Sofiane KHELLADI

École nationale supérieure d'arts et métiers | ENSAM · Centre de Paris

The growing development of lithium-ion battery technology goes along with the new energy storage era across various sectors, e.g., mobility (electric vehicles), power generation and dispatching. The need for sophisticated modeling approaches has become a crucial tool to predict and optimize battery behavior given the demand of ever-higher performan...

This study investigates the influence of separation distance between co-axially aligned Horizontal Axis Wind Turbines (HAWT) on aerodynamic performance and noise characteristics under uniform flow conditions. For this purpose, the Actuator Disk Method (ADM) had been applied within the Unsteady Reynolds-Averaged Navier-Stokes (URANS) formulation, us...

The present paper consists on numerical investigation of new proposed method-ology dedicated for HAWT noise generation and propagation predictions. It is based on the superposition of aerodynamic and aeroacoustics simulations with a particular emphasis on segregating aerodynamic calculations from sound propagation. The aerodynamic computations are...

Thermal mixing fluids in chaotic microdevices have significant importance in many potential applications and have enormous utility in thermal engineering processes. In microfluidic devices, The Two-Layer with Crossing Channels Micromixer (TLCCM) emphasized its efficiency in thermally homogenizing Newtonian fluids, which inspired us to investigate i...

Climate change is driving new and more efficient ways of producing and storing energy. In particular, batteries demonstrate to be a worthwhile storage system for their high specific power and energy density. Due to electrochemical processes inside batteries, high temperatures are achieved during fast charge and discharge. Herein, a novel jet-grid c...

In this paper, a numerical investigation of the impact of asymmetric heating on laminar mixed convection in Poiseuille-Rayleigh-Bénard water flow within parallel horizontal channels is presented. The study has been carried out in a rectangular channel with a transverse aspect ratio of 10, and considered both low (Ra=1.28×10 4) and high (Ra=1.4×10 5...

The onset of mixed convection of cold water in a horizontal channel is studied using linear stability analysis. The two walls of the channel are modeled using slip conditions and are maintained at different constant temperatures. A model with a parabolic relationship is used to predict the variation of density with temperature in the range around i...

In this study, we numerically investigate the effects of the nonlinearity in the equation of state on the structure of fingers and the transport mechanisms of salt and heat in double-diffusive finger convection, utilizing the finite volume approach with high-accuracy schemes to solve the two-dimensional Navier–Stokes equations. Our system is charac...

We consider the moving least squares method to solve compressible two-phase water-water vapor flow with surface tension. A diffuse interface model based on the Navier-Stokes-Korteweg equations is coupled with a suitable system of state equations that allows for a more realistic estimation of the pressure jump across the liquid-vapor interface as a...

In this study, advanced design technique has been introduced to determine the radial local chord distribution on the rotor blades of Horizontal Axis Wind Turbines (HAWT) based on an inverse Computational Fluid Dynamics (CFD) actuator disk method combined with linearization of both the chord and twist distributions. The overarching goal was to refin...

Interaction between purge flows and main flow path is known to impact negatively the aerodynamic performance of the gas turbines. This paper focuses on the leakage flow through hub cavity re-entering into the main flow path upstream of the second rotor blade row of a two-stage low-pressure turbine (LPT). The stator well considered in this paper con...

Given the small wavelengths and wide range of frequencies of the acoustic waves involved in Aeroacoustics problems, the use of very accurate, low-dissipative numerical schemes is the only valid option to accurately capture these phenomena. However, as the order of the scheme increases, the computational time also increases. In this work, we propose...

Although the published books or even review papers have covered different features in the field of 3D printing, almost all of them approach the topic from a specific focus. However 3D printing should be considered as a multidisciplinary field; aside from its rapid growth in novel approaches such as data science or artificial neural networks the top...

3D printing, also known as additive manufacturing, has emerged as a versatile and multidisciplinary field with widespread implications. It intersects with various domains including engineering, medicine, art, and materials science. This technology's ability to convert digital designs into physical objects layer by layer has revolutionized industrie...

In gas turbines, the stator wells play a key role in the efficiency of the turbomachine. The research for performance gains requires a good understanding and an accurate modelling of the flows and heat transfers occurring in these areas. Within the framework of the European program MAGPI WP1, a two-stage axial turbine test rig provided an experimen...

The present work is dedicated to a numerical study of natural convection through a cavity with finned surface where its base temperature is variable with linear profile. An approach based on modeling of internal fluid flow around a finned surface in laminar and at steady state conditions is used.Thermal and hydrodynamic aspects of the fluid flow we...

