Experimental study of cavitation erosion around a surface mounted semi circular cylinder

Experimental study of cavitation erosion around a surface mounted semi circular cylinder

Jahangir, S. (TU Delft Fluid Mechanics)
Ghahramani, Ebrahim (Chalmers University of Technology)
Neuhauser, Magdalena (ANDRITZ Hydro)
Bourgeois, Sébastien (ANDRITZ Hydro)
Bensow, Rickard E. (Chalmers University of Technology)
Poelma, C. (TU Delft Multi Phase Systems)

2019

The objective of this study is to investigate the collapsing behavior of cavitation, which leads to erosion. For this purpose, an experimental investigation was performed in a channel with a semi-circular cylinder obstacle at the Hydraulic Laboratory of ANDRITZ HYDRO in Vevey. Cavitation was achieved by employing a range of pressure differences over the test section. The obstacle promotes and localizes cavitation-induced erosion. The flow field behind the semi-circular cylinder was investigated as a characteristic example of bluff bodies, which exhibit a distinct separated vortex flow in their wake. A high-speed camera observed the cavitation behavior. At the same time, erosion tests were performed using paint (stencil ink). The intensity of cavitation is described by the cavitation number (σ), the lower the cavitation number, the higher the cavitation intensity. Three erosive cases at different cavitation numbers are presented here. The erosion (removal of paint) after 40-60 mins of operation revealed distinct and repeatable results. These results will serve as validation data for numerical studies. For a high cavitation number, a large number of Karman-vortex-like cavities are shed downstream of the obstacle. This results in a higher number of collapse events and ultimately more erosion. On the other hand, at lower cavitation numbers the erosion took place at the closure line of the cavity. We demonstrate that paint tests in combination with this geometry provide an efficient and economical way to investigate erosion patterns compared to expensive material loss tests.

cavitation erosion
vortex shedding
semi-circular cylinder

http://resolver.tudelft.nl/uuid:f4b8d968-4018-414e-9ca3-fdd412d78b79

10th International Conference on Multiphase Flow (ICMF 2019)

10th International Conference on Multiphase Flow, 2019-05-19 → 2019-05-24, Rio de Janeiro, Brazil

Institutional Repository

conference paper

© 2019 S. Jahangir, Ebrahim Ghahramani, Magdalena Neuhauser, Sébastien Bourgeois, Rickard E. Bensow, C. Poelma