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Can building orientation perturb micro-climatic conditions inside classrooms located in hot-humid climatic condition?

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Energy and Built Environment

Energy and Built Environment 2022年第4期3卷 467-477页

作者： Shanmugga Rani A Kannamma D Department of Architecture National Institute of TechnologyTiruchirappalliTamil Nadu 620015India

Thermal comfort inside classrooms located in an institutional building is examined as a function of air tempera-ture,relative humidity and wind velocity.The effect of east-west orientation on the thermal comfort inside the classrooms located in different floor levels is understood based on field experiments and validated using compu-tational fluid dynamics simulations.The air temperature inside the classrooms shows an increasing trend with the floor level.Air temperature and relative humidity inside the classrooms reveal an inverse relationship as a function of east-west orientation with different floor level.As time progresses,the air temperature inside class-rooms located on the eastern side of the building is apparently higher than rooms situated on the western side of the building,both field experiments and simulation acknowledge the same.Appropriate reasons have been proposed behind the discussed phenomenon using computational fluid dynamics simulation.

关键词： Air temperature Relative humidity wind velocity Orientation Thermal comfort Computational fluid dynamics

Numerical simulation on ionic wind in circular channels

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Chinese Physics B 2021年第1期30卷 311-318页

作者：张桂文杨决宽林晓辉 School of Mechanical Engineering and Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments Southeast UniversityNanjing 211189China

Ionic wind induced by direct-current corona discharge has attracted considerable interest because of its low energy consumption, low noise emission, flexible designs, and lack of moving parts. The purpose of this study is to investigate the configuration parameters to improve the velocity of the ionic wind. Accordingly, this study develops a three-dimensional(3 D) model of circular tube with multi-needle-to-mesh electrode configurations, in this model, the influences of various parameters were explored,such as the mesh gap, the distribution of needle electrodes, the number of needle electrodes,and the radius of the circular channel. The numerical research results showed that the mesh gap, the distribution of needle electrodes, and the radius of the circular tube significantly affected the velocity of the ionic wind. When mesh gap is 12 mm,which indicates that there is an optimal mesh gap which can enhance the velocity of the ionic wind. What is more, changing the distribution of needle electrodes and increasing the number of needle electrodes can effectively improve the velocity of the ionic wind, the optimum distribution α of needle electrodes is 0.7–0.9, which greatly increase the velocity of the ionic wind. However, for multi-needle-to-mesh structure, the improvement of the radius of the circular channel is conducive to enhance the velocity and improve the velocity distribution.

关键词： corona discharge ionic wind numerical simulation wind velocity

Effects of sand-fixing and windbreak forests on wind flow:a synthesis of results from field experiments and numerical simulations

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Journal of Arid Land 2017年第1期9卷 1-12页

作者： ZHAN Kejie LIU Shizeng YANG Zihui FANG Etian ZHOU Lanping HUANG Ning Key Laboratory of Mechanics on Western Disaster and Environment in China(Ministry of Education) Department of MechanicsLanzhou UniversityLanzhou 730000China Minqin National Station for Desert Steppe Ecosystem Studies Minqin 733000China

Sand-fixing and windbreak forests are widely used to protect or/and improve the ecological environments in arid and semi-arid regions. A full understanding of wind flow characteristics is essential to arranging the patterns of these protective forests for enhancing the effectiveness. In this study, the wind velocity over the underlying surface with sand-fixing forests and windbreak forests at the heights of 1–49 m was monitored from two 50-m high observation towers in an oasis of Minqin, Gansu Province of China. The wind velocities were simulated at different locations over these protective forests between those two towers by a two-dimensional Computational Fluid Dynamics（CFD） model. The results showed that at the heights of 1–49 m, the wind velocity profiles followed a classical logarithm law at the edge of the oasis and a multilayer structure inside the oasis. With increasing number of sand-fixing forest and windbreak forest arrays, the wind velocity at the heights of 1–49 m generally decreased along the downstream direction of the prevailing wind. Specifically, below the height of windbreak forests, the wind velocity decelerates as the airflow approaches to the windbreak forests and then accelerates as the airflow passes over the windbreak forests. In contrast, above the height of windbreak forests, the wind velocity accelerates as the airflow approaches to the windbreak forests and then generally decelerates as the airflow passes over the windbreak forests. Both the array number and array spacing of sand-fixing and windbreak forests could influence the wind velocity. The wind protection effects of sand-fixing forests were closely related to the array spacing of windbreak forests and increased with the addition of sand-fixing forests when the array of the forests was adequately spaced. However, if the array spacing of windbreak forests was smaller than seven times of the heights of windbreak forests, the effects were reduced or completely masked by the effects of windbreak forests. The results could offer theo

