Flamelet Modeling for Supersonic Combustion

Drozda, Tomasz G.; Quinlan, Jesse R.; Drummond, J. P.

doi:10.1007/978-981-15-2643-5_6

Cited by 7 publications

(1 citation statement)

References 62 publications

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“…If we neglect terms of the order of the kinetic energy per mass, this effect disappears. We might still retain the viscous dissipation rate τ ij ∂u i /∂x j for special cases where large strain rates are expected on the subgrid scale, as suggested by Drozda, Quinlan & Drummond (2020). The viscous dissipation rate will have exactly the same value whether it is calculated in the Newtonian frame or the rotating frame; this result is expected because it relates to the thermodynamics where the laws are independent of the reference frame.…”

Section: Governing Equationsmentioning

confidence: 99%

Three-dimensional, rotational flamelet closure model with two-way coupling

Sirignano

2022

J. Fluid Mech.

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A new flamelet model is developed to be used for subgrid modelling and coupled with the resolved flow description for turbulent combustion. The model differs from current models in several critical ways. (i) Non-premixed flames, premixed flames or multi-branched flame structures are determined rather than prescribed. (ii) The effects of shear strain and vorticity on the flames are determined. (iii) The strain rates and vorticity applied at the subgrid level are directly determined from the resolved-scale strain rates and vorticity without the use of a contrived progress variable. (iv) The flamelet model is three-dimensional without need for assuming axisymmetry or planar geometry. (v) The effect of variable density is addressed in the flamelet model. Solutions to the Navier–Stokes equations and the associated scalar equations governing the flamelet model are obtained without the boundary-layer approximation. By appropriate coordinate transformation, a similar solution is found for the rotational flamelet model, reducing it to a system of ordinary differential equations. Vorticity is shown to create a centrifugal force on the subgrid counterflow that modifies the molecular transport rates and burning rate. Sample computations of the rotational flamelet model without coupling to the resolved flow are presented first to demonstrate the importance of the new features of the model. Scaling laws are presented for relating strain rates and vorticity at the subgrid level to those quantities at the resolved-flow level for coupling with large-eddy simulations or the time-averaged mean-flow level for Reynolds-averaged flows. The time-averaged behaviour of a simple turbulent flow is resolved with coupling to the rotational flamelet model. Specifically, a two-dimensional, multicomponent, time-averaged planar shear layer with variable density and energy release is employed using a mixing-length description for the eddy viscosity. Needs for future study are identified.

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Section: Governing Equationsmentioning

confidence: 99%

Three-dimensional, rotational flamelet closure model with two-way coupling

Sirignano

2022

J. Fluid Mech.

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Flamelet-like models applied in scramjet combustors: A state of art and prospect

Tang

Wang

Huang

et al. 2023

Chinese Journal of Aeronautics

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Flow structures and combustion regimes in an axisymmetric scramjet combustor with high Reynolds number

Tang,

Sun,

Yan

et al. 2024

J. Fluid Mech.

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This study investigates the flow structures and combustion regimes in an axisymmetric cavity-based scramjet combustor with a total temperature of 1800 K and a high Reynolds number of approximately 1 × 107. The hydroxyl planar laser-induced fluorescence technique, along with the broadband flame emission and CH* chemiluminescence, is employed to visualize the instantaneous flame structure in the optically accessible cavity. The jet-wake flame stabilization mode is observed, with intense heat release occurring in the jet wake upstream of the cavity. A hybrid Reynolds-averaged Navier–Stokes/large-eddy simulation approach is performed for the 0.18-equivalent-ratio case with a pressure-corrected flamelet/progress variable model. The combustion regime is identified mainly in the corrugated or wrinkled flamelet regime (approximately 102 < Da < 104, 103 < Ret < 105 where $Da$ is the Damköhler number and $Re_t$ is the turbulent Reynolds number). The combustion process is jointly dominated by supersonic combustion (which accounts for approximately 58 %) and subsonic combustion, although subsonic combustion has a higher heat release rate (peak value exceeding 1 × 109 J (m3s)−1). A partially premixed flame is observed, where the diffusion flame packages a considerable quantity of twisted premixed flame. The shockwave plays a critical role in generating vorticity by strengthening the volumetric expansion and baroclinic torque term, and it can facilitate the chemical reaction rates through the pressure and temperature surges, thereby enhancing the combustion. Combustion also shows a remarkable effect on the overall flow structures, and it drives alterations in the vorticity of the flow field. In turn, the turbulent flow facilitates the combustion and improves the flame stabilization by enhancing the reactant mixing and increasing the flame surface area.

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Flamelet Modeling for Supersonic Combustion

Cited by 7 publications

References 62 publications

Three-dimensional, rotational flamelet closure model with two-way coupling

Three-dimensional, rotational flamelet closure model with two-way coupling

Flamelet-like models applied in scramjet combustors: A state of art and prospect

Flow structures and combustion regimes in an axisymmetric scramjet combustor with high Reynolds number

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