细长体大攻角非对称涡流的数值研究

运用数值方法模拟了细长体在不同攻角条件下亚音速绕流的背涡结构,探讨了非对称涡流的气动力特性.研究结果表明,在超临界Re数范围内,细长体大攻角绕流的非对称性是沿轴向逐步发展的,背涡结构交替形成、飘起和脱落,并诱导出呈减幅正弦形式分布的截面侧向力.由细长体两侧分离速度不等引起的当地分离涡强度不等是产生截面侧向力的主要因素.随着攻角的增大,流场非对称性越来越显著,侧向力逐渐增大;流场非对称性以及细长体尾部附近类卡门涡街形式的非定常流动都逐渐向前体聚拢.

Numerical Investigation of Asymmetric Vortical Flow over a Slender Body at Large Angles of Attack

Subsonic vortical flows over a slender body at different angles of attack were simulated numerically, and the aerodynamic characteristics of asymmetric vortical flow were also investigated. This investigation shows that the asymmetry of flows over a slender body at large angle of attack evolves stage by stage along the length in the region of supercritical Re. Asymmetric vortices rolling up and shedding alternately induce sectional side force decrescendo sinusoid along the length. The asymmetry of local separation vortex strength induced by the asymmetry of separation speed is the main reason for producing sectional side force. With the angle of attack increasing, sectional side force, together with the asymmetry of flow field, grows more prominent gradually. The asymmetry and the unsteady flow characteristics near afterbody, which are similar to the characteristics of Karman vortex street, crowd towards forebody step by step.