减压条件下近自由面气泡运动与水冢现象实验研究

Tests for bubble pulse features and bubble plume under hypobaric condition

近场水下爆炸气泡所受较大浮力,将与船体、自由液面等发生耦合,由于边界的复杂性、气泡溃灭受控制参数的敏感性,理论及数值方法较难进行求解;现有实验研究因其生成的气泡尺寸小,导致浮力较小,难以保证与真实的水下爆炸气泡的相似性。为深入探究近场气泡与自由液面相互作用规律,根据水下爆炸气泡相似理论,设计减压条件下气泡动力学实验装置,开展减压条件下气泡动力学实验,得到了计及浮力影响的近自由液面气泡运动形态变化和不同水冢现象。最后,通过大量实验数据总结归纳,得到近自由液面气泡运动周期、射流速度、水冢高度等随距离参数和浮力参数的变化规律,为相关理论与数值的研究提供参考。

Near-field underwater explosion bubble is coupled with a ship＇s hull,and free surface of liquid due to a prodigious buoyancy exerted on it. This problem can＇t be solved with theory or numerical methods,due to the complexity of boundaries and the sensitivity of bubble breaking to controlling parameters. The similarity of the current tests to the actual under water explosion bubble can＇t be guaranteed because the current tests mostly produce smaller bubbles to cause smaller buoyancy. In order to study the interaction between near-field bubble and free surface of liquid,a multi-function test apparatus operating under reduced air pressure was designed according to the similarity theory of underwater explosion bubble. The changing processes of bubble form near free surface and different phenomena of bubble plume were obtained through tests considering buoyancy changing. Finally,on the basis of a large amount test data,the change laws of motion period of bubble near free surface,jet velocity and height of bubble plume,etc. with the variation of distance and buoyancy were found. The results provided a reference for the relevant theoretical and numerical studying.