Shock/expansion fan interaction with real gas effects for Earth and Mars atmospheric conditions

Numerical simulations are performed to investigate the real gas effects on shock/expansion fan interaction. Initial perfect gas simulations at low enthalpy capture the flow structures efficiently and outcomes are found to have excellent agreement with the analytical calculations. Furthermore, the simulations with the real gas solver for different enthalpies showed that the variation in enthalpy significantly changes the flow structures. It is observed that an increase in enthalpy leads to a decrease and increase in the postshock and postexpansion fan Mach numbers, respectively. Another important observation is the decrement in the peak pressure ratio with an increment in the enthalpy. These effects are noted to be more pronounced for Mars's environment due to the higher dependency of specific heat on temperature.     

基于现代审美下的赣傩艺术元素分析与设计应用

目的 赣傩艺术元素内容丰富并保存完整,是研究我国古代赣傩地区文化与艺术的珍贵史料.研究赣傩艺术元素的提取及衍生图案的设计方法,在设计应用中表达赣傩傩面具、选取傩舞形和构筑傩庙魂,能给当代赣傩艺术元素的产品设计以指引.方法 通过直接引用、形意结合和局部强化的设计方法,增厚其丰富内涵、设计个性和主题意蕴.通过现代化审美中"绿色化、感性化、地域化"的要求,遵循"以退为进,化繁为简""多元并存,个性体现"的原则,强化赣傩艺术元素的独特风格.结论 用现代的手法,将特色的赣傩艺术元素植入到理性的产品设计中去,使赣傩艺术元素与现代设计思想有机结合.在继承传统文化与现代流行中找到契合点,深入挖掘赣傩艺术元素蕴含的文化精神、文化胸怀和文化自信,使中华传统文化在现代审美下进行创新再现.     

多尺度高阶FDTD逆时偏移在煤田地震勘探中的应用

目前煤田地震勘探的主要难点是深部复杂构造的成像。随着逆时偏移技术的发展，针对煤田地震勘探，如何在保证偏移成像精度的前提下，提高成像计算效率是急需解决的问题之一。从成像区域网格离散化的角度出发，针对高速层过采样和低速夹层采样不足问题，提出赋予研究对象多尺度网格的概念，具有较好的灵活性，能够对同一个地质模型采用疏密结合的方式成像。首先，根据速度模型设计多尺度网格模型，低速区域采用小尺度网格覆盖，高速区域采用大尺度网格覆盖;其次，采用高阶FDTD方法计算多尺度模型内各点的波场值，尤其过渡带内的点;最后，根据成像条件完成地下介质的逆时偏移成像。实验结果表明在保证模拟相同阶数精度条件下，多尺度逆时偏移方法比传统方法计算效率平均提升25.05%。     

Shape optimization of bi-directional flow passage components based on a genetic algorithm and computational fluid dynamics

The inlet/outlet is an important part of a water conveyance system in a pumped storage power station (PSPS). Its hydraulic characteristics are directly related to the operation and economic benefit of the PSPS. Frequent changes between inflow and outflow operations pose significant challenges in the design of the inlet/outlet diffusion segment shape. In this study, an effective optimization method, including three-dimensional parametric modelling, computational fluid dynamics and a genetic algorithm, is introduced and coupled to the design of the diffusion segment shape. The hydraulic characteristics of bi-directional flow, including the head loss, velocity uneven distribution and uneven discharge distribution, are selected as the objective function in the optimization method. Using this method, the recommended shape of the inlet/outlet is studied and its hydraulic characteristics are discussed. The results indicate that the optimized inlet/outlet has better performance.     

Slag eye formation in single and dual bottom purged industrial steelmaking ladles

ABSTRACT

Argon gas is often injected from the bottom of the ladle during steel refining operations. The injected gas interacts with the liquid (metal and slag) bath and enhances the momentum, heat, and mass transfer rate in the melt. However, during these gas–liquid interactions, an opening of the slag layer called slag eye is formed, which exposes the molten metal surface to the atmosphere, which is generally undesirable. In the current work, a transient, three-dimensional mathematical model is used to study the turbulent gas–liquid interactions in single as well as dual bottom blown industrial steelmaking ladles. A Coupled Level Set Volume of Fluid (CLSVOF) model is used for tracking the steel-argon, steel-slag, and argon-slag interfaces, from which the slag-eye area has been predicted. It is found that the inlet gas purging rate, melt height, slag layer thickness, angular and radial positions of the gas inlets affect the slag opening area. Non-dimensional empirical correlations are proposed to predict the slag opening area in both single as well as dual purged ladles, using non-linear regression analysis.     

