Wind Environment Study of High-rise Residential Building by using Multiple Computational Tools

<p>Wind environment is a key element of sustainable design of architecture. Concerning major trends of climate changes and urbanizations, this research aims to study the relationships between the influences on wind environments and variables related to forms and configurations of contemporary high-rise residential buildings. A novel methodology consisting of parametric design, CFD simulation, and analysis is developed by integrating multiple computational tools, and the evaluation criteria. The integration provides abundant functions and an efficient modelling-simulation-analysis solution for iterative comparison studies. By using a parametric modelling method, building models can be created automatically to help in mesh generation for CFD simulations; the actual influenced areas with different wind velocity ranges can be calculated and compared quantitatively through the calculations of wind-velocity magnitudes from simulation results, at each pixel location on a rendered section. Based on the architectural morphology of Building-Unit Forms (BUFs) and Building-Cluster Configurations (BCCs) in an area classified in China as a Hot-Summer and Cold-Winter Area (HSCWA), the parametric design sets up a bridge between building variables and CFD simulations. A series of representative BUFs and BCCs of high-rise residential buildings are designed for CFD simulations by establishing parametric design system based on the building categorization study. In the wind environment studies, influences of buildings are evaluated based on the wind-velocity magnitudes according to the criteria. The trends of influences can be studied through iterative analysis of several cases with different variables. The mechanisms are illustrated through the air-pressure magnitudes and the wind-flow streamlines. In the wind environment studies of BUFs, relationships between influences on wind environments and building variables of three representative BUFs are studied, including square form, rectangular form, and ‘T’ form. The results of the BUFs studies can be summarized: (1) the influences on wind environments increase as the height and windward length are increased, because more winds are obstructed by the increasing windward surface; (2) the influences on wind environments decrease as the ratio of length and width is increased before the ratio reaches a particular value, because influenced air-pressure area is decreased; (3) the influences on the wind environments decrease as the bulge-part sizes of the ‘T’-form buildings increase, because the increases of bulge-part sizes help to divide winds and lead them to flow around the buildings; (4) the outdoor ventilation is improved as the rotation angle increases, because the non-vertical windward surface promotes the wind flow. In the wind environment studies of BCCs, relationships between influences on wind environments and building variables of three representative BCCs are studied, including scattered configuration, linear configuration, and curvilinear configuration. Results of the BCCs studies can be summarized: (1) the outdoor ventilation of scattered configuration is the best, because it is relatively easy for winds to flow around the scattered building units; (2) the outdoor ventilation can be improved as the longitudinal distance and staggered distance are increased, because the larger building interval promotes winds to flow through the building cluster; (3) for curvilinear configuration, the convex surface on the windward side can promote the wind flow, and the concave surface on the windward side can obstruct the wind flow. The results of the BUFs studies and the BCCs studies all show that the increases of the windward projective areas of buildings can increase the influences on wind environments, because more winds are obstructed. Therefore, the relationships between the influences on wind environments and the building variables of the BUFs and BCCs can be discovered, which can give information to the optimization of wind environments. In summary, the thesis presents a challenging and significant research that contributes original knowledge for wind environment studies in the urban micro climate. And the knowledge is universal and applicable to the practical design projects and also beneficial to the sustainability.</p>

Wind Environment Study of High-rise Residential Building by using Multiple Computational Tools

