长距离渗透喷射式布袋风管送风均匀性实验研究

通过理论计算和实验研究,分别计算和测试了长度120 m渗透喷射式布袋风管内部动静压的分布,各管段的总送风量,孔口送风量和渗透送风量,在此基础上分析送风量不均匀度沿风管的变化规律.实验结果表明,在进口风速13.5 m/s,10.0 m/s和6.8 m/s三个工况下,进口风速为10.0 m/s时风管内沿程静压分布较稳定,静压及动压的计算值与实验值比较吻合.三种工况下各管段的总送风量和渗透送风量沿程增加,波动较大,但孔口送风量沿程波动较小.三种工况下的送风量不均匀度沿程增大.综合工程实际,可将10 m/s作为工程应用中的推荐进口流速.     

消防供水系统阻力测定教学装置的研制及应用

消防供水系统沿程阻力测定可为消防给水设计和火场供水实际应用提供理论基础。为加深学生对供水系统沿程阻力问题的深刻认识,基于典型实验教学中的沿程阻力测定实验,研制了一种具有可拆卸管道的消防供水系统阻力测定教学装置。该装置以模拟软件Materials Studio对减阻材料的筛选结果为依据制备阻力管道,所设计的可拆卸阻力管道便于对比流体性质、管壁粗糙度等因素对沿程阻力的影响,同时增加摄影设备,用于定量化分析实验数据。结合该装置,形成理论讲解、仿真模拟、实验演示相结合的教学模式,有助于培养学生应用模拟软件的能力,提升科研思维和自主创新能力。     

槽式太阳能集热器聚光面能流分布及传热特性

本文运用蒙特卡罗光线追踪法模拟了LS-2型槽式太阳能集热系统的聚光特性,并以此为边界条件,进一步研究传热工质为THERMINOL55合成导热油时该集热器内管壁和管内流体的温度分布特性和传热特性。结果表明,管壁和管内流体温度分布十分不均匀。并考察了不同导热油以及导热油的流速对传热效率的影响工质流速对管壁温度分布影响较大,当太阳直射辐照为1000 W/m^2,导热油入口温度为160℃,流速为0.05 m/s时,吸热管圆周方向最大温差为235℃左右,当流速增加到0.05 m/s时,最大温差减小到142℃左右。     

上倾管内油水两相流流型实验研究

国内多条成品油输送管道在投产和运行过程中,采用"水联运"投产方式所造成的上倾管道低洼处积水现象引起了严重的管道内腐蚀问题。利用上游来油将低洼处积水携出管道能有效缓解内腐蚀。采用0#柴油、去离子水在内径100 mm的上倾管道内观察油水两相流流型并测量油携水临界流速。结果表明,随油流黏性力增大和管道倾角增大,油水两相流依次呈现波状分层流、有水滴的波状分层流和油相占主导的分散流3种流型;同一流型下,油相能将水相携入上倾段的最低临界流速随倾角增大而增大;倾角从20°增大到25°使流型从波状分层流转化为有液滴的波状分层流时,油相能将水相携入上倾段的临界流速从0.203 m/s减小为0.187 m/s;倾角从30°增大至35°时,使初始流型从有液滴的波状分层流转换为水相在油相中的分散流,油相能将水相携入上倾段的临界流速从0.205 m/s减小为0.194 m/s;油相能将水相完全携出上倾段的临界流速随倾角增大而略有增大;发生流型转化的流速随倾角增大而减小。     

基于数值模拟的新拌混凝土竖直泵送流动行为

借助数值模拟研究了3种流动性的混凝土在竖直向上泵送时的管内流动行为,分析了混凝土内部压力和流速的分布规律.结果表明：泵送压力主要受润滑层性质的影响,其纵向分布与管壁阻力沿程变化规律有关,截面中心的泵送压力略高于管壁处;混凝土在管内的流动存在“前进—扩散—滞留堆积—汇聚”的行为特征,并据此分析了润滑层的形成和粗骨料的迁移,解释了泵送离析和堵管的原因.     

模拟回用水管道生物膜特征及其对铁、锰的富集

以西安市某再生水厂出水作为水源,采用4个CDC生物膜反应器,通过串联模拟回用水管网中生物膜的特征及其对铁、锰的富集.结果表明,回用水管道单位表面积累的生物膜量沿程按幂指数关系递减;生物膜中的异养菌数量沿程减少,其在HRT＜ 25 min区段的数量最多,平均为302 CFU/m2.同时,回用水管道生物膜的溶解态EPS含量沿程先增大再减小,而结合态EPS含量则沿程递减,其中蛋白质/多糖值在前者中为0.91 ～1.29,在后者中为3.18 ～3.91.此外,模拟回用水管道中分布最多的为锰,其次是铁,其中锰在第2个反应器中的质量分数最高,达到生物膜总量的53.9％.     

