Prediction method for temperature, velocity and concentration fields influenced by thermal plume with large gravity effect in the enclosure space

热羽流的湍流结构比通常的剪切流（如无浮力射流）更为复杂，且存在重力对湍流流动特性的影响。为了更准确地模拟热羽流的湍流流动，需要更精确的湍流模型，本文提出了一种新的湍流模型，能够更精确地模拟热羽流的湍流流动结构。本文采用实验、理论和大涡模拟相结合的方法建立了新的湍流模型，在研究的第一阶段，采用改进的k-E模型（Murakami，Kato，Chikamoto和Ohira）、Abe-Nagano-Kondo模型和Launder的WET模型对热羽流进行了数值模拟。模拟结果与实验数据进行了比较。结果表明，除WET模型预测的速度场和温度场的扩散性小于实验值外，其它模型都能较好地预测出扩散性较低的速度场和温度场。WET模型的计算结果与实验数据吻合较好。在研究的第二阶段，利用激光多普勒测速仪（LDV）和热电偶对含有大热源的封闭空间内的非等温流动进行了测量。其次，用大涡模拟（LES）对相同的流场进行了分析。在这项研究中，Germin-Lilly型动态亚网格尺度（SGS）模式。计算结果与实测数据进行了比较。计算得到的平均速度和平均温度与实测值吻合较好。在研究的最后阶段，采用大涡模拟（LES）分析了热空腔内的自由对流，该自由对流基于弱可压缩流动方程，考虑了高浮力效应引起的可压缩流动。

The turbulence structure of thermal plume is more complicated than the usual shear flow such as non-buoyancy jet, with existence of the gravity effect on the turbulence flow properties. More precise turbulence model should be required for its turbulence flow simulation.In this research, we develop a new turbulence model which predicts the turbulence flow structure of thermal plume preciously. The new turbulence model is developed by combination of experiment, theory and LES (Large Eddy Simulation).At the first stage of research, numerical simulation on thermal plume based on a modified k-E model (Murakami, Kato, Chikamoto and Ohira), Abe-Nagano-Kondo model, and the WET model by Launder. The simulation results are compared with experimental data. It reveals that all the models expect the WET model predicts velocity and temperature fields less diffusive than the experiment. The results of the WET model agree well with the experimental data. A new modeling based on the WET model will be required to predict thermal plume precisely.At the second stage of research, a non-isothermal flow in an enclosed space including a large heat source was measured by using a Laser Doppler Velocimeter (LDV) and a thermocouple. Next, the same flow field was analyzed by Large Eddy Simulation (LES). In this study, the Germano-Lilly type dynamic sub-grid scale (SGS) model was applied. The results given from the computation were compared with those from measured data. Mean velocity and mean temperature predicted by the computation generally showed better agreement with measured data.At the last stage of research, free convection in a thermal cavity based on weakly compressible flow equations was analyzed by LES included compressible flow caused by high buoyancy effect.