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171.
<正>由于三相流化床反应器在石油化工、湿法冶金、环境工程和煤的液化等工业领域得到越来越广泛的应用,近年来对传统的三相流化床进行了大量的基础研究并取得了很大进展。以往的研究大部分是针对低液速(u_l相似文献
172.
采用氧解吸实验,在直径190 mm的有机玻璃塔内,液相喷淋密度10~38 m3·m-2·h-1,F因子0.2~3.2 m·s-1·(kg·m-3)0.5的实验条件下测定了一种新型垂直板规整填料的流体力学及传质性能。实验结果表明:垂直板填料的操作压降及传质性能均显著优于商业波纹填料。通过与几种经改进的250型波纹填料相比发现,两者泛点F因子整体上相当;在较高液体喷淋密度下,垂直板填料传质性能及压降均高于改进250型波纹填料;在低喷淋密度下,垂直板填料可实现压降低于改进250型波纹填料,而两者传质性能相当。此外,对填料结构改进对其性能的影响进行了单因素考察。 相似文献
173.
Xuqi Song John R. Grace Hsiaotao Bi C. Jim Lim Edward Chan Brian Knapper Craig McKnight 《加拿大化工杂志》2006,84(2):161-169
The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ~20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core‐annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers. 相似文献
174.
Global hydrodynamic characteristics, liquid mixing and gas‐liquid mass transfer for a 63 L split‐rectangular airlift reactor were studied. Correlations for gas holdup and overall liquid circulation velocity were derived for the air‐water system as a function of the specific power input; these were compared to data and correlations for reactor volumes between 4.7 L and 4600 L. A partial recirculation of small bubbles in the riser was observed when Ugr > 0.03 m/s, which was attributed to the use of a single‐orifice nozzle as the gas phase distributor. The dimensionless mixing time and the overall axial dispersion coefficient were nearly constant for the range of gas flow rates studied. However, values of KL/dB were greater than those reported in previous studies and this is caused by the partial recirculation of the gas phase in the riser. While scale effects remain slight, the use of a gas distributor favouring this partial recirculation seems adequate for mass transfer in split‐rectangular airlift reactors. 相似文献
175.
周华君 《土木建筑与环境工程》2001,23(5):1
水动力数值模型是污染物和泥沙运动过程模拟的前提,已广泛应用于河流海岸工程的规划设计和管理中。用于工程的水动力模型应根据研究目的、地形和水动力特征做适当的简化。本文分析了水动力模拟的基本过程和主要问题,探讨了模型域的选择、模型维度、边界条件、初始条件、计算网格设计、小尺度过程及亚网格尺度过程的参数化、模型验证等问题。 相似文献
176.
On Shun Pak Saverio E. Spagnolie Eric Lauga 《Journal of the Royal Society Interface》2012,9(73):1908-1924
In addition to conventional planar and helical flagellar waves, insect sperm flagella have also been observed to display a double-wave structure characterized by the presence of two superimposed helical waves. In this paper, we present a hydrodynamic investigation of the locomotion of insect spermatozoa exhibiting the double-wave structure, idealized here as superhelical waves. Resolving the hydrodynamic interactions with a non-local slender body theory, we predict the swimming kinematics of these superhelical swimmers based on experimentally collected geometric and kinematic data. Our consideration provides insight into the relative contributions of the major and minor helical waves to swimming; namely, propulsion is owing primarily to the minor wave, with negligible contribution from the major wave. We also explore the dependence of the propulsion speed on geometric and kinematic parameters, revealing counterintuitive results, particularly for the case when the minor and major helical structures are of opposite chirality. 相似文献
177.
Cornelius Demuth Matthias BiedaAndrés F. Lasagni Achim MahrleAndreas Wetzig Eckhard Beyer 《Journal of Materials Processing Technology》2012,212(3):689-699
This work presents a new approach to the thermal modelling of direct laser interference patterning (DLIP). The spatial and temporal evolution of the temperature distribution within metallic substrates, which are irradiated by nanosecond pulses during the DLIP process, is computed by means of a smoothed particle hydrodynamics (SPH) method. The developed model considers the conversion of laser energy into heat within a very thin surface layer, heat conduction into the bulk material and the effect of latent heat during involved phase transformations. The importance of proper determination of characteristic SPH parameters and adequate spatial resolution of the computational domain on the accuracy of the numerical solution is discussed in detail. The computed temperature distributions are in good agreement with the results of a previously developed FEM model and correspond very well to simultaneously performed experimental investigations. 相似文献
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