初探基于BIM的家装中央空调CFD气流组织模拟

随着建筑信息技术的日渐成熟,越来越多的空调项目开始使用BIM技术进行暖通设计,并导出暖通设计所需的视图、方案数据等资料,为使BIM技术更好的服务于暖通设计,如何将BIM设计与CFD气流组织模拟相结合是我们急需攻破的一个领域,本文就某一家装中央空调设计为例,将BIM技术应用到CFD软件进行初步探讨。

关于大空间水世界空调气流组织模拟研究与优化

针对目前国内蓬勃发展的室内水乐园特点,通过CFD气流模拟,对全空气空调系统不同气流组织下室内冬夏季温度分布情况进行了分析,为今后室内水乐园空调形势的选择及空调系统的排布设计提供参考。

CFD Simulation of Film Flow and Gas/Liquid Countercurrent Flow on Structured Packing

A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.

Numerical simulation of the pulsing air separation field based on CFD

The flow field of pulsing air separation is normally in an unsteady turbulence state.With the application of the basic principles of multiphase turbulent flows,we established the dynamical computational model,which shows a remarkable variation of the unstable pulsing air flow field.CFD(computational fluid dynamics) was used to conduct the numerical simulation of the actual geometric model of the classifier.The inside velocity of the flowing fields was analyzed later.The simulation results indicate that the designed structure of the active pulsing air classifier provided a favorable environment for the separation of the particles with different physical characters by density.We shot the movement behaviors of the typical tracer grains in the active pulsing flow field using a high speed dynamic camera.The displacement and velocity curves of the particles in the continuous impulse periods were then analyzed.The experimental results indicate that the effective separation by density of the particles with the same settling velocity and different ranges of the density and particle size can be achieved in the active pulsing airflow field.The experimental results provide an agreement with the simulation results.

CFD simulation of bubbly turbulent Tayor–Couette flow

Bubbly gas-liquid Taylor-Couette vortex flow has been the subject of several recent investigations both because of interest in bubble-induced drag reduction and because such devices have potential applications to a variety of chemical and biochemical processing problems. In order to quantitatively describe the hydrodynamics of highly turbulent two phase Taylor-Couette flow, a rigorous two-fluid computational fluid dynamics （CFD） model was developed and compared with previously published experimental data. This model includes a comprehensive description of the constitutive closure for inter-phase forces and turbulence was simulated using both the k- and k-to models. In addition, the mechanism by which the dispersed fluid attains a non-uniform radial and axial distribution is analyzed and the relative importance of various interphase forces is discussed. Lastly the model was validated by comparison of simulation predictions with experimental data, and it is shown that the CFD model correctly predicts phase velocity, velocity fluctuation, and gas distribution, and may provide guidance for reactor design and scale-up.

Numerical and experimental studies of flow field in hydrocyclone with air core

For the flow field in a d50 mm hydrocyclone, numerical studies based on computational fluid dynamics (CFD) simulation and experimental studies based on particle image velocimetry (PIV) measurement were carried out respectively. The results of two methods show that air core generally forms after 0.7 s, the similar characteristics of air core can be observed. Vortexes and axial velocity distributions obtained by numerical and experimental methods are also in good agreement. Studies of different parameters based on CFD simulation show that tangential velocity distribution inside the hydrocyclone can be regarded as a combined vortex. Axial and tangential velocities increase as the feed rate increases. The enlargement of cone angle and overflow outlet diameter can speed up the overflow discharge rate. The change of underflow outlet diameter has no significant effect on axial and tangential velocities.

Measurement and Simulation of the Flow Field around a Triangular Lattice Meteorological Mast

The international standard IEC 61400-12-1 Wind turbines--Part 12-1： Power performance measurements of electricity producing wind turbines＂ aims to provide a uniform methodology that will ensure consistency, accuracy and reproducibility in the measurement and analysis of power performance by wind turbines. Annex G of this standard provides a methodology for the appropriate arrangement of instruments on the meteorological mast to ensure accurate measurement. For cup anemometers it provides recommendations about their location relative to the mast so that the effect of mast and boom interference on their output may be minimised. These recommendations are given for both tubular masts and lattice masts. This paper compares the flow distortion predicted by the IEC standard and the results of a 3D CFD （computational fluid dynamics） simulation of a triangular lattice mast. Based on the results of wind tunnel and CFD simulation it was found that the flow distortion surrounding the lattice mast was overpredicted by the method suggested in appendix G oflEC61400-12-1. Using the CFD data it was possible to determine, for a range of flow directions and mast heights, the distance from the mast that anemometers would need to be in order to be outside the flow distortion field.

高铁车厢内人员走动对病毒气溶胶扩散及传播的影响

本文建立了CR400复兴号高铁车厢的全尺寸模型,基于计算流体力学(CFD)方法模拟了特定通风方式下车厢内的气流组织及温、湿度分布,并与现场实测数据进行了对比验证。利用欧拉-拉格朗日方法和动网格技术对车厢内人员行走的动态场景进行了仿真模拟,研究了行人在通道运动过程中气流流动特性的改变,温、湿度分布变化以及车厢中部喷嚏产生气溶胶的扩散传播特性。结果表明,人员走动产生的尾流湍流会破坏初始均匀的流场结构,造成涡流产生,增加温、湿度场分布不均匀性,进而造成气溶胶蒸发特性及扩散方式的改变,不同区域内气溶胶浓度的差异也将进一步对不同位置乘客的感染风险产生影响。结果可以为评估人员走动情况下高铁车厢空气质量和感染风险性提供一定数据参考。