涡流空气分级机圆弧形叶片转笼的设计

涡流空气分级机分级粒径主要受转笼转速与入口风速匹配关系的影响。入口风速一定时,转笼转速越高,分级粒径越小,但这会造成流场速度分布不均匀,而降低分级精度。利用Fluent软件对具有直叶片转笼结构的涡流空气分级机进行建模和数值模拟,分析转笼内流场特性,针对其流场不均匀及转笼入口冲角大等现象,对转笼叶片的形状及安装角进行改进,提出一种圆弧形叶片转笼的设计方法。通过数值模拟及物料试验对改进结果进行验证,数值模拟结果表明:圆弧形叶片转笼入口冲角减小,流道内流场更加均匀,分级粒径减小。碳酸钙分级试验结果与数值模拟结果吻合:设计工况即入口风速为12 m/s,转笼转速为1 200 r/min时,采用设计的圆弧形叶片转笼在保持分级精度不变的情况下,分级粒径减小了11.5%。     

影响布袋除尘器除尘效率和滤袋寿命的因素分析

基于布袋除尘系统的结构特点及工作原理,分析了布袋除尘器影响除尘效率和滤袋寿命的几个常见因素,分析了各因素对布袋除尘器的影响,并提出了合理建议。     

变工况玻璃窑炉布袋除尘器温度控制方法

为保证变工况玻璃炉窑布袋除尘器中布袋正常工作的温度环境从而达到更好的除尘效果,根据现场高温烟气温度周期变化的工况,将模糊控制策略应用到布袋除尘器的温度控制中。当温度超过设定值时能在短时间内将温度降回到安全范围内,有效延长布袋使用寿命,保证除尘效果并降低了成本。结果表明,将模糊算法引入到变工况玻璃炉窑布袋除尘器温度控制中是可行的。     

基于离散相模型的旋风分离器内部流场数值研究

针对旋风分离器内部流场的研究,采用数值模拟的方法模拟了分离器内固体颗粒的运动轨迹。通过分析不同粒径及入口速度对旋风分离器内固相颗粒运动轨迹的影响,探索了颗粒在旋风分离器中运动的物理机理,随后对旋风分离器的灰斗长度进行了优化。结果表明:颗粒在旋风分离器中运动轨迹比较复杂,且同时受到入口速度和粒子半径的影响,相同粒径颗粒在不同入口速度下运动轨迹不同,且小粒径颗粒较容易受到入口速度的影响,旋风分离器在标准灰斗长度下的分离效率及分离性能最好。模拟结果可为工程实际应用提供一定的理论指导。     

布袋除尘器使用寿命提升的研究

布袋除尘器是一种干式滤尘装置,布袋的作用是将烟气净化后排入大气,它能够捕集颗粒小、干燥性的粉尘,其工作原理是通过布袋对含尘气体进行过滤,起到净化烟气、保护环境的作用。现介绍布袋除尘器的工作原理,在此基础上提出延长布袋除尘器使用寿命的方案,并重点对布袋除尘器快速维修技术进行分析。     

烟气转换阀流场特性及颗粒随机轨道的数值模拟

运用计算流体动力学（CFD）方法对烟气转换阀中的离散两相流场进行了数值模拟。在考虑气相与颗粒固相之间相互作用的前提下,对气相采用带旋流修正的k-ε模型,对颗粒固相采用随机轨道模型,成功地模拟出颗粒的运动轨迹。计算结果表明：阀体内的流场分布可分为4个区域,每个区域内的压力和速度分布存在明显不同的特征;另外,颗粒粒径、颗粒在入口的初始位置对颗粒运行轨迹和时间有很大的影响。该方法为阀体结构的优化设计提供了理论依据。     

一种应用于焊接工位的等离子体除尘装置

本文提出一种焊接烟尘净化新工艺,不同与单一的布袋和静电除尘,采用吸尘-滤尘-荷电吸附的多级除尘方式,最后由等离子体除尘装置将粒径微小的烟尘颗粒吸附在集尘板,达到净化有毒烟尘的效果;还通过模拟以及实验,确定本装置重要的结构参数,并且提出了追踪焊接烟尘源的方案。     

等离子体焊接除尘装置设计与数值模拟

基于等离子体放电吸附原理，提出吸尘-滤尘-荷电-除尘新工艺来净化焊接烟尘，并设计了能实时跟踪焊接烟尘源的除尘装置。确定了两电极板的长度与间距等参数，对等离子体静电吸附装置进行了荷电计算与三维电场分析，研究了烟尘颗粒在电场中的运动轨迹及其变化规律；利用COMSOL软件进行仿真分析，讨论了烟尘粒径、入口气体流速和板间电压对烟尘颗粒吸附效果的影响。分析结果表明：板间电压在0.6~2.4 kV范围内，在电场中运动时间t≥0.1 s时，该除尘装置对0.1~1 μm粒径的烟尘颗粒能够实现快速有效地吸附，且获得了显著的净化效果。     

