水下爆炸气泡作用下梁中垂损伤及流场变化特性

 以水面箱形梁模型为研究对象，利用数值计算和实验验证相结合的方法，对梁在水下爆炸气泡作用下的中垂损伤特点进行了研究，确定了中垂弯曲载荷的形成原因，深入分析了气泡运动时周围流场的变化特性；研究了爆炸参数对梁响应特性的影响，初步提出了梁发生中垂损伤的条件。研究发现：在爆炸气泡收缩阶段，结构和气泡之间的流场形成一个“凹”型分布的低压区，导致梁发生中垂弯曲变形；当爆径比参数λ满足1<λ<2.5时，爆炸气泡对梁结构的中垂损伤作用明显，且λ越小，等量炸药对梁的整体损伤作用越大。

Characteristics of Flow-Field and Sagging Damage of Free-Free Beam Subjected to Underwater Explosion Bubbles

In order to probe into the damage mode and its mechanisms, a box-like beam was designed, and numerical analysis and experimental verification were carried out. In the discussions, how vertical bending load forms was investigated, and the properties of flow-field were analyzed in details when explosion bubble oscillates, how explosion parameters affect the dynamics of beams was attained, and the basic condition for beam sagging damage was initially proposed. The results show that there exists a low-pressure zone like a "concave" in the fluid between beam and explosion bubble when the bubble contracts in the near-field, and the low-pressure field causes the sagging damage. If the parameter of λ, the ratio of stand-off to maximum bubble radius, meets 1<λ<2.5, explosion bubble will possibly cause beams damage into sagging condition. The smaller the value of parameter λ, the greater the impact damage.