Numerical 3D flow simulation of cavitation at ultrasonic horns and assessment of flow aggressiveness, erosion sensitive wall zones and incubation time

Auteurs

• Stephan Mottyll

Paramètres

• Manuels
• Manuels universitaires

En savoir plus sur le livre

Cavitation erosion is closely related to the violent collapse of gaseous voids close to a solid surface, which results in high pressure loads at the material surface and ultimately in material damage. As a contribution to a better understanding of cavitation erosion mechanisms, a compressible inviscid finite volume flow solver with barotropic homogeneous liquid-vapor mixture cavitation model is applied to the standard erosion test case of an ultrasonic horn with stationary specimen that exhibits attached cavitation at the horn tip. Void collapses and shock waves, which are closely related to cavitation erosion, are resolved, whilst dispersed bubbles are neglected. The computational results are compared to measured data as hydrophone, shadowgraphy and pressure sensor data as well as erosion test data, i. e. material surface topography profiles and incubation time. For attached cavitation at the horn tip, cavity volume and topology, subharmonic oscillation frequency and amplitude of propagating pressure waves are in good agreement with experimental data. Erosion sensitive wall zones are numerically well predicted for both, horn tip and stationary specimen, and numerical erosion probability is in good qualitative agreement with measured topography profiles of eroded samples. For the stationary specimen ultrasonic horn case, the analysis of near-wall load collectives reveals that the tip-attached coherent cavity is mainly contributing to erosion damage. A distinctive erosive ring shape at the horn tip can be attributed to frequent breakdown and re-development of a small portion of the attached cavity at each driving cycle, whereas the stationary specimen is rather unfrequently stressed at the end of each subharmonic cycle by violent collapses of the entire attached cavity.

Achat du livre

• Année de publication: 2018