Evaluation of cut cell cartesian method for simulation of a hook and claw type hydrogen pump

Hook and claw pumps are used for recirculation of excess hydrogen in fuel cells. Optimization of the pump design is essential. Computational Fluid Dynamic (CFD) is an effective method for performance optimization. However, it is difficult to conduct CFD simulation because of the sharp cusp of the rotor profile. Cut cell Cartesian mesh could be the solution to handle this complex and moving geometries. The aim of this paper is to evaluate ANSYS Forte for hook and claw pumps. Firstly, the conservation accuracy of the cut cell cartesian mesh is verified using an adiabatic piston cylinder case. Then, simulation results of hook and claw type pump are compared with experimental data. Finally, simulation results of air and hydrogen are compared. The results show that the CFD simulation of hook and claw pumps using cut cell cartesian mesh could provide an efficient and effective approach for the optimization of the system.     

Modeling and simulation of steam methane reforming and methane combustion over continuous and segmented catalyst beds in autothermal reactor

In this paper, a numerical analysis of the production of hydrogen via autothermal (ATR) steam methane reforming (SMR) is presented. The combustion reaction occurs over a Pt/Al₂O₃ catalyst, and the reforming reaction is operated using a Ni/Al₂O₃ catalyst inside the same cylindrical channel. A novel configuration with18 catalytic-bed macro-patterns alternately mounted, referred to as SDB, is designed and compared with the catalytic dual-bed reactor (conventional configuration), referred to as CDB, at the same operating temperature and pressure conditions of 900 °C and 14 bars, respectively. The results showed that hydrogen yield was improved by 4.5% compared to the conventional configuration, while a decrease of 67 °C of the highest temperature was noticed. Meanwhile, the methane conversion was 63.73% and 65.44% for the CDB and SDB configurations, respectively. Furthermore, the length of the reactor can be decreased by 27%, keeping the same hydrogen yield at the outlet of the conventional reactor, indicating a potential reduction in hydrogen cost.     

CFD模拟旋风分离器自然旋风长

利用计算流体力学软件Flowizard对不同结构尺寸的旋风分离器气相流场进行数值模拟采用分离器锥体段中心湍动能峰值定位自然旋风长的方法，分析了入口面积、芯管下口直径、下溢口直径和锥体段长度对自然旋风长的影响。拓展了分离器内部流场由多个自然转折旋风串联的概念。通过增加锥体段长度和入口风速来实现旋风串联、多级分离的效果，延长自然旋风长，有益于提高分离效率。     

fluent软件在通风工程中的应用

fluent是用于模拟计算流体流动以及热传导问题的CFD通用软件,广泛应用于工程领域和科学研究。介绍了fluent软件的基本特点,应用流体力学理论和方法,分析了解决通风领域工程问题的基本算法模型,并以巷道风流为例,利用该软件模拟了障碍物下的巷道流场。     

复杂型体悬挑屋盖风荷载风洞试验与数值模拟

基于Fluent 6.1软件平台,将Realizablek-ε模型与非平衡壁面函数搭配使用,对位于海岛强台风地区的某海洋文化中心屋盖风压分布进行了计算流体动力学(CFD)数值模拟,同时也对该建筑进行了风洞试验。模拟结果与风洞试验数据的对比显示数值模拟可较准确地反映实际风压。风洞试验和数值模拟均显示悬挑屋盖受到了很大的吸力,对屋盖结构极为不利,对此问题采取在屋盖悬挑部分开洞的减压措施,以改善屋盖悬挑部分的受风特性。对开洞后的建筑进行了CFD建模与计算,结果表明在屋面前缘开洞可有效降低屋盖悬挑部分的最大风压和所受的竖向升力,大大改善屋盖结构的受力状态。     

CFD在臭氧接触系统优化中的应用

利用计算流体力学（CFD）技术,通过计算流体的停留时间分布,模拟了深圳某水厂臭氧接触池的水力效率,对臭氧接触系统进行了优化.结果表明,未设置导流板的接触池水力效率较低,T10/HRT仅为0.40.通过设计优化,增加了导流板,可将接触池的水力效率提高73%,T10/HRT为0.66.     

Simulation of air flow in the IEA Annex 20 test room—validation of a simplified model for the nozzle diffuser in isothermal test cases

The modeling of air supply devices has been identified from the International Energy Agency (IEA) Annex 20 project as one of the most important problems in applying computational fluid dynamics (CFD) to predict air flow pattern and air distribution in buildings, and the complicated HESCO nozzle diffuser used in the IEA Annex 20 test room has been proved to be particularly difficult to model. In a previous study, a simplified model for this diffuser was developed and validated against experimental data. It has been shown that this model can yield good prediction for the wall jet flow issued from the diffuser, but whether this model is capable of correctly predicting the global flow pattern in the whole test room was not known. In this paper, the benchmark data of the IEA Annex 20 Test Cases B2 and B3 were used to evaluate the performance of the model for the prediction of the global air flow pattern in the test room. It was demonstrated that this model can predict the air flow pattern in the whole test room for both the Test Cases B2 and B3 with reasonable accuracy. The significance of a velocity correction when comparing the numerical prediction with experimental data obtained using omni-directional anemometers was also discussed.     

户外独立柱广告牌风荷载的数值模拟研究

采用计算流体力学(CFD)的方法对双面和三面户外独立柱广告牌的风荷载进行了数值模拟研究,得到了广告牌主结构设计所需的最不利风压系数和偏心距,以及广告牌面板设计所需的局部风压系数,研究成果已应用于标准图的设计,也可供此类结构设计时参考。     

CFD modelling of natural displacement ventilation in an enclosure connected to an atrium

Computational fluid dynamics (CFD) is used to investigate buoyancy-driven natural ventilation flows in a single-storey space connected to an atrium. The atrium is taller than the ventilated space and is warmed by heat gains inside the single-storey space which produce a column of warm air in the atrium and drive a ventilation flow. CFD simulations were carried out with and without ventilation openings at the bottom of the atrium, and results were compared with predictions of analytical models and small-scale experiments. The influence of key CFD modelling issues, such as boundary conditions, solution controls, and mesh dependency were investigated. The airflow patterns, temperature distribution and ventilation flow rates predicted by the CFD model agreed favourably with the analytical models and the experiments. The work demonstrates the capability of CFD for predicting buoyancy-driven displacement natural ventilation flows in simple connected spaces.     

用CFD方法研究空气通过缝隙的渗透

通过模拟计算，得到不同缝隙高度下渗透空气量与缝隙两侧压差的函数关系式，以及流量因数、缝隙局部阻力系数与缝隙几何特性量的函数关系式。实验验证了CFD模拟计算结果的可靠性。给出了负压病房和相邻洁净区域压差的推荐值。