关键词： wind velocity sand-fixing forest windbreak forest computational simulation Minqin

Investigating the Prospect of Small-Scale wind Turbines Based on Regional wind Velocities in Bangladesh

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Journal of Power and Energy Engineering 2022年第10期10卷 13-42页

作者： Md. Sabbir Alam Sabbir Hossain Md. Jahid Hasan Mahajabin Binte Mohsin Department of Mathematics Jahangirnagar University Savar Dhaka

The wind turbine has the advantage of operating uninterruptedly, which ensures a constant source of electricity. This investigation includes a clear overview of the wind velocity, the flow direction;the amount of energy reserved, suitable regions for wind turbine installation, etc. The feasibility and possibility of installing a wind energy conversion system for several locations in Bangladesh are analyzed. A brief study of wind characteristics in different locations in Bangladesh is reported. wind data obtained from the Bangladesh Meteorological Department (BMD) for Mongla, Patuakhali, Kutubdia, and Bhola stations are analyzed through wind rose, frequency distribution, and average wind velocity. The performance of suitable small-scale wind turbines will be assessed in order to confirm the prospect of wind turbines in Bangladesh.

关键词： wind velocity Flow Direction wind Turbine Power

Investigation on available wind energy at Tungku beach

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Frontiers in Energy 2012年第3期6卷 275-279页

作者： M. G. YAZDANI M. A. SALAM Department of Mechanical Engineering Faculty of EngineeringInstitute Technology Brunei Brunei Darussalam Department of Electrical and Electronic Engineering Faculty of Engineering Institute Technology Brunei Brunei Darussalam

In this paper, wind velocities and directions （sea and land） are recorded in different days and times. The data collected were compared with the weather data from the Brunei Darussalam Meteorological Service （BDMS） and the findings of other researchers and were found to be in good agreement. The potential of wind energy is predicted from the available data collected. The average generated power （forenoon and afternoon） is found to be 25 （mean） and 18W （median）, 101 （mean） and 73W （median）, 912 （mean） and 660 W （median）, 10137 （mean） and 7331 W （median） for a rotor with a diameter of 2.5, 5, 15 and 50 m, respectively. The power density Pd for wind farming is found to be 0.26 （mean） and 0.19 （median）, 0.31 （mean） and 0.22 （median） for the rotor whose diameter is 2.5 and 50 m, respectively, while the average Pd values are found to be 0.28 （mean） and 0.2 （median） for the rotor whose diameter is 5 and 15 m.

关键词： wind velocity temperature tower height,power density Raleigh distribution electrical power

Geo-environmental parametric 3D models of SARS-CoV-2 virus circulation in hospital ventilation systems

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Geoscience Frontiers 2022年第6期13卷 244-256页

作者： Carla Gabriela Carlot Zorzi Alcindo Neckel Laércio Stolfo Maculan Grace Tibério Cardoso Leila Dal Moro Alexandre Almeida Del Savio Leopoldo D.Z.Carrasco Marcos L.S.Oliveira Eliane Thaines Bodah Brian William Bodah Faculdade Meridional IMED304-Passo Fundo-RS 99070-220Brazil Universidad de Lima Avenida Javier Prado Este 4600–Santiago de Surco 1503Peru Department of Civil and Environmental.Universidad de la Costa CUCCalle 58#55–66BarranquillaAtlánticoColombia State University of New York Onondaga Community College4585 West Seneca TurnpikeSyracuseNY 13215USA Thaines and Bodah Center for Education and Development 840 South Meadowlark LaneOthelloWA 99344USA

