Investigation on film cooling characteristics from a row of converging slot-holes on flat plate

Experimental and numerical researches were conducted to investigate the cooling performance of a single row of consoles (converging slot-hole) on a large-scale flat-plate model. The results show that the coolant flow from a row of consoles shows good lateral uniformity of adiabatic effectiveness, with regions of slightly enhanced cooling occurring between the consoles. For the console cooling geometry, the interaction between coolant jet from inclined console and the mainstream flow results in reasonable vo...     

Mixed convection heat and Mass transfer in a vertical channel with film evaporation

Numerical results are presented for effects of latent heat transport associated with film vaporization on laminar mixed convection heat and mass transfer in a vertical channel with a half channel width b = 0.01 m. The influences of the inlet liquid mass flowrate and wall temperature on the film vaporization and the associated heat and mass transfer characteristics are examined for air-water and air-ethanol systems with gas Reynolds number Re_g = 2000. Predicted results obtained by including transport in the liquid film are contrasted with those where liquid film transport is neglected, showing that the assumption of an extremely thin film made in Lin et al. (1988) and Yan and Lin (1989) is only valid for systems having small liquid mass flow rates. Additionally, it is found that the interfacial heat flux is predominantly determined by latent heat transfer connected with film evaporation.     

Novel fluorescent polynorbornenes with multi-functional armed structure by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization and atom transfer radical polymerization

Novel organosoluble fluorescent polynorbornenes with multi-functional armed structure were designed and prepared by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). A bromo-containing functional norbornene (NBMBr) was prepared from the Diels-Alder reaction of cyclopentadiene and allyl bromide. The diblock copolymer of 5-(N-carbazolyl methyl)bicycle[2.2.1]hept-2-ene (CbzNB) and NBMBr was successfully prepared using living ROMP and used as a novel macroinitiator [poly(CbzNB-b-NBMBr)] for ATRP. Carbazoyl-containing multi-functional armed copolymer with poly(methyl methacrylate) (PMMA) was prepared by using poly(CbzNB-b-NBMBr) as a macroinitiator for ATRP. Strong fluorescence emissions (370-450 nm) were observed in the low excimer-forming multi-functional armed fluorescent polynorbornenes. The fact is that low excimer-forming carbazole-containing polymeric compound would apparently be favorable in photoconductive materials. The multi-functional armed structure make this compound an attractive candidate for applications as multi-modified hole transport materials in molecular electronic devices. Multi-modification could be further considered to be carried out by using such a functional bromo group at the end of multi-arms.     

光化学反应中的磁场效应 Ⅱ.电子转移光敏化1,2-二苯乙烯的顺反异构化反应

前文报道了外加磁场对吸附在硅胶表面上的芳砜光解反应的影响,本文报道外加磁场影响光化学反应的另一个例子——电子转移光敏化1,2-二苯乙烯的异构化。 近年来电子转移光敏化反应引起了有机光化学家们的极大注意。一些异构化、重排、裂解、氧化反应都可以通过电子转移机理敏化。电子转移光敏化的机理可以用(1)描述。图中A和D分别代表电子的受体和给体。     

基于表面反应和扩散迁移控制的灰岩单裂隙渗流—溶解模型及其数值模拟

针对碳酸盐类可溶岩地区水电站坝址流场、化学场以及固相介质属性等随时间发生改变,从而对工程安全运行造成不利影响等问题,研究了灰岩地区地下水运移过程中各物理场间的相互作用,分析了影响灰岩溶解速率的两个因素,即表面反应控制和扩散迁移控制。在此基础上,建立了单裂隙中的渗流—溶解耦合模型,并进行数值求解。模拟结果表明,在垂直裂隙延伸方向,其溶蚀锋面为非齐整平面,而是呈似“虫洞”状非均一变化,而沿裂隙延伸方向即自上游侧向下游方向溶蚀程度逐渐减轻;而通过裂隙的流量呈现随时间逐渐增大的趋势,但变幅不大;根据流量求得的等效水力隙宽,其增幅和增长速率均小于实际平均隙宽;同时,化学场中Ca2+浓度的分布与裂隙开度变化具有相似性,不同时刻下上游侧反应速率R均大于下游侧。就反应机制而言,在初期均受表面反应控制,而随反应进行,位于上游补给区部位转为受扩散迁移控制,但在下游位置仍受表面反应控制。     

"THERMO": COMPUTER PROGRAM FOR SIMULATION OF SURFACE PULSE HEATING

1.IntroductionTheoneofthemostimportantparametersofthethermalcycleduringsurfacepulseheatingistherateofheatingandcooling.Knowledgeofthesevaluesinparticulartemperatureintervalshelpstoprognosticatephasestructureintheheataffectedzones(HAZ),toanalyzecausesofthestructuretransformations.Todaythereisavoluminousliteratureoncalculationofthethermalconditionsforasolidduringsurfaceprocessing.Butthetemperaturevariationsareusuallyexaminedasafunctionoftimeorspacecoordinates.Sometimesthefirstderivativeofthete…     

隔直电容在弧焊逆变器中抗偏磁能力的分析

本文采用状态平均法建立了隔直电容在知式焊接逆变器中抗偏磁的动态模型，并进行了动态分析，为焊接逆变器的设计提供了理论依据。     

椭圆管外流动熵产及放热系数的数值分析

以椭圆管加热水流动为研究对象,对椭圆管加热水流动系统进行了二维数值模拟。通过联立求解流体力学基本方程和熵产方程,获得了熵产、放热系数与雷诺数和纵、横向间距的变化关系。数值分析结果表明:熵产主要发生在管壁表面附近,而在系统内部区域熵产较小,可以忽略;熵产随雷诺数的增大而增大,随纵、横向间距增加而减小,熵产与雷诺数、纵、横向间距存在对应关系,纵、横向间距宜在1.75～2.0间;在相同的雷诺数值时,熵产、放热系数沿流动方向呈现单调减小的趋势;不同的雷诺数值,熵产、放热系数不同,单调减小的趋势相同。放热系数随Re的增大而增大,且与雷诺数存在对应关系。纵向总放热系数随纵、横向间距增大而减小,且存在对应关系。     

用Mathematica解热量传递过程中的数学问题

本文建议用数学软件Mathematica计算热量传递过程,包括用符号运算功能推导保温层临界直径,用曲线拟合法处理传热实验数据,用积分法求取传热系数为温度函数时的换热面积,用Solve等命令求解换热和保温过程所产生的非线性方程,用DSolve命令求解非稳态传热过程产生的微分方程等等。同时绘制出有关函数图形,准确、形象地展示计算过程和结果,方便教师讲解和学生理解,避免复杂、繁琐、耗时的手工计算,提高学生利用计算机解决热量传递问题的能力。