三叉形自力式高效排气风帽的原理特性及应用

中重点介绍新型韧 利-自力式三叉型高效排气风帽的设计原理，结构特性以及空气动力性能检验结果，和旧式风帽相比，此产品的突出优点是不但能保障在任何风向和风力的情况下，都不发生风雨倒灌现象，而且还利用了室外风力，形成排风主管的抽力（即产生静压），变不利因素为有利因素，另外此产品阻力系数较小为0.83。     

自力式三叉形排气风帽

该风帽是一种专利产品,设计精巧,结构简单(见图1),体现了排气综合性能要求。当室外有风时排气主管产生抽力(静负压)。室外无风时,因风帽阻力系数很小(ξ=0.83),污气会自然排出室外。所以该风帽在任何风向、风力、位置条件下都不会发生风雨倒灌现象,排气效果好。图1　风帽外形图1主管道　2分支管道3主烟道该风帽可用于工业厂房、公共场馆、住宅等需要自然通风或机械通风的末端装置上。该风帽可用钢板、不锈钢、工程塑料、混凝土制作,安装时不受垂直和水平方向限制,目前该产品已在北京小批量生产,并在10余家单位使用。该风帽已通过国家空调设…     

杭州屋顶风机开发中心产品简介

杭州屋顶风机开发中心(属杭州市西湖区西溪路50号,云霞实业公司)首先推出F 型玻璃钢风帽及 FW_4-75屋顶风机等产品。玻璃钢风帽有单层或双层连座形,有外观为彩色的。筒与内园顶间排风,下口进风,性能与筒形风帽相近,且更为耐用。风帽可依室外风力或室内热气(压)排风,风帽下部可连接风管,风罩。FW_4-75屋顶风机首次采用出口电机及复合结构离心式叶轮,叶轮经动、静平衡校正。整机动力性能优越,噪音低。电机可配 Y 型及 Y 型调速电机,防爆电机,外旋调速电机。叶轮有玻璃钢,钢或不锈钢。玻璃钢有阻燃型。需排放腐蚀气体时,电机室可与叶轮室封隔开且设电机通风孔,上述特点均为本中心开发的成果。     

J型风帽的设计和原理分析

本文提出J型风帽的设计。认为如采用此风帽,每个排风系统可省去约5m 风管,并减少一定比例的风机电耗。     

背射式风帽的设计和原理分析

本文分析了当前排气风帽所应解决的主要问题。在此基础上,设计出一种新型背射式风帽,并对其主要功能进行了验证。     

排气自然通风装置系统的改造

采用自然排风装置的通风系统的局限性在于它的排风量低,而且不稳定。排风量的高低取决于所供房间的室内外空气密度差,以及排风竖风道的高度。在安装风帽的情况下通风系统的竖风量会有些增加,但由于风力不固定,因而在计算时候通常忽略风压的作用。     

小型循环流化床锅炉风帽改造分析

龙安热电在运3台150t/h循环流化床锅炉,由于锅炉炉膛风帽结构设计与选型不当,实际运行中发现风帽布风不均匀,导致风帽外罩吹损严重、床温偏高、放渣管磨损、锅炉爆管等问题。为了保证锅炉出力和长周期安全可靠运行,方便检修维护,对现场风帽吹损、放渣管磨损和锅炉爆管等原因进行分析比较,结合现场实际,更换锅炉落渣管四周风帽、加爪钉敷设高温耐磨可塑料和改变风帽孔径孔数等方法进行技术改造,解决了锅炉因风帽结构设计与选型不当造成磨损、爆管等问题。     

破碎产品风力分级系统除尘装置的改进

石菉铜矿选厂细碎产品采用风力分级工艺,细碎产品经风力分级为合格产品和不合格的粗粒级产品。投产初期,细碎产品风力分级系统用四级收尘系统,即沉降桶→CLP 型旋风除尘器→扩散式旋风除尘器→泡沫除尘器。生产后,发现该系统总的收尘效率低,排放气体含尘浓度很高;含尘气体湿度大,露点高,     

