https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Thu, 18 Jun 2026 04:59:27 GMT 2026-06-18T04:59:27Z http://hdl.handle.net/10985/9486 Performance gains provided by the use of a counter-rotating axial-flow fan with respect to a conventional rotor-stator stage WANG, Juan; RAVELET, Florent; BAKIR, Farid The adoption of counter-rotating stages for propellers, axial-flow pumps and low-speed fans has opened a way to design high performance and compact turbomachines in various industrial domains, leading to potentially high savings in energy consumption. Because of the reduction of rotational speed and a better homogenization of the flow downstream of the rear rotor, these machines may have very good aerodynamic performances. However, they are rarely used in subsonic applications, mainly due to poor knowledge of the aerodynamics in the mixing area between the two rotors, where very complex structures are produced by the interaction of highly unsteady flows. The purpose of the present work is to compare the global performances (static pressure rise and static efficiency) and the wall pressure fluctuations downstream of the first rotor for three different stages operating at the same point: a single subsonic axial-flow fan, a conventional rotor-stator stage and a counter-rotating stage that have been designed with in-house tools. The counter-rotating stage allows large savings of energy with respect to the other two systems, for lower rotation rates and by adjusting the distance between the two rotors, a solution with comparable wall pressure fluctuations levels for the three systems is found. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9486 2015-01-01T00:00:00Z WANG, Juan RAVELET, Florent BAKIR, Farid The adoption of counter-rotating stages for propellers, axial-flow pumps and low-speed fans has opened a way to design high performance and compact turbomachines in various industrial domains, leading to potentially high savings in energy consumption. Because of the reduction of rotational speed and a better homogenization of the flow downstream of the rear rotor, these machines may have very good aerodynamic performances. However, they are rarely used in subsonic applications, mainly due to poor knowledge of the aerodynamics in the mixing area between the two rotors, where very complex structures are produced by the interaction of highly unsteady flows. The purpose of the present work is to compare the global performances (static pressure rise and static efficiency) and the wall pressure fluctuations downstream of the first rotor for three different stages operating at the same point: a single subsonic axial-flow fan, a conventional rotor-stator stage and a counter-rotating stage that have been designed with in-house tools. The counter-rotating stage allows large savings of energy with respect to the other two systems, for lower rotation rates and by adjusting the distance between the two rotors, a solution with comparable wall pressure fluctuations levels for the three systems is found. http://hdl.handle.net/10985/8509 Étude expérimentale de l’écoulement et de l’interaction entre deux rotors contrarotatifs subsoniques NOURI, Hussain; BAKIR, Farid; RAVELET, Florent Recently, the need for smaller axial‐flow fans with high specific speeds leads to the design of counter‐rotating axial fans. The design of this type of machines, which have promising aerodynamic performances, suffers from a lack of knowledge about their aerodynamics. Counter‐rotating rotors, widely studied in aeronautics, are an effective alternative to conventional machines and offer many advantages: rotation ratio and diameter reduction, and high flexibility in use. However, a better understanding of their working and of the rotors interaction is required to enhance their design and to make them widely integrated in current applications. This experimental research work investigates on a ducted counter‐rotating stage designed with a home code, MFT based on an inverse design method for rotors and rotor‐stator stages, and to which a rapid and simple method is implemented to design the rear rotor. The study focuses on the effects of the rotation ratio and on the axial spacing between rotors. It highlights several aspects of the rotors interaction through global performance and local unsteady measurements. Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/8509 2014-01-01T00:00:00Z NOURI, Hussain BAKIR, Farid RAVELET, Florent Recently, the need for smaller axial‐flow fans with high specific speeds leads to the design of counter‐rotating axial fans. The design of this type of machines, which have promising aerodynamic performances, suffers from a lack of knowledge about their aerodynamics. Counter‐rotating rotors, widely studied in aeronautics, are an effective alternative to conventional machines and offer many advantages: rotation ratio and diameter reduction, and high flexibility in use. However, a better understanding of their working and of the rotors interaction is required to enhance their design and to make them widely integrated in current applications. This experimental research work investigates on a ducted counter‐rotating stage designed with a home code, MFT based on an inverse design method for rotors and rotor‐stator stages, and to which a rapid and simple method is implemented to design the rear rotor. The study focuses on the effects of the rotation ratio and on the axial spacing between rotors. It highlights several aspects of the rotors interaction through global performance and local unsteady measurements. http://hdl.handle.net/10985/10296 POD study of aerated cavitation in a venturi nozzle TOMOV, Petar; DANLOS, Amélie; RAVELET, Florent; SARRAF, Christophe; BAKIR, Farid; KHELLADI, Sofiane The fact of injecting bubbles into a cavitating flow influences typical cavitating behavior. Cavitation and aerated cavitation experiments has been carried out on a symmetrical venturi nozzle with convergent/divergent angles of 18 ◦ and 8 ◦ , respectively. A snapshot Proper Orthogonal Decomposition (POD) technique is used to identify different modes in terms of discharge flow velocity, pressure and injected quantity of air. The energy spectrum per given mode is also presented. The first four modes are outlined in the present paper for an aerated and non-aerated cavitating flows. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/10296 2015-01-01T00:00:00Z TOMOV, Petar DANLOS, Amélie RAVELET, Florent SARRAF, Christophe BAKIR, Farid KHELLADI, Sofiane The fact of injecting bubbles into a cavitating flow influences typical cavitating behavior. Cavitation and aerated cavitation experiments has been carried out on a symmetrical venturi nozzle with convergent/divergent angles of 18 ◦ and 8 ◦ , respectively. A snapshot Proper Orthogonal Decomposition (POD) technique is used to identify different modes in terms of discharge flow velocity, pressure and injected quantity of air. The energy spectrum per given mode is also presented. The first four modes are outlined in the present paper for an aerated and non-aerated cavitating flows. http://hdl.handle.net/10985/14640 Multiscale physicochemical characterization of a short glass fiber–reinforced polyphenylene sulfide composite under aging and its thermo-oxidative mechanism PEIYUAN, Zuo; SHIRINBAYAN, Mohammadali; TCHARKHTCHI, Abbas; FITOUSSI, Joseph; BAKIR, Farid In this paper, the thermo-oxidation for a short glass fiber–reinforced polyphenylene sulfide (PPS/GF) composite was experimentally and theoretically studied by a wide range of physicochemical and mechanical techniques. The accelerated thermal aging temperatures were fixed at 100°C, 140°C, 160°C, 180°C, and 200°C. Firstly, the results of weight loss under aging indicate the formation of volatile products because of chain scission of end groups. Also, Fourier-transform infrared spectroscopy (FTIR) results suggest that the formation and accumulation of carbonyl group arising from the formation of hydroperoxides in oxidative propagation process. In all cases of different thermal oxidation temperatures, it is hard to observe some significant change about the concentration of carbonyl group during the induction time. This induction time depends inversely on the oxidation temperature. Moreover, the cross-linking and chain scissions exist together according to the results of rheological results and it is easier to see the cross-linking phenomenon at the beginning of oxidation while the chain scissions are more pronounced, with the oxidation process developing further. In aspect of mechanical properties, σ max increases at the beginning of oxidation because of cross-linking, and subsequently, the σ max always decreases because of thermo-oxidation of the PPS matrix. In addition, the detailed thermo-oxidation processes are fully discussed in the end of this study. A mechanistic schema has been proposed to present different oxidation reactions of PPS polymer and then a kinetic model has been extracted from this mechanism. Afterwards, the model has been verified by experimental results at different temperatures. