为探索代用燃料液化石油气 L PG和二甲醚 DME的喷雾机理 ,采用 L DA技术测量了喷雾粒子的速度分布。为安全起见 ,用制冷剂 R12作试验液体 ,它与 L PG和 DME有相似的物理特性。为做比较 ,在相同试验条件下对传统柴油喷雾进行了测量。考...为探索代用燃料液化石油气 L PG和二甲醚 DME的喷雾机理 ,采用 L DA技术测量了喷雾粒子的速度分布。为安全起见 ,用制冷剂 R12作试验液体 ,它与 L PG和 DME有相似的物理特性。为做比较 ,在相同试验条件下对传统柴油喷雾进行了测量。考察了喷雾模式对速度分布的影响。结果表明 ,R12喷雾的速度分布比传统柴油喷雾均匀得多 ,前者的平均径向速度远大于后者。展开更多
The Metzner and Otto correlation is the single practical method for incorporating non-Newtonian effects in the mixing process. In this article, the Metzner and Otto' s idea, the role of viscoelasticity on the Metz...The Metzner and Otto correlation is the single practical method for incorporating non-Newtonian effects in the mixing process. In this article, the Metzner and Otto' s idea, the role of viscoelasticity on the Metzner and Otto coefficient, ks, effects of flow regime on ks and the determination of fc3 for Rushton turbine impeller have been studied using the direct method of the laser Doppler anemometry (LDA) velocity measurement for the case of viscoelastic liquids. The normalized mean tangential velocity profiles are independent of Rushton turbine impeller speeds. Contrary to literature findings, it is shown that the variation of local shear rate against the impeller speed is better correlated by the power equation, i.e. y= k'a Nb' , in the transition region, i. e. - 30 < Re <- 2000. Also, a correlation between improved coefficient, ks', and the elasticity number of viscoelastic liquids is given which is very helpful in designing of the mixing of both viscoelastic and inelastic non-Newtonian fluids through relating rheological properties to kinematical and dynamical parameters of the mixing process.展开更多
文摘The Metzner and Otto correlation is the single practical method for incorporating non-Newtonian effects in the mixing process. In this article, the Metzner and Otto' s idea, the role of viscoelasticity on the Metzner and Otto coefficient, ks, effects of flow regime on ks and the determination of fc3 for Rushton turbine impeller have been studied using the direct method of the laser Doppler anemometry (LDA) velocity measurement for the case of viscoelastic liquids. The normalized mean tangential velocity profiles are independent of Rushton turbine impeller speeds. Contrary to literature findings, it is shown that the variation of local shear rate against the impeller speed is better correlated by the power equation, i.e. y= k'a Nb' , in the transition region, i. e. - 30 < Re <- 2000. Also, a correlation between improved coefficient, ks', and the elasticity number of viscoelastic liquids is given which is very helpful in designing of the mixing of both viscoelastic and inelastic non-Newtonian fluids through relating rheological properties to kinematical and dynamical parameters of the mixing process.
