Chaouki Habchi

• HDR. Dr.
• Senior scientist at IFP Energies nouvelles

A fully compressible two-phase flow model consisting of four balance equations including two mass, one momentum, and one internal energy equation, formulated with the mechanical and thermal equilibrium assumptions is developed in this article. This model is closed with a real fluid equation of state (EoS) and has been applied to the simulation of d...

In this article, a fully compressible two-phase flow model combined with a multi-component real-fluid phase equilibrium solver is proposed for the cavitation modelling. The model is able to simulate the dissolving process of non-condensable gas through resolving the real-fluid phase change equations. A three-dimensional cavitating nozzle test is co...

Today, injection of liquid fuels at supercritical pressures is a frequently used technique to improve the efficiency of energy systems and address environmental constraints. This paper focuses on the analysis of the coupling between the hydrodynamics and thermodynamics of multi-species supercritical jets. Various phase transition phenomena, such as...

Numerical modeling of high-pressure liquid fuel injection remains a challenge in various applications. Indeed, experimental observations have shown that injected liquid fuel jet undergoes a continuous change of state from classical two-phase atomization and spray droplets evaporation to a dense-fluid mixing phenomenon depending on the ambient press...

The proposed Euro 7 regulation aims to substantially reduce the NOx emissions to 0.03 g/km, a trend also seen in upcoming China 6b and US EPA regulations. Meeting these stringent requirements necessitates advancements in Urea/Selective Catalytic Reduction (SCR) after-treatment systems, with the urea deposit formation being a key challenge to its de...

In-depth understanding of cavitating multiphase flows is essential for the design and optimization of efficient energy conversion systems. In addition, replacing fossil fuels with carbon-free renewable fuels for heavy-duty vehicles is a promising solution for reducing CO2 emissions. This paper proposes a new real-fluid modelling (RFM) framework to...

Machine learning based on neural networks facilitates data-driven techniques for handling large amounts of data, either obtained through experiments or simulations at multiple spatio-temporal scales, thereby finding the hidden patterns underlying these data and promoting efficient research methods. The main purpose of this paper is to extend the ca...

Machine learning (ML) based on neural network (NN) facilitates data-driven techniques for handling large amounts of data, either obtained through experiments or simulations at multiple spatio-temporal scales, thereby finding the hidden patterns underlying these data and promoting efficient research methods. The main purpose of this paper is to exte...

Because of the currently changing climate, Carbon Capture and Storage (CCS) is increasingly becoming an important contemporary topic. However, this technique still faces various challenges. For the compression of CO2 to its supercritical condition for efficient transport, one of the important challenges is mastering the two-phase flow in the pump....

The reduction of greenhouse gases (GHG) emitted into the earth's atmosphere, such as carbon dioxide, has obviously become a priority. Replacing fossil fuels with cleaner renewable fuels (such as ammonia) in internal combustion engines for heavy-duty vehicles is one promising solution to reduce GHG emissions. This paper aims to study the cavitation...

Compressible two-phase real-fluid simulation is nowadays a hot topic in many research laboratories and industries. Fast, robust, and precise real fluid models (RFM) are required to go beyond academic simulations. Two methods have already been evaluated by researchers. The first method calculates thermodynamic properties during simulation based on a...

Modeling of fuel atomization in internal combustion engines remains a challenge for modelers. The widely used Lagrangian Discrete Droplet Method (DDM) has shown shortcomings, especially in the near nozzle region, where the primary break-up initiates from the intact liquid core. Meanwhile, Interface Capturing Methods (such as VOF, Level-Set) can be...

The reduction of greenhouse gases (GHG) emitted into the earth's atmosphere, such as carbon dioxide, has obviously become a priority. Replacing the majority of fossil fuels with cleaner renewable fuels (such as methanol) in dual-fuel internal combustion engines for heavy-duty vehicles is one proposed solution to reduce GHG emissions. This paper aim...