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/14640 2019-01-01T00:00:00Z PEIYUAN, Zuo SHIRINBAYAN, Mohammadali TCHARKHTCHI, Abbas FITOUSSI, Joseph BAKIR, Farid In this paper, the thermo-oxidation for a short glass fiber–reinforced polyphenylene sulfide (PPS/GF) composite was experimentally and theoretically studied by a wide range of physicochemical and mechanical techniques. The accelerated thermal aging temperatures were fixed at 100°C, 140°C, 160°C, 180°C, and 200°C. Firstly, the results of weight loss under aging indicate the formation of volatile products because of chain scission of end groups. Also, Fourier-transform infrared spectroscopy (FTIR) results suggest that the formation and accumulation of carbonyl group arising from the formation of hydroperoxides in oxidative propagation process. In all cases of different thermal oxidation temperatures, it is hard to observe some significant change about the concentration of carbonyl group during the induction time. This induction time depends inversely on the oxidation temperature. Moreover, the cross-linking and chain scissions exist together according to the results of rheological results and it is easier to see the cross-linking phenomenon at the beginning of oxidation while the chain scissions are more pronounced, with the oxidation process developing further. In aspect of mechanical properties, σ max increases at the beginning of oxidation because of cross-linking, and subsequently, the σ max always decreases because of thermo-oxidation of the PPS matrix. In addition, the detailed thermo-oxidation processes are fully discussed in the end of this study. A mechanistic schema has been proposed to present different oxidation reactions of PPS polymer and then a kinetic model has been extracted from this mechanism. Afterwards, the model has been verified by experimental results at different temperatures. http://hdl.handle.net/10985/17778 Modelling of sintering during rotational moulding of the thermoplastic polymers HAMIDI, A.; FARZANEH, Sedigheh; NONY, Fabien; ORTEGA, Zaida; MONZON, M.; TCHARKHTCHI, Abbas; BAKIR, Farid; KHELLADI, Sofiane This paper concerns the study of sintering phenomenon during rotational molding of polypropylene(PP),Polyvinylidenefluoride (PVDF) and Polymethyl methacrylate (PMMA). First, the coalescence (first step of sintering) of two grains has been followed. Bellehumeur’s model has been tested as a model to explain this phenomenon. In order to study the effect of neighboring grains on coalescence of two grains, a third grain has been put in contact with these two grains. For modeling the phenomenon in this case, Bellehumeur’s model has been modified by a geometric parameter called Farz Factor (FF), being this model validated by experimental test. Concerning densification, two different stages have been observed. In the first stage, before welding of the grains and formation of interphases between them, the grains are not stuck yet. The air trapped between the grains escapes through free ways between grains. This first step of densification is directly related to the coalescence where the density of the polymer varies very quickly. A new tridimensional model, based on a Body Centered Tetragonal (BCT) configuration, has been proposed to explain the densification during this first stage. In the second stage, the migration of air is controlled by diffusion. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/17778 2015-01-01T00:00:00Z HAMIDI, A. FARZANEH, Sedigheh NONY, Fabien ORTEGA, Zaida MONZON, M. TCHARKHTCHI, Abbas BAKIR, Farid KHELLADI, Sofiane This paper concerns the study of sintering phenomenon during rotational molding of polypropylene(PP),Polyvinylidenefluoride (PVDF) and Polymethyl methacrylate (PMMA). First, the coalescence (first step of sintering) of two grains has been followed. Bellehumeur’s model has been tested as a model to explain this phenomenon. In order to study the effect of neighboring grains on coalescence of two grains, a third grain has been put in contact with these two grains. For modeling the phenomenon in this case, Bellehumeur’s model has been modified by a geometric parameter called Farz Factor (FF), being this model validated by experimental test. Concerning densification, two different stages have been observed. In the first stage, before welding of the grains and formation of interphases between them, the grains are not stuck yet. The air trapped between the grains escapes through free ways between grains. This first step of densification is directly related to the coalescence where the density of the polymer varies very quickly. A new tridimensional model, based on a Body Centered Tetragonal (BCT) configuration, has been proposed to explain the densification during this first stage. In the second stage, the migration of air is controlled by diffusion. http://hdl.handle.net/10985/17836 Efficiency