基于风热环境的开敞空间周边建筑围合研究

城市形态与环境舒适性的关系是城市设计的热门议题。探讨风热环境参数与街区围合度的关系及开敞空间周边建筑的围合形式，目的在于为空间形态控制提供思考路径。选取武汉市的开敞空间共68处作为研究对象，在此基础上抽象出具有代表性的街区理想空间模型，运用Phoenics软件量化模拟冬夏两季典型日的典型时刻不同围合度下室外环境空气速度、温度和空气压力值，并进行相关性分析。结果显示，城市集中建设区开敞空间周边建筑围合度与夏季空气速度呈负相关关系。最后根据风环境对人体影响的分析结果对开敞空间提出相应的城市设计建议。

The Enclosure of Open Space Buildings Based on Outdoor Wind Thermal Environments

A microclimate is vital to the life quality of residents in high-density urban areas. Improving the neighbourhood comfort levels by shaping the spatial form has received widespread consideration. However, environmental comforts in urban design guidelines are primarily a guiding opinion, with weak control over the actual operation. Recently, the quantification of urban morphology controls has become an essential issue since urban design has become more scientific. This study analyses correlation between neighbourhood enclosures around open spaces and environmental indicators. Some suggestions for spatial morphological control of neighbourhoods are proposed. 　　A total of 68 open spaces were first selected in Wuhan's centralised construction zone to get representative morphological combinations. Secondly, eight primary spatial forms (A-H) were summarised based on the architectural typology. The research methodology involved two steps. First, set the boundary conditions and mesh division. Numerical simulations in summer set the initial temperature of 30.7°C, wind speed of 2.5m/s, relative humidity of 71%, and southwest wind directionality. Numerical simulations in winter set the initial temperature of 3.8°C, wind speed of 5.1m/s, northeast wind, and air relative humidity of 80%. The SUN module was adjusted according to the annual seasons, taking solar radiation of 1000w/m2 at noon. After several experimental simulations and comparison cycles, the calculation domain range of 500m×400m×40m was determined for simulations, and the final number of divided networks was 312,120. The RNG k-ε model was chosen to simulate the velocity field by considering various heat transfer effects. The open space midpoint and four corner points were taken as observation points to record the simulation results. Secondly, calculate the neighbourhood enclosures. The enclosure is defined from the perspective of urban design, characterising the closure of the neighbourhood horizontally. In other words, the degree of the enclosure is equal to the ratio of the total perimeter of the building facade to the total perimeter of the building interface control line: C=(L1+L2+L3+...) /L. 　　Simulations allow wind speed maps corresponding to each enclosure pattern in winter and summer to be produced. Wind speeds in summer range from 0m/s to 4m/s, with higher wind speed areas mainly in the south and southwest. Wind speeds in winter range from 1m/s to 7m/s, with higher wind speed areas concentrated in the northeast. ②Scatter plots were drawn using 576 samples of the enclosure, average air velocity, air temperature, and air pressure of five measurement points at 1.5m in winter and summer. Linear regression equations were calculated, resulting in the degree of enclosure being negatively correlated with the summer air velocity at a 95% confidence level. ③ Based on the enclosure similarities, the opening position determines the direction and trajectory of the airflow inside the open space. The size of the opening determines the velocity of airflow at the opening. The number of openings determines the complexity of airflow. ④Design strategies are proposed based on the principle of optimising the microclimates of urban open space. Firstly, the construction of ventilation corridors is suggested, and reasonable adjusting of the openings. Secondly, comprehensive measures should be taken to improve the comfortable environment of open spaces. 　　This study selected spatial indicators suitable for the corresponding urban space type and explored the laws by simulating ideal spatial simulation to guide the urban construction. New technologies of natural environmental comfort were applied to the urban design process. However, the research object is relatively single, without considering vegetation, building surface material selection and other elements. The reasonable selection of the study area is more practically valuable to further study air temperature variations between day and night.