喷气涡流纺喷嘴模型——不等长同心圆管腔体内切向旋流流动特性的数值研究

将喷气涡流纺喷嘴抽象为设有切向气流喷射孔的不等长同心圆管腔体模型,采用计算流体动力学方法,对不等长同心圆管腔体内以切向喷射方法产生的高速可压缩切向旋流的流动特性进行基础研究.研究表明:在切向喷射孔上游出现反旋涡对;切向喷射孔出口外侧气流流速超过音速,随后在外管与内管间的环形区域内以亚音速向下游旋转流动;切向喷射孔入口总压对喷射孔出口附近及其下游区域内气流速度影响不明显.本研究可为喷气涡流纺喷嘴的设计提供可借鉴的思路与结论.     

The Mechanism of Eliminating Drafting Waves in Spinning

The mechanism of the staple yarn's drafting waves during roller drafting is analyzed in this paper.It's concluded that the dynamic friction coefficient is greater than the static friction coefficient on the friction behavior of fibers, and the difference is largely responsible for the " stick-slip" motion of fibers which causes the drafting waves during drafting. In this paper,it's expected that when a high frequency undulating wave is imposed on the fiber strand in the drafting zone of roller system, the friction among fibers is dominated by the dynamic friction rather than the static friction, and thus the " stick-slip" motion will be eliminated. As a result, the fiber binding effect causing drafting waves can be significantly reduced. This hypothesis is verified by an experiment, and it can be applied in developing new spinning drafting device.     

Timoshenko梁理论在抗震建筑设计中的应用

通过对Timoshenko梁理论的研究和分析,将其引入抗震建筑设计.结合有限元方法,建立抗震建筑简化模型的质量和刚度矩阵,并通过Matlab仿真进行检验,保证简化模型的有效性.研究结果为抗震建筑设计奠定一些基础.