Effects of liquid fuel/wall interaction on thermoacoustic instabilities in swirling spray flames

Schiavo, Ermanno Lo; Laera, Davide; Riber, Éléonore; Gicquel, Laurent; Poinsot, Thiérry

doi:10.1016/j.combustflame.2020.04.015

Cited by 42 publications

(23 citation statements)

References 48 publications

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“…• Finally, the same authors performed previous LES studies of the same system [28,29] revealing the coupling mechanism between the acoustic mode and the liquid film forming on the injector walls to be fundamental to trigger and sustain the thermoacoustic limit cycle. This conclusion however questions the impact of an injection angle variation which is expected to modify the liquid film and therefore its coupling with the thermoacoustic mode.…”

Section: Introductionmentioning

confidence: 90%

“…A detailed description of the numerical approach can therefore be found in Ref. [28] and only key elements are recalled hereafter. Two different flame tubes of length (1) c = 165 mm and (2) c = 280 mm are adopted for the non-oscillating and oscillating cases, respectively, as in the experiments.…”

Section: Numerical and Experimental Setupmentioning

confidence: 99%

“…Turbulent combustion is modelled using the two-phase flame extension of the dynamic thickened flame model (TP-TFLES) [33]. These flames are usually characterised by both premix and diffusion combustion regimes [28], so in order to guarantee a proper application of the thickened flame model, which is correctly defined only for premixed flames, an additional conditioning is applied using the Takeno flame index (FI) [34] classically defined as a function of the gradient of fuel and oxidizer mass fractions:…”

Section: Numerical and Experimental Setupmentioning

confidence: 99%

“…Finally, it is worth mentioning that, following previous works on the same configuration [28,29], the droplet size distribution is imposed via a Rosin-Rammler probability density function (PDF) fitted from experimental measurements of mean (D 10 ) and Sauter diameters (SMD or D 32 ) taken at z = 2.5 mm in the combustion chamber: D 10 = 10 µm and D 32 = 18 µm. Since the primary objective is to investigate only the effect of the spray angle, changes in terms of droplet diameter are only due to evaporation, neglecting phenomena like primary and secondary atomization as well as splash and liquid film break-up at the edge of the injector wall.…”

Section: Numerical and Experimental Setupmentioning

confidence: 99%

“…In the present work, the SICCA-spray rig is computed assuming three different injection spray angles starting from the results of [28] with the objective of probing their sensitivity to modeling features while deciphering the leading phenomenological process at the origin of the observed thermoacoustic instabilities in swirled liquid-fueled flames. The article is organised as follows: starting with the description of the numerical models in section 2, in section 3 results are discussed starting from the stable flame, section 3.1, followed by the limit cycle condition in section 3.2.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

On the impact of fuel injection angle in Euler–Lagrange large eddy simulations of swirling spray flames exhibiting thermoacoustic instabilities

Schiavo

Laera

Riber

et al. 2021

Combustion and Flame

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This study deals with the fundamental problem of combustion dynamics in gas turbine combustors operating with liquid fuel. In this framework the present work proposes the study of an academic liquid fueled combustor sensitive to thermoacoustic instabilities, simulated via high-fidelity Large Eddy Simulations. The experimental setup addressed is SICCA-spray from EM2C laboratory featuring both stable and unstable flames depending on the combustion chamber length. The proposed analysis, based on the Euler-Lagrange modeling approach, studies the impact of the spray injection angle θ on both the stable flame and the triggering of the longitudinal combustor acoustic mode when using a longer quartz tube. For the liquid injection modeling, the FIM-UR semiempirical model is adopted with three different θ values: θ = 35 • , 45 • and 60 • . In stable conditions, the spray angle is proven to have a negligible impact on the flame anchoring point, however, the mean flame length and fuel distribution are found to be slightly modified by the velocity at which droplets enter the combustion chamber. For the thermoacoustically unstable conditions, two well-established stable limit cycles with the same frequency and similar amplitudes are obtained when fuel is injected at θ = 45 • and 60 • . Contrarily, the system stabilizes when θ = 35 • pointing to the importance of the dynamics of the liquid film layer formed inside the injector for this setup. Likewise, this liquid film layer dynamics and its modeling appear critical as already suggested by previous studies on the same configuration. The detailed analysis of the thermoacoustically unstable different predictions is then performed through the investigation of the spatial fields of the local Rayleigh index obtained following the novel extension in the frequency domain of the Rayleigh criterion complemented by the application of Dynamic Mode Decomposition. It confirms that the injection angle of the liquid spray has a significant effect on the thermoacoustic response of the system. Indeed the influence of θ on the dynamics of the liquid fuel when entering the combustion chamber is proven to have an impact on the synchronization mechanism governing the liquid phase with respect to acoustics sustaining the observed limit cycles. More specifically, couplings at the liquid phase level are evidenced by introducing two novel indices correlating the fluctuations of liquid fuel volume fraction and evaporation rate with pressure.

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Section: Introductionmentioning

confidence: 90%

Section: Numerical and Experimental Setupmentioning

confidence: 99%

Section: Numerical and Experimental Setupmentioning

confidence: 99%

Section: Numerical and Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On the impact of fuel injection angle in Euler–Lagrange large eddy simulations of swirling spray flames exhibiting thermoacoustic instabilities

Schiavo

Laera

Riber

et al. 2021

Combustion and Flame

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Coupling of Combustion Simulation with Atomisation and Filming Models for LES in Swirled Spray Flames

Treleaven

Laera

Carmona

et al. 2022

Flow Turbulence Combust

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LES Modeling of the DLR Generic Single-Cup Spray Combustor: Validation and the Impact of Combustion Chemistry

Åkerblom,

Fureby

2023

Flow Turbulence Combust

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Turbulent spray combustion in a generic kerosene-fueled single-cup combustor at typical idle and cruise conditions of an aeroengine are studied with Large Eddy Simulations (LES) using Lagrangian spray and finite-rate chemistry combustion modeling. Three reaction mechanisms of varying complexity are used to model the combustion chemistry. The choice of turbulence-chemistry interaction model is shown to affect the results significantly. The impact of the choice of chemical reaction mechanism and the difference in operating conditions are gauged in terms of time-averaged flow, spray, and combustion characteristics as well as unsteady behavior. Good agreement between LES predictions and experimental results are generally observed but with a notable dependence on the choice of chemical reaction mechanism. The mechanism specifically targeting Jet A displays the best agreement. The choice of reaction mechanism is further demonstrated to influence the flow and thermoacoustics in the combustor, resulting in different thermoacoustic modes dominating. The spray cone is found to be too narrow and thin, an inaccuracy which could be remedied by either making the injection method more empirical or by introducing additional models.

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Effects of liquid fuel/wall interaction on thermoacoustic instabilities in swirling spray flames

Cited by 42 publications

References 48 publications

On the impact of fuel injection angle in Euler–Lagrange large eddy simulations of swirling spray flames exhibiting thermoacoustic instabilities

On the impact of fuel injection angle in Euler–Lagrange large eddy simulations of swirling spray flames exhibiting thermoacoustic instabilities

Coupling of Combustion Simulation with Atomisation and Filming Models for LES in Swirled Spray Flames

LES Modeling of the DLR Generic Single-Cup Spray Combustor: Validation and the Impact of Combustion Chemistry

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