Boiling of liquids upon impact of the spray on heated surfaces is common in many practical applications. However, a comprehensive modelling approach for these phenomena is still not available in commercial software, despite decades of experimental, theoretical, and numerical research efforts. The motivation of this paper is to clarify the state of...

The substitution of diesel by cleaner renewable fuels such as short-chain alcohols in dual-fuel internal combustion engines is considered an attractive solution to reduce the pollutant emissions from internal combustion engines. In this context, two-phase flow models for multi-component mixtures considering the real-fluid thermodynamics are require...

A fundamental understanding and simulation of fuel atomization, phase transition, and mixing are among the topics researchers have struggled with for decades. One of the reasons for this is that the accurate, robust, and efficient simulation of fuel jets remains a challenge. In this paper, a tabulated multi-component real-fluid model (RFM) is propo...

In Gasoline Direct Injection (GDI) engines, the interaction between the premixed flame front and the liquid wall film is considered as the primary source of soot. Modeling soot formation in this configuration requires the local gas mixture to be accurately predicted above the wall film which, in turn, requires an accurate wall film evaporation mode...

Accurate, robust, and fast fully compressible real-fluid simulation of fuel jets is today's one of the highly debated topics in various research laboratories and industries. Indeed, the use of real-fluid equations of state has proved to be computationally very expensive and is one of the current challenges. In this paper, a thermodynamic equilibriu...

The substitution of diesel by cleaner renewable fuels such as short-chain alcohols in dual-fuel internal combustion engines is considered an attractive solution to reduce the pollutant emissions from internal combustion engines. In this context, accurate and robust two-phase flow models taking into account the real fuel thermodynamics are required...

Accurate, robust, and fast fully compressible real-fluid simulation of fuel jets is today’s one of the highly debated topics in various research laboratories and industries. Indeed, the use of real-fluid equations of state has proved to be computationally very expensive and is one of the current challenges. In this paper, a thermodynamic equilibriu...

The substitution of diesel by cleaner renewable fuels such as short-chain alcohols in dual-fuel internal combustion engines is considered an attractive solution to reduce the pollutant emissions from internal combustion engines. In this context, accurate and robust two-phase flow models taking into account the real fuel thermodynamics are required...

Accurate, robust, and fast fully compressible real-fluid simulation of fuel jets is today’s one of the highly debated topics in various research laboratories and industries. Indeed, the use of real-fluid equations of state has proved to be computationally very expensive and is one of the current challenges. In this paper, a thermodynamic equilibriu...

In Gasoline Direct Injection (GDI) engines, the interaction between the premixed flame front and the liquid wall film is considered as the primary source of soot. Modeling soot formation in this configuration requires the local gas mixture to be accurately predicted above the wall film which, in turn, requires an accurate wall film evaporation mode...

In this paper, a fully compressible real-fluid and homogeneous equilibrium model (HEM) has been developed, in which the two-phase characteristics are obtained using a tabulated multicomponent vapor-liquid equilibrium approach. This classical HEM model consists of four balance equations posed in terms of mass density, partial species density, moment...

In this study, a mass-fraction based fully conservative multi-component two-phase flow solver is considered using characteristic-wise finite-difference (CWFD) discretization with the 5th-order WENO scheme, in order to reduce numerical interface smearing and oscillations. Real-fluid thermodynamic properties are accounted for by a vapor-liquid equili...

The interaction of single droplets with hot solid surfaces is a fundamental process for a wide range of technical applications, such as urea-water solution (UWS) injection in selective catalytic reduction (SCR) systems. Specifically, the chemical evolution and film topology and state of UWS after its deposit on a hot surface are still not well know...

A fully compressible four-equation model for multicomponent two-phase flow coupled with a real-fluid phase equilibrium-solver is suggested. It is composed of two mass, one momentum, and one energy balance equations under the mechanical and thermal equilibrium assumptions. The multicomponent characteristics in both liquid and gas phases are consider...

A fully compressible two-phase flow with four-equation model coupled with a real-fluid multi-component phase equilibrium solver is proposed. It is composed of two mass conservation equations, one momentum equation and one energy equation under the assumptions of mechanical and thermal equilibrium. The phase equilibrium solver is developed based on...

