Sound Wave Propagation in Two-Phase Flow of Magnetic Fluid

磁流体研究的进展引起了人们对磁流体技术应用的极大兴趣，并导致了许多有用器件的生产。然而，材料的物理特性尚未完全揭示。磁场作用下磁流体中的波传播是磁流体高速流动特性研究的重要问题之一，已有一些文献对此进行了研究。然而，目前对两相磁流体的研究还很少，而两相磁流体的研究对于磁流体的工程应用具有重要意义。我们测量了两相磁流体中声波的相速度，发现其随外加磁场强度的增大而增大。通过抵消空隙率的影响归一化的速度也随着场强增加，这并不导致从流体中的色散关系。相速度的增加不能用均质两相流的计算来定量解释。这些结果与我们以前对两相磁流体中冲击波的研究是一致的。

The progress of magnetic fluid research has attracted considerable interest in the technological applications of magnetic fluids and led to the production of many useful devices. However, the physical properties of the materials have not yet been fully revealed. Wave propagation through magnetic fluid under a magnetic field is one of the important problems in studying the properties of high speed flow in magnetic fluids, and some studies on it have been described in the literatures. However, there exists little knowledge about two-phase magnetic fluids, whose investigations are very important for the development of practical engineering applications of magnetic fluids.We have measured phase velocity of sound waves in two-phase magnetic fluids, and found it increses with applied magnetic field strength. The velocity normalized by cancelling the effect of void fractions also increases with field strength, which does not result from a dispersion relationship in the fluids. The increase in phase velocity cannot explained quantitatively by calculation of homogenius two-phase flow. These results are compatible with our previous investigations on shock waves in two-phase magnetic fluids.