斜流下导管桨水动力性能及流场特性数值分析

Numerical study on hydrodynamic performance and flow field characteristics of ducted propeller in drift

针对真实条件下导管桨多工况运行问题,本文基于分离涡模拟方法对多个斜流角下导管桨水动力性能进行了数值预报。采用滑移网格技术建立了三维黏性、不可压缩的非定常数值计算模型,对比了直流状态和斜流状态下导管桨水动力载荷和流场特性。数值研究表明:设计工况、小斜流角状态下导管桨的推进效率会有小幅提高,单桨叶的水动力载荷随着斜流角的增加而非定常性增强,尾流背流侧导管前缘会因流动分离产生局部漩涡并向下游传输,迎流侧和背流侧尾涡演化进程存在明显差异,斜流状态下的主流效应对整体尾流场产生切向分量作用加速二次涡的产生与演化。

As an aid in the analysis of multiple loadings in actual working status of a ducted propeller,a detached eddy simulation method is employed to predict its hydrodynamic performance in an oblique flow.Unsteady numerical computation models that are viscous,three-dimensional,and incompressible are established using the sliding mesh technology.Hydrodynamic loads and flow fields of straight and oblique flow conditions are then compared.Numerical study results show slightly improved efficiency of the ducted propeller using the working conditions designed under small oblique flow angles.Upon increasing these angles,the unstable hydrodynamic load on a single blade strengthens.Due to flow separation at the leading edge of the duct in the leeward side of the wake,a mass of shedding vortices is induced near the external duct,which is transferred downstream.Obvious differences are observed between the windward and leeward wake in the changing process.Finally,the shearing action of the main flow effect accelerates the generation and evolution of the secondary vortices of the wake field.