基于CFD方法采用“Singhal完全空化模型”和动网格技术对磁致伸缩仪超声空化流进行数值计算。计算结果表明变幅杆高频振动引起试样表面附近局部流场发生空化并且在试样表面形成脉冲压力。压力和空泡体积组分在试样表面近似呈环形分布，并且随试样振动，二者周期性变化。试样表面中心区域空泡经历两次振荡后溃灭，产生强烈脉冲压力，其峰值可达到约5MPa。脉冲压力在试样表面按间隔环形区域分布，且随试样振动在相邻环形区域上交替出现。随超声波在空化流场中传播，声压快速衰减。压力只在距变幅杆端面约20mm内有明显波动。当振幅从25μm增大到30μm，试件中心区域脉冲压力增大；振幅进一步增大到35μm，尽管空化效果增强，但试件中心区域所受脉冲压力作用减弱。
Abstract
The magnetostriction-induced ultrasonic cavitation flow was numerically simulated by using “Singhal full cavitation model” and the dynamic mesh technique. The computational results show that cavitation occurs at the local flow field proximity to the specimen and the specimen is subjected to impact of impulse pressure due to high frequency vibration of specimen. Pressure and vapor volume fraction (VVF) are annularly distributed around the center on the specimen, which vary periodically with vibration. Bubbles collapse after twice oscillation on the center region of specimen, which results in intense impulse pressure that can reach about 5MPa. Impulse pressure forms on the interval annular zones and alternately occurs on the adjacent annular zones with vibration cycle. Acoustic pressure quickly attenuates with ultrasonic propagation in the ultrasonic cavitation flow field. The considerable fluctuation of pressure occurs within the distance of 20mm to the end of ultrasonic solid horn. The impulse pressure is promoted on the central region of specimen as the vibration amplitude is increased from 25μm to 30μm. When the vibration amplitude is further increased to 35μm, the effect of cavitation is further enhanced, but the impulse pressure is diminished on the central region of specimen.
关键词
空化 /
超声空化流 /
高频振动 /
脉冲压力
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Key words
cavitation /
ultrasonic cavitation flow /
high frequency vibration /
impulse pressure
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