Simulation of Premixed Combustion with Varying Equivalence Ratio in Gas Turbine Combustor

Ruan, S.; Swaminathan, Nedunchezhian; Isono, Mitsunori; Saitoh, Takeo S.; Saitoh, Keijiro

doi:10.2514/1.b35517

Cited by 20 publications

(17 citation statements)

References 33 publications

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“…Thus, for an LES grid with a filter size similar to or larger than the typical laminar flame thickness, which is common in LES practice, the subgrid Z-c correlation can have a substantial effect on time-averaged statistics. This is consistent with the importance of Z-c correlation observed in previous RANS studies [7][8][9]12,13]. This is specifically so in flame stabilisation regions as can be seen in Figure 6 for x/D = 6.…”

Section: Significance Of Subgrid Covariancesupporting

confidence: 92%

“…Note that the two additional residual terms involving cross correlation between the temporal and spatial averaging procedures [10] are considered to be negligible for this study as in [11]. Previous RANS studies [7,8,12,13] showed that the total time-averaged correlation, {Z c }, is quite influential in partially premixed lifted flames. This was further confirmed in a recent experimental study by Barlow et al [5] showing a strong Z-c correlation in a partially premixed piloted jet flame.…”

Section: Introductionmentioning

confidence: 99%

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A priori investigation of subgrid correlation of mixture fraction and progress variable in partially premixed flames

Chen

Doan

Ruan

et al. 2018

Combustion Theory and Modelling

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Subgrid correlation of mixture fraction, Z, and progress variable, c, is investigated using direct numerical dimulation (DNS) data of a hydrogen lifted jet flame. Joint subgrid behaviour of these two scalars are obtained using a Gaussian-type filter for a broad range of filter sizes. A joint probability density function (JPDF) constructed using single-snapshot DNS data is compared qualitatively with that computed using two independent β-PDFs and a copula method. Strong negative correlation observed at different streamwise locations in the flame is captured well by the copula method. The subgrid contribution to the Z-c correlation becomes important if the filter is of the size of the laminar flame thickness or larger. A priori assessment for the filtered reaction rate using the flamelet approach with independent β-PDFs and correlated JPDF is then performed. Comparison with the DNS data shows that both models provide reasonably good results for a range of filter sizes. However, the reaction rate computed using copula JPDF is found to have a better agreement with the DNS data for large filter sizes because the subgrid Z-c correlation effect is included.

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Section: Significance Of Subgrid Covariancesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

A priori investigation of subgrid correlation of mixture fraction and progress variable in partially premixed flames

Chen

Doan

Ruan

et al. 2018

Combustion Theory and Modelling

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“…(12) 11 keep the approach general and so it is followed here. This modelling approach worked well for various flames in a range of flow and combustion conditions [17,28,35,42,48,49] as it maintains physical consistencies, which are remarked next.…”

Section: B Combustion Closurementioning

confidence: 72%

“…Closures developed for the subgrid scale (SGS) reaction rate include: dynamic thickened flame model [8,9], linear eddy model [10], fractal flame-wrinkling model [11], partiallystirred reactor model [12], and Eulerian stochastic fields [13]. Another recently developed flamelet model for LES uses Scalar Dissipation Rate (SDR) closure [14,15], which is shown to be successful in RANS studies of industrial gas turbine combustors [16,17], but this approach has not been tested for LES of reacting flows in these combustors. This provides the motivation for this work.Due to large costs for experiments at realistic operating conditions of gas turbines (i.e.…”

