Effect Of Wind Pressure Research Articles

Wind tunnel and numerical study of wind pressure coefficients on a medieval Swedish church

Air infiltration has great importance regarding energy, comfort, moisture and dust deposition in naturally ventilated historical buildings like churches. In these buildings, air infiltration is driven by stack effect and wind. When assessing the wind effect, reasonable estimation of wind pressure coefficients is crucial. Local wind pressure coefficients are significantly affected by the shape of the building and turbulence generated by its geometrical features, which – for moderately large churches – typically consist of main building body and window recesses, gable roof, tower, apse, and sacristy. To yield practically useful pressure coefficients, this study conducted wind tunnel and numerical investigations at a church, with gradual addition of these features. Wind pressure was measured on a small-scale model in a wind tunnel, while computational fluid dynamics (CFD) simulations were carried out for both small-scale and full-scale models. By comparing the experimental and numerical results, the SST k–ω turbulence model showed the best accuracy, yielding CFD results in good agreement with wind tunnel measurements. Most challenging was predicting the strong negative wind pressures occurring on a flat roof. Building structures like tower, apse, and sacristy had significant impact on the wind pressures on the central, main building body. This study adds knowledge on wind pressure effects by commonly occurring building components, with particular reference to churches and similar buildings. It was an important basis for developing further models for calculating the wind pressure coefficient.

Research on Key Problems and Optimization Based on Structural Design of Super High-rise Buildings

At present, complex super high-rise buildings and super high-rise buildings are emerging all over China, but there are still many problems to be solved in the design of super high-rise structures. For example, the wind pressure and earthquake risk of high-rise buildings, fire safety issues and personnel evacuation issues, earthquake will produce greater inertia force and bending force in high-rise buildings, wind load and wind pressure effect will be more significant, these are the parts that need to be carefully considered to ensure the safety and stability of the building structure. Therefore, it is necessary to analyze and optimize the problem of high-rise buildings. Taking a super high-rise building in Luohu District of Shenzhen City as an example, this paper analyzes the basic structure of super high-rise building, analyzes the key problems of structural design, and discusses the optimization method. This paper puts forward the optimization design method of building structure for seismic problem of super high-rise building structure, puts forward the solution to wind resistance problem, and puts forward the optimization layout method of building fire protection.

Numerical investigation on the air inflow rate for fuel-controlled compartment fire under ambient wind condition

So far, extensive researches have been conducted on compartment fire characteristics in no wind conditions. However, there are still few researches focusing on the air flow rate through opening of compartment under influence of ambient wind, noting that the air inflow rate is related to fire growth, indoor temperature, heat convection between indoor and outdoor environments, and the corresponding thermal impact to adjacent rooms. This paper investigated the air flow rate for fuel-controlled compartment fire under the ambient wind through numerical simulation. Temperature inside compartment, gas velocity along the opening vertical centerline and the air inflow rate were obtained for various fuel supply rates and wind speeds. Results show that: (1) The air inflow rate increases as the opening size increases. (2) The air inflow rate increases as the fire heat release rate increases, and the increasing rate decreases for higher fire heat release rates. (3) The air inflow rate increases as wind speed increases. Influence mechanism of ambient wind was revealed through pressure analysis, including the static pressure and dynamic pressure. A Froude number was proposed to describe the wind pressure effect, then the air inflow rate model was established, which has good consistency with the simulated data.

The Influence of Mountain Height and Distance on Shape Factor of Wind Load of Plastic Tunnel