This article provides a comprehensive investigation into the resin-bonded sand gravity casting process, with a focus on the filling, cooling, and solidification steps. The research combines numerical simulations and experi- mental validation in a three-dimensional (3D) configuration, utilizing a realistic filling system. The study em- ploys three a...

Cross-Flow Fans (CFFs) have been widely applied in the automotive and domestic air conditioning industries in recent decades. They are high-pressure coefficient turbomachines compacted diametrically, and thus, the complex interactions of these fans require thorough evaluation. Their innovation has opened up new directions in turbomachinery, and bot...

In gas turbines, the stator wells play a key role in the efficiency of the turbomachine. The research for performance gains requires a good understanding and an accurate modelling of the flows and heat transfers occurring in these areas. Indeed, engineers try to maintain sustainable temperatures of the turbine components while minimizing the amount...

The simulation of the sand gravity casting process is complicated due to its multiscale and multiphysics nature. Although there are many commercial software options available, it remains extremely difficult to accurately predict the filling, solidification, and defects such as oxidation. Smoothed Particle Hydrodynamics (SPH) is a Lagrangian simulat...

Cross-Flow Fans (CFFs), also known as Tangential fan, are widely used in various industries, particularly in automotive or domestic air conditioning, and have recently attained much attention. Alongside the significant research works, traditional techniques and additive manufacturing techniques have exclusively revealed stimulating results in turbo...

The use of a counter-rotating rotor in turbomachines can be a solution to improve performances by allowing reduction in size and weight, especially compared to multistage configuration. The present study aims are to demonstrate another advantage of the counter-rotating rotors: their application to expand the operating range of centrifugal compresso...

This study outlines the performances of finite length journal bearing with: textured liner, shear-thinning Rabinowitsch lubricants, and considering the elastic deformation of the bearing liner. The yielded nonlinear Rabinowitsch-Reynolds PDE system has been solved using finite differences method combined with Elrod's algorithm for the case cylindri...

In industrial applications such as the Organic Rankine Cycle (ORC), accurate predictions of the system performance rely on simulations of the flow properties of the working fluid. During operation, fluids may exhibit large property changes and non-ideal gas behavior due to phase changes. Especially in recent years, a large number of applications of...

Nanotechnology is progressively changing the human life and health care in recent years. This technology has the capacity of changing the entire healthcare techniques by proposing novel disease prevention techniques and inventing nanorobots. One of the most important applications of nanotechnology is in the dental medicine that is capable of coveri...

In the present study, numerical simulations have been employed to understand the effect of the density inversion on the finger structures dynamics and mixing process. A numerical methodology based on the finite volume method with high accuracy schemes were employed to solve the two-dimensional Navier-Stokes equations for high buoyancy ratio ($R_\rh...

Flows carrying bottom materials have a wide range of possible applications, especially in the technological and natural fields (Benaissa, Eléments de mécanique des sols. OPU, 1993). These flows that are loaded with granular materials are transport phenomena with diverse and complex mechanisms. They are characterized by the suspension of particles b...

Turbulent flows are characterized by the presence of 'fluctuating scales', or 'structures' of varying magnitude whose effects on mixing, heat transfer and energy dissipation are prominent. The main objective of the study is to explore and exploit two-equation models capable of numerically analyzing the dynamic and thermal behavior of unsteady turbu...

Several process variables can be taken into account to optimize the Fused Filament Fabrication (FFF) process, a promising Additive Manufacturing technique. To take into account the most important variables, a numerical-experimental roadmap toward the optimization of FFF process by taking into account some physico-chemical and mechanical characteris...

The inducers increase the pressure available at the inlet of the impellers of centrifugal pumps. This technological solution may induce instabilities, such as prerotating flow at partial flow rates. The scientific literature offers studies on the cavitation in the inducers, as well as on the associated instabilities. However, studies describing dev...

Cross-flow fans (CFFs) have become increasingly popular in recent years. This is due to their use in several domains such as air conditioning and aircraft propulsion. They also show their utility in the ventilation system of hybrid electric cars. Their high efficiency and performance significantly rely on the design parameters. Up to now, there is...

Machine component design has become a prominent topic for researchers in recent years. The analysis of bearing systems has been received considerable attention in order to avoid detrimental contact. Among the most important studies in this area are the transient problems of journal bearings, which are usually performed by coupling the Reynolds with...