基于CFD-DEM方法的净化器流场模拟与结构优化

针对空气净化器能耗高的问题，使用离散元方法(DEM)在吸附滤网中建立随机堆积柱形活性炭模型，采用计算流体力学(CFD)方法对空气净化器内部流场进行数值模拟，在模拟与实验验证的基础上，考察了压降最小、流场最均匀的吸附滤网结构。结果表明，空气净化器压降主要发生在轴向，活性炭吸附滤网中回流、沟流现象严重，流体阻力是其他两种滤网的3倍。边数对多边形填充孔结构吸附滤网内压降与流场均匀性无影响，当孔结构改为圆形时，压降减小约52 Pa，节能18.4%(49 W)；当孔直径由8 mm增至12 mm，压降减小约48 Pa，节能19.4%(45 W)；滤网间距对空气净化器压降无影响，圆形、小孔径的吸附滤网内流场最均匀。     

饮料包装中的时尚维度与时尚设计

当今的饮料包装设计从造型风格、色彩及材质都越来越时尚化,时尚具有的瞬间性、空间性、规律性等维度亦在饮料包装设计中得到了充分体现。时尚化的饮料包装设计能对消费者产生一种视觉上的审美体验与流行性的心理效应,具有先声夺人的营销效果。在未来的饮料包装设计中,应注重对流行趋势的预测、对消费者心理进行分析、合理巧妙地运用创新材质。从时尚的理念着手,以时尚元素的融入、时尚创意的设计、时尚氛围的营造,来增强消费者的购买欲望及对时尚审美的精神需求,从而提升饮料产品的附加值与销售量。     

What drives smartwatch purchase intention? Perspectives from hardware,software, design,and value

Although wearable devices are popular in recent years, the market share of smartwatches is relatively low. The main goal of this research is to investigate the antecedents of the intention to purchase a smartwatch. This research develops a conceptual model and hypotheses based on the theory of reasoned action and perceived values from the perspectives of software, hardware, and aesthetic design. An online questionnaire was developed and distributed on popular websites to collect data, and 260 usable responses are collected from the potential users of the Apple Watch in Taiwan. The thirteen hypotheses were validated by using partial least squares (PLS) techniques. Among the antecedents of purchase intention in the model, the attitude towards using smartwatches was found to have the strongest direct effect. Among the factors of the attitude, design aesthetics have the most significant effect. The results also show that all of the factors about smartwatch attributes directly affected the related perceived values. However, social value and performance/quality value did not affect the intention. The model demonstrated relatively good explanatory power for purchase intention in the context of smartwatches. The proposed model can provide insights to smartwatch vendors to develop their new products and marketing strategies.     

Cable tray FIRE tests simulations in open atmosphere and in confined and mechanically ventilated compartments with the CALIF3S/ISIS CFD software

Fire hazard in nuclear power plants (NPPs) is particularly often investigated as potential cause of safety equipment failure and confinement loss. Many fire events recorded in NPPs involve electric cables, widely used throughout facilities. IRSN is developing the CALIF3S/ISIS computational fluid dynamics software devoted to fire simulation in large‐scale confined and mechanically ventilated compartments. This paper presents two aspects of the CALIF3S/ISIS code ability to simulate fires. The first one concerns vertical and horizontal spreading of a cable tray fire in open atmosphere using an approach based on the FLASH‐CAT cable fire spread model. Resorting to the suitable parameters of the FLASH‐CAT model based on video fire analyses of tests enables to properly compute the heat release rate of the fire. The second aspect concerns the ability to simulate the evolution and consequences of fires in confined and mechanically ventilated compartments. For these cases, the heat release rate measured during the corresponding experiment is used as input data for the calculations. The predicted evolutions of pressure or gas temperatures are in relatively good accordance with the experiments. The major discrepancy concerns gas concentrations in the fire room which is attributed to a lack of information about the properties of the fuel material.     

放射性气载流出物取样代表性分析

为获取核设施放射性气载流出物单点连续监测取样位置,提出基于随机轨道模型(DRW)的气-固多相湍流耦合方法求解代表性取样区域。借助k-epsilon湍流模型模拟连续相,并引入离散颗粒模型(DPM)模拟离散相,建立基于DRW模型的排风管道内流道气-固多相湍流耦合计算模型,计算了核设施气载流出物在管道内流道流场分布规律,分析了内流道流体气旋角、气流速度、示踪气体浓度、气溶胶粒子浓度与管道高度间的关联关系。分析结果表明,随着截面高度的增加,气旋角、气流速度变异系数(COV)、示踪气体浓度COV及示踪气体浓度最大值与平均值的偏差逐渐降低并趋于稳定,气溶胶粒子浓度COV在截面6与截面8满足取样代表性要求;基于计算流体动力学方法可快速地确定出代表性取样位置,为气载流出物单点取样现场试验提供了理论参考依据。