焊管的残余应力测试与研究

通过小孔法与分割法对φ272mm螺旋埋弧焊管和φ380mm对接焊管的残余应力测试,分析探讨了螺旋焊缝、环焊缝以及焊缝热影响区的残余应力分布。研究结果表明,不同工艺焊接成型的圆管,其焊缝纵向均匀为拉应力分布,焊缝横向均为压应力分布,焊缝热影响区的残余应力分布各异。     

分离式热管换热器传热特性的实验研究

本文在自行设计分离式热管实验装置的基础上,对其传热特性进行了实验研究。其工作温度为170～250℃,热流密度为25～50 kW/m~2。蒸发段和冷凝段构成相同,均是由7根直径30 mm的无缝钢管短管束组成,管长为160 mm,带有紧套的钢帛环形肋片结构尺寸为:外径45 mm、厚1 mm、片间距4 mm。实验结果表明,在本实验条件下,分离式热管的最佳充液率按管束总容量计为18%～38%。根据实验结果拟合了最佳充液率(24%)下蒸发段内部平均沸腾换热系数和冷凝段内部凝结换热努塞尔数综合关系式。     

埋在土中的输液管道的耦联振动

本文对平面应变情况下,管道、流体与外土壤介质三者间的耦联振动进行了精确分析。在严格满足所有耦合边界条件的情况下,导出了系统自由振动的频率方程,并给出了各参数对最低阶固有频率影响的数值结果。当对更复杂水一管一土耦合系统进行数值解时,本文结果可作为检验其精度的一个依据。     

以能量密度为参量的管中导波无损检测参数选择

一般情况下，检测管状结构时采用位移分布或应力分布来选择超声无损检测的导波模式及其频厚积，这在有些情况下是不合适的。本文用总能量密度来选择检测管状结构的最佳导波模式及其频厚积，并用位移分布进行了比较，最后用混合边界元法进行了数值模拟，对其结果的有效性进行了验证。结果表明，总能量密度能有效的选择检测管材的最佳导波模式及其频厚积范围的检测的最佳位置。     

New applications of 10 MeV electrons for reeled goods

Because of their high penetration capability, electron beams produced by 10 MeV machines are increasingly used for the sterilization processing of medical devices. Worldwide there are already more than 20 such machines in action for this purpose. But compared with electron beam sterilization, the physical crosslinking of plastic products with 10 MeV has not been as much investigated as in the range of low and medium energy. So the products with high wall thickness or big dimensions are still chemically crosslinked as the penetration and power of the beam of existing accelerators was not sufficient for those products. But now radiation crosslinking is possible also for higher dimensions of reeled goods due to higher beam power up to 150 kW, and one machine with different handling systems can be used for sterilization and modification of plastic products.

The aim of our work is to examine the homogeneous crosslinking of industrial products by a 10 MeV/150 kW electron beam as for instance for XLPE-c pipes and heat shrinkable tubes. Furthermore the uniformity of crosslinking especially along the roundness is measured, which is one of the essential quality characteristics.     

Q690高性能焊接钢管轴压临界承载力实验研究

为研究国家电网输电塔中Q690高性能钢焊接圆管的临界承载力,取长细比45和60,且考虑径厚比为31.25、37.50和43.75的三种截面,以厚度为8mm的国产Q690高性能钢板设计制作了18根焊接圆管足尺试件并进行轴向受压试验。由试验结果分析表明:试件与普钢圆管发生相同的弹性整体失稳破坏,破坏瞬时突然;而相对普通钢材,Q690高性能钢材料弹性段相对较长,管材环向约束增强,试件失稳相对滞后,临界承载力相应提高。与中国和美国相关行业规范公式计算值对比分析发现:所有规范计算值均不同程度小于试验实测结果,且长细比越大,差异越明显。上述结果进一步验证了将河南省电力勘测设计院"Q690钢管杆塔设计试验研究技术报告"得出的轴压稳定系数取值的相关规范设计公式应用于指导工程设计的可行性。     

两级烟气废热热管溴化锂制冷机稳态仿真

利用热管废热溴化锂制冷机不仅能够回收工业过程的大量废热、余热,而且可以提高整个工业系统的能源利用效率。针对两级烟气废热热管溴化锂吸收式制冷机,编写了溴化锂制冷机的设计计算程序和变工况的仿真计算程序,主要研究外界参数变化对系统性能的影响,其结果与理论分析能较好得吻合。对溴化锂制冷机的设计及操作运行、控制调节等具有一定的指导意义。     

太阳能光催化-导光管北京夏季晴天降解甲醛的实验研究

太阳能光催化-导光管将太阳光导人的同时兼具光催化空气净化功能.导光管的长度为0.55 m,直径为0.28 m,导光管内表面的平均反射比为0.82.散光板的直径为0.28 m,为雪花型散光板,将光催化剂DegussaP25溶液均匀地喷涂在散光板凹凸不平的一侧,附着在散光板上的DegussaP25质量为1.75 g.实验表明,涂层背对太阳时散光板下的照度比无涂层的散光板下的照度有一定程度的减弱,但是减弱的幅度并不大,平均降幅只有3.03%,因此不会对室内采光产生明显影响.实验表明,夏季晴天上午太阳直射下,太阳能光催化-导光管能够使0.1 m3小室内甲醛体积分数从1.0×10-6下降到0.19×10-6 .中午太阳直射下1 h之内甲醛体积分数从1.0×10-6下降到0.17×10-6;比上午的降解速度加快,降解甲醛更为完全;下午太阳直射下甲醛降解,1 h之内,甲醛体积分数从1.0×10-6下降到0.2×10-6,降解速度比上午、中午都慢,但也达到了良好的降解效果.     

The design and instrumentation of an experimental rig to investigate acoustic methods for the detection and location of underground piping systems

A major UK initiative, entitled ‘Mapping the Underworld’, is seeking to improve our capability of locating buried utility service infrastructure without resorting to extensive excavations. One of the four projects aims to develop and prove the efficacy of a multi-sensor device for remote buried utility service detection, location and, where possible, identification. An essential technology to be combined into the device is low-frequency acoustics, and suitable techniques for detecting buried infrastructure, in particular buried plastic water pipes, have been proposed. In order to develop and test these techniques, an experimental rig has been built. It is the design and instrumentation of this rig along with the rationale for the chosen design which is the main focus of this paper. Preliminary measurements have been made on the rig, to determine the most appropriate acoustic excitation method and to confirm that the rig is behaving as anticipated. The results of these investigations are also reported.     

基于圆结构光照明和LED照明相结合的三维检测技术

针对孔内表面的检测问题,提出了一种新的基于结构光照明和LED照明相结合的三维检测技术。该方法主要包括三个步骤:首先通过圆结构光照明获取孔内表面的截面轮廓图像,并通过图像处理和系统标定得到当前截面上局部区域的深度值;然后通过平面光照明得到孔内表面的平面图像,并在分析成像关系的前提下,在对平面图像进行坐标变换后得到孔内表面的展开图像,结合图像处理算法,提取展开图像的局部区域的平面尺寸信息;最后将圆结构光数据和LED光源数据变换到同一全局坐标系下,得到内表面的三维信息。