自然通风潜力的多标准评估方法

自然通风技术是建筑可持续发展的一个重要发展方向，而自然通风潜力是评价自然通风的重要指标。自然通风潜力应综合考虑热压、风压、空气质量、环境噪声对自然通风应用效果的影响。本文采用Qualiflex矩阵对我国八大城市的自然通风潜力进行了多标准评估分析。其中引入自然压差帕时数来表征热压、风压潜力影响值，建立了自然通风潜力与压差帕时数、空气质量、环境噪声之间的函数模型，并通过计算分析，得到八大城市的自然通风潜力最优排列及综合比较结果。     

自然通风计算方法和计算参数的应用研究

讨论了现行自然通风计算方法中存在的问题,分析了室内空气密度、空气动力系数和室外内速等参数对热压和风压计算的影响,提出了考虑密度随温度非线性变化与室外风速垂直梯度的计算方法和公式。算例表明,计算参数的不同选择会产生计算结果的较大差异。     

红石岩隧道施工通风技术研究

介绍了红石岩隧道针对瓦斯的施工通风解决方案,主要从施工通风方式的选择、风量风压计算和通风设备的选择等方面对施工通风进行了研究,并提出相应建议,为类似的工程问题提供了经验和指导。     

自然通风的计算及理论分析

通过分别介绍在热压与风压作用下,自然通风的作用原理及计算方法,从理论上分析了强化自然通风的途径。     

自然通风设计通用流程初探

提出自然通风设计通用流程的概念,以此流程为设计人员提供了一套通用完整的设计思路,流程包括气候潜力分析及策略,建筑周围微环境优化、风压与热压的合理利用、通风设备选用、系统控制、效果评估等6个环节及其中的设计要点,为最终制定自然通风设计标准与原则建立了基本的框架体系.     

多标准评估分析成都居住建筑自然通风潜力

综合考虑热压、风压、空气质量以及环境噪声对自然通风潜力的影响,采用Qualiflex矩阵对成都地区的自然通风潜力进行多标准评估分析,并与已知城市的自然通风潜力进行比较,针对成都地区实际情况提出合理性建议。成都地区自然通风潜力一般,与PDPH相比,多标准评估自然通风潜力更具参考性。     

新武汉火车站自然通风应用研究

以新武汉火车站为研究对象,基于风洞试验得到的风压系数,采用网络法模拟软件ContamW对高架候车厅过渡季节的自然通风进行了计算分析.并依据相关文献中的自然通风标准选择室内设计温度,以室温度时数为指标,确定了自然通风设计方案.     

也铁盾构瓦斯隧道通风技术研究

介绍了地铁盾构瓦斯隧道在施工过程中,针对瓦斯的通风解决方案,主要从瓦斯涌出量计算,通风方式的选择,风量风压计算,通风设备选择等方面对实际工程施工及瓦斯防治进行阐述。     

地铁盾构瓦斯隧道通风技术研究

介绍了地铁盾构瓦斯隧道在施工过程中,针对瓦斯的通风解决方案,主要从瓦斯涌出量计算,通风方式的选择,风量风压计算,通风设备选择等方面对实际工程施工及瓦斯防治进行阐述。     

高层建筑室内自然通风特性模拟研究

基于三维RNG k～ε湍流模型的CFD数值模拟方法,对某带中庭的高层建筑分别进行了室外群体建筑物的风压模拟和室内复杂户型的自然通风模拟研究。通过室外群体建筑物风压模拟,获得了主导风向下建筑外窗、避难层等关键部位的风压分布情况,在此基础建立精细化了的室内户型模型,通过自然通风模拟研究,获得了建筑室内各功能区的风速分布与风量。结合当地风气侯数据和自然通风舒适温度,对自然通风效果进行评价,以指导工程设计。     

