Eulerian – Eulerian Large Eddy Simulations Applied to Non-Reactive Transient Diesel Sprays

Robert, Anthony; Martinez, Lionel; Tillou, Julien; Richard, Stéphane

doi:10.2516/ogst/2013140

Cited by 3 publications

(1 citation statement)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The inlet boundary condition uses the measured mass-flow rate in order to get the bulk injection velocity. LES cases use a specific inlet condition in order to generate turbulent fluctuations with a given statistical profile, based on the proposals by [30][31] and following the method described in [32]. The characteristic correlation length scale is twice the orifice grid resolution in order to resolve the generated eddies.…”

Section: Computational Model Set-upmentioning

confidence: 99%

Modelling and validation of near-field Diesel spray CFD simulations based on the Σ -Y model

Desantes¹,

García-Oliver²,

Pastor³

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

View full text Add to dashboard Cite

Diesel spray modelling still remains a challenge, especially in the dense near-nozzle region. This region is difficult to experimentally access and also to model due to the complex and rapid liquid and gas interaction. Modelling approaches based on Lagrangian particle tracking have struggled in this area, while Eulerian modelling has proven particularly useful. An interesting approach is the single-fluid diffuse interface model known as Σ-Y, based on scale separation assumptions at high Reynolds and Weber numbers. Liquid dispersion is modelled as turbulent mixing of a variable density flow. The concept of surface area density is used for representing liquid structures, regardless of the complexity of the interface. In this work, an implementation of the Σ-Y model in the OpenFOAM CFD library is applied to simulate the ECN Spray A in the near nozzle region, using both RANS and LES turbulence modelling. Assessment is performed with measurements conducted at the Advanced Photon Source at Argonne National Laboratory (ANL). The ultra-smallangle x-ray scattering (USAXS) technique has been used to measure the interfacial surface area, and x-ray radiography to measure the fuel dispersion, allowing a direct evaluation of the Σ-Y model predictions. KeywordsSprays, Diesel, atomization, CFD, OpenFOAM, X-ray Introduction Fuel injection and subsequent spray development are critical factors for charge preparation, combustion development and pollutants formation in engines. The liquid atomization process occurs at extremely small length scales and high speeds in current injection systems, which complicates both the investigation and modelling of spray flow, especially in the near-nozzle region. The lack of optical accessibility, except by means of special diagnostic techniques [1][2], hinders the flow characterization and the development of predictive primary atomization models. The common spray modelling approaches, based on the representation of the liquid phase using a Lagrangian framework [3], are not well suited to represent this dense region, while fully Eulerian approaches have recently shown their potential to simulate near-nozzle physics [4] [5]. Complex modelling techniques devoted to capturing the liquid-gas interface [6][7] [8] have been successfully applied to simulate initial spray development, but the computational requirements can make those calculations impractical for spray applications in combustion systems due to high Reynold and Weber numbers. Under these conditions, one may assume a separation of the large scale flow features, such as mass transport, from the atomization process occurring at smaller scales, as proposed in [9][10]. Then large scale liquid dispersion can be modelled as the turbulent mixing of a variable density fluid. For atomization, the surface density concept is introduced in order to evaluate the mean size of liquid fragments, assuming that interfacial details are smaller than the mesh size. The end result is a diffuse-interface treatment in an Eulerian framework. This framework i...

show abstract

Section: Computational Model Set-upmentioning

confidence: 99%