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基于光学衰减原理的盐水置换和混合流动研究 被引量:2

Experimental Study of Displacement and Mixing Flows in Salt Water Modeling Based on Theory of Attenuation of Light
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摘要 根据光线透过盐水溶液产生衰减原理,利用流场内密度与光照强度的对比关系,提出通过图像灰度确定流场内密度分布特征的测试方法。采用这种实验方法,结合单一点源羽流条件下卷吸作用,模拟由热压产生的置换流动和混合流动。对于无热源的置换流动实验,当出口面积保持在5.1 cm^2时,进口面积由28.9 cm^2增加到52.7 cm^2并不会显著增加体积流量。这表明对于置换通风,当进出口面积相差较大时,流量由进出口中较小的面积开口确定。对于有热源条件下置换流动,随着有效开口面积增加,热分层高度增加,且上部分层高度内的密度降低。实验数据显示,卷吸系数α取0.13时理论预测与实验结果一致。在有固定热羽流条件下进行了混合流动实验,确定流量修正系数ε等于2.21,该系数与开口大小和盐水密度无关,反映固定浮力通量与变浮力通量条件下通过开口流量的比值。通过理论分析和实验结果对比,证明了利用光学衰减原理确定盐水浓度的方法是一种有效的实验测试方法。 According to the attenuation principle of light passing through brine solution and the contrast between density of solution in the flow field and intensity of light,a method for determining the density distribution characteristics in the flow field by image gray level is proposed.The displacement flows and mixing flows generated by thermal pressure are simulated by this experimental method with the aid of the entrainment theory under the condition of single point source plume.For displacement flows without internal sources,when the area of openings in the bottom is kept at 5.1 cm^2 and the area of the upper openings is changed from 28.9 cm^2 to 52.7 cm^2,the volume flow through the top and lower openings do not changed much.This indicates that for displacement ventilation,when the area of inlet and outlet is obviously different,the flow rate is determined by the smaller openings.For displacement flows with internal sources,as the value of effective area is increased the height of the interface rises and the value of reduced gravity in the lower layer decreases.Good agreement between experiment and theory is found when entrainment coefficient is taken as 0.13.For mixing flows with fixed thermal plume,the revised flow coefficientεwhich does not dependent on the area of openings and the density of salt water is chosen as 2.21 and is the ratio of fixed buoyancy flux to dwindling buoyancy flux.The experimental results show that this method can clearly characterize the flow characteristics of plume in space and can quantitatively analyze the flow law in the model.
作者 刘洋 力晓晴 黄澜 袁健华 蔡丽蓉 LIU Yang;LI Xiao-Qing;HUANG Lan;YUAN Jian-Hua;CAI Li-Rong(School of architectural and surveying&mapping engineering,Jiangxi university of science and technology,Ganzhou 341000,China)
出处 《工程热物理学报》 EI CAS CSCD 北大核心 2020年第8期1861-1869,共9页 Journal of Engineering Thermophysics
基金 国家自然科学基金资助项目(No.51666003) 江西省教育厅科学技术研究项目(No.GJJ170523)。
关键词 光学衰减 光照强度 盐水模拟实验 自然通风 attenuation of light light intensity salt-water experiments natural ventilation
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