The aim of the study is to describe the ambient conditions in an underground repository of nuclear waste over a 100-year-long operation period. The evolution over time of the moisture and the temperature in the ventilation network was assessed by means of numerical simulations. Condensation events are described in terms of location, frequency and flow rate. The physical conceptual model takes into account the heat and vapour advection and exchanges with walls, and heat conduction through the host rock. The results of simulations were analysed to highlight how the architectural design, the gradual extension of storage zones, the ventilation rate and the weather conditions are likely to influence the ambient conditions all along the shafts, the galleries and the storage modules. They illustrate the significant effects on ambient conditions of the wall thermal inertia, the variation in atmospheric pressure over the shaft height, and the ventilation partition in some galleries between incoming and outgoing air from storage modules.
The current understanding of periodic transonic flow is reviewed briefly. The effects of boundary-layer transition, non-adiabatic wall conditions and modifications to the aerofoil surface geometry at the shock interactions on periodic transonic flow are discussed. Through the methods presented, it is proposed that the frequency of periodic motion can be predicted with reasonable accuracy, but there are limitations on the prediction of buffet boundaries associated with periodic transonic flows. Several methods have been proposed by which the periodic motion may be virtually eliminated, most relevantly by altering the position of transition fix, contouring the aerofoils surface or adding a porous surface and a cavity in the region of shock interaction. In addition, it has been shown that heat transfer can have a significant effect on buffet.
The aim of the paper is to investigate numerically the effect of a DC positive corona discharge between two parallel wire electrodes of different diameter along an insulating aerofoil surface in low subsonic compressible flow. The modeling takes into account the two characteristic regions of the phenomenon: the corona sheath, surrounding the smaller diameter electrode, and the ion drift zone. The electric force is modeled by a simplified form of the electromagnetic tensor via the coupling between Electrostatic and Navier-Stokes equations. The corona discharge system is effective in preventing flow separation, reducing total aerofoil drag and enhancing the heat and mass transfer between aerofoil and the surrounding flow.
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