基于CFD-PBM积分矩量法旋风分离器中颗粒聚团的数值模拟

为了得到颗粒聚团对旋风分离器分离性能的影响,在不同入口颗粒浓度与入口气速下研究其对分离效率的影响。采用雷诺应力模型(RSM)计算湍流流场,通过群体平衡模型(PBM)耦合CFD对颗粒相进行数值计算。研究结果表明:时间为2 s时,旋风分离器内的聚团作用已经趋于稳定,颗粒粒径在1.5μm到3μm范围的颗粒在旋风分离器内基本无法被捕集,而粒径大于5μm的颗粒其分离效率接近于100%;随着入口颗粒浓度的增加,总体分离效率增加,而增加入口气体速度,对分离效率的影响并不是很大。     

河南济钢450m3高炉热风炉、布袋除尘三电控制系统

结合济钢新建450m3高炉配套四座热风炉、九座布袋除尘器的自动控制工程,介绍西门子PLC在热风炉及布袋除尘中的应用,阐述系统组成,结构特点以及监控功能的完成。     

Experimental Research on Salt-out Particle Motion and Concentration Distribution in a Vortex Pump Volute

The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle motion and concentration distribution. Study on the particle hydrodynamic characteristics in the pump volute becomes a key problem, because the crystal particles are mainly distributing in this zone after they enter the pump. Phase Doppler particle analyzer(PDPA) is used to measure the two-phase flow field in a model pump volute to get more understanding about the salt-out phenomenon. The crystal particle velocities are obtained in all three peripheral, radial and axial directions. Particle size and particle number density(PND) measurements are also performed in the experiment. Results are presented and discussed along the radial direction under different pump operating conditions, as well as various axial measurement positions. It is found that particle velocity gradient of peripheral component varies with the pump discharge. There is a turning point of relation between peripheral velocity component and discharge. Radial flow velocity curves look like a saddle shape and velocity magnitudes are changing greatly with the discharge. The non-equilibrium velocity feature between liquid and solid phase on this direction is also remarkable. Particles flow into the impeller at radial position R1, and the axial velocity component increases in this region. The particle size curve shows an open-up parabola distribution. The largest particles are distributing near the casing peripheral wall. As flow rate increases, accordingly PND increases. It also grows up in the axial-outward direction towards the suction cover. Crystal particle aggregation phenomenon can be revealed from the analysis of particle size and PND distribution, and the aggregation region is determined as well. Research results are helpful for optimal design of this kind of pump preventing salt-out.     

基于数值模拟优化分析的某型汽油机发动机燃烧系统正向开发

文中主要基于喷雾标定的结果进行发动机缸内燃烧系统的正向开发和优化.在喷雾试验数据的基础上建立了喷雾模型,并利用喷雾模型和发动机相关数据进行了缸内燃烧计算,分析了缸内流场和油气混合情况.分析表明:缸内流场方面,在压缩冲程中不同工况下均形成了非常明显的滚流流场,同时滚流比大小的变化存在明显的"双峰"现象,不同工况下均有燃油...     

基于ZigBee的袋式除尘器的分布式压力监测

流场分布不均匀的袋式除尘器除尘效率会大幅度降低,因此开发分布式压力监测系统。用ZigBee技术开发终端采集节点、路由节点和中心分站等结构,节点的压力数据通过ZSC31050采集并利用温差程序进行补偿,校准后的压力数值通过ZigBee网络传送数据,利用240 cm除尘器滤袋检测实验分析压力。试验结果显示当喷吹压力为30 kPa、喷吹距离为240 cm时,检测长滤袋各点的分布压力,并测量喷口的不同压力。结果显示监测系统可以精确识别出袋式除尘器的压力分布。     

Influence of thermophoresis particle deposition and chemical reaction on unsteady non-Darcy MHD mixed convective flow over a porous wedge in the presence of temperature-dependent viscosity

An analysis is presented to investigate the effect of thermophoresis particle deposition and temperature dependent viscosity on unsteady non-Darcy MHD mixed convective heat and mass transfer of a viscous, incompressible and electrically conducting fluid past a porous wedge in the presence of chemical reaction. The wall of the wedge is embedded in a uniform non-Darcian porous medium in order to allow for possible fluid wall suction or injection. The results are compared with those known from the literature and excellent agreement between the results is obtained. The governing partial differential equations of the problem, subjected to their boundary conditions, are solved numerically by applying an efficient solution scheme for local nonsimilarity boundary layer analysis. Numerical calculations are carried out for different values of dimensionless parameter in the problem and an analysis of the results obtained show that the flow field is influenced appreciably by the applied magnetic field and thermophoresis particle deposition.     

