Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modeling at... more Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modeling atomization, even if widely used in technical literature, are not suitable in the near injector region. Indeed, the first step of atomization process is to separate the continuous liquid phase in a set of individual liquid parcels, the so-called primary break-up. Describing two-phase flow by DPM is to define a carrier phase and a discrete phase, hence they cannot be used for primary breakup. On the other hand, full scale simulations (direct simulation of the dynamic DNS, and interface capturing method ICM) are powerful numerical tools to study atomization, however, computational costs limit their application to academic cases for understanding and complementing partial experimental data. In an industrial environment, models that are computationally less demanding and still accurate enough are required to meet new challenges of fuel consumption and pollutant reduction. Application of DNS-ICM methods without fairly enough resolution to solve all length scales are currently used for industrial purposes. Nevertheless, effects of unresolved scales are generally cast aside. The Euler-Lagrange Spray Atomization model family (namely, ELSA, also called, Σ − Y or Ω − Y) developed by Vallet and Borghi pioneering work [1], and [2], at the contrary aims to model those unresolved scales. This approach is actually complementary to DNS-ICM method since the importance of the unresolved term depends directly on mesh resolution. For full interface
This PhD is a joint venture between VINCI Technologies and the CNRS Laboratory CORIA. For its app... more This PhD is a joint venture between VINCI Technologies and the CNRS Laboratory CORIA. For its application, VINCI Technologies, developed mainly oil-related equipments and in particular injection/atomization systems. Some of these injectors are characterized by a very big geometrical dimensions (several meters long), that leads to very high Reynolds and Weber number. In addition, many injectors incorporate an internal mixing zone, in which liquid and gas phases are both present in a significant proportion. Consequently, this zone belongs to the dense two-phase flow category. To simulate the liquid dispersion and to characterize the spray formation special from these injectors, appropriate models are required. On its side, the CORIA team, has developed a suitable approach, so-called ELSA, based on the pioneering work of Borghi and Vallet [1, 2]. Key points of this approach are the liquid dispersion that can be associated to the turbulent liquid flux and the amount of liquid-gas surfac...
Liquid Atomization Modeling in OpenFOAM $$^{\textregistered }$$
OpenFOAM®, 2019
Several approaches have been developed to simulate liquid-jet atomization phenomena. Despite rece... more Several approaches have been developed to simulate liquid-jet atomization phenomena. Despite recent developments in numerical methods and computer performance, direct numerical simulation of the atomization process remains inaccessible for practical applications. Therefore, to carry out numerical simulations of the injected liquid from the internal flow within flow as far as the final dispersed spray, a modeling strategy has been developed. It is composed of a set of models implemented within the open-source software \(\texttt {OpenFOAM}^{\textregistered }\). First, the so-called Euler–Lagrange Spray Atomization (ELSA) approach is introduced. This is Eulerian formulation dedicated to jet atomization that is based on the analogy of turbulent mixing in a flow with variable density in the limit of infinite Reynolds and Weber numbers. Second, ELSA’s extension to a Quasi-Multiphase Eulerian (QME) approach is proposed. This method solves the problem of a second-order closure in modeling t...
The purpose of the present article is to present a dynamic multi-scale approach for turbulent liq... more The purpose of the present article is to present a dynamic multi-scale approach for turbulent liquid jet atomization in dense flow (primary atomization), together with the possibility to recover Interface Capturing Method (ICM) / Direct Numerical Simulation (DNS) features for well resolved liquid-gas interface. A full ICM-DNS approach should give the best comparison with experimental data, but it is not industrially affordable for the time being, therefore models are mandatory. A numerical representation based on full ICM-DNS, for the initial destabilization of the complex turbulent liquid jet, going up to the spray formation, for which well established numerical models can be used, is appealing but has not yet been applied. Indeed such an approach requires the ICM-DNS to be applied up to the formation of each individual droplet. Hence, in many situation models have to be applied to the dense, unresolved and turbulent liquid-gas flow. To achieve this goal, the most important unresol...
ICLASS 2018 - 14th Triennial International Conference on Liquid Atomization and Spray Systems, Jul 22, 2018
The Euler-Lagrange Spray Atomization model, namely ELSA [18], is a multi-scale approach suitable ... more The Euler-Lagrange Spray Atomization model, namely ELSA [18], is a multi-scale approach suitable to perform Large Eddy Simulations (LES) together with the possibility to recover Direct Numerical Simulation (DNS) features for well resolved interfaces. Recent validations with experimental and DNS data were made within the primary break-up [13]. Nevertheless, the link between secondary atomization (where liquid sheets break into ligaments and bag-like structure) and dilute or dispersed zone (where spray of droplets are formed) is still an open question. One of the major challenge within the transition from dense zone (Euler) to dilute zone (Lagrange) is the droplet size and velocity probability density functions (PDF) in turbulent jets. Normally, in diffuse interface models, the averaged mixture velocity and surface interface are employed to set up the lagrangian droplet. Nonetheless, such approach is far from being realistic. Consequently, among novel strategies e.g. 1) local turbulent statistic to improve averaged velocity mixture, 2) Quasi-Multiphase Euler approach [1] to recover averaged velocity in the liquid phase, and 3) local droplet PDF. Theses techniques will allow a local statistical transition of information from Euler to Lagrange approach. Indeed, an extraction from DNS data has been made, that introduces a new formulation of the drop size distribution (DSD) based on the liquid-gas surface curvature rather than the spherical droplet diameter [3]. The aim of this work is to enhance the coupling Euler-Lagrange in the atomization model, namely ELSA, by including the DSD from DNS approach [3] and velocity PDF from turbulent statistic.