A semi-classical signal analysis (SCSA) method is presented in this paper to show the relevance of its use for the detection of compressors surge precursors. This approach provides some new spectral parameters from physical properties of flow that might be interesting for signal analysis of turbomachines unsteadiness in general and surge detection...

The inducers increase the pressure available at the inlet of the impellers of centrifugal pumps. This technological solution may induce instabilities, such as pre-rotating flow at partial flow rates. The scientific literature offers studies on the cavitation in the induc-ers, as well as on the associated instabilities. However, studies describing d...

Bonding of parts produced by fused filament fabrication (FFF) significantly depends on the temperature profile of filaments depositing one top of each other. It is necessary to evaluate the temperature profile during fabrication of structures using both theoretical and experimental approaches. This work describes the overall heat transfer (using fi...

In the present work, double-diffusive convection of salt finger is numerically investigated. A computational code based on the finite volume method with high-order accuracy and high resolution in space, implying a fifth-order scheme WENO5 for the nonlinear convective terms, a fourth-order centered scheme for the viscous terms, and the third-order T...

In this study, we were interested in free convective heat transfer into cavities with finned surface. The hot horizontal bottom wall with attached fins was under variable (sinusoidal) surface temperature while the cold one, on the upper wall side, was kept at constant temperature. The vertical walls were adiabatic. The developed model is related to...

Centrifugal compressors are widely used in many industrial fields such as automotive, aviation, aerospace. However, these turbomachines suffer instability phenomenon when the flow rate is too high or too low, called rotating stall and surge. These phenomena cause the operation failure, pressure fluctuations and vibrations of the thorough system. Nu...

Fused filament fabrication (FFF), an additive manufacturing technique, unlocks alternative possibilities for the production of complex geometries. In this process, the layer-by-layer deposition mechanism and several heat sources make it a thermally driven process. As heat transfer plays a particular role and determines the temperature history of th...

L'étude a pour objet de modéliser les caractéristiques rhéologiques des pièces imprimées en 3D. Pour atteindre cet objectif, une étude bibliographique a été réalisée sur les effets des principales variables du processus de l'évolution de la température et leur impact sur les caractéristiques rhéologiques. Puisque les caractéristiques rhéologiques t...

The present study deals with a low pressure-ratio centrifugal compressor consisting of two counter-rotating rotors called a Counter-Rotating Centrifugal Compressor (CRCC). The design method based on the loss model was presented to determine the geometric parameters of the two counterrotating rotors. According to this method, the rotor of a selected...

The wake flow characteristics downstream from the rotor blade of small HAWT have been investigated using Particle Image Velocimetry and an Actuator Disk Method developed in OpenFOAM at low Reynolds number of Re ≈ 47 000 for four TSR values of 6, 5.5, 5 and 4.5. The wind tunnel measured mean velocity distributions along the rotor radius, for two TSR...

High-performances micromixers are widely used in various industrial applications. Mixing in the laminar regime and at low Reynolds numbers is of major importance in some processes. Implementing the physical phenomenon of chaotic advection to improve the mixing efficiency is a well-established technique, therefore, the secondary flows resulting from...

3D printing, an Additive Manufacturing process, comprises the construction of parts by the deposition of extruded filaments, while moving in successive X-Y planes toward Z direction to fabricate 3D parts layer-by-layer. Since filament adhesion relies on several parameters, it is necessary to investigate both experimentally and numerically the physi...

Filament adhesion in 3D printing relies on their temperature profile. It is crucial to evaluate this issue both experimentally and numerically. Using the proposed setup for in-process monitoring of temperature profile, our developed finite volume code indicated very good agreement for the obtained results.

High-performances micromixers are widely used in various industrial applications. Mixing in the laminar regime and at low Reynolds numbers is of major importance in some processes. Implementing the physical phenomenon of chaotic advection to improve the mixing efficiency is a well-established technique, therefore, the secondary flows resulting from...

In many industries, reducing the size of the compression system represents a significant goal for designers. In fact, increasing the power density of the compressor actually means lowering production costs. The chief purpose of this study is to compare, in terms of aerodynamic performances, a centrifugal compressor consisting of an impeller and a v...

Turbomachinery with double counter-rotating impellers offers more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more publications concerning axial type turbomachines are available than centrifugal ones. This work deals with a desig...

Efficient micromixers are largely used in different industrial applications. The mixing in laminar regime at low Reynolds numbers has a major significance in some processes. Exploiting the physical phenomenon of chaotic advection to improve the mixing efficiency is a well-established technique. This work consists in studying numerically the influen...

