排风均流器的阻力系数研究

通过对排风均流器的实体实验与主风管内风速、风压的数值模拟计算,获得排风均流器在主风管中最大阻力系数的计算公式,并研究了迎风阀和背风阀的关闭度与阻力系数的关系。结果显示:当排风系统均匀排风时,主风管前半段排风均流器的背风阀全关,迎风阀关闭度逐渐减小,主风管后半段排风均流器的迎风阀全开,背风阀的关闭度总体上逐渐减小;若排风均流器背风阀全关,迎风阀关闭度逐渐增大时,其阻力系数先减小后增大;若排风均流器迎风阀全开,背风阀关闭度逐渐增大时,其阻力系数先增大后减小。     

风量分配器的试验研究

本文介绍了通过试验研究利用旋流在风管内送风以均匀分配风量的新技术,及在等截面圆风管上风口分布离散的均匀送风系统中能自动平衡各风口风量的风量分配器的研制。本试验研究在有效风管长度50D,风口间距4D时,观测在起始端设与不设匀流器等多因素变化情况,与不装风量分配器的工况进行对比试验后,成功地开发出新的均匀送风系统和设备——风量分配器。     

均流器均匀排风的实验研究

介绍了实验原理及装置,比较了自然状态排风与均流器均匀排风的支管风速以及均流器调节与常规风阀调节的排风距离。实验结果显示,均流器对改善排风管路特性的效果显著,均流器均匀排风的距离远大于常规风阀均匀送风。均流器均匀排风管路中,风口风量由主风管截面静压和均流器阻抗共同决定。     

高大空间通风气流组织2DPIV试验初探

水电站地下主厂房属于高大空间建筑,为了保障设备正常运转和工作人员正常工作,保证厂房内温度、相对湿度及有害气体浓度在允许的范围内．对其进行合理的通风气流组织设计是十分必要的。本文以鲁地拉水电站主厂房为例,创建1：50模型试验,创新性地采用2DPIV技术对主厂房内设计风口下的通风气流组织进行研究。研究表明,试验三种工况下（风速分别为0．84m／s,1．26m／s,1．67m／s）,射流轴心速度衰减变化趋势一致,其衰减程度随着与出风口距离的增大而增大。随着送风速度的增大,工作区风速的不均匀系数逐渐降低,流场的均匀性逐渐优化。随着风口间距的减小,工作区风速的不均匀系数逐渐降低,流场的均匀性逐渐增强。     

地铁区间隧道火灾通风模式的数值模拟

针对列车中部着火且停靠在区间隧道中部的地铁隧道火灾情况,提出了一种改进的纵向通风模式,即疏散平台下先送风、再采用传统的纵向通风,并进行了数值模拟.模拟结果表明,时单线矩形区间隧道,在10 MW的火源强度下,当疏散平台下送风风口组间距为10m且隧道风机风量为50 m3/s时(或风口组间距不超过30 m且隧道风机风量为70m3/s时),可以满足安全消防的温度指标、能见度指标和CO浓度指标.同时模拟得出区间隧道两端纵向通风的临界风速在2.4～2.8 m/s之间.     

关于建筑加压送风系统设计的几点思考

从风量、风管和风口的设计、防烟部位正压控制方式等角度,分析了加压送风系统设计中需要注意的几点问题:风量的确定需合理有据;楼梯间风管和风口的设计需考虑均匀送风要求,前室风口设计确保不同楼层前室风口开启时风机运行工况稳定;每个防烟部位独立设置加压送风支管和电动旁通泄压阀门,可实现防烟部位正压独立控制。     

净化器送风仰角对房间各区域PM2.5净化时间影响

为解决净化器对房间各处净化不均匀的问题,本文对房间进行分区,通过实验与模拟相结合的方法研究净化器在不同送风风速下,送风仰角角度对房间各区域PM2.5净化到15 μg/m3的净化时间(以下所述PM2.5净化时间均为PM2.5净化到15μg/m3所需的时间)的影响.结果 表明:送风风速为3 m/s时,仰角角度从0°增大到3...     