European Conference Liquid Atomization & Spray Systems, Sep 4, 2016
Several approaches have been used to simulate liquid jet atomization phenomena. Usually a modelin... more Several approaches have been used to simulate liquid jet atomization phenomena. Usually a modeling strategy is assumed for liquid jet morphology, interface capturing methods are used for primary atomization while dispersed methods such as Lagrangian particle-tracking approach may be used to model the final spray. Despite recent developments in numerical methods and computer performance, complete simulation of atomization and spray remains inaccessible for practical applications (e.g. Diesel/Gasoline injectors, Feedstock atomization on FCC riser reactors, among others). Therefore, an enhanced Euler-Lagrange Spray Atomization (ELSA) approach to the well-established LES turbulence model merged with an interface density equation for subgrid scales is introduced. Moreover, the method has been adapted for unstructured mesh within OpenFOAM framework. Furthermore, a coupling with Lagrangian particle tracking has been performed. Several validation stages are being tested by comparing experimental data (i.e. ECN Spray injectors) and DNS results against the proposed model. Finally, an industrial application case using a FCC injector® demonstrates the suitability of this novel model, based on good quantitative and qualitative agreement with experiments and DNS simulations.
Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modelling a... more Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modelling atomization, even if widely used in technical literature, are not suitable in the near injector region. Indeed, the first step of atomization process is to separate the continuous liquid phase in a set of individual liquid parcels, the so-called primary break-up. Describing two-phase flow by DPM is to define a carrier phase and a discrete phase, hence they cannot be used for primary breakup. On the other hand, full scale simulations (direct simulation of the dynamic DNS, and interface capturing method ICM) are powerful numerical tools to study atomization, however, computational costs limit their application to academic cases for understanding and complementing partial experimental data. In an industrial environment, models that are computationally cheap and still accurate enough are required to meet new challenges of fuel consumption and pollutant reduction. Application of DNS-ICM method...
Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modeling at... more Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modeling atomization, even if widely used in technical literature, are not suitable in the near injector region. Indeed, the first step of atomization process is to separate the continuous liquid phase in a set of individual liquid parcels, the so-called primary break-up. Describing two-phase flow by DPM is to define a carrier phase and a discrete phase, hence they cannot be used for primary breakup. On the other hand, full scale simulations (direct simulation of the dynamic DNS, and interface capturing method ICM) are powerful numerical tools to study atomization, however, computational costs limit their application to academic cases for understanding and complementing partial experimental data. In an industrial environment, models that are computationally less demanding and still accurate enough are required to meet new challenges of fuel consumption and pollutant reduction. Application of DNS-ICM methods without fairly enough resolution to solve all length scales are currently used for industrial purposes. Nevertheless, effects of unresolved scales are generally cast aside. The Euler-Lagrange Spray Atomization model family (namely, ELSA, also called, Σ − Y or Ω − Y) developed by Vallet and Borghi pioneering work [1], and [2], at the contrary aims to model those unresolved scales. This approach is actually complementary to DNS-ICM method since the importance of the unresolved term depends directly on mesh resolution. For full interface
This PhD is a joint venture between VINCI Technologies and the CNRS Laboratory CORIA. For its app... more This PhD is a joint venture between VINCI Technologies and the CNRS Laboratory CORIA. For its application, VINCI Technologies, developed mainly oil-related equipments and in particular injection/atomization systems. Some of these injectors are characterized by a very big geometrical dimensions (several meters long), that leads to very high Reynolds and Weber number. In addition, many injectors incorporate an internal mixing zone, in which liquid and gas phases are both present in a significant proportion. Consequently, this zone belongs to the dense two-phase flow category. To simulate the liquid dispersion and to characterize the spray formation special from these injectors, appropriate models are required. On its side, the CORIA team, has developed a suitable approach, so-called ELSA, based on the pioneering work of Borghi and Vallet [1, 2]. Key points of this approach are the liquid dispersion that can be associated to the turbulent liquid flux and the amount of liquid-gas surfac...
