Characteristics of shell thickness in a slab continuous casting mold

The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold.A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid (VOF) model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions.The results show that the jet acts a stronger impingement on the shell of narrow face,which causes a zero-increase of shell thickness in a certain range near the impingement point.The thinnest shell on the slab cross-section locates primarily in the center of the narrow face,and secondly near the comer of the wide face.Nozzle optimization can obviously increase the shell thickness and make it more uniform.     

Experimental Study on the Expansion Uniformity of Armature

A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters,which can be applied to study the expansion uniformity of armature in a helical magnetic flux compression generator (HFCG).The influences of wall thickness and initiation position on the expansion uniformity of armature in HFCG were experimentally investigated.The results show that the armature with thinner wall thickness will easily rupture due to the high pressure of detonation products inside,the armature with larger wall thickness will easily crack due to the tensile stress on the outer surface of the wall,the influence of the end effect on the expansion uniformity can be ignored if the distance between the first group of probe and the initiation point is more than 3 times the armature diameter.     

高压蒸汽管道保温研究

计算了不同管径和保温厚度下蒸汽管道输送高压蒸汽的热损失和温度降。结果表明:保温厚度越大,蒸汽的热损失越小、温度降越小;保温材料导热系数与蒸汽的热损失呈正比;环境温度越高,蒸汽的热损失越小;环境风速对热损失的影响不大。同时研究了保温材料选择和保温结构对节能的影响。     

多孔介质微波加热厚度的确定

简述了微波加热的机理，以湿木材为研究对象，通过理论计算确定了微波在木材中的穿透深度。计算表明：随着木材含水率和微波工作频率的增加，微波在木材中的穿透深度减小；当用频率为915MHz和2450MHz的微波加热或干燥具有高含水率的多孔介质时，多孔介质的最大厚度应分别控制在16cm和6cm以内。     

翼缘纵向变厚度工型截面梁变形性能试验

为研究翼缘纵向变厚度工型截面简支梁的变形性能,对2根翼缘纵向变厚度工型截面梁与2根等厚度梁进行静力加载对比试验,同时采用有限元软件ANSYS进行数值模拟.变厚度梁翼缘材料为Q345GJC等级纵向变厚度钢板,加载方式包括单点加载和两点加载.试验结果表明:试件均发生明显的板件局部屈曲;采用翼缘纵向变厚度工型截面简支梁,不仅可以在保证承载力的情况下大大减少用钢量,而且可以获得更大的强度储备;也可以达到密实截面的变形要求,满足塑性设计要求.有限元结果与试验结果吻合良好.该试验结果可为翼缘纵向变厚度工型截面钢梁的塑性变形设计提供依据.     

Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt

In order to establish the design method for T-shaped tensile connector with high strength bolt,the theoretical analysis is carried out. Firstly,it analyzes the performance of the connector and establishes prying force calculation model. Based on the model,prying force equation and function between bolt prying force and flange thickness is derived,and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally,two simplified design methods of the connector are proposed,which are bolt pulling capacity method and flange plate bending capacity method.     

Optimal Design of Two-Chamber Gas Distributor with CFD Approach

Computational fluid dynamics( CFD) is used to investigate a new type of two-chamber natural gas distributor,which has a natural gas inlet and nine nozzle outlets. The uniformity at the outlet of distributor is practice proven to have significant degree influence on its comprehensive performance. To improve the uniformity at the nozzles of the gas distributor,CFD modeling with the RNG k-ε turbulence model is undertaken to understand the mass flow rate of nozzles with reference to different length of chambers and the most optimal length is obtained. The internal flow pattern of the natural gas distributor is analyzed. It is found that the local maximum deviation of the nozzle outflow rate increases with the increase of chambers length when the length is more than 64 mm. The results provide useful suggestions for the optimal design of two-chamber natural gas distributor.     

基于涡流检测的曲面涂层厚度影响因素分析

曲面涂层厚度测量已成为涡流检测实践中的一个重要课题.本文基于涡流检测技术研究了曲面涂层厚度检测的影响因素,使用ANSYS分析软件建立了曲面的三维涡流场有限元模型;通过定义材料属性,划分网格,设置边界条件,加载及求解等,计算了曲面的曲率半径大小、厚度以及提离距离变化对涡流信号的影响,分析了检测线圈阻抗变化与涂层厚度之间的对应关系.通过仿真,得到了曲面曲率的半径大小和厚度对涡流信号的影响规律,为实际检测曲面涂层厚度提供了可靠的理论依据和技术支持.     

胡襄煤田煤层厚度变化特征及其控制因素

根据河南胡襄煤田勘探钻孔资料,对煤层的稳定性和煤厚度变化特征进行研究。研究认为,区内二1煤层可采性指数为0.81,厚度变异系数为39%,属较稳定的全区大部可采的中厚-厚煤层;二2煤层可采性指数为1,厚度变异系数为11%,属稳定的全区可采的中厚-厚煤层;区内煤层厚度呈现东部厚西部薄的分布特征,局部出现无煤带或薄煤带;影响煤厚变化的因素主要为成煤时期地壳的不均匀沉降、成煤后期的古河流冲刷与断裂构造破坏作用。     

基于TEM图像的CNT溶液分散均匀性分形方法

针对传统评价方法的不足,提出了一种以分形理论为数学模型基础的碳纳米管长度分布及分布均匀性的定量评价方法.将碳纳米管溶液TEM图像进行处理,得到简化矩阵,以简化矩阵的第1个元素为原点,提取不同步长及该步长内所有元素的和,在双对数坐标中以拟合直线的斜率作为碳纳米管长度分布参数p1.以TEM图像的中心为圆心做圆,提取不同半径圆内的碳纳米管数量,在双对数坐标中以拟合直线斜率的倒数作为分散均匀性参数p2.将该方法应用于不同方法分散的碳纳米管分散均匀性的描述,结果验证了该方法能正确地评价碳纳米管的长度分布及其分布均匀性.