Due to their soft structure and covering material, plastic greenhouses are vulnerable to wind disasters, causing large-scale damage and huge economic losses. The wind load of greenhouses depends on the surface wind pressure distribution, which is different for greenhouses located in valleys from those in plain areas. To study the wind pressure distribution law for various regions of greenhouses built in valleys, mountain and greenhouse models have been built by Computational Fluid Dynamics, in which the length direction of the greenhouse is perpendicular to the valley and the wind direction is parallel to the valley. In the analysis, the verified turbulence model and grid division method are both introduced, and the effect of the height and distance of mountains is considered. According to the distribution law of wind pressure, the greenhouse’s surface is partitioned, and the variation law of the shape factor of wind load on a plastic tunnel is analyzed. Then, the calculation model for the shape factor of the wind load on the greenhouse located in a valley is proposed. The conclusions show that: (a) When the wind inflow direction angle is parallel to the valley, the distribution pattern of wind pressure on the surface of the greenhouse is similar to that on the plain regardless of the distance and height of the mountains, while the values of the wind pressure are greatly affected by the mountain height and distance. The distance between mountains has greater influence than the effect of mountain height. (b) The shape factor of wind load on the suction area of the greenhouse decreases as the distance of mountains increases, while the shape factor on the pressure area of the greenhouse increases with the increase in the distance. It can be seen that the valley effect is non-negligible. The narrower and deeper the valley, the greater the wind pressure effect. (c) When the ratio of the distance between the foot of the mountain and the greenhouse d to the height of the mountain H is less than 5, i.e., d/H < 5, the ratio of the distance to the height has a significant impact on the shape factor of wind load on the greenhouse. When d/H is close to 10, the shape factor of the wind load in the valley area is close to that in the plain area, and the effect of the ratio between the height and the distance is negligible. (d) The proposed calculation model can be used to calculate the effect of mountain height and distance on the shape factor of wind load. The research results can be used in the wind resistance design of plastic greenhouses in valley areas, and can also provide some data support for the revision of the greenhouse structural load code.

Simulation Study on Natural Ventilation Performance in a Low-Carbon Large-Space Public Building in Hot-Summer and Cold-Winter Region of China

Recently, climate governance has entered a new phase of accelerating decarbonization. In order to achieve low-carbon buildings, natural ventilation has been widely used as it requires no fan power. However, there are great challenges for achieving effective natural ventilation in large-space public buildings especially in areas characterized by hot-summer and cold-winter climatic regions, due to empirically unsuitable ambient temperatures and theoretically complex joint effect of wind pressure and thermal buoyancy. Therefore, this numerical study was conducted on the performance of a natural ventilation strategy in a large-space public building in a hot-summer and cold-winter region by using computational fluid dynamics (CFD) methods. Simulations were performed by applying FLUENT software for obtaining airflow distributions within and around a typical low-carbon public building. The temperature distribution in the atrium of the building was simulated particularly for analyzing the natural ventilation performance in a large-space area. Results demonstrated that thermal pressure was dominant for the large-space building in the case study. The average indoor airflow velocities on different floors ranged from 0.43 m/s to 0.47 m/s on the windward side which met indoor ventilation requirements. Most areas of wind velocities could meet ventilation requirements. The natural ventilation performance could be improved by increasing the relative height difference between the air inlets and air outlets. These findings could help provide references and solutions for realizing natural ventilation in low-carbon large-space public buildings in hot-summer and cold-winter regions.

Horizontal vibration response analysis of ultra-high-speed elevators by considering the effect of wind load on buildings

Abstract. At present, the wind-induced vibration effects of super-high-rise buildings caused by wind loads can no longer be ignored. The wind-induced vibration effect of super-high-rise buildings will inevitably cause the vibration of ultra-high-speed elevators. However, for the study of the vibration characteristics of ultra-high-speed elevators, the wind-induced vibration effect of the ultra-high-speed elevator is often ignored. Based on Bernoulli–Euler theory, the forced vibration differential equation of elevator guide rail was established, and the vibration equation of elevator guide shoe and car was established by using the Darren Bell principle. The coupled vibration model of the guide rail, guide shoes, and car can be obtained through the relationship of force and relative displacement among these components. Based on the model, the effects of wind pressure and building height on the horizontal vibration of the ultra-high-speed guideway and passenger comfort were analyzed. The results showed that the influence of the wind load on the vibration of ultra-high-speed elevator can no longer be disregarded, and the maximum horizontal vibration acceleration of the guide rail is positively correlated with the height of building. The vibration acceleration of the same height rail increases with the increase in wind pressure. The vibration dose values (VDVs) increase with the increase in wind pressure and building height, respectively.

