Mathematische Modellierung einer elektrostatischen Einölmaschine

Abstract

This diploma thesis deals with the mathematical modeling of the electrostatic spraying process in an industrial oiling machine. It is used to oil continuous steel strips on both sides. A typical electrostatic oiler consists of two oiling blades supplied with high voltage. Oil is pumped to these blades where it is atomized and sprayed on the strip surface due to the high electric field strength. A numerical model of the spraying process is developed in ANSYS Fluent which includes the electric field, the oil droplet trajectories and the air flow due to the movement of the droplets and the strip. In contrast to other works, a droplet breakup model is included which describes the breakup due to the charge carried by the droplets and due to the drag force. The model is validated using measurement data of an industrial oiling machine. Furthermore, the plausibility of the model is checked using the Rayleigh limit for the droplet size. The model captures the dependence of the oil droplet trajectories on the voltage, the amount of oil, the air flow, and the distance between the blade and the strip. The model can be used in simulations to give a valuable process insight for operators and researchers and to identify optimization possibilities. The negative effect of an inclined oiler blade on the oil distribution on the strip is discussed in more detail and some improvements are proposed.