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基于欧拉-欧拉双流体模型对通气空泡尾部气泡流进行数值仿真, 并采用基于多尺寸分组模型的总体平衡方法预估气泡尺寸分布. 应用改进后湍流耗散系数计算模型, 考虑了气泡体积含量对在湍流作用下气泡扩散现象的影响. 基于上述模型对两种试验工况下流场进行了数值仿真.结果表明模型对空泡尾部回流区特性进行了准确预示, 在回流区高湍流度作用下气泡迅速破碎成小气泡. 并进一步得到试验体尾流区空泡体积分数和速度分布. 尾流区水流速度分布保持了流体经过非流线型对称体时产生的尾流分布规律. 仿真结果与试验数据相一致, 模型适用性得到验证. 相似文献
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利用欧拉-拉格朗日方法,提出了用于预测竖直管道内绝热层流泡状流中含气率分布的三维模型。该模型能够跟踪单独的气泡轨迹,从而获取更多的界面力信息;同时气泡尺寸可以作为参数之一引入模型,使含气率分布的计算更为方便。模型中分析了绝热层流泡状流中气泡的各项受力表达式,建立了两种描述方法下的气液两相间的耦合关系。利用现有实验数据对模型进行的检验表明,该模型能够预测一定尺寸范围内气泡的分布;气泡径向分布主要取决于气泡所受侧向提升力。对于更大尺寸的气泡,气泡变形和气泡尾迹与当地流场间相互作用将对侧向提升力产生很大影响。 相似文献
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激光多普勒测速技术在气液两相流中的应用 总被引:1,自引:0,他引:1
本文采用激光颗粒动态分析仪(PDA)测量了钢包底部喷吹气液两相流中气泡的直径和气泡上升速度的分布;采用激光多普勒测速仪(LDA)测量了气液两相区和液体单相循环区液体速度场的分布。测量结果表明:气泡在脱离喷嘴上浮一定距离后,其大小基本保持不变;在气液两相区中,气泡速度和液体速度的分布均服从高斯分布;液体在单相区作循环流动,在侧壁与底部交接处,存在液体流动的“死区”。 相似文献
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深海油气多相混输系统内部油气混输本质上是一种高压高含气率的气液两相流问题。现如今多采用欧拉–欧拉方法对该问题进行数值研究,然而该方法的准确性依赖于相间力模型与群体平衡子模型的构建与选择。因此,本文对现有的相间力模型进行了总结,主要包括曳力、升力、壁面润滑力、湍流扩散力、虚拟质量力,并对相关模型的理论与发展进行了阐述,总结了压力以及高含气率下泡群对相间力模型的修正方法。此外,考虑到高含气率工况下气泡与气泡之间的相互作用,针对气泡群体平衡模型进行介绍,对气泡的破碎与聚并模型进行了梳理,总结了高压情况下群体平衡模型的修正思路。以期对深海高压高含气率环境下的气液混输模拟计算提供借鉴。 相似文献
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为研究氧化沟内的固-液两相流,本文采用数值计算的方法,以典型的四沟道Carrousel氧化沟为研究对象,通过将污泥沉降速率模型与两相湍流混合物模型耦合,建立了氧化沟固-液两相湍流混合物模型,从而实现了垂向上固-液两相的分离。模拟结果显示:氧化沟内的污泥浓度变化趋势总体呈现出与水流流速变化趋势相反的分布规律,即越接近沟底,污泥浓度越大,流速越小;越接近水面,污泥浓度越小,流速越大。此外,在大弯道处,形成弯道环流,造成了外弯道的冲刷和内弯道的淤积,大弯道内壁处的污泥浓度整体高于弯道外壁处。本研究结果对实际工程中防止或减少沟内污泥沉积,提高氧化沟污水处理效率有一定的指导意义。 相似文献
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《Acta Mechanica Sinica》2014,(6)
正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987, 相似文献
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《Acta Mechanica Solida Sinica》2014,(5):F0003-F0003
Contributions: The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication. 相似文献
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Yulong Ding Qingshan Zhu 《中国颗粒学报》2008,6(1):1-1
This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group (PTSG) of the Institution of Chemical Engineers (IChemE), Particle Characterisation Interest Group (PCIG) of the Royal Society of Chemistry (RSC) and International Fine Particle Research Institute (IFPRI). The forum was supported financially by the Engineering and Physics Sciences Research Council (EPSRC) of United Kingdom, 相似文献
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针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。 相似文献
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《Acta Mechanica Sinica》2014,(3):F0003-F0003
正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica 相似文献
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G.C. Sih 《Theoretical and Applied Fracture Mechanics》2010,53(2):94-112
Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or fj/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (fmi/ma,fna/mi,fpi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10−12, 10−9, 10−6, 10−3 m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials. 相似文献