手术室气幕装置气流组织数值模拟与理论分析

本文使用标准k-ε紊流模型,基于I级标准手术室,对带气幕的洁净手术室流场和污染物浓度场进行了数值模拟,并做了相应的理论分析。得出了射流力是气幕抗干扰能力的主要影响因素,引带系数是气幕隔离能力的主要影响因素的结论,对气幕风速、气幕风口尺寸、气幕倾斜角度等工作参数的影响特性做了深入探讨,并对比了相同风量下带气幕与不带气幕送风装置的有效性。最后针对I级洁净手术室内的流场给出了建议气幕设计参数。     

新型气幕式排风柜的临界补风比确定及性能研究

本文提出了一种利用室内空气进行补风的新型气幕式排风柜,利用Fluent软件对传统排风柜与新型气幕式排风柜的气体流动差异进行比对,通过模拟得到不同射流口宽度和排风量下的临界补风比,并以控制浓度为评价指标,验证了新型气幕式排风柜的控污效果。模拟结果证明临界补风比下新型气幕式排风柜的控污性能良好。在当其他条件一致时,临界补风比只与射流口宽度有关,与排风量无关。     

气幕送风交通指挥台夏季热环境CFD模拟

气幕送风交通指挥台的优势在于在人体头顶正上方遮阳设备间内设有空调系统,并通过气幕送风口向工作人员输送空调新风达到降温解暑的作用。为了确定气幕送风系统的夏季运行参数以改善工作人员的舒适度,通过采用计算流体动力学CFD方法,对工作人员周围空气流场和温度场进行三维数值模拟,并根据人体舒适性分析确定送风系统的运行方案。模拟结果表明,气幕送风系统输送的空调新风由于受到外界环境的影响,并不能形成柱状封闭式气幕,送风气流在逐渐受到外界环境的影响后,风速逐渐减小且偏离竖直方向。根据模拟结果和人体舒适性分析确定了合理的气幕送风参数,经过分析与比较,送风风速控制在不小于7 m/s,送风温度20℃为运行参数可满足人体舒适性要求。     

正压送风-气幕联合防烟系统数值模拟

提出了正压送风-气幕联合防烟系统,以提高防烟楼梯间的防烟效果,减少系统总送风量。利用FDS模拟研究了气幕送风速率、送风角度对联合防烟系统总送风量的影响规律。结果表明,气幕的最佳设置参数为送风速率7m/s,气幕送风口向烟气区偏转25°;在最佳气幕设置参数下,当开启门数量为两扇时,联合防烟系统的总送风量为独立正压送风防烟系统送风量的50%～60%;在相同的有效送风量下,应用联合防烟系统进行楼梯间防烟时,可开启疏散门数量为应用正压送风防烟系统时的3～4倍。     

隔离粉尘用的线状空气幕

为了使空气幕能推广应用到洁净室及医院,Glasgow大学对作为隔离粉尘用的线状空气幕的性能进行了评定。气幕通常分为两种类型: (1)“再循环气幕”,它在送风口对面(通常在下部)设再循环格栅; (2)“直流气幕”,空气直接冲击到地板上,与周围的空气混合。本文仅介绍直流气幕的机理,然后讨论某些典型结果。一、气幕气流     

气幕式排风柜的实验研究

本文作者设计了一种新的排风拒──气幕式排风柜，并对气幕式排风柜的性能进行了实验研究     

沉井气幕法减低井周土体扰动原理分析及应用探讨

对气幕法沉井工艺有效减低井周土体扰动的原理进行分析,阐述气幕法沉井工艺在环境保护上的优点,建议对该工艺进一步理论化、规范化。     

隧道窑喷射气幕的设计与实践

本文对隧道窑喷射气幕的结构形式作了分析比较,运用实测资料,论证了喷射气幕的作用,並介绍了低、中、高压三种喷射气幕的设计及选型原则,对提供气源的工艺装备也作了论述。     

气垫搬运技术

目前应用的气垫技术分气幕式和空气轴承式。 1.气幕式:闭锁的环形喷嘴向行走面喷出空气,形成气幕,内部产生一定的静压,把搬运物托起(图1)。     

软土地层管幕法施工三维数值模拟

对软土地层管幕法施工过程进行了三维数值模拟,得到了施工过程中地表沉降和管幕周围土体的位移变化规律,并同实测结果进行了比较。结果表明:采用D-P模型可以在不考虑土体时变特性的情况下较好的模拟管幕法施工过程。     

A computational analysis of the train-wind to identify the best position for the air-curtain installation

This study focuses on computational analysis for the improvement of the tunnel ventilation and the environmental control system of the subway by solving Reynold-averaged Navier-Stokes equations for train-induced unsteady flow. The two-equation turbulence model can predict velocity and pressure field at the tunnel. The sharp interface method is used for the moving boundary of an immersed solid. The flow rate through the natural ventilation-shaft and the features of the train-wind in the subway tunnel help to find better installation locations for the air-curtain. The air-curtain separates two adjacent environments and reduces the transfers of bacteria and radioactive particles. The ANSYS CFX software is used to perform unsteady computations of the flow field at the subway tunnel.     

Influences of the train-wind and air-curtain to reduce the particle concentration inside a subway tunnel

Subways are used widely for public transportation in major cities and require efficient ventilation systems to maintain indoor air quality in the subway tunnel. A subway tunnel was investigated numerically and experimentally to reduce the particle concentration in subway tunnels. The subway tunnel is 54-m long, 1.65-m high, and 2.5-m wide. The subway tunnel is one-quarter scale of a real subway tunnel. The tunnel has two U-type mechanical ventilation shafts. The steady three-dimensional airflow in the tunnel was analyzed using ANSYS CFX software to solve the Reynolds-averaged Navier–Stokes equations. The airflow in the tunnel and shafts was observed numerically using the train-wind and air-curtain. The effects of the train-wind, air-curtain, and electric precipitator were examined experimentally. The ventilation performance in the subway tunnel was observed with respect to the particle concentration in the tunnel. The numerical results suggest proper operating conditions for experimental analysis of the particle concentration. The average velocity of the airflow increases in the shaft when the velocity of the air-curtain increases. The particle concentration at the dust monitoring device after ventilation shaft 1 was reduced significantly in the tunnel when the air-curtain and train-wind were operated.     

