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Flocculating characteristic of activated sludge flocs:Interaction between Al^(3+) and extracellular polymeric substances

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Journal of Environmental Sciences 2013年第5期25卷 916-924页

作者： xiaodong ruan Lin Li Junxin Liu Research Center for Eco-Environmental Science Chinese Academy of Sciences

Aluminum flocculant can enhance the flocculating performance of activated ***,the binding mechanism of aluminum ion（Al 3＋） and extracellular polymeric substances（EPS） in activated sludge is unclear due to the complexity of *** this work,threedimensional excitation emission matrix fluorescence spectroscopy（3DEEM）,fluorescence quenching titration and Fourier transform infrared spectroscopy（FT-IR） were used to explore the binding behavior and mechanism between Al 3＋ and *** results showed that two fluorescence peaks of tyrosineand tryptophan-like substances were identified in the loosely bound-extracellular polymeric substances（LB-EPS）,and three peaks of tyrosine-,tryptophanand humic-like substances were identified in the tightly boundextracellular polymeric substances（TB-EPS）.It was found that these fluorescence peaks could be quenched with Al 3＋ at the dosage of 3.0 mg/L,which demonstrated that strong interactions took place between the EPS and Al 3＋.The conditional stability constants for Al 3＋ and EPS were determined by the Stern-Volmer *** to the binding mechanism,the-OH,N-H,C=O,C-N groups and the sulfurand phosphorus-containing groups showed complexation action,although the groups in the LB-EPS and TB-EPS showed different *** TB-EPS have stronger binding ability to Al 3＋ than the LB-EPS,and TB-EPS play an important role in the interaction with Al 3＋.

关键词： extracellular polymeric substances activated sludge aluminum ion three-dimensional excitation emission matrix fluorescence quenching Fourier transform infrared spectroscopy

Experimental Study of Cavitation Phenomenon in a Centrifugal Blood Pump Induced by the Failure of Inlet Cannula

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Chinese Journal of Mechanical Engineering 2014年第1期27卷 165-170页

作者： LIN Zhe ruan xiaodong ZOU Jun FU Xin The State Key Lab of Fluid Power Transmission and Control Zhejiang University

Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomenon caused by the coupling effect of inlet cannula blocking and pumps suction. Even for cavitation studies on ordinary centrifugal pumps, similar researches on this issue are rare. In this paper, the roles of throttling, rotation speed and fluid viscosity on bubble inception and intensity in a centrifugal blood pump are studied, on the basis of experimental observations. An adjustable throttle valve installed just upstream blood pump inlet is used to simulate the throttling effect of the narrowed inlet cannula. The rotation speed is adjusted from 2 600 r/rain to 3 200 r/min. Glycerin water solutions are used to investigate the influences of kinetic viscosity. Bubbles are recorded with a high-speed video camera. Direct observation shows that different from cavitation in industrial centrifugal pumps, gas nuclei appears at the nearby of vane leading edges while throttling is light, then moves upstream to the joint position of inlet pipe and pump with the closing of the valve. It＇s found that the critical inlet pressure, obtained when bubbles are first observed, decreases linearly with viscosity and the slope is independent with rotation speeds; the critical inlet pressure and the inlet extreme pressure which is obtained when the throttle valve is nearly closed, fall linearly with rotation speed respectively and the relative pressure between them is independent with rotation speed and fluid viscosity. This paper studies experimentally on cavitation in centrifugal blood pump that caused by the failure of assembled short inlet cannula, which mav beneficial the desima of centrifugal blood Dumo with inlet cannula.

关键词： centrifugal blood pump cavitation viscosity cannula diameter rotation speed

Numerical Simulation and Experimental Research on Passive Hydrodynamic Bearing in a Blood Pump

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Chinese Journal of Mechanical Engineering 2013年第5期26卷 967-973页

作者： HAN Qing ruan xiaodong CHEN Wenyu FU Xin State Key Laboratory of Fluid Power Transmission and Control Zhejiang University

