The present study concerns the measurement of the convective heat transfer coefficient on the solid-fluid interface by the pulsed photothermal method. This non-intrusive technique is applied for the measurement of the local heat transfer coefficients in cooling of a rectangular slab that simulates an electronic component. The heat transfer coefficient is deduced from the evolution of the transient temperature induced by a sudden deposit of a luminous energy on the front face of the slab. In order to draw up the heat transfer cartography by a non-destructive tool, the infrared thermography has been used. Two inverse techniques for the identification of the heat transfer coefficient are presented here. The first one is based on the assumption that heat transfer coefficient remains constant during the pulsed experiment, and the second one considered it variable in space and time. The temporal and spatial evolutions are expressed as a constant heat transfer coefficient (h 0 ) multiplied by a function of time and space f(x,t). The function f is deduced from the resolution of the conjugated convection-conduction problem, by a control volume technique for the case of thermally thick sample. The results are given for different air velocities and deflection angles of the flow.
Improvement of the airfoil NACA 4415 aerodynamic performances by flow control using a passive technique was achieved in this study. Gothic-shaped vortex generators were added at the profile upper surface. Vortex Generators (VG) were used to avoid boundary layer separation at the profile trailing edge, thus reducing the drag force and improving aerodynamic performances. A numerical simulation with fluent code was performed. A parametric study was carried out to determine optimal disposition and dimensions of the VG. Six VG parameters were tested; thickness (E), height (H), length (L), aspect ratio (r), incidence angle (α) and the VG position relative to the chord of the profile (XVG). The results show an increase in the lift coefficient for the profile with vortex generators in the range of high attack angles. Optimal dimensions and positions of the VG were obtained.
The objective of the present study is the active flow control of blood in the aorta with atherosclerosis using an External Magnetic Field (EMF) in order to facilitate the blood flow. For that purpose, a numerical investigation has been developed with a Magneto-hydrodynamics flow modelisation. The blood is considered homogeneous, incompressible and Newtonian and the fluid flow is assumed to be unsteady, two-dimensional and laminar. The aorta tissue is electrically conductive. Fluent software has been used to solve the governing equations. The results relating to velocity, pressure and the wall shear stress indicate that the presence of the EMF considerably influences the blood flow. The flow control deals with the effects of the EMF direction of application and its intensity. The results show that by applying an EMF, the blood velocity and pressure in the aorta are entirely affected. The direction and the intensity of the EMF allow minimization of the flow instabilities due to the geometrical singularities. Therefore, applying an EMF can be considered an appropriate method for flow control in order to obtain a uniform blood circulation around the atherosclerosis.
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