考虑随机风影响的隧道通风量计算

现有隧道内通风量计算偏保守,往往需开启更多风机,导致能源浪费严重。本文提出一种考虑随机自然风影响下的隧道内通风量计算方法。将风频引入隧道通风量计算中,指出隧道内风频的两种表示方法,离散型风频分布和韦布尔风频分布,通过最小误差逼近算法计算韦布尔风频分布中的尺度系数A和形状系数K。通过算例可得,进口处考虑随机风比不考虑随机风的通风量多37.8%,说明考虑随机风影响可明显降低风机开启数量。     

浅谈自然通风原理与建筑设计

对自然通风进行了介绍,通过对风压通风和热压通风的原理进行分析,明确了自然通风原理,并进一步结合建筑设计实例进行了解析,为今后建筑设计中的自然通风设计提供了良好的技术支撑.     

框架通风锚管多年冻土边坡新型支护结构的提出及通风能力初探

针对寒区冻土边坡失稳普遍采用被动技术治理的缺陷，基于“主动降温保护冻土”的理念，结合通风管和框架锚杆各自的优势，提出一种具有主动降温、减胀、支挡锚固功能一体化的多年冻土边坡新型支护结构，对其构造和工作原理进行了阐述；在考虑风速阻力损失的情况下，根据结构自然通风的驱动力和结构风场压差的等量关系，得出结构内部的风速计算公式，进而评价通风锚管的通风能力。结合算例，采用有限元和理论计算的方法对结构通风能力及影响因素进行分析，结果表明：结构具有较好的通风能力，对保持边坡的稳定有利；风压差为结构自然通风的主要驱动力，沿程阻力损失为结构的主要风速损失；抽风弯管的设置显著提高了通风能力；结构通风的最优管径比为0.4~0.7；结构自由段长度越大，通风能力越弱。     

断面宽度对纵向通风隧道火风压影响研究

针对不同断面宽度隧道中发生火灾时的火风压变化问题,利用Fluent软件模拟隧道内发生火灾的情况,分析隧道宽度对临界风速的影响以及隧道宽度、火源功率和通风速度对火风压的影响。研究表明,火源功率较小时,宽度越小的隧道,临界风速越大;随着火源功率的增大,临界风速之间的差距减小。火风压中火区绕流阻力和热烟摩阻增量会随着风速的增大而相互作用。导致火风压会先随风速的增大而增大,到达一个峰值后会随着风速增大而减小,最后当通风速度增大到临界风速后趋于稳定的数值。随着隧道宽度的增大,通风速率对火风压的影响逐渐减弱。建立不同宽度隧道在不同通风速率和火源功率下的隧道火风压计算公式,为隧道火灾通风设计提供参考。     

自然通风建筑室内气流组织优化研究

通过fluent模拟软件对诸多因素中最为关键的风向、风速、开窗位置及面积等进行了优化模拟研究。结果表明:在西安地区,南向为最佳风向,室外风速在1.3～2.5 m/s之间,基本上都能满足自然通风要求,最佳风速为1.5 m/s;综合考虑采光和自然通风因素,窗户开在墙的中间为宜;北向面积适当减小有利于自然通风在室内形成较均匀的气流,在保证建筑节能标准的前提下,增大南向窗户面积有利于自然通风。     

Single-sided natural ventilation driven by wind pressure and temperature difference

Even though opening a window for ventilation of a room seems very simple, the flow that occurs in this situation is rather complicated. The amount of air going through the window opening will depend on the wind speed near the building, the temperatures inside and outside the room, the wind direction, the turbulence characteristics in the wind and the pressure variations caused by e.g. wind gusts. Finally, it also depends on the size, type and location of the opening. Many of these parameters are unsteady which makes the calculation of air-change rates even more complicated. In this work, full-scale wind tunnel experiments have been made with the aim of making a new expression for calculation of the airflow rate in single-sided natural ventilation. During the wind tunnel experiments it was found that the dominating driving force differs between wind speed and temperature difference depending on the ratio between the forces and the wind direction. This change is also found in the velocity profiles measured in the opening, which might change from wind dominated to temperature dominated under the same wind direction but with increasing temperature difference.     