Selective catalytic reduction (SCR) using Urea-Water Solution (UWS) is a NOx reduction method that many diesel engine manufacturers adopt to meet new regulations for mobile applications (cars, trucks, etc.,) throughout the world. However, this technology still faces many scientific and technological challenges. Indeed, the UWS injected spray can im...

The aim of this work is to improve the accuracy of cavitating flow simulations by considering real-fuel mixture thermodynamics, like gas (air) solubility and physical property deviations from ideality, and their effects on phase change. In this work, a new fully compressible two-phase six-equations model coupled with Peng and Robinson [1] real-flui...

In this work, both experimental and numerical investigations have been carried out in order to improve the modelling of the vaporization of wall liquid-deposits in internal combustion engines. A comprehensive model is suggested for the vaporization of liquid films in the different boiling regimes, including nucleate boiling regime, the Leidenfrost...

Spurious oscillation is a classical issue encountered in multispecies and multiphase compressible flows modeling, especially when the conservative form of Navier-Stokes equations is considered. This issue becomes further pronounced when dealing with the modelling of transcritical Diesel fuel conditions using real fluid equation of state. Indeed, la...

In this paper, a comprehensive two-fluid model is suggested in order to compute the in-nozzle cavitating flow and the primary atomization of liquid jets, simultaneously. This model has been applied to the computation of a typical large marine Diesel injector. The numerical results have shown a strong correlation between the in-nozzle cavitating flo...

Selective catalytic reduction (SCR) using Urea-Water Solution (UWS) is a NOx reduction method that many diesel engine manufacturers adopt to meet new regulations for mobile applications (cars, trucks, etc. ...) throughout the world. However, this technology still faces many scientific and technological challenges. Indeed, the UWS injected spray can...

In this paper, a comprehensive highly compressible and turbulent two-fluid multi-species model is presented. It involves an equation for the transport of the liquid volume fraction in addition to two different sets of partial differential equations for the gas and the liquid phase. The multicomponent gas phase is governed by an ideal gas equation o...

The diesel combustion process is strongly dependent on the rate of introduction of fuel and hence the quality of the atomization process, which in turn is significantly influenced by effects caused by the geometry of the fuel injection equipment itself as well as the potential occurrence of cavitation. In particular, the injector geometry of large...

The injector geometry of large marine two-stroke diesel engines differs substantially from the configurations used in most other diesel engine applications, because the injector orifices are distributed in a highly non-symmetric manner. In order to investigate the impact of key features of such asymmetrical orifice arrangements on the liquid jet an...

In internal combustion engines, the liquid fuel injection is an essential step for the air/fuel mix-ture preparation and the combustion process. Indeed, the structure of the liquid jet coming out from the injector plays a key role in the proper mixing of the fuel with the gas in the combustion chamber. The present work focuses on the liquid jet ato...

In this paper, a comprehensive highly compressible and turbulent two-fluid multi-species model is presented. It involves an equation for the transport of the liquid volume fraction in addition to two different sets of partial differential equations for the gas and the liquid phase. The multicomponent gas species phase is governed by an ideal gas eq...

Liquid jet atomization is an important process in engineering applications such as aerospace propulsion systems, automotive engines, food processing, and inkjet printing. For engine applications, the fuel spray characteristics are critical to determining the engine performance such as fuel consumption rate or exhaust gas cleanness. The present work...

This work is aimed to develop a multicomponent evaporation model for droplets of urea-water solution (UWS) and a thermal decomposition model of urea for automotive exhausts by using the selective catalytic reduction systems. In the multicomponent evaporation model, the influence of urea on the UWS evaporation is taken into account using a nonrandom...

This paper focuses on the analysis of multi-component droplet heating and evaporation under micro-gravity and normal gravity conditions. This analysis is based on the conventional conservation equations of species and energy for the gas phase, and the energy balance equation at the liquid-gas interface. The species diffusion is based on the Hirschf...

