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In order to overcome classic polishing techniques, a novel hydrodynamic radial polishing tool (HyDRa) is presented; it is useful for the corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. This tool enables the work on flat or curved surfaces of currently up to two and a half meters in diameter. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The functioning principle is based on the generation of a high-velocity, high-pressure, abrasive emulsion flux with radial geometry. The polishing process is repeatable by means of the control of the tool operational parameters, achieving high degrees of precision and accuracy on optical and semiconductor surfaces, with removal rates of up to 9 mm3/hour and promising excellent surface polishing qualities. An additional advantage of this new tool is the possibility to perform interferometric measurements during the polishing process without the need of dismounting the working surface. A series of advantages of this method, numerical simulations and experimental results are described.

Heat transfer enhancement technologies have witnessed a rapid growth in recent years. Passive process intensification methods are a very effective tool to reduce the size of heat exchanger equipment or to enhance the capacity of existing units. This is achieved by means of turbulence promoters of different geometries. This turbulence promoter affects the heat transfer process and the pressure drop. In this paper, turbulence promoters used under turbulent regime are analyzed based on the thermal improvement factor (η). This factor gives an indication of the improvement in heat transfer and pressure drop and provides the means for a reliable performance comparison and selection.