平导压入通风对寒区隧道风温场的影响性研究

为探明平导压入通风方式对高海拔寒区特长公路隧道风向、风速、风压和洞内温度场的影响性,以川藏公路雀儿山隧道为工程依托,通过数值仿真和现场测试,分析了不同通风方式下隧道洞内风场和温度场的分布及变化规律。研究结果表明: 气热耦合三维数值计算显示风在横通道与主洞和横通道毗邻区域形成了明显的涡流区,平导洞内风压、风速明显高于主洞;平导压入通风使平导和主洞最低风速分别增加了90%、104.5%;平导压入通风对洞内最高风温影响较小,均在7.8 ℃~8.2 ℃左右;考虑通风方式、自然风方向和因山体富热产生的隧道内外温差引起的热压差影响,对高海拔寒区特长公路隧道出入口段的防冻长度等应差别化设计,特别要加强主风向隧道一端主洞、平导和横通道的防冻措施。     

Investigating potential of natural driving forces for ventilation in four major cities in China

The potential of natural driving forces for ventilation in buildings is the possibility for providing sufficient outdoor air by only natural ventilation. Based on the early work of Fracastoro et al. (Fourth international conference on indoor air quality, ventilation and energy conservation in buildings—IAQVEC, vol. III, Hong Kong: The City University of Hong Kong; 2001. p. 1421–9.), we develop a simple prediction model for this natural ventilation potential applicable to Chinese residential buildings, using a simple analytical model of natural ventilation considering the combined effect of wind and thermal buoyancy forces. Comparing with the existing method developed by Fracastoro et al. (2001), the present prediction does not need sophisticated multi-zone modeling calculations and the constants in the model are no longer variables. Using the weather data from International Weather for Energy Calculations (IWEC) into our simple prediction model, the natural ventilation potentials for low-rise residential buildings in four representative cities of China including Beijing in the north, Shanghai in the east, Guangzhou in the south and Urumqi in the northwest were analyzed. We introduced the concept of the pressure difference Pascal hours (PDPH) for natural ventilation, and PDPH was calculated and compared for four cities. A high PDPH value means a great potential for application of natural ventilation. In addition, hourly effective pressure differences can be obtained and analyzed statistically. This information can help the designers to determine the building opening size, or to assess whether or when mechanical ventilation is necessary. The application of the model can be a simple design tool at preliminary design stage.     

Experimental study on natural ventilation performance of one-sided wind catcher

Hydrodynamic performance of a one-sided wind catcher was investigated by experimental wind tunnel and smoke visualization testing. Wind catchers or what is called Baud-Geers in Persian language was a main component of buildings in central region of Iran and the neighboring countries. A Baud-Geer is a tower used to capture wind from external air stream and induce it into the building in order to provide natural ventilation and passive cooling. Due to geographical coordinates of the region, wind power and the direction of blowing wind, wind catchers are employed in different heights, cross sections of the air passages and the places and the number of the openings. The one-sided wind catcher has only one channel as a passage of induced air and is often related to the areas where there is prevailing wind. These Baud-Geers are employed to catch the wind blowing at higher elevations and direct it to the building, causing it to leave through windows, doors or other exhausted segments. In this study a 1:40 scale model of Kharmani's School Baud-Geer was employed and the induced air flow rate into the test room and the pressure coefficients around all surfaces of its channel were measured for different values of approaching air incident angles. Using measured pressure coefficients, the theoretical values of ventilation air flow were estimated to evaluate ability of simplified models in natural ventilation studies. Due to placing of urban full-scale wind catchers in the boundary layer of atmospheric winds, the effect of this phenomenon was also examined. The experiments were conducted when the wind catcher model with adjoining house was placed in the wake of upstream objects, resembling neighboring buildings. It was found that for an isolated wind catcher model, the maximum efficiency is achieved at zero air incident angle. Also it was concluded that the angle of incidence of the wind, the presence of an upstream building around the structure and blowing of atmospheric wind influence the pressure coefficients, the rate and the direction of ventilation air flow.