行车隧道通风机射流作用下污染物浓度分布模拟试验

为研究行车隧道内污染物在通风射流风机作用下的分布规律,对行车交通风与射流场共同作用下的污染物分布进行了模拟试验研究。使用隧道试验平台测试数据检验了用于隧道通风的射流风机和隧道边界条件数值模型,在车流与风机射流共同作用下,对不同车型与行车速度下CO与NO₂的浓度场进行了计算,分析了射流纵向影响范围、通风效率与污染物通风去除效率3个指标,得出了污染气体浓度分布受通风射流风机与车辆流动影响的规律。     

全射流纵向通风在广州洲头咀珠江隧道中的应用

洲头咀隧道位于广州市珠江主航道上,总长1530m,本文结合工程的实际情况,对隧道的通风方式按全射流纵向通风方案、射流风机 洞口风道式排风型纵向通风方案、送风型半横向式通风方案进行了定量和定性比较,并综合考虑技术、投资和运营多方面因素确定采用全射流纵向通风方式。     

基于FLUENT的公路隧道通风优化配置及污染物分布模拟研究

车辆移动产生的交通风影响隧道运营通风系统,开展交通风作用下公路隧道流场分布和壁面压力特性研究,可为隧道运营期通风节能设计提供参考,具有重要意义。文章以204省道溧水段华侨城长隧道工程为背景,首先基于FLUENT建立了射流风机和隧道三维模型,采用有限体积法研究了不同射流风机组合下隧道内通风情况;然后基于组分运输模型,以CO为模拟因子,分析了隧道内汽车尾气污染物排放和扩散规律。结果表明：当开启单、双射流风机且每组射流风机距离较近时,隧道通风效果最优,污染物扩散最有利,采用该种方式开启风机,将极大有利于隧道运营的通风节能。     

集群式诱导通风技术在铁路隧道防排烟设计中的应用

本文通过对某铁路隧道通风与防排烟设计进行理论计算和数值模拟分析,并结合该隧道的防排烟效果现场测试,研究了集群式诱导通风技术应用于铁路隧道通风与防排烟设计中的可行性.结果表明,采用集中布置射流风机的诱导纵向通风方式,能够在隧道内形成较为稳定的纵向风速,能够满足隧道防排烟设计对临界风速的要求.这种通风模式可有效降低铁路隧道内连续布置射流风机的施工难度,有利于运营管理和集中维护,增强了隧道诱导通风方式的适用性.     

半横向通风在西藏南路越江隧道中的应用

西藏南路越江隧道作为2010年上海世博会场馆内专用隧道,通风系统采用了射流风机纵向通风结合半横向排烟的独特模式。在满足隧道通风排烟基本要求前提下,既考虑了日常通风系统运行低成本、低能耗,又更好地保障了火灾时乘用人员的安全。对黄浦江越江隧道通风系统进行的创新,更体现了隧道运行的安全、环保和节能。     

射流风机作用下的单隧道流场特性

射流风机作用下隧道的流场特性对火灾发生时隧道的通风、排烟效果有重要的影响.结合工程实例,采用FDS软件对射流风机作用下单隧道的流场特性进行了CFD模拟,获得了射流风机作用下单隧道内的流场特性,其研究结果对射流风机的设计具有一定参考价值.     

基于FDS的公路隧道火灾可逆射流风机通风疏散研究

随着我国公路隧道从高速建设期转变为建设与管理并重期,可逆射流风机在隧道通风系统中得到广泛应用。为探究可逆射流风机在隧道火灾下通风运行方式对人员疏散的影响,依托广东山隧道,采用5,20 MW两种火源功率,研究不同射流风机运行方式下隧道中部区域烟气、温度、CO体积分数及能见度的变化特性。结果表明,自然风和射流风机的出口气流均会破坏烟气-空气分层结构。在隧道内部1 m/s纵向自然风的影响下,面对不同功率火源,射流风机运行模式与人员疏散方向应随之改变。     

铁路双线隧道中有害气体分布规律的研究

定义了描述隧道机械通风系统空气动力特性的重要参数诱导比，以射流风机集中布置方式模拟实测了列车单列和交会时有害气体的时间变化和浓度分布，得出了保证隧道内空气卫生标准的风机台数和通风方式。     

并联双风机数值计算模型对隧道通风效果的影响

隧道通风射流风机的数值计算模型会影响计算结果,当双射流风机并联运行,需要考虑风机间相互影响时更需要研究射流风机模型对通风效果与风机工作状态的影响。本文通过风机测试与隧道通风测试分别验证了动态旋转风机模型与隧道通风射流模型的正确性,并研究了动态旋转风机模型与常用的稳态射流模型对整体隧道通风效果与风机运行工作状态的影响。通过比较了两者之间的差异,得出了动态旋转风机模型可以更好的模拟计算出风机后的瞬态射流流场、更好的计算出风机工作状态点的结论。     