大口径输水管水力计算问题

采用CFD软件FLUENT对输水管道进行三维数值模拟,将其结果和EPANET采用海曾—威廉公式或达西—韦伯公式计算结果进行比较,提出大口径输水管道使用EPANET进行水力计算时一些值得注意的地方。各管径范围内,管壁粗糙度小的时候采用达西公式的安全性较高,并且建议根据柯尔勃洛克—怀特公式确定沿程阻力系数λ,但是管壁粗糙度大的时候达西公式的安全性不高。大管径管道在一定粗糙度范围内,海曾—威廉公式选定恰当的海曾—威廉系数Cw时计算结果能够保证安全性,并且建议根据流速修正该系数。     

管内假塑性流体沿程损失数值研究

假塑性流体作为最常见的一种非牛顿流体,在工业生产、石油化工及新能源新材料开发等领域发挥着重要作用,因此对其展开针对性研究有助于适应经济发展、减少能源浪费。文章主要通过数值模拟方法对圆管内假塑性流体流动时沿程阻力损失情况展开研究及分析。分别模拟计算在层流和湍流状态下假塑性流体的流动,分析了沿程阻力系数与雷诺数及相对粗糙度之间的关系,并归纳推理管道沿程水头损失与平均流速之间的联系。     

纵向通风与侧壁开口竖井自然排烟协同作用下烟气运动模拟

为探究山岭隧道火灾烟气运移特性,采用数值模拟的方法,选取两种典型火源功率(20 MW及50 MW),分析不同纵向风速下火源位置对隧道顶棚下方沿程温度分布规律、烟气运移速率及竖井内烟气质量流量的影响规律.研究结果表明,纵向风速低于3m/s时,不同火源位置时,火源上游沿程温度均随纵向风速增加逐渐降低,而下游沿程温度随纵向风...     

综合管廊燃气舱管道压力对泄漏的影响

针对长×宽×高为200 m×1. 8 m×2. 2 m的燃气舱(舱内布置DN 150 mm燃气管,泄漏孔直径为10 mm,方向竖直向上),在换气次数为6 h~(-1)条件下,对不同管道压力条件(管道压力1:4. 0 MPa,管道压力2:1. 6 MPa,管道压力3:0. 4 MPa,管道压力4:0. 01 MPa)下天然气的泄漏进行数值模拟。天然气的泄漏与管道压力关系密切,管道压力越高,相同泄漏时间内影响范围越大。泄漏发生后,4种管道压力条件下,泄漏孔正上方燃气舱顶部天然气体积分数迅速升高,且在1s内就达到1%。管道压力1条件下,该位置天然气体积分数3 s达到5%。管道压力2条件下,该位置天然气体积分数5 s达到5%。管道压力3条件下,该位置天然气体积分数15 s达到5%。管道压力4条件下,该位置天然气体积分数不会达到5%,基本维持在3%左右。     

Numerical simulation of ventilation and dust suppression system for open-type TBM tunneling work area

In order to study the characteristics of the ventilation and dust suppression system for open-type TBM tunneling work area in a Ø8.53 diversion project, the numerical simulation method is adopted, and a three-dimensional steady airflow model, a dust flow model as well as other related flow characteristic equation models are established by considering the dust production mechanism of TBM construction. Besides, corresponding simulation models validated by experiment are established using CFD software, and the impacts of the main vent location, the air baffle length in the main beam and the exhausting air flow quantity on flow field distribution and dust flow behavior in open-type TBM tunneling work area are investigated. The results show: when the main vent is located 70–80 m away from the working face, the ventilation in TBM tunneling work area is optimal; when the air baffle is as long as the main beam, the dust collection efficiency is the highest, reaching 89.4%; under the condition that the exhausting air flow quantity is less than half of the ventilation air flow quantity required by energy consumption and the minimum backflow velocity, the best dust suppression effect can be achieved when the exhausting air flow quantity is 40% of the ventilation air flow quantity.     

特大型圆筒式尾水调压室穹顶施工通风技术

施工通风是影响地下洞室开挖施工安全和设备效率的重要因素。白鹤滩水电站特大型圆筒式尾水调压室规模大,埋深深,无通风竖井,穹顶施工通风十分困难。为确定穹顶施工通风关键因素,制定针对性的通风方案,采用流体数值软件构建了地下洞室三维非稳态湍流模型,分析了压入、压出和混合式通风的特点,提出了一套适用于穹顶施工期的高效循环置换通风技术;研究了穹顶开挖爆破污染物时空分布特点和逸散规律,并进行了现场污染物测试。数值计算和测试结果证明:洞室群内气流组织顺畅,污染物能及时排至排风洞内,通风10 min后污染物浓度可达到规范要求,循环置换通风技术高效可行。     

某电厂煤制样间除尘设计

煤制样间产生的煤尘危害性大,而常规的通风方式无法满足制样间的环保要求,介绍了一种新型除尘系统的技术特点以及在具体工程中的应用,达到了预期效果。     

湖北荆门热电厂三期通风工程设计

介绍了湖北荆门热电厂通风除尘系统设计和设备选择。根据各建筑空间不同的使用要求,采用了不同的通风系统。针对煤仓间的特殊性,采用了半集中除尘系统。该工程的设计参数和系统选型经验可供热电厂通风除尘系统设计参考。     

