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地处寒冷地区的哈尔滨铁路局,温差达到100℃,采用轨枕横向挡板,经测试可增加道床横向阻力,提高允许升温幅度,这一措施有利于扩大无缝线路的铺设范围。 相似文献
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Mohammad Reza Shekari 《船舶与海洋工程学报》2014,13(3):299-304
In thispaper, the effects of a rigid baffle on the seismic response of liquid in a rigid cylindrical tank are evaluated. A baffle is an annular plate which supplies a kind of passive control on the effects of ground excitation. The contained liquid is assumed incompressible, inviscid and has irrotational motion. To estimate the seismic response, the method of superposition of modes has been applied. To analyze the rigid tank response, Laplace's equation is considered as the governing equation of the fluid domain, in both time and frequency domains. The boundary element method (BEM) is employed to evaluate the natural modes of liquid in a cylindrical tank. To gain this goal, the fluid domain is divided into two upper and lower parts partitioned by the baffle. Linearized kinematic and dynamic boundary conditions of the free surface of the contained liquid have been considered. 相似文献
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依托实际工程,对桩基挡板式透空堤的消浪特性开展物理模型试验研究,优化堤型结构,并将前人的研究成果进行应用。结果表明,对于受越浪影响较大的防波堤,堤后透射系数与堤顶越浪和堤底透浪有关,有必要在计算时考虑堤顶越浪这个因素;对桩基挡板式透空堤进行设计优化时,可以通过增加挡浪板的入水深度或增加堤顶高程或两者同时调整等方式增强其消浪特性;推荐使用Wiegel公式进行单挡板桩基透空堤透浪系数的估算;各家公式有各自的适用条件且针对的结构形式较简单,运用到实际工程中存在误差,需要分析不同工程所处的环境特点及结构设计特点,合理选择公式进行计算。 相似文献
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在尖劈和粗糙元大气边界层模拟技术的基础上增加了格栅挡板这一涡旋发生器,有效地提高了风洞上方的湍流强度,利用该组合边界层发生装置建立了边界层风场.测量了模拟风场的平均风速剖面,湍流强度剖面,风谱等参数.讨论了格栅挡板增加后风场平均风速剖面和湍流强度剖面的变化.三角形尖劈阻风面积沿高度递减产生近似线性的风速剖面,粗糙元调整平均风速和湍流度剖面分布,格栅挡板提高了风洞上方的湍流度.结果分析表明:试验所得风场满足模型试验所要求的小粗糙度和大湍流度的要求.然而,模拟风场的湍流功率谱和积分尺度的高度变化规律和实际大气边界层相反,这是由尖劈下宽上窄的构造特点所决定的. 相似文献
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