Papers by Author: A. Ouibrahim

Abstract: Experiments were conducted on thin delta wings to investigate, for subsonic flow, the effect of both privileged apex angle values and the wing-fuselage interactions on the aerodynamic characteristics, i.e. the distribution of the defect pressure on the extrados, the drag and the lift coefficients. For this purpose, several delta wing models of various apex angle (β = 75, 80 and 85°) were realized and tested without and with fuselages of cylindrical form, with diameters of 20 and 30 mm, downstream the apex and appropriately disposed on the extrados. The impact of the apex angle as well as the interaction on the defect pressure were specially considered along the apex vortices where the pressure defect is usually maximum. The above mentioned effects were investigated via the variations of the mean velocity in the wind tunnel and the incidence (attack) angle.

Abstract: The hydrodynamic lubrication interest is still of great importance, so that more and more elaborated lubricants are considered. They, however, involve consequently more and more hydrodynamic complexity as a result of the rheological properties of the additives. In our case, we consider lubricants having viscoelastic properties described by a generalized Maxwell model used in the case of journal bearing lubrication. The complexity of the coupled associated equations (momentum and constitutive) to describe the hydrodynamic prevailing in such a geometry requires numerical solutions. Using the commercial Finite Volume software Fluent 6.3 together with an appropriate developed computational code, via UDF (User Defined Functions), we determine the pressure distribution as well as the flow velocity profile and the stress field in the core, the load bearing capacity developed and the attitude angle; all together with the effects of the viscoelastic lubricant parameters (relaxation time and shear viscosity).