The current research of hydrodynamic bearing in blood pump mainly focuses on the bearing structure *** with the typical plane slider bearing and Rayleigh step bearing,spiral groove bearing has excellent performance in load-carrying ***,the load-carrying capacity would decrease significantly with increasing flow rate in conventional *** this paper,the special treatment is made to the upper spiral groove bearing to make sure that both the circulatory flowing and load-carrying capacity are ***-dimensional computational fluid dynamics(CFD) models in the space between rotor and shaft are developed by using FLUENT *** of groove number,film height and groove depth on load-carrying capacity of the spiral groove bearings are investigated by orthogonal experiment *** experimental results show that film height is the most remarkable factor to the load-carrying *** variation tendency of load-carrying capacity reveals that the best combination of geometry is the one with groove number of 8,film height 0.03 mm and groove depth 0.08 *** velocity and pressure distributions in spiral groove bearings are also analyzed,and the analysis result shows that the distributions are in conformity with the design of the blood pump based on the principle of hydrodynamic *** displacement of the rotor with the best combination parameters is tested by using laser displacement sensors,the testing result shows that the suspending performance is satisfactory both in axial and radial *** research proposes a bearing design method which has sufficient load-carrying capacity to support rotor as an effective passive hydrodynamic bearing.

关键词： blood pump spiral groove bearing hydrodynamic bearing laser displacement measurement

Effect of Placements (horizontal with vertical) on Gas-solid Flow and Particle Impact Erosion in Gate Valve

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Journal of Thermal Science 2014年第6期23卷 558-563页

作者： LIN Zhe ZHU Linhang CUI Baoling LI Yi ruan xiaodong The Zhejiang Provincial Key Laboratory of Fluid Transmission Technology Zhejiang Sci-Tech University 1201 Chu Kochen Honor College Zhejiang University State Key Laboratory of Fluid Power Transmission and Control Zhejiang University

Gate valve has various placements in the practical *** to the effect of gravity,particle trajectories and erosions are distinct between *** in this study,gas-solid flow properties and erosion in gate valve for horizontal placement and vertical placement are discussed and compared by using Euler-Lagrange simulation *** structure of a gate valve and a simplified structure are *** simulation procedure is validated in our published paper by comparing with the experiment data of a pipe and an *** results show that for all investigated open degrees and Stokes numbers(St),there are little difference of gas flow properties and flow coefficients between two *** is also found that the trajectories of particles for two placements are mostly identical when St << 1,making the erosion independent of *** the increase of St,the distinction of trajectories between placements becomes more obvious,leading to an increasing difference of the erosion ***,the total erosion ratio of surface T for horizontal placement is two orders of magnitudes larger than that for vertical placement when the particle diameter is 250 μm.

关键词： gate valve placement flow properties erosion

Shape Memory of Elastic Capsules Under the Effect of Spontaneous Shape

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Communications in Computational Physics 2018年第6期24卷 234-252页

作者： Zhe Gou Feng Huang xiaodong ruan Xin Fu State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang UniversityHangzhou 310025P.R.China College of Metrology&Measurement Engineering China Jiliang UniversityHangzhouP.R.China

Red blood cells can recover their resting shape after having been deformed by shear *** rims are always formed by the same part of the membranes,and the cells are said to have *** as two-dimensional elastic capsules,their recoverymotion and shapememory is studied,mainly focused on the effect of the spontaneous *** fluid-structure interaction ismodeled using immersed boundary *** on the simulations,the resting shapes of capsules are obtained and the area ratio of spontaneous shape is found to play an important *** remove of shear flow,all capsules can recover their resting shapes,while only capsules with noncircular spontaneous shapes present shape *** the spontaneous shape approaches a circle but still noncircular,the capsule spends more time on recovery *** consider how these capsules deform depending on the membrane bending energy,and find that the relaxation speed is positive correlated to the range of values of dimensionless bending *** results may help to identify different spontaneous shapes for capsules especially RBCs through future experiments.

关键词： Fluid-structure interaction immersed boundary method shape memory spontaneous shape

Particle removal by a single cavitation bubble

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Science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 668-673页

作者： XU Ming JI Chen ZOU Jun ruan xiaodong FU Xin State Key Laboratory of Fluid Power Transmission and Control Zhejiang University

In the paper,the behavior of the particle acted by the oscillating bubble is studied using a high-speed video *** bubble is generated using a very low voltage of 55 *** are captured at a speed of 15000 fps(frames per second).It is found that the velocity of the particle is dependent on the liquid viscosity,particle size,and tube *** velocity decreases with the increase of the glycron-water mixture viscosity.A model is presented to predict the velocity and verified by experimental *** observations may be beneficial for the application in medical treatment.

