CFD design and simulation of ethylene dichloride (EDC) thermal cracking reactor

At high temperature, ethylene dichloride decomposes into vinyl chloride monomer and HCl by a complex reaction mechanism. Due to chemical reaction type and heat transfer mechanism, design and simulation of cracking reactors are complicated. This process is very important from either chemical reaction or transport phenomena’s point of view. In this study, 2D simulation of cracking reactor is performed with FLUENT software. Simulation results were compared with the experimental data. Then, we investigate the simulation results and effect of various parameters on the process. Results show that with process progress and temperature increase during reactor length, conversion and coke formation amount are increased. At the end of the process, conversion is 52.69 that has good agreement with industrial data. Addition of promoter to the process fluid and fluid behavior in different coil outlet temperatures was studied; finally, the effects of these factors are described in detail.     

Numerical Analysis of Thermal and Dynamic Behavior of a Roof Solar Collector

In some regions with a specific climate, summer comfort in the rooms located below the roof becomes critical if the roof system is not well designed. In order to analyze the efficiency of this system a numerical model was developed. This model is based on the study of the natural convection coupled with radiative heat transfer in an inclined air channel. The configuration studied is an inclined channel formed by two parallel plates. The upper and lower plates were maintained at fixed temperatures. The air flow in the channel which is due to the buoyancy forces is fully turbulent and the turbulence was modeled by using the k‐ε model. Some numerical results obtained were validated using the experimental works of Khedari and colleagues and those of Nouanégué and colleagues. The effect of physical and geometrical parameters and the radiative heat transfer on the channel behavior is shown. Correlations for Nusselt numbers and air flow rate were obtained as functions of the geometric parameters and the Rayleigh number. These correlations can be used in other models that represent this system.     

预冷流模式下混凝土箱梁水化热场时程分布与计算方法

推导了混凝土水化热预冷流复合降热方程,建立了混凝土水化热预冷流模式。采用大型空间有限元程序AN-SYS,对浇注箱梁墩顶块混凝土水化热场进行时程分析,分析了温度峰值和温差峰值的时程变化规律,提出了实用计算公式。结果表明:预冷流模式可明显降低浇注混凝土的水化热温度峰值和温差峰值,缩短最大温度峰值出现的时间,而不改变温差峰值发生的时间。实用计算公式简单明确。     

基于Fluent的水冷滚筒流场数值模拟与设计

水冷滚筒作为电解铅阴极板制备的核心部件之一,其内部冷却水的流场分布直接决定电解铅阴极板的结板厚度和均匀度。为准确掌握滚筒内流场分布状况,运用计算流体力学软件Fluent的多坐标参考系对水冷滚筒内部的流场进行三维模拟,直观地显示水冷滚筒内部的流场特性和流动状态。通过对不同的出水孔孔径得到的流场进行对比,确定最优孔径。设计出的水冷滚筒样机性能通过了现场试验,电解铅阴极板的结板厚度与均匀度均满足生产要求。     

聚焦波浪与直立圆柱作用的数值模拟

基于Fluent平台建立了可用于波浪传播模拟的数值计算水槽,利用不同波浪参数的线性规则波模拟分析了网格尺度L/Δx对产生波浪质量的影响,确定数值水槽的网格划分尺度,并验证了阻尼消波的有效性。在此基础上,用模拟频谱的方法对聚焦波浪的传播进行了数值模拟,通过数值模拟与物理试验不同位置处的聚焦波波面和聚焦点下水质点速度时间过程线对比,验证了模拟频谱方法数值计算的有效性。进一步对聚焦波浪与直立圆柱的作用进行了数值模拟,数值模拟聚焦波面过程、聚焦波浪水质点速度、圆柱周围波浪波动过程、圆柱上所受的波压力等,并与试验结果进行了对比,数值计算结果与试验结果吻合很好,验证了所建立的数值水槽的有效性。对聚焦波波面和压力特征值进行了误差分析,并分析了误差的产生原因,为进一步研究聚焦波浪与工程结构物的作用奠定基础。     

