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Numerical and experimental study of the glass flow and heat transfer in the continuous glass fiber drawing process Chouffart, Quentin ; ; Terrapon, Vincent in Journal of Materials Processing Technology (2016) The manufacturing process of glass fibers used for the reinforcement of composite materials consistsin drawing a free jet of a molten glass at high temperature into fibers using a winder. This process is ... [more ▼] The manufacturing process of glass fibers used for the reinforcement of composite materials consistsin drawing a free jet of a molten glass at high temperature into fibers using a winder. This process is sensitive to numerous disturbances that can cause the fiber to break during the drawing process, and thus reduce the process efficiency. The underlying physics of the forming of a single fiber is investigated here through numerical simulations, and results are validated with measurements obtained on a dedicated experimental unit. Both a two-dimensional axisymmetric and a simplified one-dimensional model are used to simulate the high-temperature region before glass transition. The influence of key parameters and physical mechanisms on the internal stress is investigated through a sensitivity analysis. The simplified model is then used to identify the optimal operating window and to assess the impact of temperature inhomogeneities at the bushing plate. Results show that the initial region close to the tip is critical, and that a low cooling rate reduces the stress. Operating at high tip temperature, large drawing velocity and small tip radius is then found to be the best strategy to minimize the stress. Finally, it is shown that the heat pattern of the bushing plate is one of the most important causes for disturbance in the process. [less ▲] Detailed reference viewed: 43 (23 ULg)PIV-based estimation of unsteady loads on a flat plate at high angle of attack using momentum equation approaches Guissart, Amandine ; ; Dimitriadis, Grigorios et al Conference (2015, November 23) The direct measurement of loads with force balance can become challenging when the forces are small or when the body is moving. An alternative is the use of Particle Image Velocimetry (PIV) velocity ... [more ▼] The direct measurement of loads with force balance can become challenging when the forces are small or when the body is moving. An alternative is the use of Particle Image Velocimetry (PIV) velocity fields to indirectly obtain the aerodynamic coefficients. This can be done by the use of control volume approaches which lead to the integration of velocities, and other fields deriving from them, on a contour surrounding the studied body and its supporting surface. This work exposes and discusses results obtained with two different methods: the direct use of the integral formulation of the Navier-Stokes equations and the so-called Noca's method. The latter is a reformulation of the integral Navier-Stokes equations in order to get rid of the pressure. Results obtained using the two methods are compared and the influence of different parameters is discussed. The methods are applied to PIV data obtained from water channel testing for the flow around a 16:1 plate. Two cases are considered: a static plate at high angle of attack and a large amplitude imposed pitching motion. Two-dimensional PIV velocity fields are used to compute the aerodynamic forces. Direct measurements of dynamic loads are also carried out in order to assess the quality of the indirectly calculated coefficients. [less ▲] Detailed reference viewed: 52 (10 ULg)On some drawbacks and possible improvements of a Lagrangian Finite Element method for simulating incompressible flows Cerquaglia, Marco Lucio ; Deliège, Geoffrey ; Boman, Romain et al Conference (2015, September 28) Detailed reference viewed: 36 (10 ULg)On some drawbacks and possible improvements of a Particle Finite Element Method for simulating incompressible flows Cerquaglia, Marco Lucio ; Deliège, Geoffrey ; Boman, Romain et al Conference (2015, September 08) Detailed reference viewed: 74 (32 ULg)Using 2D-PIV measurements to compute unsteady aerodynamic loads on a flat plate at high angle of attack Guissart, Amandine ; ; Dimitriadis, Grigorios et al in Proceedings of the 16th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2015 (2015, June 30) This work exposes and discusses results obtained for aerodynamic forces using an indirect calculation based on Particle Image Velocimetry (PIV) measurements. The methodology used is based on the integral ... [more ▼] This work exposes and discusses results obtained for aerodynamic forces using an indirect calculation based on Particle Image Velocimetry (PIV) measurements. The methodology used is based on the integral formulation of the Navier-Stokes equations and is applied to spatio-temporal data for different flows around a plate with a 16:1 chord-to-thickness ratio at high angle of attack. Experimental data are obtained in a water channel for both a static and a pitching plate. In addition to PIV data, direct measurements of aerodynamic loads are carried out to assess the quality of the indirect calculation. It is demonstrated that this indirect method is able to compute the mean and the temporal evolution of the lift and drag coefficients with a reasonable accuracy. It is also shown that the noise sensitivity of the method can be partly alleviated through the use of Dynamic Mode Decomposition (DMD) as a pre-processing step to smooth the spatio-temporal