Abstract

In this study, a numerical approach for analyzing the internal status of Molten CoreConcrete Interaction (MCCI) has been developed based on Moving Particle Semi-implicit (MPS) method. Among the key required models, such as accurate viscosity interaction model for solidifying particles and interface tension models of different liquid phases, preliminary attempts have been made with new models. Namely, a simple mixing model and gas hosting particle model has been implemented to simulate the experiment with affordable calculation cost. The analysis results for VULCANO VF-U1 experiment have shown the possible mechanisms responsible for the characteristic distribution of the solidified metallic corium, which seemed to be highly dependent on the density of surrounding oxidic corium

Abstract

Within the paper production process, certain surface properties of the paper web, e.g. smoothness and gloss, are produced or modified by so-called calenders. This paper machine device consists of several rolls, which apply high pressure and temperature on the paper web. Calenders exhibit large widths up to more than 10 m. Therefore, it is challenging to precisely adjust the required mechanical forces in order to apply a defined line load across the entire width of the paper web. By making use of Voith’s Nipco technology, both line load and roll deflection are controlled by multiple pistons which can be individually adjusted. This is achieved by pressure oil injection. The piston works also as a hydrostatic bearing in such a way that a thin lubrication film is formed between the stationary piston head and the rotating roll shell. Additional oil is injected into the roll for cooling purposes. Within this paper we present an industry-related approach to take advantage of present-day Moving Particle Simulation (MPS) methods. Hereto, we used the commercial software Particleworks® for a numerical investigation of the flow phenomena within a calender roll. The focus of our investigation were the churning losses caused by the interaction between the rotating oil and the mounted piston head. For this purpose, simulations of different oil volumes were performed. The results show that the piston head has a clear impact on the flow field. Firstly, the oil is reflected in upstream direction, causing disturbances in the subsequent flow. Secondly, the oil which streams around the piston rod leads to the formation of a Kármán vortex street. Thirdly, a reduction of oil volume results in a reduction of the churning loss.