共查询到19条相似文献,搜索用时 58 毫秒
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气液两相流在工业各领域中广泛存在,而声速是描述其声学性质的一个重要参数。本文从流体的体积弹性模量的定义出发,推导了气液两相流中的声速随含气率的变化关系式,即混合流体的Wood声速公式,将其声速的部分计算结果和其他作者的实验数据进行了比较,吻合良好。并通过COMSOL有限元模拟软件得到不同气体分布下圆管谐振腔最低阶模式的共振频率,间接数值模拟研究了含气率对声速的影响。模拟结果与理论计算结果一致,当气液两相流中含气率较低时,声速随含气率的增大急剧减小。本研究结果为确定声速与气液两相流中的含气率间的关系提供了参考依据。 相似文献
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本文基于电容耦合式非接触电导检测(Capacitively Coupled Contactless Conductivity Detection,C~4D)技术,提出了一种气液两相流相含率测量新方法。该方法基于新型六电极阵列式C~4D传感器,首先获取气液两相流电导信号,然后利用所获电导信号,结合LS-SVM回归方法分别建立三种典型流型(泡状流、环状流和层状流)的相含率测量模型。实际测量时根据流型选择相应的相含率测量模型,计算获得相含率。在内径为47.5 mm管径下进行相含率测量静态实验,研究结果表明,所提出的气液两相流相含率测量新方法是可行、有效的。在三种典型流型下的相含率测量最大绝对误差均小于9%。 相似文献
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气液两相流速度及粒径分布激光干涉测量方法的研究 总被引:1,自引:0,他引:1
为了实现对气液两相流的粒子粒径、空间分布及其速度测量。对激光干涉气液两相流测量技术(ILIDS)进行了深入研究,该技术是一种应州于气液两相流测量的新技术,其主要优点是不干扰流场和颗粒粒径、位置测量精度高。基于该技术所开发的图像自动处理方法可以利用普通粒子成像测量技术系统拍摄气液两相流的激光散射干涉图像。并利用图像卷积定位、傅里叶变换频率分析及其图像互相关测速等图像处理手段从干涉图像中自动提取粒子的位置、直径和速度信息。为了验证该方法的测量精度,对喷嘴生成的气水两相流进行了测量实验,得到了喷嘴出口处不同区域的粒径、速度矢量的空间分布,并将测得的速度矢量与用粒子成像测量技术方法测得的结果进行对比,证明两种方法测量的平均速度差别仅为0.38%。 相似文献
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本文在VOF方法的基础上,采用粗细两套网格对高密度和高粘度比率下的气液两相流动模拟进行了研究分析.在细网格中求解流体体积函数方程,在粗网格中采用交错网格求解动量方程和压力修正方程,通过粗细网格间的数据传递获得求解动量方程时需要的准确的界面密度和粘度及控制体密度,克服了高密度和高粘度比率下通过插值方法计算界面密度和粘度及控制体密度带来较大误差的困难,保证了质量和动量同时守恒.高密度和高粘度比率下气液两相流动中气液交界面处密度、速度和压力急剧变化,为了保证格式的有界性和稳定性,采用稳定的有界高阶组合格式STOIC.最后模拟了不同工况下气泡在液体中的运动,并通过实验和模拟结果验证了方法的可行性及准确性. 相似文献
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《工程热物理学报》2021,42(9):2367-2377
本文采用流体体积法(Volume of fluid,VOF)捕捉气–液态金属两相的交界面,数值研究了有、无外加磁场作用时不同工质对的气–液态金属两相流体在多入口磁流体发电通道中的混合流动过程。结果表明,气–液两相流体在通道中形成了具有周期性变化的两相流型。液态金属密度与气体密度的比值h较大时,分层流中液态金属速度的变化范围较大,但流动较稳定;h较小时,液态金属的界面容易断裂而形成柱状流,使气–液两相流体的接触面积减小,降低了气体对液态金属的携带能力。在磁场的作用下,洛伦兹力抑制了液态金属的流动,削弱了气体对液态金属的携带能力,使三维时空流型的变化周期缩短。 相似文献
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研究了电容耦合式非接触电导检测技术(C~4D)应用于气液两相流测量的可行性,建立了一套基于非接触电导的毫米级气液两相流参数检测系统。利用所建立的系统,在内径为5 mm,9 mm的水平管上进行了气液两相流实验,获得了不同流型下的电导测量信号,并对段塞流、波状流、泡状流和环状流四种典型流型下的电导信号进行了分析与比较。研究结果表明,所建立的基于非接触电导的气液两相流参数检测系统是有效的,C~4D技术应用于气液两相流参数测量是可行的。不同流型下所获的电导信号特征均表现出明显差异,有望用于流型辨识。 相似文献
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提出了一种非侵入式同时测量气固两相流型和电荷分布的可视化测试方法。数值仿真结果表明,ECT提供的介电常数分布信息可用于修正实际流型下的EST电荷灵敏场,降低了电荷分布反演的不确定性,EST的图像重建误差有所减小,有效的提高了电荷分布反演的精度。将该测试方法分别应用于粉体重力输送系统和高压密相气力输送系统,结果表明重力输送试验中颗粒浓度大的区域电荷密度值较大,而在气力输送试验中,颗粒浓度大的区域,电荷密度值反而较小,且随着管内煤粉颗粒浓度的增加,粉体总的电荷强度值减小。 相似文献
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Microstructured heat exchangers are well suited for such phase transition processes as evaporation of liquids due to their heat transfer capabilities, being two to three orders of magnitude higher than those of conventional heat transfer devices. Controlling liquid evaporation inside micro-channels to provide full evaporation in a stable way is not trivial. In most cases, such instabilities as slug flow, bubbly flow, or vapor clogging occur, based on cross-talk possibilities between the individual micro-channels of a channel array, normally caused by open void inlet structures. Therefore, fluid inlet distribution is inhomogeneous, which results, in the best