In this paper, a Diesel spray has been investigated experimentally and numerically in order to improve the understanding of transient processes of short injection typically used in multi-injection strategies of internal combustion engine. The spray was observed experimentally in a high pressure high temperature cell that reproduces the thermodynami...

A new evaporation model for multi-component hydrocarbon droplets is proposed. Compared to previously published models, it has two new features. First, an expression of the Stefan velocity is proposed which ensures gas mass conservation. In addition, the evaporation rate of each species is obtained by the integration of the exact equation of species...

A full 3D Large Eddy Simulation (LES) of a four-stroke, four-cylinder engine, performed with the AVBP-LES code, is presented in this paper.The drive for substantial CO2 reductions in gasoline engines in the light of the global energy crisis and environmental awareness has increased research into gasoline engines and increased fuel efficiencies. Pre...

This paper proposes a new model for liquid droplet breakup. The size of the droplets produced in each breakup regime is computed using new correlations based on the assumption that a breakup energy cascade exists and follows a path similar to that of the turbulent energy cascade. This Spectrum Analogy Breakup (SAB) model allows linking the size of...

The main objectif of this presentation is a fair comparison of Eulerian-Eulerian (EE) and Lagrangian-Eulerian (LE) liquid injection models in the LES framework using the AVBP software developped by IFP Energies nouvelles and CERFACS.

The adequacy of the fuels with the engines has been often a major goal for the oil industry or car manufacturers. As the formulation of fuels becomes more complex, the use of numerical simulation provides an efficient way to understand and analyze the combustion process. These conclusions become increasingly true with the appearance of second gener...

Abstract: The purpose of this article is to present a comprehensive set of tools for the simulation of the mixture preparation in diesel engines. This set includes a representative fuels model generator called ReFGen which is dedicated to the calculation of the physical properties of second-generation Biofuels; and a new version of the IFP-C3D mult...

A Comprehensive Model for Liquid Film Boiling in Internal Combustion Engines — In this paper, the main physical processes governing the nucleate and transition regimes of the boiling of a liquid film were reviewed from the available experimental observations in the literature. The physical tendencies observed in most experiments have been used to d...

Among the physical processes occurring when a liquid film is formed on the surface of the combustion chamber of a direct injection engine, heat transfer and phase changes are of primary importance. The vaporization rate of the liquid film is not only a function of the wall temperature but it is strongly affected by the gas pressure variation inside...

Contrary to the case of flame interaction with a dry wall, little is known today about liquid film evaporation effects on the physics and structure of the boundary layer and on the flame evolution when approaching a liquid film. In this paper, Direct Numerical Simulation (DNS) is used to study the boundary layer above a liquid evaporating film in t...

The objective of this work is to develop an Eulerian multiphase flow model in order to improve the prediction of fuel injection simulations in internal combustion Diesel engines. Lagrangian models, usually used in engines simulations, are based on the assumption of dispersed two-phase flow with low liquid volume fraction, which is not fulfilled in...

Due to intense flow recirculations and strong local depression, cavitation occurs in high-pressure Diesel injectors. As experiments are very difficult to perform for injection conditions (small length and time scales, high-speed flow, ...), 3D modeling seems to be an appropriate tool in order to better understand the flow features inside and at the...

This paper describes a single component liquid film evaporation model. Based on direct numerical simulation (DNS) results of liquid film evaporation in a turbulent channel, new mass, momentum and energy wall laws have been developed in order to take into account the strong gradients of gas density and viscosity near the liquid film, and the gas bou...

Les travaux de recherches présentés dans ce mémoire de HDR portent sur la modélisation multidimensionnelle (3D) de la préparation du mélange gaz-carburant dans les moteurs à combustion interne d'automobiles. Ces travaux ont conduit à l'établissement de plusieurs modèles physiques utilisés actuellement dans le code de simulation de la combustion IFP...

Future Diesel engines must comply with conflicting demands: more stringent emission standards and customer desire for "fun-to-drive" vehicles, i.e. higher torque and power output. Given such objectives, engine development investigates new clean combustion processes, such as low temperature combustion (LTC), highly premixed combustion (HPC) or homog...