燃气热水器换热器管内强化对流换热的研究

本文采用 fluent数值模拟的方法,将内插弹簧管与光管的对流换热特效进行研究,得到内插弹簧管比普通光管具有更优的传热性能,并分析其原因。引入综合性能评价标准指数,对不同水流量下的换热情况进行了进一步研究,得到在热水器水流量工作范围内管内弹簧有一定的强化换热效果。为便于热水器扰流弹簧的选择,本文进一步在研究扰流弹簧的尺寸对强化换热的影响,对不同钢丝直径、不同弹簧外径、不同节距的弹簧进行对比研究,为燃气热水器的设计提供参考。     

绝缘子在偏心冲洗时有效冲洗面积的研究

带电水冲洗在绝缘子的清洗作业中得到了大量的运用,因此进行带电水冲洗的相关研究就显得十分必要。论文通过理论分析计算出颗粒脱附所需的临界速率,利用fluent对绝缘子在小水、中水、大水的冲洗方式下的偏心冲洗进行三维仿真计算,根据仿真所得到的绝缘子表面的剪切应力云图,对比绝缘子在不同压力、不同的水平偏转角以及不同冲洗方式下有效冲洗区域的大小,同时对比了在相同压力下有效面积与流量的比值,以此来比较水的利用率。结果表明:利用小水和中水的冲洗方式对绝缘子壁面进行冲洗时,随着喷嘴水平偏转角度的增大,有效冲洗面积先增大然后减小;且随着压力的增大,有效冲洗面积的随偏转角度变化的转折点更靠近小的水平偏转角度;而大水冲洗方式下有效冲洗面随着水平偏转角度的增大而持续减少。     

双分裂导线分裂间距对次档距振动的影响

针对采用风洞试验研究双分裂导线分裂间距对次档距振动存在费用高、周期长和试验模型与实际问题的一致性难以确定等缺陷,利用simulink模块对导线次档距振动进行仿真,发现分裂导线次档距振动为椭圆型的简谐振动,为此采用计算流体力学fluent软件模拟分裂导线周围的空气流场,通过对阻力和升力系数的分析来判断导线受力情况,从而得到导线的振动规律。结果表明,当分裂导线间距与导线直径的比值在10~16之间时,导线间距对次档距的振动在可接受范围内,且fluent软件仿真结果与风洞试验结果相吻合。     

Large Eddy Simulation of a Turbulent Flow in a Differentially Heated Cavity with Rayleigh Numbers up to 1011： Part I,Numerical Methods

Large Eddy Simulations of the anisothermal turbulent flows has been used in the context of interaction problems thermal fluid, structure. In this context, the aim of this work lies not only in identifying the various elements that may underestimate the temperature fluctuations at the interface fluid-solid but also the introduction of the models capable of reproducing the physical setting Thurs. At first, the choice of convection scheme 〈optimizing〉 the scalar transport has led to the adoption of an upwind scheme of theorem 2 order. The use of models with conventional walls showed weaknesses in the estimation of temperature fluctuations bet stalls in the case of boundary layers attached. This work presents a numerical validation of LES-WALE model using the results of the K-epsilon model, this study is based on 3D numerical simulation using FLUENT code calculates to determine the longitudinal velocity, the thermal fields for the configuration the and speed vectors （U, V, W） for configuration in the plane of the recirculation zones for the case of different values of flow Rayleigh. Therefore, the results have good agreement with those of k-epsilon model, as they show the difference between the cases of flows.     

叶轮与盖板间隙fluent流体动力学验证

以机械搅拌式浮选机的最佳间距数据验证有压矿浆冲击式浮选机叶轮与盖板的最佳间距,对其叶轮和盖板间隙流场进行动力学计算,确定它们的最佳间距,以提高浮选机的整体性能。以间隙之间形成的气穴多少来断定浮选机充气量的大小,以气矿量的多少来确定浮选的优越程度。