平安隧道紧急救援站射流风机布置方案优化

在分析紧急救援站存在的通风方案的基础上对比不同风机布置方案:安全隧道、疏散横通道内布置风机(原设计);安全隧道内射流送风;疏散横通道内布置风机。得到各风机布置方案保证疏散横通道达到2.0 m/s的时间以及达到的最终风速。得到各风机布置方案皆可以保证疏散横通道防护门处风速达到2.0m/s以上,基本没有烟雾进入安全隧道和横通道;射流风机布置在紧急救援站附近与布置在隧道洞口最大的差别在于疏散横通道风速达到2.0m/s的时间不同;横通道内安装的射流风机实际达不到预计的通风效果,通风效率较低,不推荐采用。     

Analysis of the ventilation systems in the Dartford tunnels using a multi-scale modelling approach

The capabilities of the ventilation systems in the two road tunnels at Dartford (UK) are analysed using a multi-scale modelling approach. Both tunnels have complex semi-transverse ventilation systems with jet fans to control longitudinal flow. The construction and ventilation systems in the tunnels are described and the current emergency ventilation strategies are presented. The analysis includes a coupling of a 1D network model with 3D components, representing the operational jet fans, built using computational fluid dynamics. The jet fans were experimentally characterized on-site and the findings were compared to the model predictions. The predicted ventilation flows for each of the emergency ventilation strategies are presented and discussed. In cold-flow conditions, ventilation velocities significantly above 3 m/s can be generated throughout the tunnels. However, it is observed that 1/3 of the flow generated in the East tunnel is diverted from the tunnel up the extract shafts. The model was used to simulate various reduced fan combinations and thus the level of redundancy in each of the systems has been estimated. It is found that an acceptable level of ventilation may be produced in the West tunnel, even if several pairs of jet fans are disabled. In the East tunnel there is less redundancy, but an acceptable level of ventilation control can be maintained with one or two jet fans disabled.     

海底隧道腐蚀环境下射流风机升压力衰减机理及计算方法研究

海底道路隧道内高湿度、富盐雾和多酸性气体的环境特征会加速腐蚀风机,进而使通风效果无法满足洞内环境控制标准。以厦门翔安海底隧道为依托对隧道内风机升压力展开现场测试,结合理论分析和Fluent滑移网格模型研究风机升压力计算公式和表面粗糙度与风机升压力的衰减关系。研究结果表明：单台射流风机升压力计算公式还应考虑风机自身性能损失折减系数η1;海底隧道腐蚀环境通过积垢沉淀、侵蚀和腐蚀效应增大风机叶片和流通部件的表面粗糙度,进而增大风流阻力,降低风机升压力;通过数值模拟得到基于表面粗糙度的风机升压力计算方法。研究结果揭示海底隧道腐蚀环境下风机升压力衰减机理并建立了计算方法,为同类型海底隧道通风系统设计提供参考。     

高海拔隧道曲率对射流风机安装参数影响研究

射流风机的安装位置将对射流风机的效率产生直接的影响,而螺旋隧道的安装参数将有别于直线隧道.本文为探究在高海拔螺旋隧道中隧道螺旋曲率对射流风机的安装参数影响并得到较为完整的横断面安装参数,采用Fluent软件与正交试验相结合的方法,对隧道螺旋半径在R = 800 m、700 m、600 m、500 m 4种情况下进行了风...     

Numerical studies on evaluation of smoke control system of underground metro rail transport system in India having jet injection system: A case study

The rail based urban transport system is being developed for national capital of India, New Delhi. The smoke control using ventilation in case of fire inside the tunnel, similar to Delhi Metro corridor has been investigated using computational fluid dynamics technique. A section of tunnel having dimensions 400 m long, 5.5 m wide and 6 m high is considered for simulation. The analysis has been carried out by assuming a variable fire source with a peak heat release rate (HRR) of 16 MW, located at the center of the tunnel. Ventilation ducts are located in the ceiling near the tunnel portals and are inclined at 10 degrees to the plane of the ceiling through which fans discharge air. The influence of the fire HRR curve slope on the smoke flow dynamics in a realistic tunnel model fitted with jet injection type longitudinal ventilation system has been investigated. In case of fire two cases are studied: (1) fans activated immediately after detection, (2) fans activated at delayed times to take into account the response time for the fans to achieve its maximum speed. The velocity of supply and exhaust fans necessary to remove smoke in 30 s from the upstream direction is determined. The velocities of fan required to produce desired critical velocity in the longitudinal direction for different HRR of fire is predicted.     

