Large Eddy Simulations (LES) of vertical convective vortices and dust devils in the terrestrial Convective Boundary Layer (CBL) are presented. A CBL-scale simulation and a dust-devil-scale simulation are preformed at different resolutions. The CBL-scale simulation is performed to study the generation of vertical vortices and the dust-devil-scale simulation is performed to study the detailed structures and stages of dust devil development. The simulation results show that dust devils undergo three stages of development as the swirl ratio increases: a weak vortex stage, a single-celled vortex stage and a two-celled vortex stage. The structure of a dust devil can be divided into four regions: outflow, core, corner and inflow layer. The different structures and characteristics of the modelled dust devil during various stages of development and the influence of the surface on the dust devil profile are described using some of the simulation results as illustrations. The causes of the different structures and characteristics are analysed through the interplay between the rotation, the radial pressure gradient, the buoyancy and the axial pressure gradient. Dust devils are a type of concentrated vortex similar to tornadoes. The differences in the structure and characteristics of tornadoes and the modelled dust devils are discussed in this paper. The carrying aloft of sand particles within the modelled dust devil is explored using a Lagrangian coordinate system. Sand particles can be transported by the updraft with particles of varying diameters follow different tracks.

文中应用数值算法对尘卷风的发展过程进行了模拟计算与分析。通过模拟计算得到了尘卷风的内部详细结构和运动过程。研究表明尘卷风是由于地面局部增热不均匀而形成的一种特殊的旋转对流运动。在尘卷风形成的过程中，外围空气通过贴近地面的薄层被地面加热后流向中心部位，外围空气的旋转能量在中心部位得到加强形成尘卷风，其旋转能量是热泡原来具有的旋转能量的局部集中和一部分势能转化而形成的，其旋转方向是由热对流泡的初始旋转方向所决定。尘卷风是一种类兰金涡，旋转速度和压力的分布具有兰金组合涡的特点；在成熟阶段，尘卷风的详细结构可以粗略地分为4区域——地面附近的气流汇聚区域、柱状的涡核区域、旋风与地面作用形成的转角风区域以及涡核外部的外围气流区域。转角区域可以细分为两个子区域——外围的方位角风区域（在该区域，上升气流运动方向与轴线之间有一定的夹角，称为方位角）和中心的下沉停滞气流区域。尘卷风中心的低压和急速的上升气流可使大量沙尘扬起，不同直径的沙尘颗粒在尘卷风的作用下运动轨迹不同，因此卷起不同大小沙尘的尘卷风的外形也是不同的。

综合逆压突扩流动和浮力各向异性的流场特征，运用颗粒群理论，引入B474的Reynolds应力通用本构关系建立了可实现性应力代数模型。在模型中引入涡扩散理论建立了扩散方程，解决了气液两相数值模拟中流型变化带来的复杂问题。运用该模型对气化炉洗涤室内流场进行了数值预报，并进一步量化分析了出口动量与最大下降深度和夹层内侧出口含气率的关系。

Quench chamber is the most important component in the coal gasifier, and is easy to break. In older to find the pattern of turbulent flow and heat tratrsfer of synthetic gas in the Vertical downward pipe, a numerical medal based on analyzig the flow and heat tl-atrsfer features of the vertical pipe in quench chamber is first presented. The variatiotrs of temperature, velocity of synthetic gas with the char, ge in ler, gth and radius of the vertical pipe and the velocity of the gas are obtained, and the effect of l-adiation is found. The pattern of turbulent flow and heat tl-attsfer of synthetic gas in the vertical pipe is further revealed.

研究了一种NH3/CO2复叠式低温制冷系统，其中高温部分采用NH3做工质，低温部分利用CO2为工质。通过对NH3/CO2复叠式制冷系统的性能进行的热力学模拟计算，分析了该循环的运行参数和性能系数在中间温度和冷凝温度改变时的变化规律，结果表明：在同一冷凝温度下，复叠式两级低温制冷系统存在一个最佳中间温度，使系统性能系数最大，在最佳中间温度的±5K范围内，性能系数降低很少；高温级冷凝温度改变时，循环性能系数也要随之变化，随冷凝温度增加，系统达到最大性能系数时的最大中间温度也增加。研究结果为该复叠式制冷系统的优化设计和实际运行提供了理论基础。