洁净室流型及气流组织与CFD方法

介绍ＣＦＤ方法在洁净室气流流型及气流组织模拟工程中的应用，并介绍了ＣＦＤ软件的一般结构。指出了我国在ＣＦＤ技术研究领域与国际先进水平的差距及我国本领域中进一步开展ＣＦＤ研究的发展方向。     

超低层高洁净室工程的气流组织设计

本文针对一超低层高的医院制剂室净化改造工程，就净化系统的气流组织形式，换气次数计算和总体方案进行了分析和比较，提出了一个比较合理的气流组织形式。实测结果表明，制剂室洁净度等项指标均达到１０００００级洁净室标准。     

多级别洁净室系统新型气流组织的探讨

一、前言所谓“多级别洁净室系统”是指不同级别洁净室混合以形成一个系统的情况。笔者曾对此问题作了探讨,提出了采用高级别洁净室的回风作为低级别洁净室送风的设想,探索了几种简单组合模式下新型气流组织的计算方法,并分析了该气流组织的节能性。然而,多级别洁净室的组合方式是多种多样的,对于不同组合模式的系统,其计算公式自然有所不同,相应的设计指标—额定容积比和额定人员密度比也有所不同。本文对这方面的问题作了探讨。     

一种新型洁净室送、回风型式的数值模拟

本文以工程中广泛使用的紊流模型为基础，采用有限差分法，对半圆柱形送风口、相对两侧墙下部回风式洁净进行三维紊流流场和污染物扩散场的数值模拟，分析气流的流动特性和污染物的分布规律，得到了此类洁净室优化设计的技术参数表，为此种新型洁净室的设计及推广提供了依据。     

CFD技术在洁净室气流组织设计中的应用

本文运用CFD技术作为辅助工具对一ISO5级洁净室内的气流组织进行设计.我们采用CFD技术对光刻胶研发实验室内的气流组织和微尘污染进行了研究.研究中采用了k-ε模型,并用FLUENT软件进行求解.对多种洁净室的气流组织方案进行了数值模拟,并选择优化方案建造了实验室,对此实验室测试了多组数据并与数值模拟的结果进行比较,表明数值模拟的结果是准确的.说明了CFD技术是洁净室设计的可靠辅助工具.     

上送上回气流组织在非单向流洁净室中的应用

1 问题的提出 《洁净厂房设计规范》GBJ73-84规定:非单向流洁净室气流组织形式为上送下回或者侧上送侧下回。传统的洁净室设计也很少采用上送上回形式。因为从排除污染物的角度看,上回形式有明显的缺陷。它不利于工作区(距地1m左右)污染物浓度的降低,因为污染物不会被气流携带至工作区下部的“回风区”,     

带气幕的局部洁净室数值模拟

采用k-ε紊流数学方法,对带气幕的局部洁净室流场和污染场进行了模拟。分析了主流区单向流三要素。指出气幕射流力对气幕的隔断作用起主要作用。     

上侧送风—同侧下部回风洁净室的数值模拟

以计算流体力学的Ｋ－ε二方程模式为基础，采用有限差分法对上侧送风、同侧下部回风洁净室的三维流场和污染物分布的浓度场进行了数值模拟，并对模拟结果进行了分析和比较，提供了一些设计参数以供工程人员的借鉴和参考。     

某酒店大堂气流组织形式的数值模拟与分析

随着生活水平的提高,人们对室内热湿环境的要求也越来越高,而气流组织是影响空调房间室内热舒适性的重要因素。与其他建筑相比,酒店大堂有着其独特的特点。运用计算流体力学的方法,对三种气流组织形式(旋流风口上送上回、旋流风口上送下回及喷口侧送侧回)下某酒店大堂夏季室内热环境进行数值模拟,对比分析不同气流组织的室内热舒适性,探究酒店大堂类建筑最佳的气流组织方案。     

CFD软件在医药工业洁净厂房设计中的应用探讨与实例分析

针对医药工业洁净厂房设计过程中气流组织无法直观预判的问题,探讨使用CFD软件对气流组织进行模拟,并用于指导设计。采用CFD软件对送风口形式、风口布置等对气流组织的影响进行模拟比较。探索将CFD软件应用于实际工程设计。     

手术室内人员走动对手术区带菌粒子浓度的影响研究

k-ε双方程模型广泛地应用湍流模拟,使用拉格朗日法的随机轨道模型,进行带菌粒子运动,采用弹性系数法和动态垂构法,对护士来回走动所引起的气流变化进行数学模拟,计算的粒子沉降数,发现来回走动的护士的影响范围大约为其3倍的身宽,对手术区影响不大。     

