整体涡轮界面缺陷相控阵检测定位方法研究

Research on Phased Array Detection and Location Method for Integral Turbine Interface Defects

在对镶铸双金属涡轮结合层缺陷进行超声检测时,由于结合层几何结构近似垂直于底面、涡轮材料高衰减特性导致侧壁反射能量低等原因,收发分置式相控阵检测方法成为最佳选择。针对此类结合层缺陷采用的收发分置相控阵方法,首先根据涡轮结构建立二维声线模型并依此建立聚焦深度与阵元时延关系;其次在接收端接收数据后提出一种基于OCOG算法的缺陷定位方法,以缺陷波重心与直达波等效前沿之间的声程差作为定位依据,通过事先拟合的声程差-缺陷位置函数求解缺陷位置;最后对缺陷位置进行成像显示。试验结果表明,收发分置式相控阵检测方法可有效识别双金属涡轮结合层缺陷,采用基于OCOG算法的缺陷定位方法精度高。

In the field of ultrasonic testing on in-cast bimetal turbine combined layer,due to the combining layer approximately perpendicular to the floor,and the low reflection waveform energy caused by internal high attenuation in turbine materials,bistatic phased array detection model becomes the desirable choice.For this kind of bistatic model adopted by bimetal combined layer defection,firstly,depthdelay fast table was established according to a two-dimensional acoustic line model based on the actual turbine structure,and then a method was put forward based on the OCOG algorithm after the adjustment of receiving data delay interception,which can orientate the defections precisely.The difference between direct wave equivalent frontier and gravity of defect wave was used to solve the corresponding defect depth fitting function in advance.Finally,all waveform data of the same depth was displayed according to the amplitude imaging.The experiment shows that the detection method by OCOG algorithm has high detection rate and accurate location of the defect.