Jean-Gabriel Bauzin

SIMULTANEOUS ESTIMATION OF FRICTIONAL HEAT FLUX AND TWO THERMAL CONTACT PARAMETERS FOR SLIDING CONTACTS

In the dry friction between two solids in imperfect contact, the determination of temperature distribution within solids needs the knowledge of: (1) heat flux generated by friction, (2) thermal contact conductance, and (3) intrinsic heat partition coefficient. In this article, numerical study is conducted in order to estimate the values of these parameters from simulated temperatures. Numerical investigations and a sensitivity analysis are performed in order to show the feasibility and the needed conditions for an accurate estimation. In order to take into account the measurements noise, statistical investigations using a stochastic approach and Monte Carlo method are also performed.

Nu-Ra correlations for natural convection at high Ra numbers in air-filled tilted hemispherical cavities with dome oriented upwards. Disk submitted to constant heat flux

Purpose – The purpose of this paper is to propose correlations between Nusselt and Rayleigh numbers for the case of inclined and closed air-filled hemispherical cavities. The disk of such cavities is subjected to a constant heat flux. The study covers a wide range of Rayleigh numbers from 5×107 to 2.55×1012. Design/methodology/approach – Correlations are obtained from numerical approach validated by experimental measurements on some configurations, valid for several angles of inclination of the cavity between 0° (horizontal disk) and 90° (vertical disk) in steps of 15°. Findings – The statistical analysis of a large number of calculations leads to reliable results covering laminar, transitional and turbulent natural convection heat transfer zones. Practical implications – The proposed correlations provide solutions for applications in several fields of engineering such as solar energy, aerospace, building, safety and security. Originality/value – The new relations proposed are the first published for high...

Aerodynamical phenomena in a large top covered wind mill with vertical axis wind turbine

Purpose – The purpose of this paper is to examine the aerodynamical and air mass flow phenomena taking place in the channel of a modified version of one of the well-known Sistan wind mills, in order to improve its aerodynamic performance. Design/methodology/approach – The simulations are done by means of the finite volume method associated to the realizable k-e turbulence model. The computational domain consists in a rotating sub domain including the wind turbine equipped with nine blades and a fixed sub domain including the rest of the computational domain. Both are connected by means of a sliding mesh interface. Calculations are done for 8×105-4×106 Reynolds number range, corresponding to inlet velocities varying from 2 to 10 m s−1. Findings – The velocity fields are presented for the stopped and operating turbine (static and dynamic conditions). A careful examination of the aerodynamic phenomena is performed to detect potential vortices that could develop in the central cavity of the active assembly, a...

Aerodynamics in the open channel of the Sistan-type wind-mill with vertical axis wind turbine

Purpose The purpose of this paper is to examine the details of the air mass flow and aerodynamical phenomena across a channel containing a large vertical axis wind turbine. The considered model reproduces as closely as possible the real assembly of the Sistan-type wind-mill whose top is open. The technical results of this work could be used for the restoration and operation of this assembly whose historical and architectural values are recognized. Design/methodology/approach Several inlet velocities into the channel are considered, taking into account the possible local wind resources. Calculations corresponding to Reynolds number varying between 8×105 and 4×106 are made by means of the finite volume method and turbulence is treated with the realizable k-e model. The mesh consists of a fixed part associated to the contour of the channel, interfaced with a moving one linked to the turbine itself, equipped with nine partly filled wings. Findings The relative pressure and velocity fields are presented for various dynamic and static conditions. Calculation results clearly show that the vortex phenomena present in some cases are not a source of degradation of the wind turbine’s aerodynamical performances, given its location, intensity and rotation direction. Particular attention is devoted to the air mass flow and its distribution between the inlet and the outlet sections of the channel. Originality/value The present work provides technical information useful to consider the restoration and modernization of this installation whose architecture and technical performance are very interesting. This survey complements a previous one examining the aerodynamical phenomena occurring in a modified version of this assembly with a closed top channel.