用子波分析修正检测壁湍流猝发的VITA法

应用壁湍流脉动速度信号子波分析的一系列方法对检测壁湍流猝发事件的VITA法进行了修正。其中,用能量最大准则确定VITA法短时间平均周期;以子波变换能量最大尺度脉动速度的短时间平均方差的局部极大值点作为检测函数的中心点,取代了传统VITA法中对短时间周期平均方差选用门限值的方法,避免了VITA法检测结果对门限值的主观经验依赖性,提高了VITA法检测壁湍流猝发事件的客观性和准确性。

On the Modification of VITA Method for Detection of Turbulence Burst on Wall Surface by Wavelet Analysis

A series of methods based on the analysis of wall turbulence pulse velocity signal wavelet are adopted to modify VITA method used in detecting wall surface turbulence burst events.Among which,the short time average period T in VITA method is determined by maximum energy criterion;the local maximum point of short time average variance of the maximum scale fluctuation velocity in energy wavelet transform is used as the detection function center;threshold value selection for short period average variance in traditional the dependence of detection subjective experience on threshold value is avoided;therefore,objectivity and accuracy of VITA method in detecting turbulence burst events on wall surface are improved.