Author(s): Zhiyong Dong; Xinming Cai; Chunsheng Ding
Linked Author(s): Zhiyong Dong
Keywords: Cavitation; Cavitation control by aeration; Air concentration; Pressure
Abstract: This experimental investigation was systematically conducted with the aid of a non- circulating water tunnel in the Hydraulics Laboratory at Zhejiang University of Technology in China. The test velocity is between 20m/s and 40m/s. The least air concentration to prevent cavitation erosion lies between 1. 7% and 4. 5% . Pressure waveforms with and without aeration within cavitation and cavitation erosion regions were measured. Time-averaged pressure profiles with and without aeration were compared. Pressure behaviors corresponding to least air concentration to prevent cavitation erosion within cavitation and cavitation erosion regions were analyzed. The experimental results show that pressure waveform with and without aeration within cavitation region of high velocity flow is stepped, and aeration remarkably increases pressure in this region, thus enhancing cavitation number of high velocity flow; concrete specimen has no any phenomenon of cavitation erosion although aerated high velocity flow greatly increases pressure within the cavitation region. However, serious cavitation erosion occurs though pressure of non-aerated high velocity flow is much lower than that of aerated high velocity flow; overall, time-averaged pressure in different velocities increases with enhancing in air concentration within cavitation erosion. Time- averaged pressure arisen from cavitation erosion is not always positive pressure
Year: 2005