Using a nonlinear sound wave equation for a bubbly liquid in conjunction with an equation for bubble pulsation, we theoretically predict and experimentally demonstrate the appearance of a gap in the frequency spectrum...Using a nonlinear sound wave equation for a bubbly liquid in conjunction with an equation for bubble pulsation, we theoretically predict and experimentally demonstrate the appearance of a gap in the frequency spectrum of a sound wave propagating in a cavitation cloud comprising bubbles. For bubbles with an ambient radius of 100μm, the calculations reveal that this gap corresponds to the phenomenon of sound wave localization. For bubbles with an ambient radius of 120 μm, this spectral gap is related to a forbidden band of the sound wave. In the experiment, we observe the predicted gap in the frequency spectrum in soda water. However, in tap water, no spectral gap is present because the bubbles are much smaller than 100μm.展开更多
The unsteady behaviors of cloud cavitating flow would lead to structural vibration and deformation that conversely affect its development. The present paper aims to preliminarily discuss the influences of structural v...The unsteady behaviors of cloud cavitating flow would lead to structural vibration and deformation that conversely affect its development. The present paper aims to preliminarily discuss the influences of structural vibration on the development of the cavitating flow. Simulations of a slender body are carried out under different vibration amplitudes and frequencies. The results show that the structural vibration causes alternate variation of local attack angle at the head of the body, and thus changes the development of cavitation and re-entrant jet. On the downstream side, the length and thickness of the cavity are larger than that on the upstream side due to larger area of negative pressure. For a large vibration amplitude, alternate variations of the local attack angle change the adverse pressure gradient at the closure of the cavity, and then affect the development of the re-entrant jet, so that the phenomena of local shedding of the cavitation happen, compared with global shedding in the case of no structural vibration. For a frequency larger than 0.05, transverse speed of the vibration is suggested to be a dominant factor in controlling the behavior of the cavitating flow besides the local attack angle, since it causes local cavitating phenomena.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11334005the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20120002110031the Tsinghua Fudaoyuan Foreigh Visiting Support Project
文摘Using a nonlinear sound wave equation for a bubbly liquid in conjunction with an equation for bubble pulsation, we theoretically predict and experimentally demonstrate the appearance of a gap in the frequency spectrum of a sound wave propagating in a cavitation cloud comprising bubbles. For bubbles with an ambient radius of 100μm, the calculations reveal that this gap corresponds to the phenomenon of sound wave localization. For bubbles with an ambient radius of 120 μm, this spectral gap is related to a forbidden band of the sound wave. In the experiment, we observe the predicted gap in the frequency spectrum in soda water. However, in tap water, no spectral gap is present because the bubbles are much smaller than 100μm.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11402276,11772340 and No.11332011)
文摘The unsteady behaviors of cloud cavitating flow would lead to structural vibration and deformation that conversely affect its development. The present paper aims to preliminarily discuss the influences of structural vibration on the development of the cavitating flow. Simulations of a slender body are carried out under different vibration amplitudes and frequencies. The results show that the structural vibration causes alternate variation of local attack angle at the head of the body, and thus changes the development of cavitation and re-entrant jet. On the downstream side, the length and thickness of the cavity are larger than that on the upstream side due to larger area of negative pressure. For a large vibration amplitude, alternate variations of the local attack angle change the adverse pressure gradient at the closure of the cavity, and then affect the development of the re-entrant jet, so that the phenomena of local shedding of the cavitation happen, compared with global shedding in the case of no structural vibration. For a frequency larger than 0.05, transverse speed of the vibration is suggested to be a dominant factor in controlling the behavior of the cavitating flow besides the local attack angle, since it causes local cavitating phenomena.
