Thierry Lemenand - Academia.edu (original) (raw)
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Papers by Thierry Lemenand
Aps Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2002
The emulsification process in a vortex generating static mixer in turbulent flow is investigated.... more The emulsification process in a vortex generating static mixer in turbulent flow is investigated.This type of mixer generates coherent large-scale structures, enhancing momentum transfer in the bulk flow and hence providing favourable conditions for phase dispersion.The mixer design is based on curved baffles fixed on the tube walls that generate large-scale longitudinal vortices.The study focuses on the granulometric characterization of oil emulsions in water obtained with the static mixer. The stability of the emulsion is obtained by encapsulating of oil drops, and droplets are sized using optical microscopy. The mean size, size distribution, and power consumption are compared with those in some existing devices. The size distribution was modelled according to the method proposed by Schwarz and Bazemer. In a log-linear coordinate system the data showed a linear relation between the cumulative volume (in droplet diameters and the inverse of the bounding diameter d, showing this model is verified here. From the energy consumptin point of view, it was shown that in some range of interfacial areas this mixer is 1000 times more energy efficient than other mixers.
Chemical Engineering and Processing Process Intensification, Oct 1, 2009
International Journal of Thermal Sciences, Oct 1, 2010
International Journal of Multiphase Flow, 2003
Vortex generators are being increasingly incorporated in modern multifunctional heat exchanger / ... more Vortex generators are being increasingly incorporated in modern multifunctional heat exchanger / reactors due to their proven influence on heat and mass transfer enhancement. Longitudinal and transverse pressure-driven vortices and shear instability driven flow structures generated by flow separation behind the turbulence promoters play a crucial role in convective transport phenomena. The High Efficiency Vortex (HEV), an innovative static mixer and a low-energy consumption heat exchanger designed to exploit these vortices, is a circular tube equipped with several rows of four diametrically-opposite trapezoidal vortex generators each. The tabs are fixed at a 30º inclination angle with respect to the wall [1] (figure 1a). The pressure difference generated on the trapezoidal tab initiates a streamwise swirling motion in the form of two longitudinal counter-rotating vortex pairs (CVP). Moreover, owing to the Kelvin-Helmholtz instability, the shear layer generated at the tab edges serve...
Attempts to determine the energy spectrum (or spectral energy distribution) for all values of its... more Attempts to determine the energy spectrum (or spectral energy distribution) for all values of its wave number argument are a fundamental objective of turbulence theory. Detailed predictions of the energy spectrum are not yet possible for more than a very few classes of idealized flows. Nevertheless, to make practical headway, it is necessary to evolve a heuristic physical picture of turbulent flow. Of particular interest in partic1e-fluid interaction is the comparison of scale lengths in each region of the spectrum. When partic1e inertia can be neglected, the diffusion, energy-containing, and inertial subranges of the spectrum are of most interest. While the Kolmogorov theory on the energy cascade is useful for describing the energy processes in an idealized turbulent flow, its applicability to the prediction of turbulence is restricted to isotropic or homogeneous flows (or the isotropic portion of turbulent flows, namely the smaller-scale characteristics of the flow). Most practica...
Aps Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2002
The emulsification process in a vortex generating static mixer in turbulent flow is investigated.... more The emulsification process in a vortex generating static mixer in turbulent flow is investigated.This type of mixer generates coherent large-scale structures, enhancing momentum transfer in the bulk flow and hence providing favourable conditions for phase dispersion.The mixer design is based on curved baffles fixed on the tube walls that generate large-scale longitudinal vortices.The study focuses on the granulometric characterization of oil emulsions in water obtained with the static mixer. The stability of the emulsion is obtained by encapsulating of oil drops, and droplets are sized using optical microscopy. The mean size, size distribution, and power consumption are compared with those in some existing devices. The size distribution was modelled according to the method proposed by Schwarz and Bazemer. In a log-linear coordinate system the data showed a linear relation between the cumulative volume (in droplet diameters and the inverse of the bounding diameter d, showing this model is verified here. From the energy consumptin point of view, it was shown that in some range of interfacial areas this mixer is 1000 times more energy efficient than other mixers.
Chemical Engineering and Processing Process Intensification, Oct 1, 2009
International Journal of Thermal Sciences, Oct 1, 2010
International Journal of Multiphase Flow, 2003
Vortex generators are being increasingly incorporated in modern multifunctional heat exchanger / ... more Vortex generators are being increasingly incorporated in modern multifunctional heat exchanger / reactors due to their proven influence on heat and mass transfer enhancement. Longitudinal and transverse pressure-driven vortices and shear instability driven flow structures generated by flow separation behind the turbulence promoters play a crucial role in convective transport phenomena. The High Efficiency Vortex (HEV), an innovative static mixer and a low-energy consumption heat exchanger designed to exploit these vortices, is a circular tube equipped with several rows of four diametrically-opposite trapezoidal vortex generators each. The tabs are fixed at a 30º inclination angle with respect to the wall [1] (figure 1a). The pressure difference generated on the trapezoidal tab initiates a streamwise swirling motion in the form of two longitudinal counter-rotating vortex pairs (CVP). Moreover, owing to the Kelvin-Helmholtz instability, the shear layer generated at the tab edges serve...
Attempts to determine the energy spectrum (or spectral energy distribution) for all values of its... more Attempts to determine the energy spectrum (or spectral energy distribution) for all values of its wave number argument are a fundamental objective of turbulence theory. Detailed predictions of the energy spectrum are not yet possible for more than a very few classes of idealized flows. Nevertheless, to make practical headway, it is necessary to evolve a heuristic physical picture of turbulent flow. Of particular interest in partic1e-fluid interaction is the comparison of scale lengths in each region of the spectrum. When partic1e inertia can be neglected, the diffusion, energy-containing, and inertial subranges of the spectrum are of most interest. While the Kolmogorov theory on the energy cascade is useful for describing the energy processes in an idealized turbulent flow, its applicability to the prediction of turbulence is restricted to isotropic or homogeneous flows (or the isotropic portion of turbulent flows, namely the smaller-scale characteristics of the flow). Most practica...