Combining EnergyPlus and CFD to predict and optimize the passive ventilation mode of medium-sized gymnasium in subtropical regions

Thermal stratification is considered to be common in large space buildings, which constitutes a complex indoor thermal environment of gymnasiums. In consideration of the combined effect of wind pressure and thermal buoyancy on natural ventilation efficiency, this work combining the building energy modeling (BEM) and computational fluid dynamics (CFD) to evaluate the impact of climatic conditions and building forms on natural ventilation of medium-sized gymnasiums in subtropical regions. The ventilation efficiency at peak time (13:00-15:00) is significantly higher than that at valley time (08:00), which indicates that thermal buoyancy plays a positive role in air change rate (ACH) and wind velocity conditions, and the thermal pressure form with low-inlet and high-outlet has a higher climate adaptability. Using the Adaptive Predicted Mean Vote (APMV) to evaluate the comfort of the combining results, and to effectiveness predict the passive ventilation mode in each quarter. There is a large operating time range (71.35% ∼ 100%) for a medium-sized gymnasium in the subtropical regions to apply the passive ventilation mode in transition seasons of spring and autumn, and the thermal comfort condition of the sports area is better than that of the spectator area. On the other hand, the operating time range shows 36.96%–64.93% in summer as the peak time comfort exceeds the upper limit of the standard value. Since the sports crowd has stronger thermal endurance than the sitting crowd, it is possible to achieve a higher range of energy saving by effectively controlling the operation time and power consumption of air conditioning measures in non-event time (no consideration of the use in spectator area) in hot summer.

Study of Interference Effect of Wind Pressure on Roof of Multi-storey Residential Buildings

In this paper, a series of wind tunnel experiments were carried out on the rigid model of 5-6 storey residential buildings to study the influence of the location, spacing and wind direction of the buildings on the roof wind pressure of multi-storey residential buildings. The test results show that the maximum average wind pressure and extreme negative wind pressure of a single building occur in the roof ridge area at the corner and both ends of the roof, taking a multi-storey building with length × width × height of 60m×12m×20m as an example. For the buildings with three rows and three columns, when the building is located at the corner, the most unfavorable wind direction is 30°, 210°, and 330°. The most unfavorable extreme value of negative wind pressure is -8.72. The negative wind pressure coefficient of the most unfavorable extreme value of the building roof at the corner position and the middle position of the first row decreased with the length-width ratio and the spacing increased. The negative wind pressure coefficient of the most unfavorable extreme value of the building roof at the edge and middle of the second row did not change significantly with the increase of length-width ratio but increased with the increase of space. In the corner area of the roof, the interference factor of the corner position and the middle position of the first row decreased with the space, while the interference factor of the edge position and the middle position of the second row increased with the space. The variation trend of the middle area of the roof is the same as that of the corner area, but the interference factor is generally small. The interference factor of the wall area is always greater than 1.0.

Heat Losses Caused by the Temporary Influence of Wind in Timber Frame Walls Insulated with Fibrous Materials.

The paper presents the results of research concerning three fiber materials—mineral wool, hemp fiber and wood wool—as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest.

Effect of Wind Pressure on Glass Facade

Effect of Wind Pressure on Glass Facade

Assessment of the Wind and Temperature Loads Influence on the PVC Windows Deformation

The PVC windows application experience in various climatic conditions shows that at their operation the windows profile deformations can be observed. One of the reasons for these deformations is the climatic loads influence on the windows – wind pressure, solar radiation, negative outside temperatures. The profile elements deformations affect the window tightness and the normal window hardware operation. The calculated loads combinations on windows in winter and summer were analyzed. For window as external element of building is more critical winter loads combination – the combined effect of wind pressure and negative temperature. The work was done the analysis of the effect of negative temperatures and wind pressure on the PVC window deformation. The studies were performed in laboratory conditions on the basis of two testing centers. Three PVC Windows with different profile thickness were tested. The temperature deformation of the casements and mullions profiles of this windows were analyzed. These deformations have to take into account in the static calculations. But the engineering methods creation for calculating windows for the wind and temperature loads effect requires additional research. They are associated with the study of the joint work of the windows constituent elements (profiles, insulating glass units, hardware).

MODELING OF THE VENTILATION SYSTEMS USING THE SOFTWARE EPANET

The software EPANET is designed to simulate the movement of water (incompressible fluid) in hydraulic networks. When designing ventilation systems, the density of air inside them is also often considered constant. Thus, theoretically, the application can be used to simulate the operation of many types of ventilation systems. It is shown that, provided the system is represented as a graph using the proposed method of adjusting the gravitational head, EPANET can be successfully used to calculate natural and hybrid ventilation systems. At the same time, not only the required accuracy is achieved, but it is possible to verify the correctness of the design solutions for various combinations of parameters of the outside and inside air. The engineer has the opportunity to take into account the effect of wind pressure, features of the operation of supply and exhaust devices of various types and thereby significantly reduce the design time.

