波包在后掠翼三维边界层中的演化特征

研究了点源产生的孤立波包在后掠平板三维边界层中的演化特征．理论计算的波包增长路径和ＮｉｔＳＣｈｋｅ－Ｋｏｗｓｔｙ所做流场显示得到的条纹结构一致，证明条纹是波包的等相位线；波包方程的渐近解表明在三维边界层中ｅＮ方法应沿着为实数的方向积分；ｅＮ方法过高预测了扰动幅值的增长率，与Ｄｅｒｈｌｅ的实验结论一致．

EVOLUTION OF WAVE-PACKET IN THREE-DIMENSIONAL BOUNDARY LAYER ON A SWEPT WING

The evolution character of a isolated wave-packet produced by a point source in threedimensional boundary layer on a swept flat plate is investigated. From numerical solution of lineareigenvalue problem of spatial mode, the amplitude and phase of wave-packet at each position onthe growing path is obtained from the integral over all spanwise wavenumbers of colltribution toit's amplitude. The steepest descent method is also used to evaluate it's asymptotic behavior. Itis demonstrated that the streaks observed in Nitschke-Kowsky's flow visualization are equivalentto the constant phase-lines of wave-packet; eN method applied in 3D boundary layer should beevaluated along a path which make real; However, in good accordance with the conclusionof Deyhle's experiment, eN method is overpredicted the growth of the disturbances.