均匀送风风管构件流量特性实验

提出了一种新型均匀送风风管构件,将该构件应用于所搭建的实验平台,对构件流量特性及系统的均匀送风特性进行了实验研究。结果表明,风机运行在10~50Hz时,各风口的风量不平衡率均能维持在5%以内,可实现均匀送风。采用这种形式的构件,在实际长风管空调系统风量调节时,大大降低了调节工作量。     

婴儿躺卧场景下个性化送风有效性实验研究

提出在婴儿躺卧场景下应用个性化送风方案。基于婴儿暖体假人进行实验,利用示踪气体衰减法测算房间内不同位置的空气龄和污染物残留浓度,以此评价个性化送风系统的有效性,并与织物风管混合通风系统进行了对比。基于3～11 L/s的送风量和50～90 cm的送风距离,针对个性化送风设计了15组工况;基于11,40 L/s的送风量,针对织物风管混合通风设计了2组工况。结果显示:采用个性化送风,仅在不利工况下新风无法穿透婴儿热羽流,其他工况呼吸区空气龄均小于36 min,最小达到19.13 min;个性化送风在运行前4 min内污染物浓度下降即超过50%,显著快于织物风管混合通风;送风量相同时,个性化送风下呼吸区空气龄较混合通风小51%。     

厦门国际会展中心空调通风工程

简要介绍了该会展中心空调通风系统及防排烟系统设计。该工程空间高大，展览大厅气流组织采用上送上回方式，旋流风口送风，回风管兼作排烟管用；进深48m的西侧门厅沿门厅山墙外设喷口、沿进门主柱的6个巨型送风柱侧送以及沿玻璃窗下设侧向地送风口侧送解决送风问题。工程采用电制冷机制冷，大温差二级泵运行，运行效果良好。     

超高层建筑施工中氨气抑制的数值模拟

针对超高层建筑施工中典型空气污染物氨气,运用CFD方法构建武汉中心三维立体模型,模拟标准k ε条件下自然通风和机械通风2种抑制措施对氨气浓度整体影响效果并确定其影响进深。结果表明:稳态下机械通风对降低模型整体氨气浓度效果有限,单个送风口沿送风方向影响进深约为6.1 m,垂直于风速方向约为1.2 m,且送风口影响进深随风速变化极小;自然通风对降低模型整体氨气浓度效果明显,进风口对氨气浓度影响进深约为17.5 m,随高度增加逐渐递增的进风速度在通风前15 s对氨气浓度影响明显,稳态时风速增加自然通风影响进深增加有限;施工中可主要采用自然通风抑制氨污染,幕墙封闭后可利用机械通风并辅以导风板等设施提高机械通风影响效果。     

风管出口位置对隧道施工通风效果影响的研究

为研究风管出口位置对公路隧道施工通风效果的影响,利用流体力学软件Fluent,建立隧道三维模型并进行了数值模拟。通过分别对风管管口与工作面5种布设距离及4种布设形式下流场特性的对比,分析了管口与工作面距离及风管附壁程度对流速变化和有效射程的影响。并进一步探讨了风管出口不同位置对局部风阻压力的影响。模拟结果表明:在相同的入口速度条件下,风管附壁程度越高、距离工作面越近,射流速度变化梯度越大,通风效果越明显;风管管口离工作面越近引起的局部压力损失越大。     

送风口高度对碰撞射流气流特征影响实验研究

通过实验研究了碰撞射流热风供热时不同的送风口高度下室内空气温度、速度和热舒适参数分布情况。分析了送风口高度影响作用,结果表明碰撞射流热风供热系统的送风口高度对室内热环境有显著影响。     

地板送风终端单元空调房间速度场和温度场的数值模拟

建立了数值模拟模型,通过实验验证了该模型在等温送风情况下的适用性。对非等温送风不同风量下房间内的速度场和温度场进行了数值模拟,结果表明,出口风速主要影响送风口附近区域的速度场,而对整个空调房间影响不大,室内空气流速分布较均匀,基本维持在0·25m/s以下;出口风速对温度场的分布有很大影响,垂直平面温度梯度较大,水平平面温度分布均匀。为了保证地板送风的有效性和节能性,在满足风量的同时,必须严格控制出口风速,使射流高度在工作区域附近。     

Effects of the solid curtains on natural ventilation performance in a subway tunnel

