细长体绕流流态拓扑结构轴向演化的数值研究

Numerical Investigation on Axial Evolution of Flow-pattern Topological Structure over Slender Body

运用数值方法研究了细长体大攻角绕流背风面两侧主涡沿轴向交替形成、飘起、脱落的过程,提出了绕流截面流态拓扑结构的轴向演化规律,详细描述了主涡诱导产生二次涡、二次涡分割主涡衍生出tertiary涡、主涡与异侧二次涡绕合、主涡分割异侧主涡形成脱体涡等现象,突出了二次涡、tertiary涡的作用。分析了攻角大小对拓扑结构的影响:随攻角增大,轴向演化进程加快,非对称性增强,非对称流态向头部靠拢,准定常流动区域向前体收缩。

The process of primary vortices forming, lifting and shedding alternately along central axis from opposite sides of a slender body placed at high incidence to an oncoming stream is investigated numerically, and laws on axial evolution of its sectional flow-pattern topological structure are advanced. Some important phenomena, including primary vortex inducing reattached shear layer to form secondary vortex, secondary vortex dividing primary vortex to generate tertiary vortex, primary vortex merging with opposite secondary vortex, and primary vortex dividing opposite primary vortex to form shed vortex, are described, where the roles of secondary and tertiary vortex are stressed. The influence of incidence magnitude on the process is also discussed. With the incidence increase, the axial process is accelerated, and flow asymmetry gets harder; in addition, asymmetric flow pattern moves closer to nose, and quasi-steady flow region shrinks towards forebody.