Vortex Cavitation

by Prof. Hitoshi Soyama (Tohoku University, Sendai, Japan)

Tuesday 19 Mar 2024, 09:30 → 10:30 Europe/Berlin

XHQ / E1.173 (European XFEL )

As impact at cavitation collapse causes severe erosion, cavitation is harmful phenomenon for hydraulic machineries. However, the cavitation impact can be utilized for enhancement of materials properties which is named as “cavitation peening” [1,2] and water treatment. The microjet mode collapsing of “a spherical bubble” is a very interesting and well-known phenomenon [3]. However, “vortex cavitation” is more aggressive and useful for practical applications [4]. Vortex cavitation is a type of hydrodynamic cavitation that occurs in vortex flows. At the seminar, the following subjects are introduced and discussed. 

(1) Type of hydrodynamic cavitation which causes severe erosion in hydraulic machineries is visualized by visible light. The cavitation aspect and beneficial effect of cavitation impacts such as cavitation peening are also introduced. 

(2) Luminescence intensity of hydrodynamic cavitation is closely related to vortex cavitation and sound pressure at vortex cavitation collapsing region [4]. 

(3) The frequency of severe impact is a few hundredths of the number of vortex cavitation generated (Fig. 38 in [1]). 

(4) Aspects of vortex cavitation were visualized using high-speed X-ray imaging at SPring-8 and European XFEL. It was discovered that vortex cavitation in a Venturi tube consisted of angulated rather than spherical bubbles [5]. 

 

[1] H. Soyama and A. M. Korsunsky, A Critical Comparative Review of Cavitation Peening and Other Surface Peening Methods, Journal of Materials Processing Technology, Vol. 305, (2022), 117586.

[2] H. Soyama, et al., Comparison of the effects of submerged laser peening, cavitation peening and shot peening on the improvement of the fatigue strength of magnesium alloy AZ31, Journal of Magnesium and Alloys, Vol. 11, (2023), pp. 1592-1607. 

[3] M.S. Plesset and R.B. Chapman, Collapse of an initially spherical vapour cavity in neighbourhood of a solid boundary. Journal of Fluid Mechanics, Vol. 47, (1971), pp. 283–290. 

[4] H. Soyama, Luminescence intensity of vortex cavitation in a Venturi tube changing with cavitation number, Ultrasonics Sonochemistry, Vol. 71, (2021), 105389. 

[5] H. Soyama, et al., Revealing the Origins of Vortex Cavitation in a Venturi Tube by High Speed X-Ray Imaging, Ultrasonics Sonochemistry, Vol. 101, (2023), 106715. 

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