共查询到20条相似文献，搜索用时 31 毫秒
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文章介绍了一种整体长度为0.64m,重约为4kg,轻巧、便携的烟风洞装置的特点.该装置有着良好的烟气发生装置和烟气流动质量,方便的燃油补充机构和试件磁力固定结构,是流体力学学科中一种较完美的教学工具.轻巧的结构使得这种烟风洞装置可以很方便地携入教室用于教学演示.各种研究对象在风洞中的绕流情况可以很好地用高质量的数字照片显示出来,这些照片如圆柱绕流,平面叶栅的流线分布,都能较好地反映了流体力学流动基本规律;同时,通过对一个模型汽车所进行的流体力学数值计算（FLUENT）与实验对比,其结果显示出它们的流动状态吻合较好,说明这种便携式烟风洞的良好性能. 相似文献
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南京奥体中心的观光塔为一高耸结构,其风荷载是必须考虑的问题之一.由于观光平台及观光塔本身形状的复杂性,建筑规范无法准确给出其风荷载,因此需要在风洞中进行测压测力试验,以测定观光塔整体及局部风载,获得风场数据.文章介绍了整个试验过程,并对试验结果进行分析,根据各风向角下的风压分布特征给出了结构抗风设计和考虑载人时的最不利风向角与最大风压值,可为观光塔结构强度设计、电梯间及观光平台的玻璃幕墙设计提供风荷载依据. 相似文献
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超高层酒店在结构设计中涉及到诸多难题，本文结合无锡某超高层酒店的结构，着重对基础大体积混凝土、风洞试验、高位转换的处理以及加强层的设置等进行了探讨。 相似文献
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To provide physically based wind modelling for wind erosion research at regional scale, a 3D computational fluid dynamics
(CFD) wind model was developed. The model was programmed in C language based on the Navier-Stokes equations, and it is freely
available as open source. Integrated with the spatial analysis and modelling tool (SAMT), the wind model has convenient input
preparation and powerful output visualization. To validate the wind model, a series of experiments was conducted in a wind
tunnel. A blocking inflow experiment was designed to test the performance of the model on simulation of basic fluid processes.
A round obstacle experiment was designed to check if the model could simulate the influences of the obstacle on wind field.
Results show that measured and simulated wind fields have high correlations, and the wind model can simulate both the basic
processes of the wind and the influences of the obstacle on the wind field. These results show the high reliability of the
wind model. A digital elevation model (DEM) of an area (3800 m long and 1700 m wide) in the Xilingele grassland in Inner Mongolia
(autonomous region, China) was applied to the model, and a 3D wind field has been successfully generated. The clear implementation
of the model and the adequate validation by wind tunnel experiments laid a solid foundation for the prediction and assessment
of wind erosion at regional scale. 相似文献
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This paper presents the simulation results of the wind environment around a single high-rise building and that around two tall buildings in tandem arrangement by using the lattice Boltzmann method with an aim to understand the ventilation issues around high-rise buildings in an urban environment. We analyzed the velocity distribution around the buildings and performed numericl simulations to reveal the formation and evolution law of the complex vortex system around the high-rise buildings. Numerical simulation results manifest a periodicity phenamenon in the process of the vortex evolution. For the case of two high-rise buildings, wind velocity in the space between the two buildings is very small, which is nearly a silent regime. Wind velocity above the front building is relatively larger and the maximum wind velocity is approximately 2.5 times the incoming wind velocity. The numerical results can be used in layout planning of high-rise residential buildings to create better environment for ventilation purpose in an urban area. 相似文献
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通过刚性模型风洞测压试验,研究了风向沿马鞍低点连线时菱形马鞍屋盖表面的风压特性.首先给出了屋盖表面的平均及脉动风压分布,通过脉动风压谱,从微观角度阐述了迎风前缘附近旋涡从生成、发展直到最后破裂的过程,进而解释了迎风前缘易损区域的平均及脉动风压分布机理.分析马鞍高点附近的风压谱形状,发现结构对于来流的干扰作用在风压脉动上体现为高频脉动.此后用测点风压时程的三、四阶矩对风压的非高斯特性进行描述并给出了划分高斯、非高斯区的标准,在此基础上对马鞍屋盖表面进行了分区.通过研究脉动风压谱,发现风压非高斯特性是由于来流的分离运动及结构对来流的干扰作用引起的,且前者引起的非高斯特性较后者更为显著. 相似文献
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In this paper, the wind load on an arc-shaped canopy roof was studied with numerical wind tunnel method (NWTM). Three-dimensional
models were set up for the canopy roof with opened or closed skylights. The air flow around the roof under wind action from
three directions was analysed respectively. Wind pressure coefficients on the canopy roof were determined by NWTM. The results
of NWTM agreed well with those of wind tunnel test for the roof with opened skylights, which verified the applicability and
rationality of NWTM. The effect of the closure of skylights was then investigated with NWTM. It was concluded that the closure
of the skylights may increase the wind suction on the top surface of the roof greatly and should be considered in the structure
design of the canopy roof. 相似文献
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To reduce the wind-induced drag and improve the wind-resistance performance of a high-rise building, steady suction control is introduced into the building structure. Based on validation of the numerical methods by experiment with suction control over the flow separation ofa 3D backward-facing step, the Reynolds stress equation model is used to investigate the drag reduction （DR） properties of a high-rise building whose side faces are controlled by all-height suction. Effects of the orifice geometrical parameters and suction flux parameters on the DR and the separation control are analyzed, and the detailed flow fields are shown to clarify the mechanism of suction control. The results indicate that suction control is very effective in reducing the wind loads on the high-rise building model, and only the dimensionless suction flux dominates. Lastly, the power consumed and the counterforce induced by suction are discussed, the suction models become the ＂zero-drag＂ model under certain suction angles. 相似文献
9.