of bio- and socio-inspired optimization algorithms for axial turbomachinery design AIT CHIKH, Mohamed Abdessamed; BELAIDI, Idir; PARIS, José; DELIGANT, Michael; BAKIR, Farid; KHELLADI, Sofiane Turbomachinery design is a complex problem which requires a lot of experience. The procedure may be speed up by the development of new numerical tools and optimization techniques. The latter rely on the parameterization of the geometry, a model to assess the performance of a given geometry and the definition of an objective functions and constraints to compare solutions. In order to improve the reference machine performance, two formulations including the off-design have been developed. The first one is the maximization of the total nominal efficiency. The second one consists to maximize the operation area under the efficiency curve. In this paper five optimization methods have been assessed for axial pump design: Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Cuckoo Search (CS), Teaching Learning Based Optimization (TLBO) and Sequential Linear Programming (SLP). Four non-intrusive methods and the latter intrusive. Given an identical design point and set of constraints, each method proposed an optimized geometry. Their computing time, the optimized geometry and its performances (flow rate, head (H), efficiency (η), net pressure suction head (NPSH) and power) are compared. Although all methods would converge to similar results and geometry, it is not the case when increasing the range and number of constraints. The discrepancy in geometries and the variety of results are presented and discussed. The computational fluid dynamics (CFD) is used to validate the reference and optimized machines performances in two main formulations. The most adapted approach is compared with some existing approaches in literature. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17836 2018-01-01T00:00:00Z AIT CHIKH, Mohamed Abdessamed BELAIDI, Idir PARIS, José DELIGANT, Michael BAKIR, Farid KHELLADI, Sofiane Turbomachinery design is a complex problem which requires a lot of experience. The procedure may be speed up by the development of new numerical tools and optimization techniques. The latter rely on the parameterization of the geometry, a model to assess the performance of a given geometry and the definition of an objective functions and constraints to compare solutions. In order to improve the reference machine performance, two formulations including the off-design have been developed. The first one is the maximization of the total nominal efficiency. The second one consists to maximize the operation area under the efficiency curve. In this paper five optimization methods have been assessed for axial pump design: Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Cuckoo Search (CS), Teaching Learning Based Optimization (TLBO) and Sequential Linear Programming (SLP). Four non-intrusive methods and the latter intrusive. Given an identical design point and set of constraints, each method proposed an optimized geometry. Their computing time, the optimized geometry and its performances (flow rate, head (H), efficiency (η), net pressure suction head (NPSH) and power) are compared. Although all methods would converge to similar results and geometry, it is not the case when increasing the range and number of constraints. The discrepancy in geometries and the variety of results are presented and discussed. The computational fluid dynamics (CFD) is used to validate the reference and optimized machines performances in two main formulations. The most adapted approach is compared with some existing approaches in literature. http://hdl.handle.net/10985/17817 Numerical analysis of unsteady cavitating flow in an axial inducer CAMPOS–AMEZCUA, Rafael; CAMPOS–AMEZCUA, Alfonso; PALACIOS-GALLEGOS, Manuel; REY, Robert; BAKIR, Farid; KHELLADI, Sofiane This work presents the results of numerical simulation of unsteady cavitating flow through a two–bladed axial inducer. First, the analysis was carried out in a blade cascade, this two–dimensional simplified model, obtained from the studied axial inducer, was used as a test case. Later, the numerical simulations were extended to the original three-dimensional inducer. All numerical calculations were realized in cavitating flow regime. Initially, the results were obtained in steady state, and then in unsteady state. The main purpose of this study is to explore the local cavitation instabilities, such as alternate blade cavitation and rotating blade cavitation, which can appear in this type of devices when they work under certain operating conditions. The numerical results show that the fluid