data. [less ▲] Detailed reference viewed: 64 (20 ULg)Direct Numerical Simulation of Mixed Convection in Turbulent Channel Flow: On the Reynolds number dependency of momentum and heat transfer under unstable stratification Sid, Samir ; ; Terrapon, Vincent in Proceedings of the 8th International Conference on Computational Heat and Mass Transfer, ICCHMT 2015 (2015, May 27) Direct numerical simulations of unstably stratified turbulent channel flow have been performed in order to investigate the Reynolds number effect on mixed convection. Six different cases are considered ... [more ▼] Direct numerical simulations of unstably stratified turbulent channel flow have been performed in order to investigate the Reynolds number effect on mixed convection. Six different cases are considered with friction Reynolds number Re_\tau =180 and 395 and friction Richardson number Ri_\tau = 0, 100 and 1000. It is shown that both friction coefficient and Nusselt number increase under unstable stratification for a sufficiently large Richardson number. At low Richardson number, the friction coefficient can either increase or decrease depending on the Reynolds number. The drag reduction is associated with an increase of mean velocity due to an enhanced dissipation of Reynolds shear stress by pressure strain in the buffer region. The breakdown of the Reynolds analogy is demonstrated as the turbulent Prandtl number exhibits a non-constant behavior due to buoyancy. [less ▲] Detailed reference viewed: 85 (21 ULg)An efficient flamelet-based combustion model for compressible flows ; Terrapon, Vincent ; in Combustion and Flame (2015), 162(3), 652-667 A combustion model based on a flamelet/progress variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and ... [more ▼] A combustion model based on a flamelet/progress variable approach for high-speed flows is introduced. In the proposed formulation, the temperature is computed from the transported total energy and tabulated species mass fractions. Only three additional scalar equations need to be solved for the combustion model. Additionally, a flamelet library is used that is computed in a pre-processing step. This approach is very efficient and allows for the use of complex chemical mechanisms. An approximation is also introduced to eliminate costly iterative steps during the temperature calculation. To better account for compressibility effects, the chemical source term of the progress variable is rescaled with the density and temperature. The compressibility corrections are analyzed in an a priori study. The model is also tested in both Reynolds-averaged Navier–Stokes (RANS) and large-eddy simulation (LES) computations of a hydrogen jet in a supersonic transverse flow. Comparison with experimental measurements shows good agreement, particularly for the LES case. It is found that the disagreement between RANS results and experimental data is mostly due to the mixing model deficiencies and the presumed probability density functions used in the RANS formulation. A sensitivity study of the proposed model shows the importance of the compressibility corrections especially for the source term of the progress variable. [less ▲] Detailed reference viewed: 64 (9 ULg)On some drawbacks and possible improvements of a Lagrangian finite element approach for simulating incompressible flows Cerquaglia, Marco Lucio ; Deliège, Geoffrey ; Boman, Romain et al in Oñate, E.; Bischoff, M.; Owen, D.R.J. (Eds.) et al Proceedings of the IV International Conference on Particle-Based Methods – Fundamentals and Applications (2015) Detailed reference viewed: 45 (11 ULg)Implementation of the blade element theory to investigate the aerodynamic performance of a ducted fan UAV Guissart, Amandine ; ; Terrapon, Vincent et al Scientific conference (2015) Detailed reference viewed: 55 (22 ULg)On the role of pressure in elasto-inertial turbulence Terrapon, Vincent ; ; in Journal of Turbulence (2014), 16(1), 26-43 The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of ... [more ▼] The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 are used to study the formation and dynamics of elastic instabilities and their effects on the flow. Based on the splitting of the pressure into inertial and polymeric contributions, it is shown that the polymeric pressure is a non-negligible component of the total pressure fluctuations, although the rapid inertial part dominates. Unlike Newtonian flows, the slow inertial part is almost negligible in elasto-inertial turbulence. Statistics on the different terms of the Reynolds stress transport equation also illustrate the energy transfers between polymers and turbulence and the redistributive role of pressure. Finally, the trains of cylindrical structures around sheets of high polymer extension that are characteristics of elasto-inertial turbulence are shown to be correlated with the polymeric pressure fluctuations. [less ▲] Detailed reference viewed: 91 (18 ULg)Numerical Investigation of Cooling in the Continuous Fiber Glass Drawing Process Chouffart, Quentin ; ; Terrapon, Vincent in Proceedings of the 15th International Heat Transfer Conference (2014, August) The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through an array of thousands of small orifices (i.e., the ... [more ▼] The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through an array of thousands of small orifices (i.e., the bushing plate) into fibers using a winder. This process is sensitive to numerous disturbances that can cause a fiber to break during the