different spectral properties, i.e. low-frequency in the core and high-frequency towards walls. At the combustor exit, the vortical field is dominated by the swirl in the air inlet, which is found to have little influence on the entropy perturbations. Further, the importance of considering the interaction of multiple fuel injectors and combustion zones in an annular combustor is investigated. It is shown that pulsating circumferential vorticity modes can occur in multi-sector annular combustors but these, however, do not affect the entropy wave distribution.

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Section: Computational Detailsmentioning

confidence: 99%

Entropy and Vorticity Wave Generation in Realistic Gas Turbine Combustors

Semlitsch¹,

Hynes²,

Langella

et al. 2019

Journal of Propulsion and Power

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“…More advanced approaches such as the generalise gradient diffusion hypothesis (GGDH) can also be used to model heat fluxes in Eqn. (1). A numerical scheme has also been developed by Luff [8] to tackle problems associated with non-orthogonality of the mesh for more complex geometries.…”

Section: The Pedestal Sub-grid-scale Methodsmentioning

confidence: 99%

The Subgrid-Scale Approach for Modeling Impingement Cooling Flow in the Combustor Pedestal Tile

Ammour

Page

2017

Journal of Heat Transfer

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The widely used gas turbine combustor double-walled cooling scheme relies on very small pedestals. In a combustor it is impractical for computational fluid dynamics (CFD) to resolve each pedestal individually as that would require a very large amount of grid points and consequent excessive computation time. These pedestals can be omitted from the mesh and their effects captured on the fluid via a pedestal subgrid-scale (SGS) model. The aim is to apply the SGS approach, which takes into account the effects on pressure, velocity, turbulence, and heat transfer, in an unstructured CFD code. The flow inside a two-dimensional (2D) plain duct is simulated to validate the pedestal SGS model, and the results for pressure, velocity, and heat transfer are in good agreement with the measured data. The conjugate heat transfer inside a three-dimensional (3D) duct is also studied to calibrate the heat source term of the SGS model due to the pedestals. The resolved flow in the combustor pedestal tile geometry is numerically investigated using Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) in order to first assess the viability of the RANS and LES to predict the impinging flow and second to provide more validation data for the development of the SGS pedestal correlations. It is found that the complexity of such a flow, with high levels of curvature, impingement, and heat transfer, poses a challenge to the standard RANS models. The LES provides more details of the impinging flow features. The pedestal model is then applied to the complete tile to replace the pedestals. The results are close to both the fully resolved CFD and the measurements. To improve the flow features in the impingement zone, the first two rows were resolved with the mesh and combined with the SGS modeling for the rest of the tile; this gave optimum results of pressure, velocity, and turbulence kinetic energy (TKE) distribution inside the pedestal cooling tile.

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“…The velocity equations were solved using the incompressible PRECISE-UNS [28] solver with a second order accurate linear upwind flux calculation with a van Albada limiter. The pressure equation was solved using second order central flux calculation and the turbulent quantities solved using a linear upwind method.…”

Section: Mass Flow Forcingmentioning

confidence: 99%

“…These values are considered current best practice for this solver and were also used for the recycled and PODFS simulations described below. The interest in using this solver is that it has access to specialised combustion models that have been used to model academic and industrially relevant combustors [28].…”

Section: Mass Flow Forcingmentioning

confidence: 99%

An Efficient Method to Reproduce the Effects of Acoustic Forcing on Gas Turbine Fuel Injectors in Incompressible Simulations

Treleaven

Garmory

et al. 2019

Flow Turbulence Combust

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Previous 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.

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An Advanced Unstructured-Grid Finite-Volume Design System for Gas Turbine Combustion Analysis

Cited by 42 publications

References 0 publications

Entropy and Vorticity Wave Generation in Realistic Gas Turbine Combustors

Entropy and Vorticity Wave Generation in Realistic Gas Turbine Combustors

The Subgrid-Scale Approach for Modeling Impingement Cooling Flow in the Combustor Pedestal Tile

An Efficient Method to Reproduce the Effects of Acoustic Forcing on Gas Turbine Fuel Injectors in Incompressible Simulations

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