用子波分析能量最大准则修正检测壁湍流猝发的mu-level法

将壁湍流脉动速度信号子波分析技术引入壁湍流相干结构猝发检测的研究,基于子波分析能量最大准则确定相干结构猝发的时间尺度,对能量最大时间尺度的子波系数进行子波逆变换,获得能量最大时间尺度的脉动速度信号。根据其自相关函数的波长确定相干结构的平均猝发周期;根据能量最大时间尺度的子波系数的正极大值和负极小值检测壁湍流喷射和扫掠事件,获得壁湍流相干结构喷射和扫掠事件的相位平均波形。该方法可以不需要确定门限值,有效排除了小尺度脉动的干扰。

On the Modification of mu-Level Method used to Detect Wall-Bounded Turbulence Burst by Maximum Energy Criterion Based on Wavelet Analysis

Introduces wavelet analysis technology for wall-bounded turbulence fluctuating velocity signals into the study of wall turbulent coherent structure burst detection. The time-scale of coherent structure burst is determined by wavelet analysis of maximum energy criterion. The wavelet inverse transformation for wavelet coefficients corresponding to energy maximum time-scale was carried out, based on which, the fluctuating velocity signals corresponding energy maximum time-scale were obtained. According to the wavelength of autocorrelation function, the average burst period of coherent structure is determined. Eject and sweep events in wall-bounded turbulence can be detected according to the positive maximum and negative minimum of wavelet coefficients corresponding to energy maximum time-scale. The phase average waveforms for eject and sweep are also obtained. This method does not need the threshold level and can effectively exclude interference of small-scale fluctuation.