drawing process. This paper analyzes how the stress in the fiber depends on the controlling parameters of the process. The approach relies on numerical simulations and sensitivity analysis. Both a semi-analytical one-dimensional model and a more complex two-dimensional axisymmetric model are used. It is first found that radial variations across the fiber are small compared to changes in the axial direction and that the one-dimensional approximation is accurate enough to describe the major trends in the process. Sensitivity analyses on some physical parameters controlling the heat transfers and on process parameters are then performed to identify strategies to reduce the axial stress. In particular, it is shown that, for a given fiber diameter, the stress is minimized if the glass melt temperature and the drawing velocity are increased. This approach is then applied to quantify the effect of inhomogeneous heat patterns on a bushing plate with a large number of fibers. [less ▲] Detailed reference viewed: 137 (32 ULg)Numerical Investigation of Continuous Fiber Glass Drawing Process Chouffart, Quentin ; ; Terrapon, Vincent Conference (2014, May 30) The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through the bushing plate into fibers using a winder. This ... [more ▼] The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing a glass melt at high temperature through the bushing plate into fibers using a winder. This process is sensitive to numerous disturbances that can cause the fiber to break during the drawing process. In order to understand the origin of these failures and improve the process efficiency, it is important to understand the physics of the forming fiber. We investigate here the underlying physics of the forming of a single fiber through numerical simulations. In particular, we focus on the region from the hole tips at the bushing plate to the glass transition point. The influence of key parameters (e.g. operating windows, and heat transfers mechanisms) on the fiber radius attenuation and the internal stresses is investigated through a sensitivity analysis. In addition, the impact of the temperature variations at the bushing plate is investigated. Finally, we show how the forming stress is influenced by these parameters. It is found that the internal stress can be minimizing by varying the operating windows. On the other hand, results also demonstrate that the heat pattern of the bushing plate is one of the most important causes for disturbance in the process. [less ▲] Detailed reference viewed: 60 (8 ULg)Using POD and DMD for comparing CFD and experimental results in unsteady aerodynamics Guissart, Amandine ; Andrianne, Thomas ; Dimitriadis, Grigorios et al Conference (2014) Detailed reference viewed: 61 (14 ULg)Elasto-inertial turbulence in polymeric flows Terrapon, Vincent ; ; Conference (2013, November 26) The dynamics of elasto-inertial turbulence (EIT) is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations ... [more ▼] The dynamics of elasto-inertial turbulence (EIT) is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 are used to study the formation and dynamics of elastic instabilities and their effects on the flow. Based on the splitting of the pressure into inertial and polymeric contributions, it is shown that the trains of cylindrical structures around thin sheets of high polymer extension that are characteristics to elasto-inertial turbulence are mostly driven by polymeric contributions. [less ▲] Detailed reference viewed: 21 (7 ULg)On the mechanism of elasto-inertial turbulence ; Terrapon, Vincent ; in Physics of Fluids (2013), 25(110817), 1-16 Elasto-inertial turbulence (EIT) is a new state of turbulence found in inertial flows with polymer additives. The dynamics of turbulence generated and controlled by such additives is investigated from the ... [more ▼] Elasto-inertial turbulence (EIT) is a new state of turbulence found in inertial flows with polymer additives. The dynamics of turbulence generated and controlled by such additives is investigated from the perspective of the coupling between polymer dynamics and flow structures. Direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 (based on the bulk and the channel height) are used to study the formation and dynamics of elastic instabilities and their effects on the flow. The flow topology of EIT is found to differ significantly from Newtonian wall-turbulence. Structures identified by positive (rotational flow topology) and negative (extensional/compressional flow topology) second invariant Qa isosurfaces of the velocity gradient are cylindrical and aligned in the spanwise direction. Polymers are significantly stretched in sheet-like regions that extend in the streamwise direction with a small upward tilt. The Qa cylindrical structures emerge from the sheets of high polymer extension, in a mechanism of energy transfer from the fluctuations of the polymer stress work to the turbulent kinetic energy. At subcritical Reynolds numbers, EIT is observed at modest Weissenberg number (Wi, ratio polymer relaxation time to viscous time scale). For supercritical Reynolds numbers, flows approach EIT at large Wi. EIT provides new insights on the nature of the asymptotic state of polymer drag reduction (maximum drag reduction), and explains the phenomenon of early turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian flows observed in some polymeric flows. [less ▲] Detailed reference viewed: 161 (28 ULg)Dynamics of Elasto-Inertial Turbulence in Flows with Polymer