Πλοήγηση ανά Συγγραφέα "Sideridis, A."
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Τεκμήριο Development of a ball valve with PVD-coated Metal-to-Metal sealing mechanism(2012) Bouzakis, K. D.; Klocke, F.; Tsouknidas, A.; Kombogiannis, S.; Missirlis, D.; Vlahostergios, Z.; Sideridis, A.; Yakinthos, K.Conventional ball valves are based on elastomeric sealing technologies which exhibit restricted wear resistance in the presence of network impurities while requiring high operating torques. In the described investigations, the elastomeric sealing of a 2-inch floating ball valve was replaced by a metal-to-metal seating for attaining specific application requirements, without major dimensional changes. In order to avoid the use of elastomerics and achieve a high performance rating of the valve (Class VI shut-off), computational fluid dynamics (CFD) simulations were employed to predict the optimum contact geometry of ball/seating.A high accuracy contact was obtained through precision turning of the hardened metal shell (ball seating) and by grinding of its counter ball body. Both components, ball and seating, were appropriately heat treated and subsequently coated with a nanostructured diamond like carbon (DLC) coating, applied by physical vapour deposition (PVD) techniques, providing superior surface strength characteristics and nearly frictionless operation.Nanoindentations provided information regarding the coatings properties, while nanoimpacts were employed to determine the impact abrasive wear of the developed components.Τεκμήριο Modelling Operation of System of Recuperative Heat Exchangers for Aero Engine with Combined Use of Porosity Model and Thermo-Mechanical Model(2012) Yakinthos, K.; Missirlis, D.; Sideridis, A.; Vlahostergios, Z.; Seite, O.; Goulas, A.The present work describes an effort to model the operation of a system of recuperative heat exchangers of an aero engine for real engine operating conditions. The modelling was performed with the combined use of a porous medium model and a thermo mechanical model. The porous medium model was taking into account the heat transfer and pressure loss behaviour of the heat exchangers while the thermo mechanical one was used for the calculation of the wall temperature distribution of the elliptic tubes of the heat exchangers. As it is presented, the combined use of these models can provide a useful tool which can help in the prediction of the macroscopic behaviour of the system of recuperative heat exchangers of the aero engine which can be used for optimization purposes and numerical studies.