<p>Wind environment is a key element of sustainable design of architecture. Concerning major trends of climate changes and urbanizations, this research aims to study the relationships between the influences on wind environments and variables related to forms and configurations of contemporary high-rise residential buildings. A novel methodology consisting of parametric design, CFD simulation, and analysis is developed by integrating multiple computational tools, and the evaluation criteria. The integration provides abundant functions and an efficient modelling-simulation-analysis solution for iterative comparison studies. By using a parametric modelling method, building models can be created automatically to help in mesh generation for CFD simulations; the actual influenced areas with different wind velocity ranges can be calculated and compared quantitatively through the calculations of wind-velocity magnitudes from simulation results, at each pixel location on a rendered section. Based on the architectural morphology of Building-Unit Forms (BUFs) and Building-Cluster Configurations (BCCs) in an area classified in China as a Hot-Summer and Cold-Winter Area (HSCWA), the parametric design sets up a bridge between building variables and CFD simulations. A series of representative BUFs and BCCs of high-rise residential buildings are designed for CFD simulations by establishing parametric design system based on the building categorization study. In the wind environment studies, influences of buildings are evaluated based on the wind-velocity magnitudes according to the criteria. The trends of influences can be studied through iterative analysis of several cases with different variables. The mechanisms are illustrated through the air-pressure magnitudes and the wind-flow streamlines. In the wind environment studies of BUFs, relationships between influences on wind environments and building variables of three representative BUFs are studied, including square form, rectangular form, and ‘T’ form. The results of the BUFs studies can be summarized: (1) the influences on wind environments increase as the height and windward length are increased, because more winds are obstructed by the increasing windward surface; (2) the influences on wind environments decrease as the ratio of length and width is increased before the ratio reaches a particular value, because influenced air-pressure area is decreased; (3) the influences on the wind environments decrease as the bulge-part sizes of the ‘T’-form buildings increase, because the increases of bulge-part sizes help to divide winds and lead them to flow around the buildings; (4) the outdoor ventilation is improved as the rotation angle increases, because the non-vertical windward surface promotes the wind flow. In the wind environment studies of BCCs, relationships between influences on wind environments and building variables of three representative BCCs are studied, including scattered configuration, linear configuration, and curvilinear configuration. Results of the BCCs studies can be summarized: (1) the outdoor ventilation of scattered configuration is the best, because it is relatively easy for winds to flow around the scattered building units; (2) the outdoor ventilation can be improved as the longitudinal distance and staggered distance are increased, because the larger building interval promotes winds to flow through the building cluster; (3) for curvilinear configuration, the convex surface on the windward side can promote the wind flow, and the concave surface on the windward side can obstruct the wind flow. The results of the BUFs studies and the BCCs studies all show that the increases of the windward projective areas of buildings can increase the influences on wind environments, because more winds are obstructed. Therefore, the relationships between the influences on wind environments and the building variables of the BUFs and BCCs can be discovered, which can give information to the optimization of wind environments. In summary, the thesis presents a challenging and significant research that contributes original knowledge for wind environment studies in the urban micro climate. And the knowledge is universal and applicable to the practical design projects and also beneficial to the sustainability.</p>

The Icing Distribution Characteristics Research of Tower Cross Beam of Long-Span Bridge by Numerical Simulation

The cross beam of a long-span bridge will freeze in low temperature. When the temperature rises, the ice on the cross beam will thaw and fall off. If the ice is too heavy, it may cause vehicle damage and casualty. In order to reduce the risk of falling ice, a scale model of the cross beam was taken as an example, and a kind of numerical simulation method is presented to study the icing distribution characteristics on surface of the cross beam. This paper simulates the ice accretions process of the cross beam by Fluent module and FENSAP-ICE module of ANSYS and investigates the influence of wind and temperature in the process. This is a new numerical simulation method for studying ice accretions of buildings. The results indicate that water freezes mainly on the windward surface, and the thicker ice is near the top and bottom edge of windward surface. According to the results of numerical simulation, a measure of ice melting based on electric heating method is proposed in this paper, and the feasibility and effectiveness of this method are verified by numerical simulation. The results show that the icing distribution characteristics are accord with the fact and the ice-melting measure is feasible and effective.

Aerodynamic characteristics of detachable fairing shells in a subsonic incompressible flow

The purpose of the work was to mathematically simulate the flow around the fairing shell of the launch vehicle at a low subsonic free-stream velocity in the α = 0...360° angle-of-attack range. The calculations were performed using the SolidWorks Flow Simulation software package and the open source OpenFoam package based on the use of numerical methods for simulating the motion of liquid and gas. Within the research, we obtained the flow patterns and the aerodynamic coefficients of the longitudinal and normal forces, the pitch moment, and calculated the aerodynamic quality of the shell. Furthermore, we determined the positions of the stable equilibrium of the model and revealed the features of the flowing around the shell of the combined form at flow from the convex and concave sides. Next, we analyzed the leeward lift-off zones and the zones with increased pressure on the windward surface during flow from the concave side. Finally, we compared the obtained characteristics with the experimental data of TsAGI.

Wind Load on Complex-Shape Building

Wind load on complex-shape building, the wind tunnel test and numerical simulation were carried out. The two technologies supplement each other and their results meet well. There are mainly positive pressures on the windward surface, negative pressures on the roof, the leeward surface and the side. Especially, negative pressure is higher in the leeward region of the building corner. Its effect induced by the shape of the complex-shape building is remarkable.