球型风帽 研制成功

国内目前已研制成功一种新型屋顶通风器——球型风帽。样品经北京大学环境科学中心在大型风洞内测试;排风能力强,竖向风适应性能好,水平风时单位面积排风量比筒形风帽高20～50％,竖向风时高出200～300％。防倒风、防雨雪溅落功能好,造型美观、结构牢固。综合性能优于苏欧,日本等国家的风帽,该项成果已获国家专利。球形风帽设计为组合式结构,分部件制     

下伞形帽锥度对锥形风帽局部阻力系数影响的数值模拟研究

通过运用数值模拟结合试验验证的方法,研究锥形风帽下伞形帽锥度γ对风帽局部阻力系数ζ的影响。通过建立相关数学模型,运用数值模拟计算的方法得到不同工况下风帽的局部阻力系数ζ,对不同工况下风帽的局部阻力系数进行比较分析,得到锥形风帽下伞帽锥度对局部阻力系数的影响规律;在数值模拟之外,还针对文中数值模拟的工况开展了相关试验以和模拟结果进行比较,试验结果进一步佐证了数值模拟得到的结论。研究结果表明:在γ=70.61°~80.72°下伞帽锥度变化范围内,随下伞形帽锥度增加,锥形风帽的局部阻力系数增大。     

太阳房集热墙风口平均风速测定方法研究

本文对被动式太阳房集热墙风口平均风速的测定进行了研究。通过实验室模拟风口实验,测量分析风口截面上不同风量下风口的平均风速,找出测点风速等于平均风速的分布区域,将一个风速传感器探头放在该区域测出的风速即可代表风口的平均风速。将实验结果在青藏铁路线上被动式太阳房现场进行了校核,从而实现了对被动式太阳房集热墙风口平均风速的自动监测。     

Static split duct roof ventilators

Split-duct roof ventilators or windcatchers are used to provide both supply and extract ventilation to the spaces which they serve. However, buildings are often erected in conditions where there is no prevailing wind direction. An investigation into four and six segment windcatchers to determine their relative performances under different wind conditions was undertaken usind scale models in a wind tunnel. Conclusions indiciate that six segment windcatchers have a more predictable, reliable performance in uncertain or variablewind conditions. However, a four segment windcatcher that is orientated 45 degrees to the prevailing wind will generate the highest pressure differences and consequently the highest duct speeds in an installation. Further work on strategies for windless conditions are summarized, and scope for further research is indicated.

On utilise des ventilateurs de toit à fentes ou des capteurs de vent dans le but à la fois d'alimenter et d'évacuer l'air des locaux pour lesquels ils sont prévus. Cependant, les bâtiments sont souvent érigés dans des conditions où il n'y a aucune direction de vent dominante. Des recherches ont été menées en soufflerie sur des capteurs de vent à quatre et à six segments afin de déterminer leur fonctionnement relatif dans des conditions de vent différentes en se servant de maquettes en soufflerie. Les conclusions indiquent que les capteurs de vent à six segments ont des performances plus prévisibles et fiables dans des conditions de vent incertaines ou variables. Cependant, les ventilateurs à quatre segments orientés à 45 degrés par rapport au vent dominant, produiront la différence de pression la plus haute et par conséquent les vitesses de transmission les plus élevées dans une installation.     

风井出口废气扩散的模拟及控制研究

为了解自风井出口排放出的污染物的浓度分布以及对其周围空气形成的污染范围,采用三维数值模拟的方法,对风井出口废气的对流扩散特征进行了模拟和分析,揭示了在不同外界风速和风向的条件下,出口处废气的扩散特征.计算结果表明,外界风速越高,废气扩散得越快;但因浓度衰减得也越快,故其能对大气形成污染的扩散范围加大到一定程度时又有减小的趋势;出口污染物会对距风井近距离范围内的大气产生一定程度的污染,可适当加高风井高度以使周围建筑物及人员免受污染物的危害.     