Wind-induced natural ventilation of re-entrant bays in a high-rise building

This paper reports a systematic computational study of wind-induced natural ventilation and pollutant transport of re-entrant bays on a total of 30 generic building models of different building heights and with bays of different dimensions. Mean wind flow around each building model and wind-induced flow inside re-entrant bays are computed. To determine the ventilation efficiency of the bay, the computed flow field is used to disperse a scalar pollutant initially occupying the entire bay at a uniform concentration. The subsequent time decay of pollutant concentration inside the bay is studied and the ventilation efficiency is quantified by the retention time. The results show that wind-induced flow inside the bay, especially on the building side face, is complex and highly three-dimensional. Air exchange rates through the roof opening and vertical side opening are analyzed for each bay and their relationship to the ventilation efficiency is discussed. The bays on the building side faces are much worse ventilated than those on the windward or leeward building face. The deeper the side bay, the worse is the air exchange and ventilation. The building height is found to have a governing effect on the ventilation of the windward and leeward re-entrant bays.     

静电净化装置在医院洁净空调系统中的应用

医院室内的空气净化是预防感染的重要措施之一,但目前常用的空气净化方案皆存在一些弊端。静电净化装置能够有效地除尘除菌,本文对其进行了实验测试,测试结果表明：所使用的静电净化装置能够达到高中效过滤器的除尘效率;在一定风量下对空气中浮游菌的除去率能够达到90％以上;在通风量很小的情况下,静电净化装置运行行时送风口处的臭氧浓度有可能超标：并且本文设计了静电净化装置在医院洁净空调系统中的一个应用方案一存新方案中将静电净化装置加装在空调系统的通风管道中,并对过滤器进行重新配置。通过理论的分析说明所设计的厅案能够有更好的空气净化效果,并且能减少系统运行费用,是一种较为合理的空气处理方案。     

Doorway flow induced by a propane fire

A series of full-scale steady-state experiments was conducted to study the high temperature fire-induced flows through doorway openings connecting a burn room to a second room containing a hot gas layer. A propane diffusion burner served as the energy source. Fire strength and doorway width were varied. Measurements included two-dimensional velocity and temperature profiles within the opening and vertical gas temperature profiles within the rooms. Opening mass flows were determined from the opening data. These mass flows are explained in terms of a static pressure model based on actual gas temperature profiles in the two rooms and an orifice coefficient of 0.68. It is also shown that the simple relationship between mass flow rate through the opening, M_a, and ventilation parameter, (W, opening width; H, opening height) holds even when the opening is in the wall between two rooms. The proportionality constant for this simple relationship may depend on the configuration.     

Transient pollutant flushing of buoyancy-driven natural ventilation

The transient flushing of neutrally-buoyant pollutants from a naturally ventilated enclosure is investigated. A simplified transient model for buoyancy-driven natural ventilation produced by a point source of heat is presented to describe the ventilation development from the plume generation to its steady state. The instantaneous thermal stratification interface height and ventilation flow rate and the time taken for the flow to reach the steady state are then examined by the transient model. The results indicate that the decrease of the thermal stratification interface height with dimensionless time, the steady-state interface height and the dimensionless time taken for the flow to reach the steady state are only determined by the dimensionless effective area of the vents. The ventilation flow rate can be increased by decreasing the enclosure floor area or increasing the effective vent area, enclosure height or source buoyancy flux. Accordingly, for rooms with smaller floor area, larger effective vent area or larger source buoyancy flux, ventilation airflow provides more effective flushing of neutrally-buoyant pollutant. Nevertheless, increasing the enclosure height is only beneficial to flush the pollutant from the lower layer rapidly and is disadvantageous to reduce the pollutant concentration of the upper layer.     

影响燃煤电厂除尘器选择的定量研究

通过对200个电厂的不同煤质和飞灰成分进行偏相关分析,得出了影响电除尘器除尘难易性的关键因素,通过多元回归分析,获得燃煤电厂采用湿法烟气脱硫执行不同烟尘排放标准30mg／m^3和20mg／m^3时的除尘器选型方法,并对选型方法的准确率和涵盖率进行了验算,以供参考。     

地铁车站补风对烟流影响的数值模拟

运用FDS对某地铁车站站厅层火灾工况下的排烟和补风效果进行模拟。模拟结果表明,依照规范设计的排烟系统能够满足烟气蔓延范围控制和楼扶梯口下行风速的要求;单侧补风导致烟气滞留现象较为严重,不能保证起火站厅层人员疏散的安全性。针对模拟结果进行优化补风设计,通过优化补风口的位置,使站厅层形成双向补风,提高了站厅层的排烟效率。建议在楼扶梯口位置不能保证地铁车站有效补风的情况下,在补风盲区增设机械或者自然补风系统。