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The fluid film pressure and temperature fields have been measured simultaneously under laboratory conditions at one land of a circumferential groove journal bearing (CGJB), together with friction torque and oil flow rate, during a time span from stand-still startup to the development of a thermally stabilized steady operating regime.A very fine measurement grid—that is, 216 pressure and 180 temperature points spread across the axial and circumferential directions—has been obtained by joining and synchronizing measurements from separate test runs while rigorously re-creating the test conditions.The study confirmed that the pressure field is established faster than the temperature field, that film rupture occurs both from cavitation nuclei downstream the minimum film thickness and through air ingestion from the environment. Furthermore, the high pressures in the convergent zone stabilize relatively quickly, whereas the low pressures in the divergent zone cavitated region require a longer time to stabilize. The cavitated region reverse flow appearance has been identified thermally through upstream-oriented isotherms. This study is the first to present the transient evolutions of pressure and temperature fields. 相似文献
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Jiaxiang Guo Zhiyong Yuan Xiangyun Liao Yaoyi Bai Qianfeng Lai 《Computer Animation and Virtual Worlds》2015,26(3-4):337-345
The vessel wall and the blood flow interact and influence each other, and real‐time coupling between them is of great importance to the virtual surgery as well as the research and diagnosis of vascular disease. On the basis of smoothed particle hydrodynamics (SPH), we present a new approach to solve non‐Newtonian viscous force of blood and a parallel mixed particles‐based coupling method for blood flow and vessel wall. Meanwhile, we also design a proxy particle‐based vessel wall force visualization method. Our method is as follows. Firstly, we solve the non‐Newtonian viscous forces of blood through the SPH method to discretize the Casson equation. Secondly, in each time step, we combine blood particles and sampling proxy particles on the blood vessel wall to form mixed particles and calculate the interaction forces through the SPH method between every pair of the neighboring mixed particles inside the graphics processing unit. Thirdly, the forces of the proxy particles will be mapped to the color display of the proxy particle. Experimental results demonstrate that our method is able to implement real‐time sizeable coupling of blood flow and vessel wall while mainly ensuring physical authenticity and it can also provide real‐time and obvious information about vessel wall force distribution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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We propose a geometric approach to animating thin surface features of smoothed particle hydrodynamics‐based water. Explicit interparticle connections are created among smoothed particle hydrodynamics particles to approximate the geometries of thin surfaces while addressing the issue of unresolved surface areas. The deformations measured on the connections actuate the animations of the surfaces by disconnecting the stretched and bent connections. The reconstruction of thin surfaces and the accuracy of the animation are improved by adding auxiliary particles over the connections via Poisson‐disk sampling. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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选取卧式单轴捏合反应器为研究对象,搭建了一个可视化实验装置来研究其分布混合过程,并且通过三维有限元数值模拟方法和网格重叠技术获取了高黏牛顿流体在反应器中的流速分布、剪切速率分布与混合指数分布,进一步采用粒子示踪技术分析了全局与局部分布混合过程,对示踪粒子的运动轨迹进行统计分析得到了拉伸率与混合效率,并且考察了搅拌结构对流动与混合过程的影响。结果表明,实验与数值模拟结果吻合较好。捏合反应器中几乎不存在流动死区,搅拌轴上的动态捏合杆与搅拌槽壁面上的静态捏合杆之间存在周期性的捏合作用,可以强化自清洁性能、剪切作用、整体与局部分布混合过程、分散混合性能以及混合效率。拉伸率随着混合时间以指数形式增加,时均混合效率大于零。 相似文献
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运用高速摄像技术对流量脉动条件下旋流分离器内气泡动力学行为及气液两相流流型展开研究。研究发现,在完整脉动周期内,流量在3.62~4.18 m3/h范围内波动,流量增大段的气核整体向溢流口方向运移,流量减小段的气核整体向底流口方向运移,气核大小及形态变化呈现周期往复性。通过脉动周期内特殊帧的分析,得出流量脉动条件下旋流场内气液两相流流型主要包括:气泡流、塞状流、弹状流、丝状流及波状流等五种形式。根据实验得出的气液两相折算速度,确定了脉动条件下气液两相流流型转换界限图,而气泡间的聚并破碎行为是产生气液两相流型的主要原因,最终构建了表征截面含气量和分离效率之间关系的评价模型。 相似文献
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介绍了一种基于循环流化床的动力系统方案———循环流化床置换燃烧。这种燃烧系统能在没有能量损失的前提下,将CO2从燃烧产物中分离出来。本文设计建立了一套燃煤循环流化床置换燃烧冷态实验系统,以此为研究对象,选择具有代表性的实验物料,利用测试系统取得多种信号参数,获得反应装置之间的气固流动特性,总结出一定的规律,为以后的热态实验以及进一步探索奠定基础。 相似文献
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Adhesives have become the method of choice for many structural joining applications. Therefore, there is a need for improved understanding of adhesive joint performance, especially their failure, under a variety of loading conditions. Various numerical methods have been proposed to predict the failure of adhesive bonded material systems. These methods generally use a cohesive zone model (CZM) to analyze crack initiation and failure loci. The CZM incorporates a traction–separation law which relates the jump in surface tractions with the jump in displacements of abutting nodes of the cohesive segment; the area under the curve relating these jumps equals the energy release rate which is determined from experimental data. Values of parameters in the CZM are usually obtained through the comparison of results of numerical simulations with the experimental data for pure mode I and mode II deformations. Here a numerical approach to simulate crack initiation and propagation has been developed by implementing CZM in the meshless method using the symmetric smoothed particle hydrodynamics (SSPH) basis functions, and using the design of experiments technique to find optimal values of CZM parameters for mode I failure. Unlike in the finite element method where a crack generally follows a path between element boundaries, in the meshless method a crack can follow the path dictated by the physics of the problem. The numerical technique has been used to study the initiation and propagation of a crack in a double cantilever beam under mode I and mixed mode in-plane loadings. Computed results are found to agree well with the corresponding experimental findings. Significant contributions of the work include the determination of optimum values of CZM parameters, and simulating mode I, mode II and mixed mode failures using a meshless method with the SSPH basis functions. 相似文献