设计并实现了一个小型风力发电机的外特性测试平台,平台包括低速开放式风洞、数据采集系统两部分.风洞设计成口径3.5 m的直流式风洞,实验段采用圆形截面,动力段采用多风机提供动力,在风流通过蜂窝器后,大大改善了风流效果并提高了可靠性.数据采集系统通过工业控制数据采集卡对风速、风力发电机转速、输出电压、电流等进行数据采集和处理.通过对某小型风力发电机进行测试的结果表明,平台可满足测试小型风机外特性的实验要求. 相似文献
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Turbulence in the wake generated by wind flow over buildings or obstacles may produce complex flow patterns in downstream areas. Examples include the recirculating flow and wind deficit areas behind an airport terminal building and their potential impacts on the aircraft landing on nearby runways. A computational fluid dynamics （CFD） simulation of the wind flow over an airport terminal building was performed in this study of the effect of the building wake on landing aircraft. Under normal meteorological conditions, the studied airport terminal building causes limited effects on landing aircraft because most of the aircraft have already landed before entering the turbulent wake region. By simulating the approach of a tropical cyclone, additional CFD sensitivity tests were performed to study the impacts of building wake under extreme meteorological conditions. It was found that, in a narrow range of prevalent wind directions with wind speeds larger than a certain threshold value, a substantial drop in wind speed （〉3.6 m/s） along the glide path of aircraft was observed in the building wake. Our CFD results also showed that under the most critical situation, a drop in wind speed as large as 6.4 m/s occurred right at the touchdown point of landing aircraft on the runway, an effect which may have a significant impact on aircraft operations. This study indicated that a comprehensive analysis of the potential impacts of building wake on aircraft operations should be carried out for airport terminals and associated buildings in airfields to ensure safe aviation operation under all meteorological conditions and to facilitate implementation of precautionary measures. 相似文献
13.
球壳结构风压相关性研究（英文） 总被引：1，自引：0，他引：1
引入相关函数以描述不同矢跨比的球壳上2点间的风压相关性.根据风洞试验的风压测量数据,研究了2点间距离不同、2点连线与风向间角度不同时相干函数的大小.结果表明球壳结构上毗邻的2点在低频段具有强相关性,而非相邻点的风压相关性不明显.风压相关性随2点距离的减小而增大.距离相同时,风压相关性在顺风向最强,在横风向最弱.根据风洞试验数据,提出了球壳结构风压相关性指数模型,并给出了确定该模型的详细过程.结果表明该指数相关函数模型能恰当地描述距离较近2点间的相关性,且能较好地反映风向角变化的影响.此外,根据准定常理论对风压、风速间的相关性进行了研究,结果表明准定常理论对球壳结构风压、风速间的相关性不适用. 相似文献
14.
We used computational fluid dynamics （CFD） and mode superposition method instead of the energy balance method to compute transmission line aeolian vibrations induced by the Karman vortex. Firstly, we obtained the wind power inputs using CFD theory. The result is effective for aeolian vibration analyses compared with the power which were measured in wind tunnel tests. Then a new aeolian excitation was derived using the wind power equivalent principle, and the aeolian vibration distribution along transmission lines and the wind power input obtained by CFD can be account. Secondly, we formulated the motion equation of a conductor-damper system and derived a semi-analytial solution using the mode superposition method. The Stockbridge-type dampers attached were simplified to the forces transmitted by the clamps. Finally, the semi-analytical solution can be solved by iterative methods. Taking a 1 000 kV Ultra High Voltage transmission line as an example, we analyzed the line with and without dampers by the semi-analytical solution. Compared with the results which were computed by the energy balance method, the semi-analytical solution is precise enogh for aeolian vibration analyses. Besides, we also analyzed the influence of damper position and quantity. 相似文献
15.
