基于PIV的明渠紊流压强场测量技术研究  

PIV Based Pressure Field Measurement Technique for Open-channel Turbulence

作　　者：王忠祥 陈启刚[1] 段炎冲 钟强 WANG Zhongxiang;CHEN Qigang;DUAN Yanchong;ZHONG Qiang(School of Civil Eng.,Beijing Jiaotong Univ.,Beijing 100044,China;State Key Lab.of Hydroscience and Eng.,Tsinghua Univ.,Beijing 100084,China;College of Water Resources and Civil Eng.,China Agricultural Univ.,Beijing 100083,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]清华大学水沙科学与水利水电工程国家重点实验室,北京100084 [3]中国农业大学土木与水利工程学院,北京100083

出　　处：《工程科学与技术》2023年第4期207-215,共9页Advanced Engineering Sciences

基　　金：中央高校基本科研业务费专项资金(2020JBM044);青海省重点研发与转化计划科技成果转化专项项目(2021–SF–161);水沙科学与水利水电工程国家重点实验室开放研究基金资助课题(sklhse–2020–B–03)。

摘　　要：基于粒子图像测速(particle image velocimetry,PIV)的压强场测量技术可实现流动内部瞬时压强的非接触式、高时空分辨率的全场测量。本文采用欧拉法根据时间解析的速度场重构压强梯度场,再采用虚拟边界全向积分法结合边界条件得到压强场,实现了基于PIV的明渠紊流压强场测量技术。为了使用基于PIV的压强场测量技术准确测量明渠紊流压强场,利用时间解析的明渠紊流直接数值模拟数据和PIV速度场对该测量技术的精度、误差来源及主要影响因素进行了分析。基于本文数据,发现该测量技术的测量结果几乎无平均偏差,但均方根误差相对较大,约为25%;通过分析由速度场重构压强梯度场及由压强梯度场积分得到压强场两个阶段的测量误差表明,压强场测量误差主要发生在由速度场重构压强梯度场这一阶段,主要受流场测量参数和边界条件给定方法的影响。进一步分析了上述主要影响因素对压强测量误差的影响规律,发现压强场测量误差随流场采样时间间隔的增加而增大,随流场测点间距的增加先减小后增大;基于本文数据得到在内尺度无量纲测点间距约为7时误差最小,但该测点间距最优值的普适性尚待更多数据支撑;在矩形测量区域边界4个角点布置压强边界点时,压强场测量误差会显著降低。将该压强场测量技术初步应用于明渠均匀紊流,发现时均压强测量结果较为准确,压强紊动强度测量结果误差相对较大,但垂向分布趋势接近。研究结论为明渠紊流压强场的试验测量提供理论依据和实践参考。PIV-based pressure field measurement technique enables a non-intrusive,high spatial and temporal resolution and full-field measure-ment of the instantaneous pressure of flows.The pressure field measurement technique was realized by reconstructing the pressure-gradient field from time-resolved velocity fields with an Eulerian approach and integrating the pressure-gradient field with an omnidirectional integration al-gorithm under given boundary conditions.To accurately measure the pressure field in open channel flows using PIV-based pressure field meas-urement technology,the accuracy,error sources,and major influencing factors on the measurement accuracy of the technique were analyzed with time-resolved direct numerical simulation data and PIV measured velocity fields of open channel flows.Based on the data,the measured pressure fields had a negligible mean bias error and a root mean square error of about 25%.By analyzing the measurement errors in the two stages of the pressure gradient field reconstruction from the velocity field and the pressure field integration from the pressure gradient field,the error was mainly introduced in the stage of reconstructing the pressure gradient field from the velocity fields and was affected by the measurement paramet-ers of the velocity field and the method of setting boundary conditions.The influence rule of the above main influencing factors on the pressure measurement error was further analyzed.It was found that the error increased monotonously with the increase of the sampling interval of velocity fields.However,it decreased first and then increased with the increase of the measurement point spacing of velocity fields,with an optimal inner-scaled point spacing of about 7.However,the universality of the optimal value of measuring point spacing needed more data to support it.The measurement error was significantly reduced when the pressure boundary was given at the four corners of the rectangular measurement region.The PIV-based pressure field measurement technique was appli

关 键 词：压强测量 明渠紊流 PIV 测量精度 误差来源 

分 类 号：TV131.6[水利工程—水力学及河流动力学] TV133