case, in a parabolic shape of a stable evaporation frontline. The parabolic shape occurs due to the residence time distribution of the fluid, generated by shorter path length in the array center and longer ones in the outer areas of the micro-channel array. Computational fluid dynamics simulation approves this result. Such a frontline can be kept stable when the process parameters are well controlled. Small deviations of the inlet parameters may lead to strong disturbances of the evaporation process, destabilizing it. When changing the inlet fluid distribution system to provide the most equal flow distribution possible, the span of the parabolic shape of the evaporation frontline can be reduced drastically. Finally, a stable evaporation frontline perpendicular to flow direction can be obtained. This status is no longer very sensitive to process deviations. This article presents an optimized micro-channel device for the optical investigation of phase transition phenomena. The device allows the exchange of integrated micro-channel arrays to investigate different designs for their suitability. It is separated into three independent sections, which can be heated or cooled individually. Therefore, very strict and rapid temperature jumps can be obtained within relatively short distances. The micro-channel array foils used for the experiments have been manufactured by mechanical micro-machining. Thus, the cross-sections of the micro-channels are always rectangular. Hydraulic diameter and length of the micro-channels, as well as the shape of the inlet and outlet voids, can be varied. Using a simple triangular or rectangular open inlet void, a stable evaporation line was generated, showing a parabolic shape. Depending on the mass flow and the size and shape of the inlet void, the span of the parabolic arc was influenceable. 相似文献
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《理论物理通讯》2015,(11)
This paper describes the theoretical analysis for peristaltic motion of water base nanoBuid containing distinct types of the nanoparticles like Cu,TiO_2,and Al_2O_3.Equations of nano Quid are modelled and simplified by constructing the suppositions of low Reynolds number as well as long wave length.The reduced equations are solved exactly.Solutions are represented through graphs.Outcomes for the velocity,temperature,pressure rise and stream lines are analyzed graphically.The work presented here is based on the fictitious values,however some other values can be tested experimentally. 相似文献
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This paper describes the theoretical analysis for peristaltic motion of water base nanofluid containing distinct types of the nanoparticles like Cu, TiO2, and Al2O3. Equations of nano fluid are modelled and simplified by constructing the suppositions of low Reynolds number as well as long wave length. The reduced equations are solved exactly. Solutions are represented through graphs. Outcomes for the velocity, temperature, pressure rise and stream lines are analyzed graphically. The work presented here is based on the fictitious values, however some other values can be tested experimentally. 相似文献