旋风分离器简捷设计计算方法

运用Ｋａｌｅｎ和Ｚｅｎｚ跳跃速度概念导出旋风分离器的计算方法，方法简捷，实用，且能保证最好的分离效率。     

高效旋风分离器的设计

介绍大流量 ,低压降 ,分离效率高的新型旋风分离器的设计 ,满足了特殊功能的要求 ,拓宽了旋风分离器的用途。     

不同湍流模型下旋风分离器数值模拟结果比较

文章分别采用重整化群（RNGk-ε漠型）、线性压应力（LinearPressure．strain）和二次压应力（QuadraticPressure—Strain）的雷诺应力模型（RSM）及不同的方程离敞格式对旋风分离器内流场进行数值模拟,并与实验结果进行比较,通过对计算结果与实验结果的比较分析,发现二次压应力雷诺应力模型（RSM）模型下模拟结果更为精确。     

循环旋风分离器内流场的数值模拟

采用CFD模拟软件Fluent6．2提供的雷诺应力模型（RSM）对循环旋风分离器内的流场进行了数值模拟研究,并与实验结果进行了比较,模拟结果与实验结果基本吻合。结果表明,循环旋风分离器特殊的流路设计,提高了内部流场的对称性,规整了气流,减少了紊流的产生,降低了设备的压降。时局部涡的分析,为进一步了解循环旋风分离器的分离机制和优化结构提供了参考依据。     

对称多入口型旋风分离器的数值模拟

利用Fluent软件提供的RSM模型,使用Simplec算法,对对称多入口型旋风分离器进行数值模拟。通过模拟,分析旋风分离器内的切向速度场、轴向速度场及压力场的分布。结果表明,对称性的结构有助于对称流场的形成,从而保持流场的稳定;切向速度分布有着明显的驼峰特征,轴向速度分布分为上行流、下行流区域,压力为顺压分布。     

旋风分离器选用的程序设计

按不同使用要求，设计出旋风分离器选用的计算程序，利用本程序可快速、准确地选出所适用的型号规格。     

旋风分离器旋进涡核的数值模拟

采用雷诺应力模型对旋风分离器内三维非稳态流场进行了模拟计算。结果表明,旋风分离器全空间内都存在旋进涡核现象。对旋进涡核现象和旋进涡核中心的运动规律进行了详细的描述,分析了不同轴向位置的旋进涡核区域内不同点的速度波动幅值和频率,得到了旋进涡核影响范围以及速度波动规律;通过分析旋进涡核中心的运动频率,得到了旋进涡核出现的强度。模拟结果与采用热线风速仪以及激光粒子成像技术(PIV)测定的实验结果基本吻合。研究结果可以分析旋进涡核对分离效率和压降的影响。     

旋风分离器的内部流场模拟分析

以旋风分离器内部流场模拟分析为基础,分别对1、30、100μm三种不同粒径的煤粉与滑石粉在分离器中的颗粒轨迹做了分析,首先得出其内部流场速度方向及大小的分布规律,从内部气流走势上看,分离器具有不对称性;从速度矢量图颜色上看,在分离器中心部分的气流具有强烈旋转,气流在壁面附近的位置速度快速降低。再得出不同粒径颗粒在分离器中的轨迹分布规律。为进一步的研究及改进旋风分离器的性能有参考意义。     

旋风分离器内颗粒质量浓度分布数值模拟

采用颗粒随机轨道模型和单元内颗粒源法,对旋风分离器内不同粒径颗粒质量浓度分布进行了数值模拟。结果表明,粒径较小的颗粒(dp≤4μm)大部分在旋风分离器分离空间锥段进行分离,而较大颗粒(dp>4μm)大部分在环形空间与分离空间筒段即被分离。随着颗粒粒径增加,分离器外壁的颗粒质量浓度逐渐呈螺旋灰带分布,内旋流夹带减小,环形空间顶板下方出现顶灰环。升气管入口0.25D(筒体直径)附近的短路流对小颗粒的影响较大。在分离空间下部排尘口附近0.5D有明显的颗粒返混,返混量随着颗粒粒径增大而减少。     

旋液分离器的计算机设计

在综合分析切割粒径、压降、效率和分股比数学模型的基础上,建立了旋液分离器的设计模型。采用FORTRAN语言,开发了可用于串并联组合旋液分离系统设计的计算机程序。实例表明该设计程序与其它软件相比具有较高的准确性和更宽的适用范围。     

Electrostatically enhanced cyclone separators

The separative performance of a cyclone can be enhanced if electrical forces are employed to supplement the inertial forces. By precharging the particles and applying a radial electric field within the cyclone, collection efficiency is improved. In the present paper, a model is developed for such an electrostatically augmented cyclone. The model assumes that turbulence promotes complete radial mixing within each of three regions: the entrance region, the downflow region and the core (or upflow) region. Based on this model, an analytic expression for the collection efficiency of cyclone separators is developed.     

