为研究水力机械空化初生瞬态特性，应用分子动力学的模拟方法，对存在空化核的水分子计算域进行了研究，得到空化核初始尺寸与系统亚稳态对空化初生的影响，并对空化核的演变过程、系统压力以及系统分子势能、分子径向分布函数等相关的热力学参数进行分析。研究表明：空化初生于液态水中的空化核，空化初生时空化核及其周围小范围内的液态水处于负压状态；一定体积的空化核系统存在临界亚稳态，未进入临界亚稳态的体系中空化核不能稳定存在，体系进入临界亚稳态后空化核体积增大，空化发生，空化核体积越大的系统越容易进入临界亚稳态，从而诱发空化；空化初生时体系压力迅速增加，分子势能减小，分子排布也发生改变。

In order to study the transient characteristics of hydromechanical cavitation inception,the molecular dynamics simulation method was applied to study the calculation domain of water molecules with cavitation nucleus,and the influence of the initial size of cavitation nucleus and system metastable on cavitation inception were obtained.System pressure,molecular potential energy,molecular radial distribution function and the related thermodynamic parameters of cavitation nucleus evolution were analyzed.The cavitation is formed from cavitation nuclei in liquid water.The cavitation nuclei and the liquid water in a small area around it are in a negative pressure state when cavitation occurs.System with a certain volume of cavitation nuclei has a critical metastable state.The cavitation nuclei of the system which does not enter the critical metastable state cannot exist stably.After entering the critical metastable state,the cavitation nuclei volume increases and cavitation occurs.The larger the cavitation nuclei,the easier it is for the system to enter the critical metastable state,thereby inducing cavitation.At the time of cavitation inception,the system pressure increases rapidly,the molecular potential energy decreases,and the molecular arrangement changes.

TK72

江苏省“333工程”科研项目（BRA2017505）；江苏省建设系统科技项目（指导类）（2018ZD140006）；江苏城乡建设职业学院科研项目（2018KYC019）