flow in the axial inducer is altered by the emergence of the cavitation. These vapor regions are formed, firstly near to the leading edge of each blade. The behavior of the cavitation depends on the operating conditions of the inducer, mainly by the flow rate and the suction pressure. The numerical simulation was performed using a commercial code based on a cell–centered finite–volume method. The cavitation model used for calculations assumes a thermal equilibrium between phases. It is based on the classical conservation equations of the vapor phase and a mixture phase, with mass transfer due to the cavitation appearing as a source and a sink term in the vapor mass fraction equation. The mass transfer rate is derived from a simplified Rayleigh–Plesset model for bubble dynamics. Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/17817 2015-01-01T00:00:00Z CAMPOS–AMEZCUA, Rafael CAMPOS–AMEZCUA, Alfonso PALACIOS-GALLEGOS, Manuel REY, Robert BAKIR, Farid KHELLADI, Sofiane This work presents the results of numerical simulation of unsteady cavitating flow through a two–bladed axial inducer. First, the analysis was carried out in a blade cascade, this two–dimensional simplified model, obtained from the studied axial inducer, was used as a test case. Later, the numerical simulations were extended to the original three-dimensional inducer. All numerical calculations were realized in cavitating flow regime. Initially, the results were obtained in steady state, and then in unsteady state. The main purpose of this study is to explore the local cavitation instabilities, such as alternate blade cavitation and rotating blade cavitation, which can appear in this type of devices when they work under certain operating conditions. The numerical results show that the fluid flow in the axial inducer is altered by the emergence of the cavitation. These vapor regions are formed, firstly near to the leading edge of each blade. The behavior of the cavitation depends on the operating conditions of the inducer, mainly by the flow rate and the suction pressure. The numerical simulation was performed using a commercial code based on a cell–centered finite–volume method. The cavitation model used for calculations assumes a thermal equilibrium between phases. It is based on the classical conservation equations of the vapor phase and a mixture phase, with mass transfer due to the cavitation appearing as a source and a sink term in the vapor mass fraction equation. The mass transfer rate is derived from a simplified Rayleigh–Plesset model for bubble dynamics. http://hdl.handle.net/10985/17775 Performance of hydrodynamic journal bearing under the combined influence of textured surface and journal misalignment: A numerical survey MANSER, Belkacem; BELAIDI, Idir; HAMRANI, Abderrachid; BAKIR, Farid; KHELLADI, Sofiane A wisely chosen geometry of micro textures with the favorable relative motion of lubricated surfaces in contacts can enhance tribological characteristics. In this paper, a computational investigation related to the combined influence of bearing surface texturing and journal misalignment on the performances of hydrodynamic journal bearings is reported. To this end, a numerical analysis is performed to test three texture shapes: square “SQ”, cylindrical “CY”, and triangular “TR”, and shaft misalignment variation in angle and degree. The Reynolds equation of a thin viscous film is solved using a finite differences scheme and a mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. Preliminary results are compared with benchmark data and are consistent with a positive enhancement in misaligned bearing performances (load carrying capacity and friction). The results suggest that the micro-step bearing mechanism is a key parameter, where the micro-pressure recovery action present in dimples located at the second angular part of the bearing (from 180° to 360°) can compensate for the loss on performances caused by shaft misalignment, while the micro-pressure drop effect at the full film region causes poor performances. Considering the right arrangement of textures on the contact surface, their contours geometries can have a significant impact on the performance of misaligned journal bearings, particularly at high eccentricity ratios, high misalignment degrees and when the misalignment angle α approaches to 0° or 180 °. Tue, 01 Jan 2019 00:00:00 GMT http://hdl.handle.net/10985/17775 2019-01-01T00:00:00Z MANSER, Belkacem BELAIDI, Idir HAMRANI, Abderrachid BAKIR, Farid KHELLADI, Sofiane A wisely chosen geometry of micro textures with the favorable relative motion of lubricated surfaces in contacts can enhance tribological