CFD analysis of a realistic reduced-scale modeling equipped with axial jet fan

Typically, in the experimental scale road tunnel model, the air flow induced by ventilation system is provided by an external fan. In this paper, the authors have numerically simulated full and reduced-scale tunnel in order to evaluate the possibility to realize a reduced scale of a road tunnel model with a realistic ventilation system consisting of impulsive jet fans.In particular, two different types of longitudinal ventilation systems were considered, traditional and alternative. The last one was equipped with jet fans that have the inlet/outlet sections inclined at a fixed pitch angle (α=6°) toward the tunnel floor. The jet fan was simulated as a simple momentum source that provides a pressure rise (pressure drop) across them as a function of the outflow air velocity.The analyzed tunnel consists in a 800 m one directional bore with circular cross section 5.05 m radius; the jet fans were installed at 5.67 m from the floor. Furthermore a burning Heavy Good Vehicle (HGV), placed at 450 m far away the tunnel entrance, was considered. To simulate numerically the burning vehicle, the species transport equation combustion model with Eddy-Dissipation-Concept (EDC) model was adopted.In order to create a reduced-scale model from a full scale, Froude method was applied to preserve geometrical, kinematical and dynamical similitude. Temperature and axial velocity profiles, in different tunnel sections for both considered models (full and scaled) and ventilation systems, were provided. The numerical results showed a good agreement for the both ventilation systems.     

Computational study of effects of jet fans on the ventilation of a highway curved tunnel

A computational study was carried out to investigate the aerodynamic behavior of jet fans in a curved road tunnel and its effects on the tunnel ventilation system. It has been found that the variations of the static and dynamic pressure in a curved tunnel are non-monotonic. After the issue of the jets, the pressure initially increases gradually, but this is followed by a sudden drop and then a recovery. This is attributed to the interaction between the jets and the curved walls of the tunnel. A sudden increase in pressure is resulted as the jet reaches the convex wall, whereas that the concave wall is approached causes a pressure reduction. The flow becomes asymmetrical downstream of the jets. The development of the jets depends on the separation of the fans and the distance between the fans and the tunnel walls. Increasing the space between the fans or moving them away from the tunnel ceiling makes the jets spreading more quickly across the cross-section. However, it takes a longer distance for the jets to develop when the fans are close to each other or to the tunnel wall. The distance required for pressure to be fully recovered is approximately 90–120 m in this study. The biggest pressure-rising coefficient is obtained when the fans are arranged according to the distance of 2.4 m between the fans, the fans offset of 0.5 m from the centre line towards the convex wall, and the ratio of the distance between fans and the ceiling to the diameter of fans of 1.77.     

公路隧道超长距离纵向排烟试验研究

为研究5 km以上公路隧道超长距离全射流纵向排烟可行性与有效性,依托全长6 015 m的羊鹿山隧道,在不利于排烟的左线隧道（单向下坡）内开展20 MW现场火灾全射流纵向排烟试验。试验期间自然风速为1.0~1.6 m/s,与通风排烟方向相反,表现为排烟阻力。研究表明：左洞内开启6组射流风机时,洞内沿程风速约为3.5 m/s,开启12~15组风机时,下坡隧道内沿程风速约为5.5~7.0 m/s;20 MW油盘火试验从点火开始到烟气全部排出洞外的时间约为30 min。根据现场火灾排烟试验,对于羊鹿山隧道,在保证人员安全的情况下,采用全射流纵向排烟是可行的。     

盖下列检库射流风机与机械排烟系统协同排烟效果分析

应用FDS软件对某典型上盖开发式动车车辆段的盖下列检库射流风机与机械排烟系统协同排烟效果进行了模拟研究。通过分析火灾时烟气扩散速度、烟气层分布特征、一氧化碳浓度分布以及排烟效率等指标,对射流风机协同机械排烟和单独机械排烟的排烟效果进行对比研究。研究表明：射流风机协同机械排烟可有效减慢烟气的扩散速度,并且可降低库内大部分区域的烟层厚度,增加排烟口处的局部烟层厚度,以提高机械排烟系统的排烟效率。与单独的机械排烟工况中排烟效率相比,射流风机协同排烟将最不利排烟效率从33.1%提升至53.9%,最佳排烟效率从44.3%提升至55.1%。且在射流风机协同排烟工况中,对于库内一氧化碳的沉降控制和排烟效率,开启两组射流风机且距火源近端的风机组与相近排烟支管距离为风机的有效射程时效果最佳,且随火源远端风机组的向下倾斜射流角度逐渐增大至与水平面呈45°夹角,一氧化碳的沉降控制效果和排烟效率都提升。     

双洞单向公路隧道横通道定位及风机选型

运用双向换气设计算法,确定2000m双洞单向公路隧道车行横通道最佳位置。单横洞距下坡隧道入口为650m,相邻两横通道相距300m。基于流场分析原理,运用CFD ansys软件三维数值模拟横通道及其附近区域的速度场,在合理定位横通道的前提下设置风机调压,选定最佳风机类型和数量,保证通风负荷较小的下坡隧道内的新风量通过横通道送至上坡隧道内。