含沙水下粒径对螺旋离心泵磨蚀效应的数值分析

为研究含沙水中固相颗粒粒径对螺旋离心泵磨蚀的影响,采用N-S方程和标准k-ε湍流模型对螺旋离心泵的内部流场进行数值模拟计算。结果表明,在含沙量一定时,颗粒的粒径对磨蚀影响显著,且随着粒径的增加,叶轮域的体积浓度梯度变化不均匀,更加促进了磨蚀效应,尤其对叶轮的轮缘磨损最为严重。

中国旅游产业投资及旅游发展空间结构响应——基于2000～2015年旅游业三大核心部门数据的分析

以旅游业三大核心部门(旅游饭店、旅游景区和旅行社)的固定资产和人力资源投资为研究变量,分析了2000～2015年中国旅游产业投资演化及旅游发展空间结构的响应。研究发现,中国旅游产业投资存在与旅游发展总体协调、省域空间分布不均、年际变化多样和部门差异明显的特征;省域旅游发展响应系数的变化,反映了中国旅游产业投资的"时间磨蚀效应"和"绩效累积效应";在"空间牵引效应"作用下,中国旅游产业投资促进了中国旅游发展空间结构特征由离散型"核式极化"向连续型"域状扩散"转变。最后,提炼了旅游发展对旅游投资空间响应的实质:以投资为驱动,依据循环积累因果机制,促进区域旅游产业可持续增长。

弹体侵彻混凝土靶板过程中磨蚀问题的计算

对弹丸在混凝土材料中侵彻时表面磨蚀速度的经验公式进行了改进。假设侵彻过程中密度保持不变,据此编制了可以计算弹丸磨蚀后弹头形状、弹体质量损失以及侵彻深度的简单差分程序。将计算得到的磨蚀后的弹头形状、质量损失与卵形弹侵彻无围压强度为63MPa的混凝土(石英骨料)实验结果进行比较,两者基本吻合。

Review on corrosion-wear resistance performance of materials in molten aluminum and its alloys

The failure caused by the corrosion-wear of molten aluminum and its alloys is one of the main problems in aluminum industry. In this work, the resistance behavior of various materials, including Fe-based alloys, ceramics and corresponding high apparatus of corrosion-wear in molten aluminum and its alloys, were reviewed. The synergistic effect of corrosion and wear was discussed based on corrosion and wear mechanics. The effects of dynamic agitation due to rotating of friction pairs, physical property of liquid metal and size of grain etc., on the corrosion-wear resistance performance were investigated. In addition, the characteristics of corrosion-wear resistance performance of materials in molten aluminum and its alloy were summarized. According to our recent progress referred to kinds of materials, especially a TiA13/Ti3A1C2/A1203 composite, the ceramics/metal composites with a co-continuous structure will be of great advantage in the field of corrosion-wear environment of molten aluminum and its alloys.