Purpose The purpose of this paper is the development of a new turbocharger compressor is a challenging task particularly when both wider operating range and higher efficiency are required. However, the cumbersome design effort and the inherent calculus burden can be significantly reduced by using appropriate design optimization approaches as an alt...

Centrifugal compressors are widely used in many industrial applications because of their advantages. However, these turbomachines suffer at a low-flow rate from instabilities, such as rotating stall and surge. That leads to operational failure, pressure fluctuations and vibrations of the thorough system. Many mechanical solutions minimize these ins...

In recent years, machine component design has been a major concern for researchers. Emphasis has been placed especially on the analysis of bearing systems in order to avoid detrimental contact. The shaft misalignment is one of the most problems that affects directly the operating conditions of these components. In this context, the present study pr...

In the present study, the static characteristics of hydrodynamic circular journal bearings of finite length are highlighted, using the combined influences of textured surface and non-Newtonian lubricants behavior, obeying to the Rabinowitsch fluid model. The associated nonlinear Rabinowitsch-Reynolds equation has been discretized using finite diffe...

In many industries, reducing the size of the compression system represents a significant goal for designers. In fact, increasing the power density of the compressor actually means lowering production costs. The chief purpose of this study is to compare, in terms of aerodynamic performances, a centrifugal compressor consisting of an impeller and a v...

A thorough understanding of the various parameters that affect the vertical axis wind turbine performance and lifespan will make design this model of turbine not difficult task. This article presents a study of the blade profile effect on the aerodynamic performance of a vertical axis wind turbineDarrieus H-rotor. A complete series of simulations b...

Purpose Fused deposition modeling (FDM) draws particular attention due to its ability to fabricate components directly from a CAD data; however, the mechanical properties of the produced pieces are limited. This paper aims to present the experimental aspect of multi-scale damage analysis and fatigue behavior of polylactic acid (PLA) manufactured by...

The present study focuses on the inception, the growth, and the potential unsteady dynamics of attached vapor cavities into laminar separation bubbles. A viscous silicon oil has been used in a Venturi geometry to explore the flow for Reynolds numbers ranging from Re = 800 to Re = 2000. Special care has been taken to extract the maximum amount of di...

In this work we present a δ-Smoothed Particle Hydrodynamics (SPH) scheme for weakly compressible flows with automatic adaptive numerical dissipation. The resulting scheme is a meshless self-adaptive method, in which the introduced artificial dissipation is designed to increase the dissipation in zones where the flow is under-resolved by the numeric...

Fused filament fabrication (FFF), which is an additive manufacturing technique, opens alternative possibilities for complex geometries fabrication. However, its use in functional products is limited due to anisotropic strength issues. Indeed, the strength of FFF fabricated parts across successive layers in the build direction (Z direction) can be s...

Fused filament fabrication, an additive manufacturing technique, is used to produce prototypes and a gradually more important processing route to get final products. Due to the layer-by-layer deposition mechanism involved, bonding between adjacent layers is controlled by the thermal energy of the material being printed. Thus, it is strongly in conj...

Turbomachinery with double counter-rotating impellers offer more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more published works are available concerning axial type turbomachines than centrifugal ones. This work deals with a pre...

This work deals with sound generation and transmission in a fan stage. The study is done on a subsonic Fan stage and interaction noise between the fan wakes and the Outlet Guide Vanes (OGV) is considered. For this purpose, the Linearized Euler Equations (LEE) are solved with a steady axisymmetric flow. The acoustic sources are modelled by a scatter...

High-order lattice Boltzmann (LB) models with pseu-dopotential interactions set a compelling case as a numerical method for solving the dynamics of non-ideal fluid mixtures. In this paper, purely fundamental study on high-order LB pseudopotential model capability to simulate non-ideal fluid mixtures is presented. The capability of this model for no...

Inducers in centrifugal pumps are generally placed upstream to increase the pressure before the impeller and prevent cavitation occurrence. Their general goal is to obtain a positive impact on the performances of a pump in a two-phase regime. Cavitation phenomenon has been the subject of many studies, however the influence of the presence of dissol...

Fused filament fabrication (FFF) is an additive manufacturing technique that is used to produce prototypes and a gradually more important processing route to obtain final products. Due to the layer‐by‐layer deposition mechanism involved, bonding between adjacent layers is controlled by the thermal energy of the material being printed, which strongl...