壁湍流猝发事件检测与提取方法研究

Extracting Accurately and Efficiently Burst Events of Wall Turbulence

在重力式低速水洞中完成了湍流边界层流场测量,并分别利用自相关方法和小波分析方法,对对数律区中一测点处的速度信号进行了分析。结果表明,自相关方法对于平均猝发周期的检测精度较高;小波分析方法可用于猝发事件的提取,但对平均猝发周期的检测精度较低。为此,进一步提出了一种同时基于自相关方法和小波分析方法的壁湍流猝发事件快速检测与提取方法,并总结了该方法的具体实施步骤。与原方法相比,该方法既能够精确检测湍流平均猝发周期,又能够提高猝发事件的提取精度。

Flow field measurement of turbulent boundary layer was accomplished in a gravitational low-speed water tunnel set up by us. The velocity signal of a test point in logarithmic layer is analyzed respectively with two methods （ autocorrelation method and wavelet transform method） , and the results and their analysis demonstrate preliminari- ly that the autoeorrelation method has high precision for the detection of average burst period, while the wavelet transform method can be used to extract burst events but with low precision. Consequently, an improved method with high precision and efficiency is put forward based both on autocorrelation and wavelet transform, and the spe- cific implementation steps are summarized in section 3 of the full paper. Compared with old methods, our improved method can indeed extract burst events of wall turbulence both accurately and efficiently.