Solid curtains can be installed in subway tunnels for the promotion of air ventilation in ventilation ducts in association with the piston effect caused by a running train. With an aim to analyze the effects of solid curtains on duct ventilation performance in a subway tunnel, the current study adopts the tunnel and subway train geometries which are exactly the same as those in a previous model tunnel experiment, but newly incorporates two ventilation ducts connected vertically to the tunnel ceiling and two solid curtains placed at an upstream position of a duct near the tunnel inlet and at a downstream position of another duct near the tunnel outlet, respectively. A three-dimensional CFD model adopting the dynamic layering method for tracking the motion of a train, which was validated against the reported model tunnel experiment in a previous study, is employed to predict the train-induced unsteady airflows in the subway tunnel and in the ducts. The numerical results reveal that the duct ventilation performance in a subway tunnel strongly depends on the operation of the solid curtains. The suction mass flow of the air through the duct near the tunnel inlet and the exhaust mass flow of the air through the duct near the tunnel outlet are increased considerably in the case with the solid curtains in comparison with those in the case without the solid curtains.     

百叶风口送风射流的数值模拟

为简化风口入流边界条件的描述,提出用N个简单开口代替不同方向出流的百叶风口,建立了N点风口模型,据此模型对不同出流条件的百叶风口射流进行了数值模拟,并就轴心速度衰减,射流扩展角及断面流速分布等与实验数据进行了对比。结果表明,当N=1或3时,模拟结果令人满意。     

上置置换通风-顶板辐射供冷室内热环境研究

利用计算流体力学(CFD)方法,对上置置换通风-顶板辐射供冷复合空调办公建筑室内采用不同气流组织方式的通风效果进行了模拟研究,分析比较了气流组织特性指标--温度不均匀系数k1、速度不均匀系数ku空气分布特性指数ADPI及温度效率ηt等,给出了送、排风口适宜的上置安装位置.并从舒适性、供冷情况、竖直温度梯度以及温度、速度场分布等方面与传统置换通风.顶板辐射供冷复合空调系统进行了比较,指明了这种新型空调模式可行性、优点及不足.     

Control of Airborne Particle Concentration and Draught Risk in an Operating Room

The influence of location of airborne particle source, ventilation rate, air inlet size, supply air velocity, air outlet location, and heat source on the dkributiuns of airborne particle concentration and draught risk in an operating room is investigated. The investigation is carried out by using a flow program with the k-E mdel of turbulence. Based on a standard case, five cases, each with one changed parameter, are computed, and the detailed field distributions of air velocity, temperature, airborne particle concentration, and draught risk are presented. The parametric study concludes that, for a better air quality and thermal comfort, it is desirable to use a higher inflow rate, a larger inlet area, and a uniform velocity profile of supply air. Outlet location and heat source have little influence on the disrributions of the particle concentration in the room. It has also been found that the distributions of particle concentration in the recirculating zone are very sensitive to the location of the particle sources.     

Influence of the boundary thermal conditions on the air change efficiency indexes

The influence of a thermal heterogeneity boundary conditions on the air change efficiency (ACE) of a mechanical ventilation system in a test room was experimentally evaluated by means of the "step-down" tracer gas technique in 24 different experimental conditions. The experiments were performed under isothermal condition, varying the air supply temperature with respect to the walls and varying the surface temperature of a wall with respect to the other walls and the supply air, simulating both heating and cooling situations. Changing the position of the outlet grid two different configurations of the ventilation system were tested. The nominal supply air velocity varied between 0.04 and 0.11 m/s, corresponding to a range from 1 to 3 ach, and the temperature differences varied from 0 to 5 degrees C. Results are reported in terms of air change efficiency indexes, both local and global. The global air change efficiency (ACE), values are presented as a function of the Archimedes number (Ar), whose values were in the range 0 to 181. The reported results suggest that the Ar number may be used to organize the ACE values when in the presence of thermal heterogeneity, both in the external envelope and in the supplied air. The obtained results show that there is a logarithmic relation between Ar and ACE. In particular, for both ventilation strategies tested, the increase of the absolute value of Ar leads to an increase of ACE when the supply air is warmer than the walls, and to a decrease of ACE when the supply air is colder than the walls. Under isothermal conditions the Reynolds number (Re) fairly correlates the experimental results.     

椭圆与圆截面消防水炮炮座流动对比及试验

在内径66 mm大回转结构形式水炮炮座的缩小试验模型上,提出含有椭圆截面形式的新型流道,采用数值模拟方法对比研究流道截面改变带来的差异,采用粒子图像测试技术PIV试验验证数值模拟结果.对比的结论为:当炮座的一部分圆截面管竖向压扁为相同过流面积的椭圆截面后,流道总流动损失增加且增量非常小;同样,反映出口紊流程度的湍动能变...