The novel coronavirus, SARS-CoV-2, has the potential to cause natural ventilation systems in hospital environments to be rendered inadequate, not only for workers but also for people who transit through these environments even for a limited duration. Studies in of the fields of geosciences and engineering,when combined with appropriate technologies, allow for the possibility of reducing the impacts of the SARS-CoV-2 virus in the environment, including those of hospitals which are critical centers for healthcare. In this work, we build parametric 3D models to assess the possible circulation of the SARS-CoV-2 virus in the natural ventilation system of a hospital built to care infected patients during the COVID-19 pandemic. Building Information Modeling(BIM) was performed, generating 3D models of hospital environments utilizing Revit software for Autodesk CFD 2021. The evaluation considered dimensional analyses of 0°, 45°, 90° and 180°. The analysis of natural ventilation patterns on both internal and external surfaces and the distribution of windows in relation to the displacement dynamics of the SARS-CoV-2 virus through the air were considered. The results showed that in the external area of the hospital, the wind speed reached velocities up to 2.1 m/s when entering the building through open windows. In contact with the furniture, this value decreased to 0.78 m/s. In some internal isolation wards that house patients with COVID-19, areas that should be equipped with negative room pressure, air velocity was null. Our study provides insights into the possibility of SARS-CoV-2 contamination in internal hospital environments as well as external areas surrounding hospitals, both of which encounter high pedestrian traffic in cities worldwide.

关键词： COVID-19 global epidemic Dimensional analysis wind velocity Hospital environment Contamination

Running safety analysis of a train on the Tsing Ma Bridge under turbulent winds

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 307-318页

作者： Guo Weiwei Xia He Xu Youlin School of Civil Engineering Beijing Jiaotong Univ Beijing 100044 China Dept. of Civil and Structural Engineering The Hong Kong Polytechnic Univ. Kowloon Hong Kong China

The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be closed as the mean wind velocity reaches 30 m/s.

关键词： Tsing Ma Bridge turbulent wind dynamic interaction running safety threshold wind velocity

Thermal Conductivity and Heat Transfer Coefficient of Concrete

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Journal of Wuhan University of Technology(Materials Science) 2011年第4期26卷 791-796页

作者：郭利霞 North China University of Water Resources and Electric Power

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

关键词： thermal conductivity heat transfer coefficient relative humidity wind velocity

Effects of Different Ventilation Modes and Outlet Height on Nursery Piggery Environment

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Journal of Northeast Agricultural University(English Edition) 2022年第2期29卷 73-85页

作者： Fang Jun-long Ba Wen-ge Wu Zhi-dong Wu Shuang Tan Ke-zhu College of Electrical and Information Northeast Agricultural UniversityHarbin 150030China College of Mechanical and Engineering Qiqihar UniversityQiqihar 161006HeilongjiangChina

In order to study the effects of ventilation modes and outlet height on the airflow field of a nursery piggery,computational fluid dynamics (CFD) technology was used to simulate the wind speed and temperature of an experimental pig house in the cold northern region.This study was conducted with simulation and a comparative analysis of transverse ventilation,longitudinal ventilation and roof air intake modes.Furthermore,the effects of the air outlet height of 0.7,0.6 and 0.5 m with the roof air inlet mode on the environment in the pig house were studied.Field experiments verified the model of roof air intake model.The results showed inadequate ventilation in both the vertical and horizontal ventilation.However,the airfield gradients were less variable and more balanced when using the rooftop air intake mode.The variation of outlet height significantly affected nursery pig houses’ airflow velocity and temperature.Roof air inlet mode with an outlet height of 0.7 m was better than the other two.The normalized mean square error (NMSE) of air velocity and temperature was less than 0.01,and the simulation analysis could genuinely reflect the distribution of the airflow field in the nursery.

关键词： nursery piggery wind velocity temperature air outlet height ventilation mode