关键词： oscillating bubble particle removal viscosity influence

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基于主动转速调制的离心旋转血泵流场分析

中国机械工程 2021年第24期32卷 2915-2923页

作者：黄峰王楚晨阮晓东浙江科技学院机械与能源工程学院杭州310023 中国计量大学计量测试工程学院杭州310018 浙江大学流体动力与机电系统国家重点实验室杭州310027

为研究血泵主动转速调节对血泵内部流场以及血液损伤的影响,采用计算流体动力学(CFD)方法模拟血泵在转速调制下的全流道内部流动。通过集总心血管系统数学模型和旋转血泵模型的联合数值模拟得到血泵辅助条件下的心室和主动脉压力,并设... 详细信息

为研究血泵主动转速调节对血泵内部流场以及血液损伤的影响,采用计算流体动力学(CFD)方法模拟血泵在转速调制下的全流道内部流动。通过集总心血管系统数学模型和旋转血泵模型的联合数值模拟得到血泵辅助条件下的心室和主动脉压力,并设置为血泵CFD模拟的进出口边界条件。分析了匀转速以及正弦波、方波、三角波三种异步转速调制波形下的血泵流场情况,得到了旋转血泵的速度分布图以及剪切应力分布图。结果表明,转速调制下血泵的流量脉动得到了增强,是一种恢复血流搏动性的可行方案。三种速度调制波形中,正弦波转速调制下的血泵流量脉动指数高且血泵内剪切应力小,是相对理想的转速调制波形。

关键词：旋转血泵计算流体动力学转速调制心血管系统脉动性指数

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带分流叶片混流式水泵非定常流动特性研究

农业机械学报 2021年第11期52卷 153-160页

作者：张旭王鹏飞阮晓东浙江大学流体动力与机电系统国家重点实验室杭州310027 浙江大学自贡创新中心自贡643000

为研究在流固耦合作用下分流叶片对混流式水泵的性能影响,以某型号的大流量混流式水泵作为研究对象,采用双向流固耦合方法和动网格变形技术对有/无分流叶片混流泵进行流场和结构场计算。对比分析了有/无分流叶片对混流泵非定常流动特性... 详细信息

为研究在流固耦合作用下分流叶片对混流式水泵的性能影响,以某型号的大流量混流式水泵作为研究对象,采用双向流固耦合方法和动网格变形技术对有/无分流叶片混流泵进行流场和结构场计算。对比分析了有/无分流叶片对混流泵非定常流动特性和动力学特性的影响。研究发现,分流叶片的添加使得动静干涉产生的压力脉动幅值的最大值大幅降低,但减小了脉动衰减的速度。有/无分流叶片对轴向力平均值影响不大,但考虑流固耦合效应时轴向力有所减小并有波动产生。分流叶片的添加可以降低应力以及形变的波动幅值。叶片最大应力区主要集中于靠近叶轮轮毂及轮缘处,分流叶片的添加使得叶片最大应力减小,且改善了应力变化梯度,使得应力分布更加均匀。分流叶片的添加也使得叶片形变在圆周方向更加均匀,改善了形变分布的偏心问题。研究结果可以为混流泵叶片的优化设计提供相应参考。

关键词：混流式水泵分流叶片流固耦合压力脉动非定常流动

基于拉格朗日跟踪法的微混合器内混沌混合特性

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机械工程学报 2008年第11期44卷 64-68页

作者：傅新刘素芬阮晓东浙江大学流体传动及控制国家重点实验室杭州310027 江苏技术师范学院电气信息工程学院常州213001

为了分析三维交叉导流式(Staggered oriented ridges,SOR)微混合器内混沌混合特性,在计算流体力学的基础上,采用拉格朗日跟踪技术数值模拟SOR混合器中流道截面上流体物质线和物质面的变形、拉伸情况,并通过平均对数线拉伸计算定量地评价... 详细信息

为了分析三维交叉导流式(Staggered oriented ridges,SOR)微混合器内混沌混合特性,在计算流体力学的基础上,采用拉格朗日跟踪技术数值模拟SOR混合器中流道截面上流体物质线和物质面的变形、拉伸情况,并通过平均对数线拉伸计算定量地评价SOR混合器的混合效果。研究结果表明:SOR微混合流道内可诱发混沌对流,并在其作用下可增加流体粒子的接触面积,提高混合效率。在小雷诺数时,线拉伸随雷诺数增大变化不大,但在雷诺数较大时,线拉伸随雷诺数增大而增大。

关键词：静态微混合器混沌对流拉格朗日跟踪微流控