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confidence: 99%

Large-Eddy Simulation of Reacting Flows in Industrial Gas Turbine Combustor

Langella

Chen

Swaminathan

et al. 2018

Journal of Propulsion and Power

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The turbulent reacting flow in an industrial gas turbine combustor operating at 3 bar is computed using LES paradigm. The subgrid scale (SGS) combustion is modelled using a collection of unstrained premixed flamelets including mixture stratification.The non-premixed combustion mode is also included using a simple closure involving the scalar dissipation rate of the mixture fraction. A close attention is paid to maintain physical consistencies among sub-closure models for combustion and these consistencies are discussed on a physical basis. The importance of non-premixed mode and SGS mixture fraction fluctuations are investigated systematically. The results show that the SGS mixture fraction variance plays an important role and comparisons to measurements improve when contributions from the premixed and non-premixed modes are included. These numerical results and observations are discussed on a physical basis along with potential avenues for further improvements. a Research Associate, il246@cam.ac.uk b Research Associate, zc252@cam.ac.uk c Professor, ns341@cam.ac.uk d Engineer, suresh.sadasivuni@siemens.com 4 combustors. Thus, the ability of reacting flow CFD (Computational Fluid Dynamics) to capture these phenomena is crucial for their use in the design of next-generation combustors [2].Past studies have demonstrated that Large Eddy Simulation (LES) is suitable to capture aerodynamics of swirling flows, and the continuous increase of computing power allows application of LES-based models to practical burners [3][4][5][6][7]. Combustion requires modelling as it is a subgrid phenomenon in LES. Closures developed for the subgrid scale (SGS) reaction rate include: dynamic thickened flame model [8,9], linear eddy model [10], fractal flame-wrinkling model [11], partiallystirred reactor model [12], and Eulerian stochastic fields [13]. Another recently developed flamelet model for LES uses Scalar Dissipation Rate (SDR) closure [14,15], which is shown to be successful in RANS studies of industrial gas turbine combustors [16,17], but this approach has not been tested for LES of reacting flows in these combustors. This provides the motivation for this work.Due to large costs for experiments at realistic operating conditions of gas turbines (i.e. with optical access, high pressure, and preheated air), high quality validation data is rare [18]. One widely studied database is the set of laser-diagnostics obtained for Siemens SGT-100 combustor at 3 bar [19]. Analyses of these measurements and past LES results suggest that the combustion has flamelet-like properties despite the highly turbulent flow [5-7, 20, 21]. Flamelet models assume that the combustion time scale, τ c = s L /δ is shorter than the smallest turbulent scales (this also applies for length scales) implying that the flamelet structure is undisturbed by the turbulence. Thus, the SGS reaction rate can be calculated a priori using laminar flamelets. Hence, this methodology is also known as tabulated chemistry approach.Turbulent eddies can penetrate the flame-front di...

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“…The combustion model discussed earlier in section 2 was implemented in a commercial CFD package FLUENT as described in (Chen et al, 2015;Ruan et al, 2015). This CFD package solves the necessary transport equations using finite volume methodology along with SIMPLE algorithm for pressure-velocity coupling, including the density variations in space and time.…”

Section: Cfd Setupmentioning

confidence: 99%

Computation of Forced Premixed Flames Dynamics

Ruan

Dunstan

Swaminathan

et al. 2016

Combustion Science and Technology

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Bluff body stabilised turbulent premixed flames subject to inlet velocity oscillation over a wide range of forcing frequency and amplitude are simulated using a flameletbased combustion model. Two sets of detailed chemical kinetic schemes are used to model combustion chemistry. It is observed that the computed dynamics of forced flames agree reasonably well with experimental measurements. The flame elongation and shortening at a frequency of 40 Hz and strong flame-vortex interaction at a higher frequency of 160 Hz are captured well in the computations. The global flame describing function extracted from the computational results shows a linear response at 40 Hz and a nonlinear behaviour at 160 Hz as observed in the experiments. The nonlinear response is due to vortex roll-up and its subsequent shedding. The quantitative agreement of the computed flame describing function (FDF) with experimental measurement is uniformly good over a wide range of forcing frequency and amplitude. SomeA c c e p t e d M a n u s c r i p t influence of chemical kinetics on the FDFs is observed, which mainly stems from the difference in laminar burning velocity and spatial heat release rate distribution.

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Simulation of Premixed Combustion with Varying Equivalence Ratio in Gas Turbine Combustor

Cited by 20 publications

References 33 publications

A priori investigation of subgrid correlation of mixture fraction and progress variable in partially premixed flames

A priori investigation of subgrid correlation of mixture fraction and progress variable in partially premixed flames

Large-Eddy Simulation of Reacting Flows in Industrial Gas Turbine Combustor

Computation of Forced Premixed Flames Dynamics

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