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B.S. Cheong 《Chemical engineering science》2004,59(11):2145-2157
The focus of this paper is on the effect of gravity stretching on disturbed capillary jet instability. Break-up and droplet formation under low flows are simulated using finite difference solution of a one-dimensional approximation of disturbed capillary jet instability chosen from the work by Eggers and Dupont (J. Fluid Mech. 155 (1994) 289). Experiments were conducted using water and aqueous glycerol solutions to compare with simulations. We use a gravity parameter, G, which quantifies gravity stretching by relating flow velocity, orifice size and acceleration and is the reciprocal of the Froude number. The optimum disturbance frequency was found to be inversely proportional to G. However, this relationship appears to be complex for the range of G's investigated. At low G, the relationship between and G appears to be linear but takes on a weakly decaying like trend as G increases. As flows are lowered, the satellite-free regime decreases, although experimental observation found that merging of main and satellite drops sometimes offset this effect to result in monodispersed droplet trains post break-up. Viscosity did not significantly affect the relationship between the disturbance frequency and G, although satellite drops could be seen more clearly close to the upper limit for instability at high G's. It is possible to define regimes of satellite formation under low flows by considering local wavenumbers at the point of instability. 相似文献
85.
本文利用震动磨对羟基磷灰石进行超细粉碎,优选出震动磨超细粉碎的最佳工艺条件。利用震动磨研磨可以得到粒度分布单一的粉体样品,D50为2.001μm。 相似文献
86.
The ablation rate of frozen mixtures of water or wax with finely divided solids subjected to a turbulent axisymmetric water jet was investigated both experimentally and theoretically. The range of the water jet Reynolds number was 8700–29300 and the jet temperature varied between 22 and 60°C. The solids used were very fine kaolinite clay, titanium oxide and aluminium powder. The type of solids and their concentration were found to affect the ablation rate of ice-solids and wax-solids mixtures. This is mainly due to changes in the physical properties of the melt layer of the water-solids or wax-solids mixtures which forms between the impinging jet and the frozen mixtures. 相似文献
87.
陈文怡 《武汉理工大学学报(材料科学英文版)》2009,24(1):38-41
A stainless steel/10wt%TiC nanocomposite particles were prepared by high-energy ball-milling method using stainless steel,
carbon and titanium as raw materials. The evolution of phase composition, microstructure and specific surface area of the
stainless steel/TiC nanocomposite particles with increasing ball-milling time in the range of 0–100 h were investigated by
XRD, SEM, TEM and BET techniques. The results showed that the stainless steel/TiC nanocomposite particles were fabricated
when the ball-milling time was longer than 20 h. However, the nanocomposite particles were soldered and agglomerated again
when the ball-milling time was longer than 60 h. The microstructure of the composite particles transformed from lamellar structure
to nanostructure during the repeated process of the cold welding and cracking. TEM image reveals clearly that the in-situ
TiC nanoparticles with grain size of 3–8 nm are in the interior of the stainless steel/TiC nanocomposite particles obtained
by ball-milling 100 h.
Funded by the Natural Science Foundation of Hubei Province (No. 2006ABA304) 相似文献
88.
将W80Cu20(n(W):n(Cu)=4:1)混合粉末在QM-BP式行星式高能球磨机中球磨进行机械合金化,研究了不同球磨时间对W-Cu混合粉末组织的影响.采用XRD和SEM对不同球磨时间的粉末进行分析,结果显示随着球磨时间的增加,混合粉末产生合金化效果不断增强,Cu固溶于W中,并且晶粒尺寸得到一定的细化. 相似文献
89.
自激振荡脉冲射流的研究与进展 总被引:2,自引:1,他引:1
指出了自激振荡脉冲射流的产生机理,概述了国内外主要的研究和应用成果,并对这些成果进行分析后指出:目前的研究方法主要基于经验,基于理论或基于方法;目前主要的应用领域为石油钻井、油罐清淤和渔业充氧等.最后对进一步研究的方向和应用的领域作出了展望,可为相关研究参考. 相似文献
90.
喷嘴偏心距对射流泵性能影响的数值模拟 总被引:1,自引:0,他引:1
对射流泵内部流动进行了数值模拟,计算了射流泵在不同喷嘴偏心距下的性能参数,分析了射流泵喷嘴轴线偏离泵体轴线的偏心距对其性能和流场的影响.结果表明:喷嘴偏心距对射流泵大流量比工况的性能有较大的影响,而对小流量比工况影响较小,可忽略不计;随着偏心距的增加,射流泵效率最高点下降并向流量比小的方向移动.在工程应用中,射流泵同轴度精度要求可以定为12级以上. 相似文献