characteristics. In this paper, a computational investigation related to the combined influence of bearing surface texturing and journal misalignment on the performances of hydrodynamic journal bearings is reported. To this end, a numerical analysis is performed to test three texture shapes: square “SQ”, cylindrical “CY”, and triangular “TR”, and shaft misalignment variation in angle and degree. The Reynolds equation of a thin viscous film is solved using a finite differences scheme and a mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. Preliminary results are compared with benchmark data and are consistent with a positive enhancement in misaligned bearing performances (load carrying capacity and friction). The results suggest that the micro-step bearing mechanism is a key parameter, where the micro-pressure recovery action present in dimples located at the second angular part of the bearing (from 180° to 360°) can compensate for the loss on performances caused by shaft misalignment, while the micro-pressure drop effect at the full film region causes poor performances. Considering the right arrangement of textures on the contact surface, their contours geometries can have a significant impact on the performance of misaligned journal bearings, particularly at high eccentricity ratios, high misalignment degrees and when the misalignment angle α approaches to 0° or 180 °. http://hdl.handle.net/10985/17849 Multi-scale analysis of the effect of loading conditions on monotonic and fatigue behavior of a glass fiber reinforced polyphenylene sulfide (PPS) composite ZUO, Peiyuan; BENEVIDES, R.C.; LARIBI, M.A.; SHIRINBAYAN, Mohammadali; TCHARKHTCHI, Abbas; FITOUSSI, Joseph; BAKIR, Farid In this paper, two kinds of PPS/GF composite samples (PPS-0°, PPS-90°) were prepared with two different fiber main orientations related to the injection direction. A wide range of their properties were discussed. Using DMTA analysis, it was shown that the PPS/GF composite under study obeyed the time-temperature equivalence principle. Moreover, Perez model was verified and gave a good estimation of the viscoelastic properties of the PPS/GF. Monotonic and fatigue behaviors and fatigue life of PPS/GF were investigated. Fiber's orientation, applied amplitude and loading frequency effects were emphasized. Self-heating effect on fatigue strength was also analyzed. SEM fracture surface observations allowed analyzing, at the local scale, the main deformation mechanisms occurring during mechanical loading. No evident damage development was observed for both monotonic and fatigue loading. PPS matrix plasticity appeared to be the predominant deformation mechanism until a semi-ductile or semi-brittle final failure depending on the loading conditions and local microstructure. Mon, 01 Jan 2018 00:00:00 GMT http://hdl.handle.net/10985/17849 2018-01-01T00:00:00Z ZUO, Peiyuan BENEVIDES, R.C. LARIBI, M.A. SHIRINBAYAN, Mohammadali TCHARKHTCHI, Abbas FITOUSSI, Joseph BAKIR, Farid In this paper, two kinds of PPS/GF composite samples (PPS-0°, PPS-90°) were prepared with two different fiber main orientations related to the injection direction. A wide range of their properties were discussed. Using DMTA analysis, it was shown that the PPS/GF composite under study obeyed the time-temperature equivalence principle. Moreover, Perez model was verified and gave a good estimation of the viscoelastic properties of the PPS/GF. Monotonic and fatigue behaviors and fatigue life of PPS/GF were investigated. Fiber's orientation, applied amplitude and loading frequency effects were emphasized. Self-heating effect on fatigue strength was also analyzed. SEM fracture surface observations allowed analyzing, at the local scale, the main deformation mechanisms occurring during mechanical loading. No evident damage development was observed for both monotonic and fatigue loading. PPS matrix plasticity appeared to be the predominant deformation mechanism until a semi-ductile or semi-brittle final failure depending on the loading conditions and local microstructure. http://hdl.handle.net/10985/17815 A New Hemodynamic Ex Vivo Model for Medical Devices Assessment MAUREL, Blandine; CHAI, Feng; MATON, Mickael; SOBOCINSKI, Jonathan; HERTAULT, Adrien; BLANCHEMAIN, Nicolas; HAULON, Stephan; LERMUSIAUX, Patrick; SARRAF, Christophe; BAKIR, Farid Introduction: In stent restenosis (ISR) remains a major public health concern with an increased morbidity, mortality and health-related costs. Drug-eluting stents (DES) have reduced ISR, but are associated with healing-related issues or hypersensitivity reactions, leading to an increased risk of late acute stent thrombosis. Evaluations of