High-speed optical imaging is introduced as a visualization method to investigate the film-flow properties of liquids with different surface tensions and viscosities (water, poly-alpha-olefin oil, and glycerol) over free rotating surfaces with different surface energies and polarities (steel, and two different diamond-like-carbon - DLC coatings, i.e. DLC, and F-DLC). It was found that the polar surface energy strongly influences the structural dynamics of the liquid film's flow and the film's slip. Namely, a decrease in the polar surface energy results in a less stable film with de-wetting areas and breakups into streams, as well as in a larger amount of film slip, which was most clearly expressed by the F-DLC. It was also found that the combination of a high surface tension and a low viscosity provides the largest amount of liquid slip, with the most obvious breakup of the liquid film being observed with water, which clearly exhibits these properties. Results presented in this paper are an important starting point for the work package (WP) 2, especially regarding the melt film formation on spinner wheels. Poor melt film adhesion and its inhomogeneous structure present one of the main obstacles in improving the efficiency and quality of mineral wool fiberization process on spinning machines.
COBISS.SI-ID: 15511579
In this paper, the industrial process of stone wool primary layer formation has been investigated. The blow-away airflow, collecting chamber suction pressure, and peripheral velocity of collecting member effects on primary layer area density have been investigated. Computer-aided visualization has been carried out simultaneously at two locations: the first one at the beginning of fibre accumulation, forming the primary layer, and the secondary one at the end of the formation zone. The mass attenuation coefficient was calculated for each operating point and then used to calculate the primary layer area density. It was determined that primary layer bulk density distribution and primary layer texture are significantly influenced by accumulation grid peripheral velocity and blow-away airflow. Interdependence of these parameters was accounted for by forming regression models that are in a very good agreement with measured data (R^2 ) 0.94). Results presented in this paper are an important starting point for the work package (WP) 4 (Mineral wool primary layer formation by fiber settling on the accumulation grid of the collecting chamber). In the paper, we have already partially developed methodogy for processing and evaluation of data, which will be obtained from experimental station developed in WP1, and from industrial environment. Consequently, WP4 can be executed in less time, which is additional assurance that all planned activities of this research project will be completed within predicted timeframe.
COBISS.SI-ID: 15545371