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Guo Z.,Shanxi Water Technical Professional College | Guo Z.,Zhejiang University of Technology | Dong Z.,Zhejiang University of Technology
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

The behavior of cavitation bubble wall pressure under the influence of aeration bubble of different radii is studied to consider the effects of vapor and noncondensable gas inside a cavitation bubble and the effects of air inside an aeration bubble in this study. Dynamical models for interaction of these two bubbles in viscous compressible liquid are developed, and coupling equations are used for description of the effects of aeration bubble on the cavitation bubble. Calculations indicate that with a given initial radius of the aeration bubble, the maximum collapsing pressure on the wall of cavitation bubble increases when its air content is reduced. As the initial radius is increased, this maximum pressure temporally climbs up and then declines, resulting in a peak value. This means that if collapsing in a higher pressure region, the cavitation bubble would be prevented from excessive compression and its capacity of cavitation erosion be lowered. Therefore, in terms of bubble interaction behavior, the radius of aeration bubble has an optimum value, which is valuable to cavitation control by aeration. © right. Source


Han W.,Zhejiang University of Technology | Dong Z.,Zhejiang University of Technology | Guo Z.,Zhejiang University of Technology | Guo Z.,Shanxi Water Technical Professional College
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

Effective air concentration was experimentally studied on a non-circulating water tunnel with advanced measurement instruments. This paper presents an analysis on the dependence of cavitation number on flow velocity and aeration air content, and develops a relationship between effective air concentration and flow velocity. The results would provide a technical support to design of large discharge structures. © right. Source


Guo Z.,Shanxi Water Technical Professional College | Guo Z.,Zhejiang University of Technology | Dong Z.,Zhejiang University of Technology
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

In this paper, an impulse pressure equation was developed for bubble collapsing in areated flows on the basis of bubbly dynamics, and the behaviors of bubble collapse were studied and simulated by varying the parameters of flow velocity, air concentration and cavitation number, with the effects of these parameters examined. It is shown that the calculated cavitation curves at different flow velocities and different air concentrations agree well with the experimental results. And for a fixed flow velocity, cavitation number increases with air concentration, weakening the flow's capability of cavitating erosion. Such an increase is greater at lower flow velocity than that at higher flow velocity. Higher flow velocity generally leads to lower air concentration and smaller cavitation number. Source


Guo Z.,Shanxi Water Technical Professional College | Guo Z.,Zhejiang University of Technology | Dong Z.,Zhejiang University of Technology
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

This paper develops an equation of energy conservation for cavitation flow region based on the equations of cavitation bubble and bubble motion. For the cavitation region behind cylindrical irregularity, numerical simulations are presented to demonstrate the effects of cavitation under two different flow velocities. An experiment was conducted in an open-loop water tunnel to test a cylindrical irregularity of 5 mm high and 6 mm in bottom diameter under the condition of flow aeration by an aeration hole of 5 mm in diameter. The results indicate that bubble radius gradually decreases with increase of air concentration at a fixed flow velocity while it becomes smaller if air concentration is higher at the higher flow velocity. Cavitation number for a fixed velocity increases with air concentration, and the peak cavitation number at the lower velocity is larger than that at the higher velocity. The experimental and numerical results agree very well. Source


Wang H.-X.,Taiyuan University of Technology | Wang H.-X.,Shanxi Water Technical Professional College | Chen J.-J.,Taiyuan University of Technology
Advances in Intelligent and Soft Computing | Year: 2012

On the basis of analyzing the newly time sequence research achievement nowadays, this paper addresses the problem of the whole event sequences matching, a type of sequence matching that retrieves and matching the occurrences patterns from chaotic and nonlinear event sequences. In this paper, several definitions on event relativity are put forward, 3-tuple is employed to present the event, the chain table is developed to describe the event sequence, and the whole similarity sequence matching model for the compact storage of the event sequence is presented, and then it is analysis. In this paper, we first given the definition of event sequences and then propose a 3-tuple method to descript events and employs chain tables to storage them. © 2012 Springer Science+Business Media Dordrecht. Source

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