Liquid Atomization Modeling in OpenFOAM $$^{\textregistered }$$
OpenFOAM®, 2019
Several approaches have been developed to simulate liquid-jet atomization phenomena. Despite rece... more Several approaches have been developed to simulate liquid-jet atomization phenomena. Despite recent developments in numerical methods and computer performance, direct numerical simulation of the atomization process remains inaccessible for practical applications. Therefore, to carry out numerical simulations of the injected liquid from the internal flow within flow as far as the final dispersed spray, a modeling strategy has been developed. It is composed of a set of models implemented within the open-source software \(\texttt {OpenFOAM}^{\textregistered }\). First, the so-called Euler–Lagrange Spray Atomization (ELSA) approach is introduced. This is Eulerian formulation dedicated to jet atomization that is based on the analogy of turbulent mixing in a flow with variable density in the limit of infinite Reynolds and Weber numbers. Second, ELSA’s extension to a Quasi-Multiphase Eulerian (QME) approach is proposed. This method solves the problem of a second-order closure in modeling t...
The purpose of the present article is to present a dynamic multi-scale approach for turbulent liq... more The purpose of the present article is to present a dynamic multi-scale approach for turbulent liquid jet atomization in dense flow (primary atomization), together with the possibility to recover Interface Capturing Method (ICM) / Direct Numerical Simulation (DNS) features for well resolved liquid-gas interface. A full ICM-DNS approach should give the best comparison with experimental data, but it is not industrially affordable for the time being, therefore models are mandatory. A numerical representation based on full ICM-DNS, for the initial destabilization of the complex turbulent liquid jet, going up to the spray formation, for which well established numerical models can be used, is appealing but has not yet been applied. Indeed such an approach requires the ICM-DNS to be applied up to the formation of each individual droplet. Hence, in many situation models have to be applied to the dense, unresolved and turbulent liquid-gas flow. To achieve this goal, the most important unresol...
ICLASS 2018 - 14th Triennial International Conference on Liquid Atomization and Spray Systems, Jul 22, 2018
The Euler-Lagrange Spray Atomization model, namely ELSA [18], is a multi-scale approach suitable ... more The Euler-Lagrange Spray Atomization model, namely ELSA [18], is a multi-scale approach suitable to perform Large Eddy Simulations (LES) together with the possibility to recover Direct Numerical Simulation (DNS) features for well resolved interfaces. Recent validations with experimental and DNS data were made within the primary break-up [13]. Nevertheless, the link between secondary atomization (where liquid sheets break into ligaments and bag-like structure) and dilute or dispersed zone (where spray of droplets are formed) is still an open question. One of the major challenge within the transition from dense zone (Euler) to dilute zone (Lagrange) is the droplet size and velocity probability density functions (PDF) in turbulent jets. Normally, in diffuse interface models, the averaged mixture velocity and surface interface are employed to set up the lagrangian droplet. Nonetheless, such approach is far from being realistic. Consequently, among novel strategies e.g. 1) local turbulent statistic to improve averaged velocity mixture, 2) Quasi-Multiphase Euler approach [1] to recover averaged velocity in the liquid phase, and 3) local droplet PDF. Theses techniques will allow a local statistical transition of information from Euler to Lagrange approach. Indeed, an extraction from DNS data has been made, that introduces a new formulation of the drop size distribution (DSD) based on the liquid-gas surface curvature rather than the spherical droplet diameter [3]. The aim of this work is to enhance the coupling Euler-Lagrange in the atomization model, namely ELSA, by including the DSD from DNS approach [3] and velocity PDF from turbulent statistic.
European Conference Liquid Atomization & Spray Systems, Sep 4, 2016
Several approaches have been used to simulate liquid jet atomization phenomena. Usually a modelin... more Several approaches have been used to simulate liquid jet atomization phenomena. Usually a modeling strategy is assumed for liquid jet morphology, interface capturing methods are used for primary atomization while dispersed methods such as Lagrangian particle-tracking approach may be used to model the final spray. Despite recent developments in numerical methods and computer performance, complete simulation of atomization and spray remains inaccessible for practical applications (e.g. Diesel/Gasoline injectors, Feedstock atomization on FCC riser reactors, among others). Therefore, an enhanced Euler-Lagrange Spray Atomization (ELSA) approach to the well-established LES turbulence model merged with an interface density equation for subgrid scales is introduced. Moreover, the method has been adapted for unstructured mesh within OpenFOAM framework. Furthermore, a coupling with Lagrangian particle tracking has been performed. Several validation stages are being tested by comparing experimental data (i.e. ECN Spray injectors) and DNS results against the proposed model. Finally, an industrial application case using a FCC injector® demonstrates the suitability of this novel model, based on good quantitative and qualitative agreement with experiments and DNS simulations.
Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modelling a... more Traditional Discrete Particle Methods (DPM) such as the Euler-Lagrange approaches for modelling atomization, even if widely used in technical literature, are not suitable in the near injector region. Indeed, the first step of atomization process is to separate the continuous liquid phase in a set of individual liquid parcels, the so-called primary break-up. Describing two-phase flow by DPM is to define a carrier phase and a discrete phase, hence they cannot be used for primary breakup. On the other hand, full scale simulations (direct simulation of the dynamic DNS, and interface capturing method ICM) are powerful numerical tools to study atomization, however, computational costs limit their application to academic cases for understanding and complementing partial experimental data. In an industrial environment, models that are computationally cheap and still accurate enough are required to meet new challenges of fuel consumption and pollutant reduction. Application of DNS-ICM method...
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