In this paper, we address the issue of accurate modelling of experimental data in order to provide numerical settings for Reynolds averaged Navier–Stokes (RANS) numerical simulation of the gas–gas jet generated by a single-hole diesel-like injector. Since experimental operating conditions usually do not document the inlet boundary conditions, both...

In piston engines and in gas turbines, the injection of liquid fuel often leads to the formation of a liquid film on the combustor wall. If a flame reaches this zone, undesired phenomena such as coking may occur and diminish the lifetime of the engine. Moreover, the effect of such an interaction on maximum wall heat fluxes, flame quenching, and pol...

This work consists in studying the effects of Diesel injector internal flow on liquid jet atomisation phenomenon downstream the nozzle exit. A 3D numerical multiphase code (referred to as CAVIF) has been developed to calculate both cavitation and jet atomisation processes for high pressure conditions. This code is based on a homogeneous description...

Future diesel engines must comply with conflicting demands: more stringent emission standards and customer desire for "fun-to-drive" vehicles, i.e., higher torque and power output. Given such objectives, engine development investigates new clean combustion processes, such as low-temperature combustion (LTC), highly premixed combustion (HPC) or homo...

As the new emissions standards lead to a reduction of the exhaust pollutants and fuel consumption, the engine efficiency must be improved. The knock phenomenon represents the main limitation for the performance of gasoline engines, especially in the downsizing turbo-charged direct injection approach. The aim of this paper is to study the influence...

Due to huge stress in the orifice, cavitation occurs in high-pressure Diesel injectors. As experiments are very hard to manage for injection conditions (small space and time scales, high-speed flow, …) 3D modelling seems to be an appropriate tool in order to better understand the flow features inside and at the exit of the injector nozzle. The purp...

In port fuel injection engines, the liquid fuel film accumulated in the vicinity of intake valves is torn away and goes into the cylinder during the intake phase. In order to predict the fuel mixture preparation inside the cylinder, a model for the fuel film separation near the sharp edges of the intake valves has been developed. A separation crite...

In port fuel injection engines, the liquid fuel film accumulated in the vicinity of intake valves is torn away and goes into the cylinder during the intake phase. In order to predict the fuel mixture preparation inside the cylinder, a model for the fuel film separation near the sharp edges of the intake valves has been developed. A separation crite...

In order to predict the fuel mixture preparation inside the cylinder of port fuel injection engines, a model for the aerodynamic stripping of the fuel film deposited on the manifold walls is discussed, and a model for the fuel film separation and atomization near the sharp edges is developed. A separation criterion is set up using an analogy with R...

Due to excessive stress in the orifice, cavitation occurs in high-pressure Diesel injectors. As experiments are very hard to manage for injection conditions (small-scaled, high-speed flow), a numerical model seems to be the right tool to get a better understanding of the flow features inside and at the exit of the injector nozzle. The purpose of th...

The purpose of this paper is to present a simulation code based on a Homogeneous Equilibrium Model. The validation of the code for typical cavitating flow configuration is presented. Then numerical results of cavitating flows in Diesel injectors are shown. Then we report concluding remarks and objectives.

Progress in Diesel spray modelling highly depends on a better knowledge of the instantaneous injection velocity and of the hydraulic section at the exit of each injection hole. Additionally a better identification of the mechanisms which cause fragmentation is needed. This necessitates to begin with a precise computation of the two-phase flow which...

The Lagrangian-Eulerian approach is commonly used to simulate engine sprays. However typical spray computations are strongly mesh dependent. This is explained by an inadequate space resolution of the strong velocity and vapor concentration gradients. In Diesel sprays for instance, the Eulerian field is not properly computed close to the nozzle exit...

To provide better understanding of fuel distribution in direct injection gasoline engines, models for spray-wall interaction and a liquid film transport are developped. An eulerian approach is used to describe the wall film over a three dimensional complex surface. Phenomena taken into account include liquid film formation on the walls by an impact...