Heat transfer and flow of He II in narrow channels

Heat transfer and fluid flow of He II in a long, narrow channel connected to a bath that supplies a constant supply of heat have been investigated by numerical simulations by using the simplified model of Kitamura et al. [Cryogenics 37 (1) (1997) 1]. Such channels are used to cool compact, stable, low-temperature magnets. The fluid flow is driven by natural convection and the mutual friction between the normal fluid and the superfluid.In this model, the thermomechanical effect and the Goter-Mellink mutual friction balance each other. A consequence of this balance is that the velocity and temperature distributions of He II can be characterized by a dimensionless, dependent parameter equal to the ratio of the fluid speeds of internal convection to the total fluid flow. After a sudden application of heat flux, the internal convection dominates over the total fluid flow until the establishment of steady-state temperature gradients. This predicts that the time required to set up the steady-state total fluid flow is proportional to the total heat capacity in the channel.     

Complementary modelling of fluid separation processes

Optimal functioning of numerous technological processes depends primarily on relevant process design, properly selected column internals and sufficient understanding of the process behaviour. This can be achieved only with the help of accurate and reliable process models capable of considering process rates in a rigorous way, with respect to both transport phenomena and chemistry. In this article, a new modelling concept called complementary modelling is suggested for a large class of fluid separation processes. Since the conditions and criteria for these processes vary considerably, it is impossible to develop a unified modelling approach. Instead, a reasonable and effective combination of different modelling approaches provides solutions to many present and future tasks. The complementary modelling is discussed in detail and illustrated with several case studies.     

非定常流弯肘型尾水管不规则压力脉动预测

尾水管内螺旋状涡带引起的压力脉动是造成混流式水轮机机组振动的主要原因之一,直接威胁机组的安全运行。为此,提出一种基于CFD数值计算的水轮机尾水管压力脉动数字化预测法,并利用此法对一大型混流式水轮机偏工况下尾水管内水流流动进行了长时间非定常流计算,讨论该工况下尾水管内死水域与涡带的运动规律,预测了尾水管的不规则压力脉动,压力脉动分析结果表明,其波形、频率、相位与实际基本一致。     

Effect of spray nozzle design on liquid-solid contact in fluidized beds

In industrial fluid cokers the feedstock, consisting of heavy bituminous hydrocarbons, is atomized with steam and injected into a hot fluidized bed of coke. Good and uniform contact of the liquid droplets with the solid particles is required to provide heat for the cracking reactions while minimizing mass transfer effects. Experiments in a pilot plant coker have suggested that the initial particle/liquid mixing, in the spray jet, is rather poor. Experiments in a X-ray scanner showed that liquid droplets and entrained particles accumulate just below the tip of the jet plume to form agglomerates.An experimental technique was used to quantitatively determine the quality of mixing with a variety of nozzle configurations including several novel designs. By improving spray stability, redistributing liquid droplets to the solids-rich region of the jet and increasing the surface area of the gas-liquid jet-fluidized bed interface, liquid/solid contact is improved.     

吐哈神泉地区钻井液技术

吐哈神泉地区钻井过程中,由于盐膏层的污染,引起长井段划眼、卡钻、甚至井眼报废等复杂事故。介绍了该地区井不同井段的钻井液配方、维护处理措施及钻井液性能控制范围。现场应用结果表明,该钻井液体系抑制能力、抗盐膏污染能力、携砂能力强,满足了该地区不同井段钻井施工的要求。     

Enhancement of hydrocyclone performance by controlling the inside turbulence structure

A new hydrocyclone was designed with a winged core fixed below the vortex finder in this study. With the winged core, the turbulence structure characteristics inside the hydrocyclone, including time-averaged pressure, pressure fluctuation, relative pressure fluctuation characteristics, and distribution characteristics of the probability density of the turbulence pressure, were all positively controlled. By controlling the turbulence structure, the performance of the new hydrocyclone was improved effectively. Compared with the common hydrocyclone, the new hydrocyclone was featured with lower energy loss coefficient, higher reduced separation efficiency, higher separation sharpness and larger capacity.     

低荧光阳离子防塌剂WFT─666的合成与性能

ＷＦＴ－６６６是由磺甲基腐殖酸钾、有机硅聚合物、低分子阳离子有机化合物、苯酚、甲醛缩聚而成的一种新型阳离子低荧光防塌剂。本文介绍了ＷＦＴ－６６６的合成及室内性能评定结果。ＷＦＴ－６６６可抗盐至饱和盐水，抗钙和镁，耐２００℃高温，荧光显示低。用该剂处理的钻井液性能稳定，流变参数合理，页岩回收率高，页岩相对膨胀率低，页岩稳定指数高，与其它处理剂的配伍性好。     

Investigation of the stability of tablets prepared from sucrose and citric acid anhydride utilizing response surface methodology

Inversion of sucrose is a stability problem particularly of candies with acidic taste that contain sucrose and small amounts of organic acids such as citric acid, since the free d-fructose produced by hydrolysis is hygroscopic. The following possibilities were investigated for preventing the hydrolysis of sucrose in tablets containing sucrose and citric acid: Adding various amounts of tri-sodium citrate to the formulation to neutralize the citric acid, (Hot) melt coating of citric acid and tri-sodium citrate with a vegetable fat at different coating ratios, variation of the ratio of coated citric acid and tri-sodium citrate in formulations, and compressing the formulations with different compression forces. After tablet processing and storage of tablets, the concentration of d-fructose was determined on the basis of enzymatic reactions. A response surface central composite design was used. The above-mentioned variations were chosen as independent variables and the amount of d-fructose was chosen as response variable. The lowest rates of inversion could be achieved by increasing the content of tri-sodium citrate and the ratio of coating material and decreasing the ratio of coated citric acid and tri-sodium citrate in the tablet formulations. The compression force had no significant effect on the inversion of sucrose.     

粘合剂流变特性的研究(待续)

本文从流变学的观点出发,分析粘合剂在配制及粘结过程中,反映出不同的流变特性,而粘合剂本身的流动、粘度、触变性与涂胶及其粘合的质量关系重大。     

有关H－Ⅱ运载火箭的动力学课题研究

重点介绍有关Ｈ—Ⅱ运载火箭（以下简称Ｈ—Ⅱ）的一些动力学课题的研究状况。其中，重要的动力学课题有全箭振动、ＰＯＧＯ、防液体晃动、分离动力学试验、动力学环境试验等。针对这些动力学课题，日本有关部门已研究多年，既作了充分的地面试验，又进行了有效的工程应用研究，最终保证了Ｈ—Ⅱ的首次飞行成功。