Durability of Stone Cladding in Buildings: A Case Study of Marble Slabs Affected by Bowing

Bowing is an uncommon pathology that can affect marble stone cladding of building façades, causing a large permanent deflection and the degradation of the flexural and anchoring strength of the stone slabs, which can lead to the cladding falling from the façades. Moreover, the combination of bowing with wind pressure effects on the building façades can increase the risk of fracture and collapse of the stone slabs, especially if this combination is not properly evaluated during design. Motivated by a case study, this work describes a stability evaluation of a 15-year-old building façade coated with marble stone cladding affected by bowing and subjected to wind pressures. This evaluation was focused on the stone slabs, and was performed through finite element model (FEM) numerical simulations of these slabs submitted to wind pressures and through lab tests using samples of stone slabs removed from the building façade. The results obtained demonstrated stability problems on the stone slabs caused by wind pressure-induced stresses combined with the loss of strength due to aging and bowing effects, especially for slabs with larger dimensions.

Effect of wind pressure and modulation schemes on rain interrupted optical wireless links under tropical climates

Tropical and subtropical regions experience heavy rain intensities often accompanied with medium to strong winds. In this work, the effect of perpendicular wind flow and various modulation formats on a rain interrupted optical wireless link is investigated experimentally under controlled laboratory conditions. Attenuation as a function of rain rate is observed at different wind pressure. It is found that rain induced scattering dominates the rain specific attenuation however significant attenuation is expected at much higher wind pressure which normally increases with altitudes. A comparative performance of modulation formats like direct intensity modulation (D-IM), pulse width modulation (PWM) and various subcarrier intensity modulated (SIM) signals under heavy rain conditions is reported. It is found that SIM-FSK and SIM-AM offer better signal to noise performance (approximately two times) followed by subcarrier phase (SIM-PM) and frequency (SIM-FM) respectively. Also, SIM-FSK and PWM are least attenuated in heavy precipitation.

A model for calculating single-sided natural ventilation rate in an urban residential apartment

Natural ventilation is an energy-efficient ventilation method for residential buildings, but it is not easy to determine the natural ventilation rate. This investigation developed a simple model for calculating the ventilation rate for an apartment with single-sided natural ventilation with buoyancy and wind pressure effects, based on a wind-driven model. To validate the model, field measurements were conducted in an apartment in an urban residential building in Tianjin, China. The experiment measured indoor and outdoor air temperature, wind speed and direction, wind pressure coefficient at an opening of the apartment, and ventilation rate through the single opening. The results indicated that the wind pressure coefficients calculated by Eq.12 did not agree well with the measured data. However, most of the measurements show a stronger buoyancy effect than wind pressure effect. Our new model was able to predict the ventilation rate with an average error of 13.1%. When we used six other models found in the literature to predict the ventilation rate, the errors ranged from 12.9% to 46.1%. Thus, not only does our model perform very well in predicting the ventilation rate, but it also shown the interaction between buoyancy and wind pressure.

Wind load effects on high rise buildings in Peninsular Malaysia

Wind is a randomly varying dynamic phenomenon composed of a multitude of eddies of varying sizes and rotational characteristics along a general stream of air moving relative to the ground. These eddies give wind its gustiness, creating fluctuation and results in a complex flow characteristics. The wind vector at any point can be regarded as the sum of mean wind vector and the fluctuation components. These components not only vary with height but also dependant on the approach terrain and topography. Prevailing wind exerts pressure onto the structural surfaces. The effects of wind pressure in the form of shear and bending moments are found to be a major problem in structural failure. This study aims to study the effects of wind load on a fifteen-storey high rise building using EN 1991-1-4 code and MS1553:2002. The simulation results showed that by increasing the wind speed, the storey resultant forces, namely storey shear and storey moment increases significantly. Furthermore, simulation results according to EN 1991-1-4 yield higher values compared to the simulation results according to MS1553:2002.

