空气湍射流速度时间序列的最大Lyapunov指数以及湍流脉动

摘要

The velocity time series of round air jets are acquired with the hot-wire anemometer. We compute the largest Lyapunov exponent and the turbulent incoherent perturbation of the velocity signals at 939 ≤ Re ≤ 3758 using an analytical method of chaotic time series which is based on the invariant of the largest Lyapunov exponent. The results show that the largest Lyapunov exponent increases with exit Reynolds number, and decreases with the distance away from nozzle exit. The reciprocal of the largest Lyapunov exponent is positively correlated with correlation time. The incoherent perturbation of turbulence increases either with exit Reynolds number or with the distance away from nozzle exit. The incoherent perturbation of turbulence is negatively correlated with Kolmogorov scale.%用热线风速仪采集了圆喷嘴空气射流的速度时间序列，并采用一种基于最大Lyapunov指数不变性的混沌时间序列分析方法，计算了出口雷诺数在939≤Re≤3758范围内的速度信号的最大Lyapunov指数以及湍流的非拟序脉动．结果表明，最大Lyapunov指数随着雷诺数的增加而增大，随着离开喷嘴出口距离的增加而减小，而且最大Lyapunov指数的倒数与关联时间是正相关的．湍流的非拟序脉动随着雷诺数的增加以及随着离开喷嘴出口距离的增加均是逐渐增大的，而且湍流的非拟序脉动与Kolmogorov尺度是负相关的．