舞台自然排烟口风量计算

本文着重介绍了舞台自然排烟排烟口面积的计算及排烟口风量计算。     

大跨钢桁梁悬索桥风-车-桥分析系统建立与可视化实现

从钢桁梁断面风荷载和车辆荷载加载角度对现有风-车-桥耦合振动系统进行精细化改进。首先基于钢桁梁自身结构特性,以桁杆为单位,对静风力和抖振力,采用合力等效原则,使得任意时刻每个截面内所有节点所受静风力和抖振力的合力与作用在该截面形心的等效静风力和抖振力相等,求取每个节点的静风力和抖振力;对于自激力,依据刚体运动学理论,推导了钢桁梁截面节点与相应截面形心两者运动状态之间的关系式,采用响应不变原则,获取每个节点的自激力。其次在已建立适用于单主梁模型的分析系统的基础上,融入提出的钢桁梁风荷载精细化分析方法,构建大跨钢桁悬索桥风-车-桥分析系统,并基于OpenGL技术集成开发风荷载作用下随机车流过桥的动态可视化功能。最后依托一座典型大跨钢桁悬索桥,采用建立的分析系统,对不同风速和车流密度作用下的桥梁响应进行分析。结果表明：桥梁跨中竖向位移响应主要受车辆荷载控制,横向位移同时受风荷载和车流密度控制,但风荷载起主要作用;随着风速和车流密度的逐渐增大,跨中内力与位移响应极值明显增大。     

Gas dispersion near a cubical model building. Part I. Mean concentration measurements

The dispersion of effluent plumes emitted on or in the near-wake region ($\text{x/H ? 5.0}$) of a cubical model building has been examined. The model study was performed in a wind tunnel with a simulated neutrally stratified shear layer. Mean concentration measurements were made on the model building for three different roof vent locations and three different building orientations. A full-scale measurement was conducted in the near-wake region for central roof vent release.The concentration level on the lee face of a model building is greatly reduced by the presence of a sharp edge on the model. The optimum location for the intake vent on the building, for equal vent exhaust to vent intake distance, is a position away from the downwind direction and where it cannot “see” the exhaust vent. Orientation of the building at an angle of 45° results in a secondary peak concentration on the building and in the near-wake region.     

A numerical study on the characteristics of flow field,temperature and concentration distribution according to changing the shape of separation plate of kitchen hood system

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3D numerical analysis method and improving the system to expel pollutes more efficiently. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values. The three models having different shapes have one exhaust port and the model which has the vent at the closest position to where pollutes are generated is discovered to be the most efficient model. Compare to the initial model (having no separation plate), it was 1.4–1.9% more efficient at temperature distribution and 9.4–11.9% more at CO₂ concentration distribution.     

An experimental technique for distribution of dynamic wind loads on tall buildings

An experimental technique to determine the distribution of wind loads along the height of a slender and tall building has been presented using an aeroelastic model which simulates the correct mode shape of the prototype. The dynamic pressures acting on the model have been measured simultaneously from two pressure tappings at a time to compute the auto and cross power spectral densities, from which the modal force and, hence, the acceleration at any height is computed to determine the distribution of dynamic shear and moment. The technique could also be implemented using a rigid model when the motion of the building is not expected to modify the pressure distribution significantly. Since simultaneous measurements of pressures from all the tappings are not required, the proposed technique can be easily implemented in any wind tunnel laboratory.     

Effect of relative intensity of wind load on the RC column reliability in tall buildings

Wind loads are very important in the design of tall buildings as often the load combinations containing the wind load govern the design. As for reliability, however, because of the higher inherent uncertainty in the wind load in comparison to the gravity load, safety indices decrease as the ratio of wind load to gravity load increases. The safety indices in RC columns depend on the nominal wind to gravity load ratios. Due to the interaction between bending moment and axial force, a single ratio cannot be defined, because the eccentricity is not similar for wind and gravity loads. In this paper, the ratio of wind to gravity loads is considered separately for axial force and bending moments. Unlike conventional approach, here it is assumed that the wind and gravity loads' eccentricities are not equal, and the final load eccentricity used in either the design or the reliability analysis is a function of applied loads. The results demonstrate that the sensitivity of RC columns' safety indices to bending moment ratios is higher than that of axial force ratios. Furthermore, the variation of RC columns' safety indices with a low rebar percentage is very different from RC columns with high rebar percentages. Copyright © 2010 John Wiley & Sons, Ltd.     

建筑朝向对自然通风的分析及确定

通过分析气流组织、风影区长度、室内平均风速、室内通风量以及室内空气的均匀性等影响自然通风效果的因素,确定在群体性建筑自然通风时,建筑来流入射角的取值。在此基础之上,确定了风向季节变化区的建筑朝向,并且综合考虑多项因素,最终确定建筑朝向。