亚临界雷诺数细长体绕流流态随迎角的变化和分区

Zonal study of flow patterns around an ogive-cylinder at subcritical Reynolds numbers

通过在北航1.2m水洞中利用染色液显示和激光片光技术的显示实验以及在西工大NF-3风洞中进行的表面测压实验,对拱形头部细长旋成体在无侧滑条件下的流场结构和流动特性随着迎角的变化进行了实验研究。在流动显示和测压结果分析的基础上,对迎角从0°到90°范围内绕细长体的流动进行了流态分区,即细长体绕流经历6种流态:极小迎角下(0°≤α≤3°)物面附着绕流流态、小迎角下(3°<α≤25°)背部对称旋涡流态、中等迎角下(25°<α≤40°)背部2个非对称旋涡流态、大迎角下(40°<α≤60°)的非对称多涡系复杂流态、特大迎角下(60°<α<75°)背部多个旋涡依次破裂的流态、极大迎角下(75°≤α≤90°)背部类卡门涡街(或随机尾迹)流态。阐述了不同区域的流动特性和气动特性。

Experimental study on the flow structure and aerodynamical characters around an ogivecylinder at different angles of attack and zero sideslip is conducted by streak and laserinduced fluorescence techniques in water tunnel of BUAA, and by surface pressure measurement in wind tunnel of NPU NF3. By zonal analysis of different angle of attack range from 0° to 90°, the flow patterns with angles of attack can be classified into six regimes, that is: (1)attached flow at very small angle of attack (0°≤α≤3°); (2)symmetric twin vortices flow at small angle of attack (3°<α≤25°); (3)asymmetric twin vortices flow at moderate angle of attack (25°<α≤40°); (4)multiasymmetric vortices system flow at high angle of attack (40°<α≤60°); (5)multiasymmetric vortices break down in turn at extremely high angle of attack (60°<α<75°); (6)Karman vortices street like or a random wake shedding at maximal high angle of attack (75°≤α≤90°). The different flow pattern over slender body is presented, the correlation between vortices system structure and its sectional pressure distribution, local side force distribution of different regimes are discussed. 