new DES are based on animal models or in vitro release systems which show several limitations. The role of flow and shear stress on endothelial cell and ISR has also been emphasized. The aim of this work was to design and first evaluate an original bioreactor, reproducing ex vivo hemodynamic and biological conditions similar to human conditions, to further evaluate new DES. Methods & Results: This bioreactor was designed to study up to 6 stented arteries connected in bypass, immersed in a culture box, in which circulated a physiological systolo-diastolic resistive flow. Two centrifugal pumps drove the flow. The principal pump generated pulsating flows by modulation of rotation velocity, and the second pump worked at constant rotation velocity, ensuring the counter pressure levels and backflows. The flow rate, the velocity profile, the arterial pressure and the resistance of the flow were adjustable. The bioreactor was placed in an incubator to reproduce a biological environment. A first experience of feasibility was realized over a period of 24 days. Three rat aortic thoracic arteries were placed into the bioreactor, immersed in cell culture medium change every 3 days, and with a circulating systole diastolic flux circulating among the entire experimentation. There was no infection, no leak. At the end of experimentation, a morphometric analysis was performed confirming the viability of the arteries. Conclusion: We design and patent an original hemodynamic ex vivo model to further study new DES and ISR. We will next validate this ex vivo model of ISR reproducing this experimentation with stented arteries. Once validated, this bioreactor will allow characterization of the velocity field and drug transfers within a stented artery with new functionalized DES, with experimental means not available in vivo. Another main point will be the reduction of animal experimentation, and the availability of first results of new DES in human tissues (human infra popliteal or coronary arteries collected during human donation). Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/17815 2015-01-01T00:00:00Z MAUREL, Blandine CHAI, Feng MATON, Mickael SOBOCINSKI, Jonathan HERTAULT, Adrien BLANCHEMAIN, Nicolas HAULON, Stephan LERMUSIAUX, Patrick SARRAF, Christophe BAKIR, Farid Introduction: In stent restenosis (ISR) remains a major public health concern with an increased morbidity, mortality and health-related costs. Drug-eluting stents (DES) have reduced ISR, but are associated with healing-related issues or hypersensitivity reactions, leading to an increased risk of late acute stent thrombosis. Evaluations of new DES are based on animal models or in vitro release systems which show several limitations. The role of flow and shear stress on endothelial cell and ISR has also been emphasized. The aim of this work was to design and first evaluate an original bioreactor, reproducing ex vivo hemodynamic and biological conditions similar to human conditions, to further evaluate new DES. Methods & Results: This bioreactor was designed to study up to 6 stented arteries connected in bypass, immersed in a culture box, in which circulated a physiological systolo-diastolic resistive flow. Two centrifugal pumps drove the flow. The principal pump generated pulsating flows by modulation of rotation velocity, and the second pump worked at constant rotation velocity, ensuring the counter pressure levels and backflows. The flow rate, the velocity profile, the arterial pressure and the resistance of the flow were adjustable. The bioreactor was placed in an incubator to reproduce a biological environment. A first experience of feasibility was realized over a period of 24 days. Three rat aortic thoracic arteries were placed into the bioreactor, immersed in cell culture medium change every 3 days, and with a circulating systole diastolic flux circulating among the entire experimentation. There was no infection, no leak. At the end of experimentation, a morphometric analysis was performed confirming the viability of the arteries. Conclusion: We design and patent an original hemodynamic ex vivo model to further study new DES and ISR. We will next validate this ex vivo model of ISR reproducing this experimentation with stented arteries. Once validated, this bioreactor will allow characterization of the velocity field and drug transfers within a stented artery with new functionalized DES, with experimental means not available in vivo. Another main point will be the reduction of animal experimentation, and the availability of first results of new DES in human tissues (human infra popliteal or coronary arteries collected during human donation).