Cavitation, due to its typically harmful effects (erosion, collapse of delivery, strong pressure fluctuations, noise), is an important yet inadequately understood phenomenon. In modeling cavitating flows, on one hand, bubble dynamic models are used that consider individual bubbles or clusters of interacting single bubbles based on the Rayleigh-Plesset equation. On the other hand, CFD methods are employed that assume a homogeneous mixture in each cell and are either linked to a thermodynamic model (compressible processes, thermodynamic equilibrium) or a simplified bubble dynamic cavitation model (volume fraction transport equation with source/sink term based on, for example, the Rayleigh equation). With sufficient spatial resolution, CFD methods are increasingly used for the detailed 3D representation of individual bubbles. The phase boundary and mass and heat transfer can be modeled in equilibrium or non-equilibrium.
In the development of CFD methods for cavitating flows, at HSM, compressible methods are further developed that accurately depict the dynamics of pressure waves, as only these methods can precisely predict erosion. Compressible methods are used in conjunction with an equation of state. Current developments aim to extend compressible methods to include bubble dynamics, as used in a simplified form (e.g., based on the Rayleigh equation) to determine the source and sink terms of volume fraction transport equations. Due to the high temporal and spatial resolution and the enormous computational effort, efficient, for example, implicit computational methods are being developed that allow the application of new cavitation models to real flows in hydraulic machines with sufficient accuracy. Another focus is on the scarcely researched area of cavitation in complex fluids, such as practically relevant fluid mixtures like fuels and hydraulic oils, which can behave quite differently from water.
Fluid- und Fertigungseinfluss auf Kavitation
Numerische Vorhersage von Kavitationserosion in Pumpen.
Vorhersage von Kavitationserosion in Dieselinjektoren für Schiffsmotoren.
3D Simulation der akustischen Kavitation und der Kavitationserosion in Sonotroden.
Einzelblasenmodellierung mit Luftausgasung.
Einfluss der thermophysikalischen Eigenschaften von Fluidgemischen auf Kavitation und Kavitationserosion.
Entwicklung von CFD-Verfahren für die Simulation kavitierender Strömungen in hydraulischen Strömungsmaschinen.
Einfluss des gelösten Luftgehaltes auf die Zwangsentgasung bei der Kavitation.
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Letzte Änderung: 24. Jul. 2024