Approaches for improving airflow uniformity in unidirectional flow cleanrooms

Airflow behavior inside a cleanroom with vertical unidirectional flow has been investigated. The design parameters, such as porosity and height of raised floor, width of cleanroom and inlet velocity profile, which affect the uniformity of air velocity distribution inside the cleanroom have been studied computationally. The Reynolds-averaged Navier–Stokes equations governing the flow are solved using a finite-volume code STAR-CD. The standard k-ε turbulence model has been used. Approaches for improving airflow uniformity have been proposed and quantitatively examined based on intensive case studies. The present results show that the uniformity increases along with the height of raised floor. Alternatively, better airflow uniformity can also be achieved through a proper allocation of floor porosity or by controlling the distribution of inlet velocity profile. Suggestions on how to design unidirectional cleanrooms with desired airflow uniformity under practical constraints have been given.     

高大厂房热风采暖及节能

针对高大厂房供热特点,分析认为热风炉为热源的横向热风幕采暖方式是解决高大厂房采暖的有效方式,并具明显的节能效果.结合高大厂房的采暖方式实例,计算了热风炉为热源横向热风幕传统供热方式下的采暖热负荷,得出该方式节能效果不明显的结论,并在送风方式上提出了改进措施,计算结果表明采用该方式可取得比较好的节能效果.     

Dispersion of gas pollutant in a fan-filter-unit (FFU) cleanroom

Numerical simulation and experimental measurement of flow and concentration fields in a working fan-filter-unit (FFU) cleanroom have been conducted in this study. The purpose of the study is to find out the unsteady concentration distribution of a leaking gas pollutant. The standard K–ε model was used for the simulation of the flow field. To obtain the gas concentration field, SF₆ gas with a certain concentration was released as a simulated leaking source from a valve manifold box (VMB) for 5 or 10 min, respectively. Three Fourier transform infrared spectrometers (FTIRs) were simultaneously used to measure the spatial and temporal distributions of SF₆ concentrations. The measured data were then compared with the numerical results and the agreement is seen to be quite good. From the numerical results, the pollutant hot spots, peak pollutant concentration at the end of leaking, and time taken for the concentration to reduce to near background level are obtained.     

Analyses of smoke management models in TFT-LCD cleanroom

This study evaluated the effectiveness and performance of smoke management models in a TFT-LCD cleanroom. Several smoke management models are discussed in a distinct 3-level cleanroom compartment. The tools used included a fire dynamics simulator (FDS) and SIMULEX. The design fires were 3 MW and 5.4 MW in ultra fast fire, respectively. In life safety, both a downward smoke exhaust system and upward smoke exhaust system, incorporating a decrease of filter fan unit air supply rate, could be used in a cleanroom, according to the simulation results of performance-based design. For occupant evacuation, the SIMULEX results showed a total evacuation time less than smoke layer descending time, which descended to 1.8 m height from floor to smoke layer in all FDS simulations. In view of property protection, insurance companies generally require significantly higher standards of property protection. For 3 MW or more heat release rate, smoke was hardly controlled by any smoke exhaust system in the cleanroom without sprinklers.     

不同送风面积下洁净室浓度场的数值模拟分析

本文以典型上送双侧下回洁净室为研究对象，建立相应数学模型，利用计算机进行模拟分析，总结出不同面积送风口布置方式对洁净室流场及浓度场的影响，并通过实验对比，验证数值计算方法及结论的可靠性。     

某生物芯片洁净室空调系统设计

本文依据生物芯片生产工艺流程和药品生产质量管理规范,介绍了生物芯片洁净室平面布置和空调系统设计。     

Using air curtain to control pollutant spreading for emergency management in a cleanroom

The present investigation aims to examine the pollutant dispersion flowfield in an IQC cleanroom. Experimentally, the airflow velocities were measured using a TSI 8495 hot-wire anemometer to inspect the flow characteristics. Three ppbRAE PGM-7240 photoionization detectors were employed to concurrently measure the spatial and temporal distributions of ethanol concentration from a gas-pollutant leaking source. The computational analysis was based on the time-dependent three-dimensional conservation equations of mass, momentum and species concentration for the incompressible isothermal turbulent flow with a k-? two-equation turbulent model adopted for turbulence closure. Considering a massive amount of gaseous ethanol released from a malfunction machine, we presented a novel application of using an air curtain to resolve the personnel safety concern for emergency management in a contaminated cleanroom. For the cases without and with activation of an air curtain device, the airflow and contaminant characteristics were explored to better understand the pollutant spreading process for contamination control purpose. Numerical simulations were extended to verify if the air curtain device can establish a satisfactory shield for constraint of pollutant dispersal and optimize the sealing performance by systematically varying the parameters of ejection velocity, ejection angle and installation height.     

A numerical study on airflow and dynamic cross-contamination in the super cleanroom for photolithography process

We performed the numerical study on the characteristics of airflow and cross-contamination in the photolithography process cleanroom. The nonuniformity, the deflection angle and the global cross-contamination were used to analyze the characteristics and performances of cleanroom. From the numerical results, we found that the airflow characteristics of the cleanroom are largely affected by the porosity of the access panel and adjustment of dampers and the cross-contamination varies with the location of source and the passage of time through the concentration ratio.