TA15钛合金焊接温度场的仿真模拟分析

薄板钛合金结构在焊接生产中得到了广泛的应用。焊接过程的传热问题十分复杂,焊接过程中的温度分布对于焊接变形有着重要的作用。针对平板TA15钛合金对接接头,对焊接温度场进行了仿真模拟计算,得出了焊接热循环曲线,并进行了试验验证。经过测量比对,焊接热循环曲线变化趋势与模拟所得结果大体一致,说明了模拟计算的正确性。     

复合喷管热结构耦合计算的一种新的策略

基于流固耦合完成复合喷管流动换热、传热过程温度场的数值模拟,编写了计算流体力学(CFD)与有限单元法(FEM)的接口程序,快速实现温度载荷和机械载荷数据的传递,提出了复合喷管热结构耦合计算一种新的策略。利用直接约束法考虑了复合喷管部件界面间高温碳化带来的结构边界非线性因素。计算结果表明耦合方法得到的复合喷管温度场是合理的,高温下界面间结构功能退化问题对于变形特征以及应力场影响很显著。     

加压渗流铸造制备多孔铝的工艺研究

本文研究了通孔多孔铝合金的制备工艺。采用正交试验法确定了模具及粒子的预热温度，铝液的浇注温度，渗液压力三者的最佳配合关系。     

低温热水地板辐射采暖施工要点与能效分析

以中国矿业大学教师公寓小高层住宅项目为例,介绍了低温热水地面辐射采暖系统的特点及施工要点,并进行了能效分析,根据实际运行情况对该系统进行了分析和总结。达到了预期的设计目的,提高和改善了供暖使用功能,具有较高的推广价值。     

煤样工业分析温控系统的设计

介绍一种用于煤样分析的温度控制系统,硬件主要由热电偶专用放大器,８０３１单片机及其数字调功电路组成,软件采用了智能产生控制算法,应用结果表明,仪器的各项指标均满足国标ＧＢ２１２－７７。     

Effect of Stagnation Temperature on the Supersonic Two Dimensional Plug Nozzle Conception. Application for Air

When the stagnation temperature of a perfect gas increases, the specific heats and their ratio do not remain constant any more and start to vary with this temperature. The gas remains perfect, its state equation remains always valid, except it will name in more calori-cally imperfect gas or gas at High Temperature. The goal of this research is to trace the profiles of the supersonic plug nozzle when this stagnation temperature is taken into account, lower than the threshold of dissociation of the molecules, by using the new formula of the Prandtl Meyer function, and to have for each exit Mach number, several nozzles shapes by changing the value of this temperature. A study on the error given by the PG (perfect gas) model compared to our model at high temperature is presented. The comparison is made with the case of a calorically perfect gas aiming to give a limit of application of this model. The application is for the air.     

Cr12MoV钢电火花辅助铣削实验研究

以典型难切削金属材料Cr12MoV模具钢为研究对象,使用ABAQUS对其在电火花放电条件下温度场进行数值模拟,在不同进给率下对其进行传统铣削和电火花辅助铣削对比试验。借助高速摄像机、扫描电镜和测力计等设备,对其切削力特征、表面形貌和刀具磨损进行了对比分析研究。结果表明,电火花辅助铣削的切削力比传统铣削降低28.57%～51.47%,表面粗糙度降低2/3。与传统铣削相比,电火花辅助铣削在降低切削力、提高表面质量和减少刀具磨损方面具有显著优势。     

合成射流激励器阵列实现共轴射流掺混控制研究

文中分别对单列和多列合成射流激励器控制共轴射流掺混流场进行了详细的二维非定常数值模拟,通过对其温度场分布和掺混过程进行分析,探讨激励器阵列进行掺混控制的机理。在研究过程中,考虑了相邻合成射流的影响。结果表明,激励器的采用使得整个流场的非定常性增强、湍流度增大,从而增强了共轴射流及其与周围流体间的掺混;两列激励器较单列激励器相比,前者具有更强的控制能力,这主要是由于相邻合成射流比单个合成射流有着更显著作用力的缘故。     

溅射薄膜热电偶在非金属结构表面瞬态温度测量中的应用研究

介绍了利用薄膜成型技术,在非金属试验件表面用真空离子溅射技术制作薄膜热电偶,进行表面温度测量,并探讨薄膜热电偶在瞬态加热条件下与粘贴的常规热电偶在测温结果上的区别,为今后将薄膜制作技术应用于温度、热流密度及高温应变测量打下基础。     

Evidence of change after 2001 in the seasonal behaviour of the mesopause region from airglow data at El Leoncito

Airglow intensities and rotational temperatures of the OH(6-2) and O₂b(0-1) bands acquired at El Leoncito (32°S, 69°W) provide good annual coverage in 1998–2002, 2006, and 2007, with between 192 and 311 nights of observation per year. These data can therefore be used to derive the seasonal variations during each of these seven years, in airglow brightness and temperatures at altitudes of 87 and 95 km. From 1998 to 2001, seasonal variations are similar enough so that they can be well represented by a mean climatology, for each parameter. On the other hand, these climatologies do not agree with what is usually observed at other sites, maybe due to the particular orographic conditions at El Leoncito. With respect to the last three fully documented years (2002, 2006, and 2007), the similarity from year to year deteriorates, and there are greater differences in the seasonal behaviour, more or less in all the parameters. The differences include, e.g., maxima occurring earlier or later than “normal”, by one or two months. All this may suggest the build-up of a new regime of intraseasonal variability, with a possible relationship to corresponding changes in wave activity.