超重力下粒子图像测速系统性能测试与评价  

Performance testing and evaluation of PIV system in centrifugal environment

作　　者：徐春瑞 薛阳 郭畅 黄博[1,2] XU Chunrui;XUE Yang;GUO Chang;HUANG Bo(Institute of Geotechnical Engineering,Zhejiang University,Hangzhou 310058,Zhejiang,China;Center for Hypergravity Experimental and Interdisciplinary Research,Zhejiang University,Hangzhou 310058,Zhejiang,China;Department of Civil and Environment Engineering,The Hong Kong Polytechnic University,Hong Kong 999077,China)

机构地区：[1]浙江大学岩土工程研究所,浙江杭州310058 [2]浙江大学超重力研究中心,浙江杭州310058 [3]香港理工大学土木与环境工程学系,中国香港999077

出　　处：《地基处理》2024年第6期547-556,共10页Journal of Ground Improvement

基　　金：浙江省自然科学基金资助项目(LCZ19E080002);国家自然科学基金资助项目(51988101)。

摘　　要：粒子图像测速(PIV)技术作为一种无扰、瞬态、全速度场的测量手段,能够测量试验过程中土体的位移场变化、土体的瞬时运动速度等,具有传统的点或线式测量手段不具备的优势,近年来,已被推广应用于岩土工程离心模型试验中。然而,离心超重力的极端环境使PIV系统测速的准确性面临严峻考验。通过自行设计的一套可在超重力下提供稳定速度场的伺服调速标定装置,并以该装置提供的速度场为基准,对一套PIV系统在不同离心加速度、基准速度以及拍摄模式下的测速误差进行了测试和分析。研究结果显示:PIV系统的测速误差主要源自系统自身的时序控制误差,在50g离心加速度内,g值对系统性能的影响有限,常重力下测试结果提出的速度修正式同样适用于超重力工况;PIV系统的测试精度与相机的工作模式相关,连续拍摄时,两幅图像间隔时间越短,测试数据的离散程度越低;双曝光工作模式测试的数据点更为集中,系统精度更高;在像场的不同区域,PIV系统均能保持较小的系统误差和变异系数,能够实现全域测量。本研究为超重力条件下PIV技术的应用提供了可靠的校准方法,也为其他PIV系统的超重力性能测试与评价提供了参考。Particle Image Velocimetry(PIV)is a non-intrusive,transient,and an entire region measurement technique that is capable of measuring soil deformation behavior and the instantaneous particle velocities during testing.Compared to traditional point or line measurement methods,PIV offers distinct benefits and has been increasingly applied in geotechnical centrifugal model tests.However,the extreme environment of centrifugal hypergravity poses a severe challenge to the accuracy of PIV system speed measurements.In this study,a self-designed servo-controlled calibration apparatus was introduced,which is capable of providing stable velocity fields under hypergravity conditions.Using the velocity fields generated by this apparatus as benchmarks,the performance of a set of PIV system under various centrifugal accelerations,reference velocities,and shooting modes was tested.The measurement errors of the PIV system were analyzed and assessed.The results show that the velocity measurement error of the PIV system mainly originates from the timing control error of the system itself.Within 50g centrifugal acceleration,the g value has a limited influence on the system performance,and the velocity modification formulas proposed in the test results under normal gravity are also applicable to the hypergravity working conditions.The test accuracy of the PIV system is related to the camera’s working mode.In continuous shooting,the shorter the interval between two images,the lower the degree of dispersion of the test data.The data points of the double-exposure working mode test are more concentrated,and the system accuracy is higher.In different areas of the image field,the PIV system can maintain a small systematic error and coefficient of variation,and can realize the full range of measurement.This study provides a reliable calibration method for the application of PIV technology under hypergravity conditions and provides a reference for the hypergravity performance testing and evaluation of other PIV systems.

关 键 词：粒子图像测速技术 离心模型试验 伺服调速标定装置 系统误差 变异系数 

分 类 号：TU411[建筑科学—岩土工程]