Fringe probing of an evaporating microdroplet on a hot surface

The phenomenon of droplets impacting and evaporating on a hot surface is of interest in many areas of engineering. Quantitative measurement of these processes provides great help to reveal the physics behind. A novel technique was developed to quantitatively measure the volume evolution and contact diameter of an evaporating microdroplet on a hot surface utilizing interference fringe scattering method. In this method, fine fringes produced by the interference of two coherent laser beams was scattered by the droplet and projected onto a screen. The profile and volume of the droplet can be derived from the spatial fringe spacing on the screen. The number of total fringes measurable on the screen was used to determine the instantaneous contact diameter of the microdroplet. Validation experiments demonstrated that the measurement errors are less than ±5% and ±1% for microdroplet volume and contact diameter, respectively. By using this method, the dynamic of droplet impingement, evaporation and boiling using ethanol, pure water and water solution of a surfactant (sodium dodecyl sulfate) with impact velocity of 7.5 m/s and diameters ranged from 0.19 to 0.46 mm were investigated.     

再制干酪的技术难点

阐述了重制干酪结构形成的原理。主要是天然干酪的稳定结构被加热和搅拌破坏，而乳化盐中的Na^ 和酪蛋白的Ca^ 进行离子交换，从而增加酪蛋白的水合性，提高脂肪的乳化稳定性，经过熔融和冷却，混料中的蛋白、脂肪和水形成一个稳定的新结构。在阐明原理的基础上分析了配方和工艺方面的关键参数，包括混料中的酪蛋白含量，混料中的乳化盐，混料的水分含量和pH值，熔融温度、熔融时间、搅拌强度、脱气程度和冷却程度。     

内冷却砂轮工装研制

由于磨削加工中过高的磨削温度,可采用内冷却砂轮磨削,将切削液直接浇注到磨削区内部,破坏了磨削区的封闭性,从根本上解决磨削温度高引起的工程实际问题.在普通磨床上采用内冷却砂轮磨削就必须提供内冷却砂轮工装,通过对砂轮内冷却总体方案、内冷却砂轮工装设计进行了研究,研制出了结构简单,性能可靠高的内冷却砂轮工装,将该工装用于M7130C平面磨床进行磨削加工,大大降低了磨削区温度,有效避免磨削烧伤,提高了磨削加工质量,效果良好.实验表明内冷却砂轮可加工某些难加工材料,扩大了磨床加工范围.     

发动机通风冷却系统的影响因素分析

整理了风斗进入短舱的冷气流量的变化规律,对发动机通风冷却系统各影响因素进行分析,分析了发动机状态、飞行状态（高度、马赫数）对飞机短舱内温度变化的影响规律。结果表明,发动机状态是影响发动机通风冷却系统的主要因素,飞行状态对涡喷和涡扇发动机通风冷却系统的影响规律不同。     

绿色磨削加工技术研究现状及进展

传统的磨削加工大量采用磨削液浇注法降低加工区温度,磨削液的大量使用给环境和操作者健康带来了很大危害,而且增加了磨削液排放回收的成本.本文分析了绿色磨削加工技术,如干磨削技术、微量润滑、液氮冷却、低温气体冷却、高压射流冷却、内冷却和固体润滑冷却技术在机械制造中的应用及其技术特征.绿色磨削加工技术将逐渐取代传统的浇注供液方...     

Effect of cooling structure on thermal behavior of copper plates of slab continuous casting mold

A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30℃ and 15℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 mm, respectively. The surface temperature without nickel layers is depressed by 10℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.     

合金元素对TRIP钢连续冷却固态相变和硬度的影响

为了研究Al和P合金元素在TRIP钢固态相变过程中的重要作用,利用热膨胀实验、金相观察、显微硬度测量等方法绘制了4种不同Al和P含量的C-Mn-Al-P TRIP钢的CCT图.结果表明,Al元素强烈缩小奥氏体相区,提高Ac3与Ms,促使CCT图左移和上移.P元素能够阻碍碳化物的生成,当钢中w(P)达到0.14%时,能显著将CCT曲线图中的珠光体区与贝氏体区右移.P元素对先共析铁素体相变和马氏体相变没有显著影响.随着冷却速率的增加,材料的显微硬度增加.对于每一种成分超过其临界冷却速率时将得到完全的马氏体组织.添加固溶强化元素可以强化铁素体基体,增加铁素体基体的硬度,P元素固溶强化能力最强,Mn元素稍弱,Al元素很弱.     

超快冷供水系统自动化控制研究及优化

超快冷是轧机后冷却钢板的重要生产工艺设备,其供水系统的合理、稳定对冷却工艺、钢板温度的准确性及均匀性有良好的作用,并且合理的供水系统自动化控制减少了人工操作,有节能作用。介绍了沙钢3 500 mm宽厚板生产线的超快冷供水系统,采用可编程序控制器PLC和交流电机变频调速技术在原有设备控制的基础上进行了优化改进,节能降耗、保持水压平稳及自动化控制方面效果明显。     

火电厂炉烟处理循环冷却水防垢试验研究

结合电厂炉烟处理循环冷却水防垢机理,在实验室条件下,利用自主设计制造的炉烟处理循环冷却水防垢模拟试验台,进行了炉烟防垢动态模拟试验研究.试验结果表明,炉烟防垢法在低浓缩倍率及pH＜8的条件下,防垢效果尤为显著.     

工业循环冷却水处理药剂阻垢性能实验的探讨

通过实验对比,得出实验温度、实验时间及浓缩倍数对水处理药剂阻垢率的影响,筛选出显著影响因素,用于指导阻垢剂的选择及性能的鉴定。