In recent years, much attention has been given to hydrostatic/hybrid journal bearings in research due to their wide spread engineering applications, such as: high speed turbomachinery, machine tools spindles, cryogenic equipment, and precision grinding. However, the activity toward improved understanding of the flow regimes and the associated pressure pattern in the recess flow phenomena is still needed. The objective of this work is to provide an understanding of the influence of regime flow in recess on the pressure field of hydrostatic bearing flat pad fed by orifice restrictor and orifice inertia. 3D Reynolds averaged Navier Stokes equations with the SST-kω turbulence model are applied in order to investigate the effects of pressure supply, dynamic viscosity and recess depths on the pressure profile. The finite volume method implemented in the ANSYS-CFX software is used. To prove the robustness of CFD code, a comparison of the numerical results and the Reynolds equation is performed at very deep recess. The results exhibit very good agreements between CFD and Reynolds equation methods. On the other hand, the several cases treated in this work contribute also to analyze and to explain the main reasons providing the inertia and the Rayleigh effect in recess flow.

Significant progress in turbo-machinery's speed is made recently. To cope with that; many fluids having large differences in rheological properties are introduced as lubricant in hydrostatic bearing systems. The present study aims to improve the understanding of the pressure patterns within hydrostatic bearing flat pads according to different parameters. The main ones are the squeeze film velocity, the feeding pressure and the fluid viscosity. To consider efficiently, the influence of the turbulent and inertia effects numerical simulation are based on transient Navier-Stokes equations. The results of the present study confirm many patterns already mentioned by other authors, and also showed different flow behaviour in terms of vortex evolution according to the studied parameters combinations. This is part of a special issue featuring papers based on presentations given at the TurkeyTrib'15 Conference, which have been revised and extended before inclusion in Tribology -Materials, Surfaces & Interfaces.

Showerhead cooling process which consists of internal convective cooling and external film cooling of a turbine blade is investigated using ANSYS-CFX software. The aim of the present investigation is to provide a better understanding of the fundamental nature of showerhead cooling using the three dimensional Reynolds averaged Navier Stokes analysis. A numerical model has been developed to study the effects of coupled internal and external cooling of the leading edge for a semi-elliptical body shape with the SST k-ω model. This model consists of all internal flow passages and cooling hole rows at the leading edge. The numerical results obtained are discussed and compared with experimental data available in the literature. The results show that the cooling efficiency increases with the increase of the blowing ratio and the Mach number, therefore, the overall efficiency for the steel becomes less important compared to the plexiglas which has a low thermal conductivity.