基于小波分析的淹没水跃脉动压力时频变化研究

A Study on Time-Frequency Variation of Flow Pulsating Pressure of Submerged Hydraulic Jump Based on Wavelet Analysis

利用Morlet小波变换对淹没式闸孔出流试验测得的脉动压力信号进行时频特征分析.通过标准化处理所采集的信号数据,选取合适的尺度伸缩因子和时间平移因子绘制各测点脉动信号的小波变换系数图.从小波系数的模平方图和实部图分析不同尺度下脉动压力的时频分布及强弱变化.应用小波方差图进一步验证各时间尺度下的压力信号时频变化主周期.结果表明:脉动压力第一主周期较小的点位于闸后淹没水跃段,不同工况第一主周期最小点与脉动压力能量最强点基本吻合;当淹没系数较小时,相邻测点间存在主周期一致现象增多.

The Morlet wavelet transform is used to analyze the time-frequency characteristics of pulsating pressure signals measured by the experiment of submerged sluice flow. By standardizing the collected data,the wavelet coefficient diagrams of each measuring points were drawn by appropriate scale expansion factor and time translation factor. The time-frequency distribution and the intensity evolution of pulsating pressure were analyzed from modulus square diagram and the real part figure of wavelet coefficient. The wavelet transform variogram was applied to verify the major period at different time scale. The results show that the pulsating pressure point with smaller first principal period is located in submerged hydraulic jump. The minimum point of first principal period is coincided basically with the strongest point of pulsating pressure energy for different runs. When the submerged coefficient is small,there is an increase in the coincidence of principal period between adjacent measuring points.