局部通气空泡尾部微气泡流减阻仿真研究

Numerical Research on Microbubble Drag Reduction Downstream of Partial Ventilated Cavity

基于欧拉—欧拉双流体模型开展了局部通气空泡尾部气泡流仿真及减阻特性研究。模型中建立了局部通气空泡尾部回射流泄气模型,并通过改进湍流耗散系数计算模型考虑了高气含量对两相作用的影响。通过将模型应用于轴对称体微气泡减阻试验,验证了多相流模型的准确性。通过开展不同工况下局部通气空泡流仿真,正确预示了空泡后回流区及其下游气泡分布特点。基于仿真结果,对试验体摩阻和压阻进行分析,研究表明对于高压阻航行器,局部通气空化综合利用空化减阻和微气泡减阻,既能有效减小摩擦阻力,又能保持较小压阻,能实现比超空泡更高的减阻率。

Numerical research on microbubble drag reduction downstream partial ventilated cavity is carried out based on an Eulerian-Eulerian two-fluid approach.The gas leakage model resulted from the re-entrained jet at the rear of partial ventilated cavity is proposed and integrated into the numerical model.The turbulent dispersion force model was improved to take into account the effect of high void fraction.Numerical model was firstly validated through application on a microbubble drag reduction experiment for an axisymmetric object.Then simulations on bubbly flow created by partial ventilated cavity were implemented where the vortex regions behind the cavity and the bubble distribution were successfully captured.Based on the simulation results,the friction drag and form drag caused by bubbly flow downstream of the ventilated cavity is analyzed.It is concluded that for the objects with high form drag coefficient,it can be more effective to use partial cavity for drag reduction than supercavity,because the partial cavity which is composed of cavity drag reduction and microbubble drag reduction can obtain high friction drag reduction while keep low form drag.