室外热环境研究中景观水体动态热平衡模型及其数值模拟分析

为解决室外热环境数值模拟研究中水体边界条件设定的问题,借鉴水库和湖泊水温分布的计算方法,并根据室外景观设计中的水体特点,对水面蒸发换热项和对流换热项进行了修正。建立了室外热环境研究中水体温度的动态热平衡模型,编制了水体温度分布的数值计算程序,并使用该程序分析了水面植被遮挡系数、水体深度及水面尺寸等因素对水面温度的影响。数值分析结果表明:1)由于存在蒸发现象,水面温度一般低于空气温度,而当水面有漂浮植被时,水体表面温度会显著降低;2)水体表面温度随水体深度的增加而减少,但当水体深度超过4 m后,影响变得较小;3)水面尺寸对水面温度的影响比较小,只要水体深度设计适当,室外环境中的水体可以获得较低的表面温度。

Analysis on Dynamic Thermal Balance Model of Landscape Water and its Numerical Simulation

In this paper,in order to solve the problem of boundary assignment in the numerical simulation of outdoor thermal environment,the calculation model of water temperature distribution that suitable for reservoirs and lakes was used for reference,and according to the characteristics of water in outdoor landscape design,the items of evaporative and convective heat exchange of water surface were modified at first.Furthermore,a dynamic thermal balance model was established, and a numerical calculation program of water temperature distribution was worked out.Finally,influences of shading effect of floating plant,water depth and water surface dimension on water surface temperature were analyzed.The results indicated that,firstly,water surface temperature was lower than the air temperature due to evaporation,and this difference would increase when water surface was covered by floating plant.Secondly,water surface temperature would decrease with the increase trend of water depth,while when the water depth exceeds 4 m,the increase of water depth would had little influence on water surface temperature.Thirdly,water surface dimension had little effect on water temperature,water surface would have relatively lower temperature with proper design of water depth.