叶片电解加工机床的研制

为了能够实现按最优进给角度加工叶片,研制出三轴进给的叶片电解加工专用机床。介绍了机床的加工原理、机床结构、性能规格以及相应的控制系统。实践证明在该机床上电解加工方料毛坯,加工出的叶片经专用量具检测,叶片型面精度符合要求。     

二阶方程稳定性的简易计算判别

很多实际问题都可归结为二阶周期性线性方程,这类方程的稳定性意味着所有解皆为周期解或拟周期解,于是初值如何都对应稳定的周期解或拟周期解。在应用上就说明该实际问题总有稳定运动状态。本文应用Hill方程的一个判别式给出了一个通过简单计算即可判定二阶方程稳定性的方法。数值例子说明该方法具有很好的实用性,同时有较高的精确度。     

Effects of Optimized Operating Parameters on Combustion Characteristics and NO_x Emissions of a Burner based on Orthogonal Analysis

To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_x,a self-circulating low NO_x combustion technology was used to design a new type of flue gas self-circulating low NO_x burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_x emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_x emissions greatly increased from 6.23×10~(-6) (volume fraction) at the preheating temperature 973 K to 3.5×10~(-3) at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_x emissions decreased from 352.29×10~(-6) to 159.73×10~(-6).     

Gd0.98LuTb0.02O3透明陶瓷的真空烧结和光学性能

利用燃烧法制备得到了Gd0.9BLuTb0.02O3纳米陶瓷粉体.在不加任何添加剂和烧结助剂的情况下,粉体采用干压和等静压成型.研究了烧结温度和烧结时间对陶瓷的致密化和晶粒长大过程的影响.在此研究的基础上调整烧结制度,于1 750℃真窄烧结6h制备得到了Gd0.98LuTb0.02O3透明陶瓷.厚度为0.2mm的透明陶瓷在可见光区的透过率高于70%,相对密度达到99.8%.该透明陶瓷在X射线激发下发射出黄绿光,发射主峰位于540nm,对应于Tb3+的5D4→7F5跃迁.     

Constructal optimization for an organic fluid shell-and-tube condenser based on entransy theory

A complex function composed of linear weighted sum of the entransy dissipation rate (EDR) caused by heat transfer and total pumping power is established in this paper. Under the conditions of fixed total condensation rate and heat transfer area, constructal optimization of a shell-and-tube condenser (STC) with organic fluid is carried out by taking minimum complex function as optimization objective. The minimum complex function and the optimal external diameter of the condensation tube are obtained. The results show that compared with the initial design construct, the optimal construct of the STC increases the total EDR caused by heat transfer by 10.70%, and reduces the total pumping power and complex function by 54.94% and 6.46%, respectively. This illustrates that the complex function sacrifices a certain heat transfer performance, and improves the fluid flow performance evidently, which leads to the overall performance improvement of the STC. The twice minimization of the complex function can be realized by choosing an appropriate number of the condensation tubes. New guidelines for the optimal structure designs of the STCs are provided by introducing entransy theory into constructal optimizations of the organic fluid STCs, and this method can be further extended to the optimal designs of the cycle systems with organic fluids.     

含不饱和聚醚的新型聚羧酸类减水剂的合成与应用

采用了工业化的不饱和聚醚多元醇为反应单体,合成了一种高减水率,长缓凝时间的新型聚羧酸系高效减水剂.     

液压/燃油管道系统的管径及其支撑的动力优化设计

建立了有、无弹性刚度支撑的液压/燃油管道系统,采用了动力优化的有限元分析方法,分析了在一个频率约束下以质量最轻为目标的管道系统,得出了管径、支撑刚度和固有频率的定量关系,提出了防止管道系统强迫共振的方法,最终为管道系统的安全性指导和设计提供了理论依据。     

12Cr2Mol锻件法兰低温冲击韧性不合格的原因分析

12Cr2Mol锻件法兰在进行力学性能检测时,-30℃低温冲击不合格.通过对试样进行理化分析及模拟性试验发现,工件在进行热处理时,正火条件是造成低温性能不合格的关键因素.由于正火温度较低和保温时间较短,使得工件在热处理时奥氏体均匀化程度不好,因此材料的韧-脆转变温度提高,造成低温冲击不合格.     

基于VXI总线的某型飞机导弹发控系统性能测试仪的设计与实现

传统的导弹发控性能测试技术含量低,不能满足现代战争的需要。为提高部队的快速反应能力,研制了一种基于VXI总线的某型飞机导弹发控系统性能测试仪,并给出了测试仪的硬件配置和在LabWindows/CVI环境下的软件模块化设计方案及实现方法。导弹发控系统性能测试仪的研制,为部队战时或训练现场实时测试导弹发控系统的主要性能提供了方便。     

汽车焊装车间烟尘的治理与除尘系统优化

分析汽车焊装车间烟尘的组成及特性,阐述基于整体除尘混合送风和分层送风方式下气流特点和除尘原理.从除尘原理出发,优化设计送风口的形式和送风位置,并对比分析除尘效果,分层送风置换通风除尘效果明显,能有效降低工作场所烟尘浓度,为从业者的健康安全提供保障.