This paper discusses the unsteady aerodynamic behavior of long-span vaulted roofs. First, a forced vibration test in a turbulent boundary layer is conducted in a wind tunnel. The models are force vibrated in the first anti-symmetric mode to investigate the effects of wind speed, rise/span ratio, and the amplitude and frequency of forced vibration on the distributions of wind pressures and unsteady aerodynamic forces. Then, a large eddy simulation (LES) is carried out to clarify the physical mechanism of wind-roof interaction as well as to investigate the influences of a roof’s vibration on the flow field around the roof. From the results of the wind tunnel experiment and the LES, we discuss the characteristics of unsteady aerodynamic forces on a long-span vaulted roof over a wide range of the reduced frequency of vibration. The effect of unsteady aerodynamic forces on the dynamic response of the roof is also discussed. A comparison between the wind tunnel experiment and the LES indicates that the LES can be used effectively to evaluate the unsteady aerodynamic behavior. 相似文献
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The construction of a building may change the microclimate in the vicinity, and planning indicators in a master plan may directly affect the outdoor physical environmental quality in residential areas. An inappropriate plan for a site may accelerate wind and intensify vortexes over places on the pedestrian levels, which leads to an adverse outdoor environment. Therefore, the design of a cluster of buildings should not focus only on the buildings but also provide a good outdoor environment around the buildings. To tackle the problem of inadequate wind environment, the relationship between the building’s floor area ratio and height was identified in this study as the main planning indicator to be examined on its effects on the outdoor wind environment. A computational fluid dynamics (CFD) model was hence developed to simulate the wind conditions generated by some typical site layouts with different values for planning indicators under relevant weather conditions, which were typical of those in Hangzhou, China. The simulated wind conditions are assessed using the wind speed ratio over the whole area of the building cluster at the pedestrian level. The effects on the local wind condition due to the varying of the planning indicators are discussed whilst considering the potential construction costs. The indicators resulting in better external conditions are highlighted in the conclusion as the recommendation which could be used as a rule of thumb by architects and planners at the master planning stage. The study disproves the common belief in the practice that a lower floor area ratio means fewer buildings and therefore greater external comfort. In fact, the higher the building, the greater the outdoor comfort wind zone for pedestrians. However, the increment in comfort area is limited to buildings extending from 25 to 30 levels. 相似文献
17.
The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better natural ventilation of residential buildings, external comfort, and pollution dispersion. The main purpose of this study was to develop a set of methods for wind environment assessment in coastal concave terrains. This set of methods can be used to provide quantifiable indicators of preferable wind conditions and help site analysis. Firstly, a total of 20 types of coastal bays with concave terrains in East Asia were characterized to find ideal locations. The selected areas were divided into five categories according to the main terrain features. Then a sample database for the concave terrains was compiled for modelling comparisons. Secondly, a number of key wind variables were identified. Computational fluid dynamics (CFD) models of the typical coastal concave terrains identified as a result of the study were created, and the local wind environments were simulated with input from geographic information system (GIS) and statistic package for social science (SPSS) analysis. A measure of wind suitability was proposed that takes wind velocity and wind direction into account using GIS. Finally, SPSS was used to find the relationship between wind suitability and key terrain factors. The results showed that wind suitability was significantly associated with terrain factors, especially altitude. The results suggest that residential building sites should be selected such that their bay openings face the direction of the prevailing wind and that the opposite direction should be avoided. 相似文献
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中国某传统民居选址对自然通风的影响(英文) 总被引：1，自引：0，他引：1
利用计算流体动力学模拟了传统民居当大门建筑群丘陵地形下选址与自然通风的关系.该模拟包括不同气候与地形下的4个案例及其建筑周边风压与风速分布.模拟结果显示:山体能够降低建筑迎风面和背风面的风压绝对值;在有山体的地形中天井对自然通风的促进效果大于没有山体的地形,对比冬季与夏季天井效果时也可得到同样结论;作为障碍物,山体还能降低建筑周边的风速,且由于冬夏季风向不同,山体的影响程度呈现出较大区别.分析结果表明,丘陵位于建筑北向的选址方式可以解决亚热带气候条件下住宅冬夏2季不同的自然通风需求而造成的矛盾,尤其在含天井的住宅中最为显著. 相似文献
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An improved cluster thermal time constant (CTTC) and surface thermal time constant (STTC) numerical model was introduced,which took into account the effect of vegetation coverage and modified the expression of net longwave radiation of the canyon layer.In the case study the model was used to calculate the air temperature variation at downtown of Tianjin City.The relative error between the calculated and measured air temperatures was less than 3%.The tendency of air temperature variation was predicted when the building aspect ratio,vegetation rate,and wind speed changed respectively.It is demonstrated that when the aspect ratio of a building with south-north orientation increased,the heat island intensity at day time was mitigated; however,it became worse after sunset.The vegetation coverage rate and wind speed both had negative relationship with the urban heat island intensity. 相似文献