声相关流体速度测量理论和信号处理方法

研究了测量流体速度的声相关测速理论和信号处理方法。获得了在声呐阵夫琅和费区域内适用的声呐阵时空相关函数,它是指数函数,这是相关测流速的理论模型。重点研究了时空声相关函数最大值附近的特性,它包含流速的主要信息。提出了局域最小二乘估计作为速度估计准则,采用序列二次规划作为最优化的方法,由此建立了声相关流速测量的信号处理方法。进行多次海上系统试验,验证了理论模型;给出了声相关海流剖面仪测得的流速、流向和流速剖面,与声多普勒海流剖面仪进行了对比,结果符合;最后给出了声相关海流剖面仪的测速均方差,稍大于理论值。

Theory and signal processing of acoustic correlation techniques for current velocity measurement

The theoretical model and signal processing of correlation measurements to estimate current velocity are discussed.The sonar space-time correlation function of volume reverberations within Fraunhofer zone is derived.The function,which is the theoretical model of acoustic correlation measurements,is in exponential forms.The characteristics of the correlation values around the maximum of the amplitude of the correlation function,where most information about current velocity is contained,are primarily analyzed.Localized Least Mean Squares(LLMS)criterion is put forward for velocity estimation.Sequential Quadratic Programming(SQP)method is adopted as the optimization method.So the systematic signal processing method of acoustic correlation for current velocity measurements is established.A prototype acoustic correlation current profiler(ACCP)underwent several sea trials,the results show that theoretical model approximately coincides with experimental data.Current profiles including the speed and direction from ACCP are compared with those from acoustic Doppler current profiler(ADCP).The current profiles by both instruments agree reasonably well.Also,the standard deviation of velocity measurement by ACCP is statistically calculated and it is a little larger than predicted value.