The effect of wind pressure on surface erosion of soft rocks in arid regions

The wind acts as a land-shaping agent in desert and coastal regions, with more significant effects on soft, porous rocks than on massive rock formations. Air-suspended particles degrade rock surfaces, form cavities, and produce drift channels; however, abrasions that have been formed without the impacts of suspended particles are occasionally observed on very soft rock surfaces in areas exposed directly to the wind. The effect of wind without abrasive particles on soft and porous rock samples was examined using a newly designed wind tunnel. Samples were exposed to various wind speeds of 6–9 m/s to determine the most efficient wind speed. Ignimbrite, mudstone and sandstone specimens, all of which possess high porosity and low strength, were tested in the wind tunnel under a constant air temperature for 1 year. During that time, changes in sample weight were measured at weekly intervals. The specimens started to decrease in weight after losing surface moisture, with the highest weight loss observed in the samples with high porosity and low strength. Air pressure from the wind caused tension on rock surfaces. Surface strain measurements were carried out to determine the effects of wind pressure on weight loss. The maximum strain (250 μ) was recorded on mudstone samples with high porosity and low strength. A good relationship was detected between surficial strain and weight loss. The air pressures on the sample surfaces caused by the wind forces were measured with a new sensor. The air pressure values measured on the surface oscillated between −56 and 133 Pa.

Effectiveness of a perforated light shelf for energy saving

Light shelves are natural lighting systems, which have been highlighted in various studies as a suitable approach for reducing energy consumption. However, external light shelves are at risk of being destroyed by high wind pressure when used on the upper stories of high-rise buildings. Therefore, this study proposes a perforated light shelf that minimizes the effect of wind pressure. Its effectiveness is verified by comparing its lighting energy saving performance with that of previously tested light shelves in an actual testbed. The results showed that at vent ratios of 29.55%, 32.58%, 34.27%, and 35.35%, the lighting energy consumption of the proposed perforated light shelf (Case 4) increased by 20.6%, 20.6%, 42.9%, and 48.3%, respectively, in comparison with that of a nonperforated light shelf. However, at the same four vent ratios, the perforated light shelf was found to be capable of reducing the lighting energy consumption by 74.0%, 74.0%, 56.0%, and 51.4%, respectively, in comparison with a case without a light shelf (Case 1) and a case with a 0° fixed nonperforated light shelf (Case 2). In Case 4, the lighting energy saving rate of the perforated light shelf may be improved by increasing its width.

건물 내 공기유동 해석에 외부 바람이 미치는 영향의 분석

Abstract The air flows in building caused by thermal buoyancy, known as the stack effect, have a pronounced influenceon both the indoor environment (thermal environment, noise, draught and contaminant diffusion) and energy needs in high-risebuildings. Prior studies for airflow in high-rise buildings were focused on the degree of stack effect and countermeasures. The wind pressure was neglected during the calculation of the indoor airflow in high-rise buildings to clarify the effectof thermal buoyancy in previous studies. However, wind is an important driving force of indoor airflows in buildings withthe stack effect. In this study, the effect of wind pressure on indoor airflow in high-rise building when the stack effectis dominant in winter was analyzed. In this paper, methods that involved considering the wind pressure in airflow networksimulation were analyzed. Key words Stack effect(연돌효과), High-rise building(초고층빌딩), Wind-pressure(풍압)†Corresponding author, E-mail: dssong@skku.edu 기호설명

Development of CO2 Balance for Estimation of Ventilation Rate in Naturally Cross-Ventilated Dairy Barns

Abstract. The determination of ventilation rates through naturally ventilated livestock barns is complicated and shows large uncertainties. One key issue is to develop further the measurement methods. Experiments were performed to study air exchange rates (AER) occurring in a naturally ventilated dairy barn during spring seasons. The ventilation rates (VR) were determined simultaneously by three different methods: the combined effects of wind pressure and temperature difference forces (WT method), the exact CO 2 balance (CO 2 -ex), and the CO 2 balance for a one-hour interval (CO 2 -h). During each experiment, CO 2 concentrations and air temperatures were continuously measured and recorded inside and outside the barn. Furthermore, the wind velocity (speed and direction) was recorded by a weather station. The CO 2 concentration measurements required to implement the CO 2 -ex were conducted at the same time interval as the measurements of wind velocity and temperature required to implement the WT method. However, the CO 2 concentration measurements required to implement the CO 2 -h were conducted at a wider time interval, and the measurements for the WT method fell in the middle of this time interval. The results showed that the CO 2 -h produced reliable results (p 2 = 0.856) in relation to the VR values derived from the independent variables outdoor temperature, indoor temperature, and wind velocity (speed and direction). Therefore, the hourly CO 2 balance is more accurate than the exact CO 2 balance.