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[EN] This paper presents experimental and numerical studies to determine the particle size distributions (PSD) and concentrations in paint overspray. Two kinds of paint materials, solvent borne and water borne paints, both with and without manufactured nanomaterials (pigments), and an industrial spray gun were used. Different aerosol measuring techniques, namely the Spraytec Fraunhofer type particle sizer for micro-sized droplets in the spray jet and the Scanning Mobility Particle Sizer (SMPS) for nano particles in paint overspray were applied. It was found, that solvent borne clear coats create significantly higher number concentration of nano-sized droplets than the water borneprimers. Only small differences in PSD between paints with and without manufactured nanomaterials were found. Numerical simulations of droplet trajectories within the spray booth, for both micro and nano sized droplets, were carried out. Based on the experimental and numerical results, a representative particle size distribution (smaller than 1 μm) for the given spray gun was obtained. Effects of turbulence models on the particle deposition on targets, especially for submicron particles, have been analysed in detailed.

Die vorliegende Arbeit befasst sich mit der Isolationszuverlässigkeit und Lebensdauermodellierung für die Gehäusekonstruktion von Halbleitersensoren. Bei den untersuchten Gehäusekonstruktionen handelt es sich insbesondere um Stromsensoren, die auf der Messung des Magnetfeldes eines stromdurchflossenen Leiters basieren. Dabei werden spannungsinduzierte Fehlermechanismen und ihre Auswirkung innerhalb des Sensors diskutiert und ein Lebensdauermodell für den Sensor beschrieben, das auf dem Fehlermechanismus der anodischen Oxidation basiert.:1 THEORETISCHE GRUNDLAGEN DER SENSORKONSTRUKTION 1.1 Grundlagen der Isolationskoordination 1.2 Grundlagen der Sensorkonzeption 1.3 Stand der Technik 1.4 Aufgaben für die Gehäuseentwicklung 2 SPANNUNGSINDUZIERTE FEHLERMECHANISMEN 2.1 Teilentladung 2.2 Dielektrischer Durchbruch 2.3 Chemische Umsetzung von Si 2.4 Migrationsmechanismen 2.5 Leckstrom 3 LEBENSDAUERMODELLIERUNG 3.1 Beschleunigte Alterung 3.2 Modellfunktion für die Lebensdauer 3.3 Lebensdauerkalkulationen

[EN] For high-quality spray painting of small parts, a rotary bell atomizer with a narrow spray pattern is used in the automotive industry. The required unusual high shaping air flow rate yields in an atomization process predominated by a pneumatic atomization and rather than by a rotary atomization, called hybrid bell atomizer in this article. Numerical and experimental investigation on typical high-speed rotary bell atomizers, with rotation type of high rotational speed 40000-60000 rpm of the bell, were already successful demonstrated. For these high-speed rotary bell atomizer for painting bigger areas the ratio between tangential velocity at the bell edge and axial shaping air velocity at the bell edge is in the range of 0.8 and 4, depending on the process parameter. At the hybrid bell atomizer (10000-20000 rpm), this ratio is between 0.2 and 0.4. The first step of the present study includes the theoretical characterization of spray cone velocity profile using two definitions of swirl-number compared to experimental measurements of particle velocities using Laser-DopplerVelocimetry (LDV). This study was carried out on varying shaping air settings and rotational speeds. The results show that the the swirl of the main airflow field is dominated by the secondary airflow, which is induced coaxial in an angle of 45°. The influence of the circumferential speed of the bell cup on the swirl of the main airflow field plays a subordinate role, so the resulting spray pattern is only weakly influenced by the number of revolutions of the bell-cup. In the second step, the hybrid bell atomizer was examined numerically. In order to implement the hybrid atomization concept in the simulation correctly, methods for creating droplet initial conditions in the trajectory calculation was developed. The simulation results were verified through comparisons of calculated and measured velocity profiles inside the spray cone and calculated and measured film thickness distributions on the wo