合成纹影技术在二维密度场测量中的应用和精度研究  

Application and accuracy study on synthetic schlieren technique in two-dimensional density field measurement of fluids

作　　者：陈铂[1,2] 黄筱云 CHEN Bo;HUANG Xiaoyun(School of Hydraulic Engineering,Changsha University of Science 8^Technology,Changsha 410004,Hunan,China;Key Laboratory of Water-Sediment Sciences and Water Disaster prevention of Hunan Province,Changsha 410114,Hunan,China)

机构地区：[1]长沙理工大学水利工程学院,湖南长沙410004 [2]水沙科学与水灾害防治湖南省重点实验室,湖南长沙410004

出　　处：《实验力学》2021年第5期704-712,共9页Journal of Experimental Mechanics

基　　金：长沙市自然科学基金项目(kq2014102);湖南省自然科学基金项目(2021JJ30704)

摘　　要：流体内部的密度差异会对流体运动产生很大影响,为观测流体内部密度场,本文采用了一种新的密度场测量技术——合成纹影技术,该技术根据流体内部密度(或溶质浓度)差异产生的折射率变化,定量分析得到流体平面二维偏移梯度分布,并通过计算得到密度场。合成纹影技术仅需要光源、背景板、摄像机和处理图像数据的计算机软硬件,即可实施非接触二维密度场测量。为明确背景图案对测量的影响,使用不同尺寸随机圆点背景图的合成纹影技术测量相同初始条件的瞬时点源羽流扩散运动,相互对比后得到定性结果:试验图片圆点直径在3~5pixel时,所得密度场分辨率高且噪点少。本文应用有合适背景图案的合成纹影技术测量了分层剪切流内部的密度分布,其结果与试验阴影图和流速分布相符合。The density difference within the fluid has a significant effect on its movement.For observing the internal density field of the fluid,the synthetic schlieren,novel techniques for producing visualisation of density fluctuations and for obtaining quantitative whole-field density measurements in two-dimensional flows is used.The two-dimensional concentration(temperature)field is obtained by analyzing the refractive index changes,which caused by the concentration(temperature)vary;and the density field is calculated.This technology only needs light panel,textured mask,camera and computer software and hardware for image processing,which can realize non-contact two-dimensional density field measurement.After comparison and analysis,using the dots pattern,when the diameter of the dots in the test image is 3~5pixels,the resulting density field has high resolution and less noise.The synthetic schlieren technique is used to measure the density distribution of the stratified shear flow.Comparative Experiment velocity distribution and the shadowgraph,the results are reliable and the measurement method is simplicity.

关 键 词：合成纹影 密度场测量 流动显示 

分 类 号：O359.2[理学—流体力学]