大迎角三角翼旋涡运动及其破碎特性的数值研究

Numerical Analysis on the Vortex Motion and Bursting of Delta Wing at High Angle of Attack

从流体力学的基本方程出发，利用Ｈａｌｌ的涡核准柱假设，导出反映涡核运动的Ｎ－Ｓ方程。采用差分方法计算旋涡流场，进而分析三角翼上前缘分离涡的运动特点及其破碎机理。从计算结果可以看出，旋涡的轴向速度和旋转速度向下游逐渐下降，且涡心处下降较快，外缘下降较慢，反映了粘性作用自涡心向外缘逐渐下降的特点，涡核外缘的径向速度开始为负值，说明开始阶段有流体流入涡核，随着旋涡向下游运动，径向速度有所增加，到一定位置后增加迅速，说明旋涡已经破碎。破碎位置与迎角和雷诺数有关，当迎角增大时，破碎点前移；当迎角相同时，若雷诺数较小，则雷诺数变化对破碎位置影响较大，反之较小。这些计算结果与实验数据是十分吻合的。

The N-S equations representing vortex-core motion are derived by using the basic equations of fluid mechanics and Hall's quasi-cylindrical vortex-core hypothesis. The vortex flow field is calculated with difference methods, and the motion characteristics and the bursting mechanism of the leading-edge separated vortices of delta wing are analyzed.Based on the calculated results, the axial and revolution components of the velocity reduce gradually along axial direction, and both velocities reduce quickly in the vortex center, and slowly in the vortex-core edge, which reflects the characteristics of the viscous action reducing gradually from vortex center to vortex-core edge. The radial component of velocity in vortex-core edge is negative initially because of the outer fluid flowing into the vortexcore, and grows slowly with the vortex moving down, and quickly behind a position due to the vortex bursting. It has been proved in the calculation that the vortex-bursting location of leading-edge separated vortices may be determined reasonably where the variability of total pressure on vortex-core along axial direction is zero,i. e. 0. The vortexbursting location is related to angle of attack and Reynolds number. The location of bursting-point moves forward when the angle of attack increases. At same angle of attack and smaller Reynolds number, the vortex-bursting location is affected more greatly by the variation of Reynolds number, otherwise it is affected much smaller as a result of the viscous action decreasing at fairly large Reynolds number. These calculated results are well consistent with the experimental data.