Additives Terrapon, Vincent ; ; in Proceedings of the 8th International Symposium on Turbulence and Shear Flow Phenomena (TSFP-8) (2013, August 30) The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of ... [more ▼] The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 are used to study the formation and dynamics of elastic instabilities and their effects on the flow. Based on the splitting of the pressure into inertial and polymeric contributions, it is shown that the trains of cylindrical structures around sheets of high polymer extension that are characteristics to elasto-inertial turbulence are mostly driven by polymeric contributions. [less ▲] Detailed reference viewed: 64 (13 ULg)Torsional flutter of bluff bodies Terrapon, Vincent ; Guissart, Amandine ; Andrianne, Thomas et al Scientific conference (2013, July 15) Detailed reference viewed: 49 (18 ULg)Numerical and experimental investigation of fiber drawing process Chouffart, Quentin ; ; Terrapon, Vincent Conference (2013, July 05) The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing liquid glass at high temperature into fibers. This process is very complex and sensitive to ... [more ▼] The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing liquid glass at high temperature into fibers. This process is very complex and sensitive to numerous disturbances that can cause the breaking of the forming fibers. Breaks have a strong negative impact on the process efficiency. It is thus very important to understand the mechanisms of fiber breaking in order to optimize the manufacturing process. As a first step towards elucidating the causes of these failures, we investigate here the underlying physics of the forming of a single fiber through numerical simulations. In particular, we focus on the region from the hole tips at the bushing plate to the glass transition point. The influence of key parameters (e.g., glass flow rate, drawing velocity, external environment, glass properties) on the fiber radius attenuation and the internal stresses is investigated through a sensitivity analysis. Finally, these numerical studies are compared with experimental data measurements obtained from a dedicated fiberization unit for a single fiber. These experimental results also serve as additional insight into the forming process and as validation of the physical models, such as glass rheology or heat transfers. Comparisons between numerical and experimental results show a good agreement and demonstrate that simulations can provide a useful tool to gain insight into the underlying physics and to devise new strategies for adjusting the process operating window. [less ▲] Detailed reference viewed: 94 (22 ULg)Using Proper Orthogonal Decomposition and Dynamic Mode Decomposition Methods for Comparing CFD Results Experimental Measurements Guissart, Amandine ; Andrianne, Thomas ; Dimitriadis, Grigorios et al in Proceedings of the 15th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2013 (2013, June 26) A method for the quantitative comparison of numerical and/or experimental data of unsteady aerodynamics around static and oscillating bodies is introduced. It is based on Proper Orthogonal Decomposition ... [more ▼] A method for the quantitative comparison of numerical and/or experimental data of unsteady aerodynamics around static and oscillating bodies is introduced. It is based on Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) to extract the dominant structures of the unsteady flow. The proposed method is applied to spatio-temporal data for the flow around a 4:1 rectangular cylinder. Exper- imental data are obtained from wind tunnel testing and two dimensional Time-resolved Particle Image Velocimetry (Tr-PIV) measurements, while unsteady Reynolds Averaged Navier-Stokes (uRANS) are used to compute numerical results. It is demonstrated that the two approaches are complementary and represent a powerful tool that enables the analysis and the quantitative comparison of the main spatial (POD) and temporal (DMD) characteristics of unsteady aerodynamic data. [less ▲] Detailed reference viewed: 188 (55 ULg)Numerical investigation of continuous fiber glass drawing Chouffart, Quentin ; ; Terrapon, Vincent in Idelsohn, Sergio R; Papadrakakis, Manolis; Schrefler, Bernhard A (Eds.) Proceedings of the V International Conference on Computational Methods for Coupled Problems in Science and Engineering (2013, June) The physics of glass fiber drawing is studied through numerical simulations and experimental measurements, with a focus on the fluid region, from the hole tip at the bushing plate to the glass transition ... [more ▼] The physics of glass fiber drawing is studied through numerical simulations and experimental measurements, with a focus on the fluid region, from the hole tip at the bushing plate to the glass transition point. The influence of the different heat transfer mechanisms is investigated to understand their respective impact on fiberization, such as fiber radius attenuation and internal stresses. Numerical predictions are then compared to experimental data measurements obtained from a dedicated fiberization unit. Numerical and experimental results show a good agreement. In particular, it is found that the ambient air temperature and the radiation have an important impact on the fiber cooling rate. Moreover, for a prescribed fiber diameter, internal stresses are lower when operating at a higher temperature. [less ▲] Detailed reference viewed: 144 (33 ULg) |
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