Propagation of Pressure Waves, Caused by a Thermal Shock, in Liquid Metals Containing Gas Bubbles

Abstract

Propagation of pressure waves caused by a thermal shock in liquid metals containing gas bubbles is performed by a numerical simulation. The present study examined the influences of bubble radius and void fraction on the absorption of thermal expansion of liquid metals and attenuation of pressure waves. As the result of the calculation, since the large bubbles have a smaller natural frequency than small bubbles, the peak pressure at the heated region increases with increasing bubble radius. Contrary, the peak of propagated pressure wave to the wall decreases. But, when the bubble radii are around 500μm, the pressure wave propagates through the mixture not with the sonic speed of the mixture but with that of liquid mercury. And the peak of such pressure wave becomes higher than that of the pressure waves which propagate with sonic speed of mixture. On the other hand, decreasing the void fraction makes behavior of bubbles nonlinear and a collapse of bubble produces a high pressure wave. However, the calculation shows that the method of introducing micro gas bubbles into liquid metals is effective to prevent cavitation erosion on the wall.