两级串联旋风分离器组性能试验研究

试验在吸风状态下进行,选用直径为400mm的旋风分离器组为模型,用325目滑石粉,研究了入口气速和入口含尘浓度对两级串联PV型旋风分离器组的影响规律。试验结果表明:一级粒级效率随入口含尘浓度的增加而增加,但二级粒级效率却有下降的趋势。在相同入口含尘浓度下,分离器组的总效率及粒级效率随入口气速的增加而增加,并且二级的粒级效率曲线呈现特殊的“鱼钩状”。     

Modeling and multi-objective optimization of cyclone separators using CFD and genetic algorithms

In the present study, multi-objective optimization of cyclone separators is performed at three steps. At the first step, pressure drop (Δp) and the cut-point (D₅₀) in a set of cyclone separators are numerically investigated using CFD techniques. Two meta-models based on the evolved group method of data handling (GMDH) type neural networks are obtained, at the second step, for modeling of Δp and D₅₀ with respect to geometrical design variables. Finally, using obtained polynomial neural networks, multi-objective genetic algorithms are used for Pareto based optimization of cyclone separators considering two conflicting objectives, Δp and D₅₀.It is shown that some interesting and important relationships as useful optimal design principles involved in the performance of cyclones can be discovered by Pareto based multi-objective optimization of the obtained polynomial meta-models.     

Artificial neural network-based modeling of pressure drop coefficient for cyclone separators

In order to build the complex relationships between cyclone pressure drop coefficient (PDC) and geometrical dimensions, representative artificial neural networks (ANNs), including back propagation neural network (BPNN), radial basic functions neural network (RBFNN) and generalized regression neural network (GRNN), are developed and employed to model PDC for cyclone separators. The optimal parameters for ANNs are configured by a dynamically optimized search technique with cross-validation. According to predicted accuracy of PDC, performance of configured ANN models is compared and evaluated. It is found that, all ANN models can successfully produce the approximate results for training sample. Further, the RBFNN provides the higher generalization performance than the BPNN and GRNN as well as the conventional PDC models, with the mean squared error of 5.84 × 10^?4 and CPU time of 120.15 s. The result also demonstrates that ANN can offer an alternative technique to model cyclone pressure drop.     

Effects of flow and geometrical parameters on the collection efficiency in cyclone separators

A mathematical model has been developed for calculation of cut-off size and fractional efficiencies in cyclone separators, by taking into account the effects of flow, particle and geometrical parameters, and acceleration assuming that the mixture of fluid and particles is homogenous, and acceleration diminishes depending on the friction and geometry. Collection efficiency curves and cut-off size values predicted by the proposed model showed a good agreement with experiments over a wide range of inlet velocities for different types of cyclones. Comparison of the obtained results with semi empirical models available in literature also indicated that the present model may be used successfully for determination of the performance of a tangential inlet cyclone. Analyses of the effects of various parameters reveals that, in addition to flow and geometrical parameters, surface friction, vortex length and flow regimes play an important role on cyclone performance especially in small cyclones.     

Function and effect of the inner vortex on the performance of cyclone separators

The inner vortex plays a key role in the performance of cyclone separators. To explore the function and effect of the inner vortex in cyclone separators, a series of metal rods and metal blades are inserted in the typical Lapple cyclone separator to reduce the intensity of the inner vortex. First, the changes in general performance of cyclones are measured by experimental methods after insertion of the metal rods and metal blades. The flow field and particle motion are then simulated, respectively, by means of a Reynolds stress model (RSM) and a Lagrangian particle tracking (LPT) model. The results show that when the length of the metal blades is less than the boundary between the inner and outer vortexes, that is, the outer vortex remains unchanged and the inner vortex is destroyed partly, the separation efficiency remains constant and the pressure drop significantly decreases. When the length of the metal blades exceeds the boundary, the inner vortex is completely destroyed, and the outer vortex is significantly damaged, which results in sharp decrease of both the separation efficiency and pressure drop. The results indicate that the inner vortex has a notable effect on the pressure drop and virtually none on the separation efficiency. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4508–4518, 2017     

子午线轮胎性能的计算机仿真和优化设计

以205／60R15轿车轮胎为例,介绍子午线轮胎性能的计算机仿真和优化设计技术。在轮胎结构设计的CAD模型中,将轮胎轮廓曲线形状数字化并采用包含层单元的FEM模块,有效控制了轮胎模型有限单元总数。利用在此基础上建立的轮胎有限元模型,模拟了205／60R15轿车轮胎自由状态、充气静止状态、充气旋转状态以有与地面接触状态等多种工况,以及在水平牵引力和垂直载荷共同作用下的从动轮工况（从静止到滚动的过程）,并给出了带束层帘线角度和胎体帘线假定伸张值对轮胎性能影响的趋势。试验证明,模拟分析结果与实际情况较吻合。     

大型烟气脱硫塔配置旋风分离器的流场模拟

利用RNGk-ε湍流模型对出口配置1台和2台旋风分离器的大型烟气脱硫塔的流场进行了数值模拟。模拟结果表明,脱硫塔出口配置旋风分离器的方式对脱硫塔内的流场会产生不同程度的影响。运用速度不均匀度的概念定量描述脱硫塔内流场的均匀性,出口配置1台旋风分离器时脱硫塔内部流场速度不均匀度大于出口配置2台旋风分离器时脱硫塔内部流场速度不均匀度0.1以上;出口布置2台旋风分离器时,径向出口布置方式的脱硫塔内部流场速度不均匀度小于切向出口布置方式的脱硫塔内部流场速度不均匀度,最小不均匀度为0.3。脱硫塔出口径向配置2台旋风分离器为优选方案。