Investigation of air filter properties of nanofiber non-woven fabric manufactured by a modified melt-blowing method along with flash spinning method

Nanofibers are used in various fields and applications, such as medical care, environment protection, apparel, and agriculture; it is believed that they will continue to show substantial growth in the future. In this study, we focused on the filtration application of nanofibers. The filtration performances achieved polymeric nanofiber mass production by a melt-blowing method. First, the filtration performances of the fiber were experimentally tested with different thicknesses. Then, the computational fluid dynamics flow-analyzing software was used to simulate the pressure loss and flow resistivity of the trial-produced filter under the same conditions as those used in the experiment. Then, a three-directional physical model was proposed and used to calculate the fiber's gap size with different diameters under the same filling rate and the assumption that the fibers always exhibit uniform distribution. Consequently, it was confirmed that the trial-produced non-woven filter possessed excellent filtration abilities and that the investigated data can be used as a standard to manufacture non-woven fabric for producing high-performance filters and face masks. However, the manufacturing method of non-woven fabric filters must be investigated to satisfy both high particle filtration efficiency and low pressure loss in order to develop a high-performance filter.     

脉冲式滤袋除尘器在工业中的应用

脉冲式滤袋除尘器是采用滤袋过滤气体中尘粒的设备。随着工业化大生产格局形成及环境保护的日趋重视,脉冲式滤袋除尘器的应用以其处理烟气量范围大、使用范围广泛、运行高效可靠、维护管理费用低等优势越来越受用户的青睐。简述了脉冲式滤袋除尘器的工作原理、结构形式及组成,以及在运行过程中易出现的问题和注意事项。     

高速飞行子弹周围空气流场可视化与仿真系统的初步研究

这里以高速飞行子弹周围空气流场为研究对象,通过二维建模和非结构化网格划分,采用Spalart-Allmaras湍流模型进行离散求解,考察了子弹周围空气场的温度、压力、速度分布及子弹壁面的受力情况,并对其进行数值分析与仿真,同时根据仿真与实际情况的比较,肯定了仿真的可靠性和Spalart-Allmaras模型的可行性,为子弹的优化设计提供了理论参考。     

内置过滤器边界对小型化液压油箱内流场的影响

随着液压油箱向小型化方向不断发展,体积占比较大的过滤器对油箱内流场影响愈加明显。为明确内置过滤器边界对流场的具体影响规律,以液压油箱回油区和吸油区为研究对象,结合Fluent模块中的多孔介质模型对过滤器进行有限元数值模拟。探究过滤器安装位置、边界范围对油箱内部流场影响,并对比不同边界下内流场速度值、能量耗散以及颗粒沉降情况。同时,通过理论计算和PIV可视化试验验证文中过滤器模型和仿真方法的正确性以及仿真结果的准确性。最终得到物理边界对流场影响的评价指标,基于指标参数揭示出过滤器边界对内流场的影响规律,给出较优边界范围的选择依据。通过总结过滤器边界对于油箱内流场的影响规律,为液压油箱的小型化设计提供参考。     

基于细胞沉积的人工骨微管设计及三维流场分析

针对人工骨微管中细胞均匀粘附和营养成分顺利运输所需流速条件,研究支管与主管道之间的夹角对支管中流速的影响以及沿主管道不同位置的支管中液体速度分布,并结合自然骨微观结构以及流体力学中的能量守恒和流量守恒原理,提出一种强化微循环结构并进行三维粘性流场数值分析,将分析结果与单纯仿形结构的流场分析结果比较,结果表明,该结构流速分布更均匀,支管内流速得到很大程度的提高,有利于细胞均匀粘附和进一步提高人工骨设计孔隙率。     

Permeability effects of the ceramic candle filter on back-pulse cleaning system

The flow characteristics inside the ceramic candle filter system used in hot gas cleanup was investigated. The filter system admits high pressure back-pulse air to blow out the dust cake. The pressure drop across the filter barrier plays a critical role in dust removal. The filter medium and dust cakes were considered as multi-layered porous media and were then modeled using Darcy’s effective permeability model. Theκ-ε model was adopted to study the turbulent flow in the filter system using FLUENT. A parametric study of the permeability of the filter media was performed to investigate the effects of dust cakes on the flow phenomena, in conjunction with the non-Darcian effect of the porous media flow and non-homogeneous boundary conditions in the inlet and the outlet.