Comparison of numerical methods and combustion models for LES of a ramjet

Roux, Anthony; Reichstadt, S.; Bertier, Nicolas; Gicquel, Laurent; Vincent, François; Poinsot, Thiérry

doi:10.1016/j.crme.2009.06.008

Cited by 15 publications

(16 citation statements)

References 15 publications

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“…For practical reasons detailed below, the entire set-up is computed by LES. Note that previous numerical studies on the reacting configuration are available in [12,13,22,24]. Contrarily to these initial LES computations that treat a single operating condition, the work presented here, deals with the entire operating range for which data are available.…”

Section: Target Configuration and Scope Of The Studymentioning

confidence: 99%

“…The first set of results relies on the "standard one-step scheme" while the second one uses the "fitted onestep scheme". Details on this specific comparison are also available in [24] where specific diagnostics are provided in terms of the thermo-acoustic response of the two simulations. Complementary mean field diagnostics are given here and allow to further exploit the limitations of both approaches in the context of the ramjet burner before an extensive validation of the methodology to the entire range of operating conditions.…”

Section: Chemical Scheme Impactmentioning

confidence: 99%

“…The current section focuses on the effect of the chemical model for LES of the ramjet burner by use of the DTF model, numerical issues and potential turbulent combustion as well as chemistry effects being investigated in [24]. Only Case I of Table 1 is used for the comparison: i.e.…”

Section: Chemical Scheme Impactmentioning

confidence: 99%

See 2 more Smart Citations

LES to Ease Understanding of Complex Unsteady Combustion Features of Ramjet Burners

Gicquel

Roux

2010

Flow Turbulence Combust

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Ramjet burners are known to produce highly unsteady operating conditions with strong couplings between combustion, acoustics and flow dynamics. Predicting such operating limit-cycles still remains a difficult task for Computational Fluid Dynamics (CFD) although recent use of Large Eddy Simulation (LES) clearly opens new possibilities. The main difficulties for LES are to properly address numerically specific flow features at the same time. For example, a proper representation of the acoustic ramjet eigenmodes necessitates for the solver to be able to treat shocks often present at the inflow conditions without interfering with the low Mach number flow in the region of combustion. Chemistry modelling is another difficulty and it is still not clear what level of description is sufficient to reproduce the unsteady coupling between heat release and acoustics. Turbulent combustion modelling is an additional problem. Finally, such confined burners are strongly influenced by heat losses and although such issues are rarely addressed numerically, the burner stability is expected to be strongly dependent on its thermal equilibrium. Despite these difficulties and as discussed in this work, LES can greatly contribute in the understanding of the key mechanisms at play in the expression of the ramjet oscillatory operation. Prior to this demonstration, key elements needed for such LES are detailed: shock capturing techniques and chemical modelling. The effect of the chemistry model on the LES results is briefly discussed. The proposed strategy is then confronted to three operating conditions of an experimentally measured ramjet burner. Although the scheme is quite simple and essentially relies on the dynamical response of combustion, i.e. competition between the local flow and flame speeds, most of the mean flow features are well reproduced for the three operating L. Y. M. Gicquel (B) CERFACS, Flow Turbulence Combust (2011) 87:449-472 conditions. Peak pressure spectra are well predicted indicating the proper relative energy content distribution of the unsteady LES predictions.

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Section: Target Configuration and Scope Of The Studymentioning

confidence: 99%

Section: Chemical Scheme Impactmentioning

confidence: 99%

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LES to Ease Understanding of Complex Unsteady Combustion Features of Ramjet Burners

Gicquel

Roux

2010

Flow Turbulence Combust

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“…As an example, highorder chimera techniques [3] or embedded Cartesian methods [4] are emerging. Note that the discussion of the use of unstructured codes in a hybrid RANS-LES frame [2,[5][6][7] is beyond the scope of this paper, and only structured grid methods that are largely based on a strong validation background are considered.…”

Section: Introductionmentioning

confidence: 99%

“…This approach is called the zonal immersed boundary condition (ZIBC) (see Fig. 1) and combines the best features of the IBC method associated with the zonal detached-eddy simulation (ZDES) [10,11], which is based on a large validation base and is implemented in several industrial solvers commonly used by the aeronautical industry [2,[5][6][7]12]. In the same spirit, the local use of an immersed boundary method has been applied on a trailing-edge flap problem using unsteady RANS simulations [13].…”

Section: Introductionmentioning

confidence: 99%

Zonal Immersed Boundary Conditions: Application to a High-Reynolds-Number Afterbody Flow

2014

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The present paper focuses on a new numerical strategy consisting of the zonal use of the immersed boundary conditions combined with the ability of zonal detached-eddy simulation to simulate high-Reynolds-number separated flows. The validation test case is a simplified space launcher afterbody with a control device in the form of a short cylindrical serrated skirt. "Zonal immersed boundary conditions" are used to handle the introduction of the skirt into the preexisting structured curvilinear grid that describes the noncontrolled configuration. The governing equations are solved using a standard body-fitted finite volume technique over the whole grid. A direct forcing source term is added when cells are internal to the skirt (that is, solid) to drive the velocity and the turbulence variables to the chosen values. Numerical simulations are performed at a Reynolds number of 1.2 × 10 6 and a freestream Mach number of 0.702. The numerical results demonstrate the ability of the zonal immersed boundary conditions to successfully impose the desired values at solid nodes. The first-and second-order moments, as well as the fluctuating pressure field, illustrate a fairly good agreement between the experiment and the numerical simulation. It is shown that the serrated skirt acts as a smooth device, which does not affect the global dynamics of the flow and only delays the location of the separation. Finally, the zonal immersed boundary conditions appear to successfully reproduce the effect of the skirt while drastically reducing the time of the grid generation.

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On the Coupling of a Zonal Body-Fitted/Immersed Boundary Method with ZDES: Application to the Interactions on a Realistic Space Launcher Afterbody Flow

Weiss

Deck

2017

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

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Comparison of numerical methods and combustion models for LES of a ramjet

Cited by 15 publications

References 15 publications

LES to Ease Understanding of Complex Unsteady Combustion Features of Ramjet Burners

LES to Ease Understanding of Complex Unsteady Combustion Features of Ramjet Burners

Zonal Immersed Boundary Conditions: Application to a High-Reynolds-Number Afterbody Flow

On the Coupling of a Zonal Body-Fitted/Immersed Boundary Method with ZDES: Application to the Interactions on a Realistic Space Launcher Afterbody Flow

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