强脉冲激光金属表面烧蚀热场的数值仿真

用有限差分法对强脉冲激光难熔金属表面烧蚀过程的温度场进行了三维数值仿真计算。计算模型在能量平衡方程的基础上,将入射的脉冲激光在时间与空间上的分布以Ｇａｕｓｓ分布考虑,同时考虑工件尺寸、工件材料热物理性质及对流辐射造成的表面热损失等对温度场的影响。文章应用交替方向隐式方法建立差分方程,对该数学模型进行计算,数值模拟了难熔金属钛、钼在强脉冲激光烧蚀下的温度场变化,并将数值解与热导方程的解析解进行了分析     

模板匹配算法的两种实现方法比较

模板匹配算法是图像配准和视频跟踪等系统中常用的一种算法,首先对它进行了详细的分析研究,在此基础上比较了它在VS2010和System Generator两种环境下实现的性能指标。实验结果表明,基于System Generator环境的模板匹配算法效率更高,开发周期更短。     

A comparison of two conformal methods for FDTD modeling

Two conformal finite-difference time-domain (FDTD) methods are considered, the contour path (CPFDTD) method of Jurgens et al. (see IEEE Trans. Antennas Propagat., vol.40, p.357, 1992) and the overlapping grid (OGFDTD) method of Yee et al. (see IEEE Trans. Antennas Propagat., vol.40, p.1068, 1992). Both TE and TM scattering from a two-dimensional (2-D), perfectly conducting circular cylinder are used to test the accuracy of the methods for curved surfaces. Also, TE and TM scattering from a 2-D, perfectly-conducting rotated square cylinder are used to test the accuracy for corners and edges. It is shown that the conformal method proposed by Yee et al. provide significant improvement in accuracy over the original FDTD algorithm for most of the geometries studied. However, implementation becomes more difficult as the geometries become more complex. The conformal method proposed by Jurgens et al. provide significant improvement in accuracy as well for most of the geometries studied. However, improvement does not occur for the TM case when the square cylinder is not aligned properly with the grid. Implementation of the CPFDTD method is relatively straightforward. For the majority of the cases studied, the OGFDTD method is more accurate than the CPFDTD method     

A comparison of two design methods for MRI magnets

Designs of magnetic resonance imaging (MRI) main magnets obtained from both a functional method and a genetic algorithm method have been compared. While most features in the two approaches are similar, there are several important differences. The functional method leads to fewer coil bundles and a reduced total current, i.e., total ampere turns, (e.g., 6-8 MA) that can be as much as 70% of the total current found with the genetic analysis. While the conclusion about stress is that it is a sensitive function of the choice of wire current density, the designs found with the functional method have a larger hoop stress than that of the genetic design, which may require new or refined manufacturing techniques. Furthermore, the functional approach requires much less computing power (i.e., a personal computer is quite sufficient) while the genetic algorithm method in general demands massively parallel computing techniques. However, in order to search for the optimal magnetic resonance design at a given field strength, it is likely that a combination of these two methods will lead to the best results.     

Performance comparison of two input access methods for a multicastswitch

A comparison of the performance of two input access mechanisms for multicast switching is presented. The first of these-a cyclic priority input access method-is a derivative of the ring token reservation method which eliminates the unfairness of the ordinary ring token reservation. It has the advantage of being relatively simple and easy to implement. A second approach employs a neural network to resolve output port conflict. While more difficult to implement, it has a delay-throughput performance advantage over the cyclic priority approach. The primary performance measurements are the switch throughput and the packet delay. A key assumption is that all copies of the same packet must be switched in the same slot     

Performance comparison of two text marking methods

A text document typically consists of a collection of regular structures such as words, lines, and paragraphs, a slight movement of which seems less perceptible than, say, dithering of the document image. We exploit this property to watermark formatted text documents by shifting slightly certain lines and words in order to discourage illicit distribution. We analyze two methods for reliable document identification in the presence of severe distortions introduced by photocopying, facsimile transmission, and other processing. The correlation method uses document profiles directly for detection. To eliminate the effect of certain distortions, the centroid method bases its decision on the distances between the centroids of adjacent profile blocks. We present the maximum likelihood detectors for both methods and evaluate their relative performance. Our analysis indicates that line-shift generally has a smaller error than word-shift detection, and that the correlation detector outperforms the centroid detector provided certain distortions can be accurately compensated for before detection is attempted. These results have been applied to implement a marking and identification system and preliminary experimental results have been very promising     

多晶硅锭定向凝固过程的数值模拟

研究了多晶硅锭定向凝固过程中晶体和熔体中的温度分布、固液界面的温度场,并对定向凝固过程进行了数值模拟,对热场对多晶硅晶体生长的影响进行了系统的理论分析和试验验证。     

A comparison of two methods used for the synthesis of active RC networks

A new criterion for choosing the gain of the amplifier in Srinivasa's method is suggested so as to accommodate any arbitrary gain constant realized by the 3-terminal network. The method is thus shown to be superior to the one proposed by Dutta Roy.