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| 1 | 混流式水轮机主轴中心孔补水对尾水管性能的影响显示文摘混流式水轮机在低负荷工况下运行时,尾水管内出现旋转的偏心涡带,会引起强烈的压力脉动和振动,严重威胁厂房的安全。为了使机组稳定运行,该文提出了一种通过从上冠泄水锥引入高压补水的方法来降低尾水管的不稳定性。该文首先采用商业软件CFX16.0,对某电站混流式水轮机在低负荷工况下进行了可靠而准确的全三维非定常数值模拟,结果表明在该工况下尾水管内部存在明显的偏心涡带,并伴随着振幅较大的压力脉动,这与试验结果相吻合。其次,对该工况下不同补水流量进行了数值模拟计算,研究表明:尾水管内补高压水可以有效降低尾水管内部的流动损失,且随着补水量的增加而越小,但过大的补水量会引起叶片正背面压力的降低,影响水轮机的空化性能,故补水量的大小必须综合考虑;主轴中心孔高压补水可以增加转轮出口的轴向速度,从而改变涡带内速度场的分布,可有效消除回流现象,当补水流量过小时,抑制回流作用不明显;当补水量为进口流量1%时,尾水管内部压力脉动振幅变化不大,改善效果不明显;当补水量为进口流量3%时,尾水管内部涡带由双螺旋变成单螺旋,锥管段压力脉动振幅不减反增,不稳定性有所加剧;当补水量为进口流量5%时,尾水管内部压力脉动振幅从18.4%降低至1.63%,同时改变了压力脉动的主频,使其远离转轮主频,避免发生共振,提高了机组的稳定性。 | 冯建军 李文锋 席强 朱国俊 罗兴锜 | 2017 | 农业工程学报2017，33，3： | 7 |
| 2 | A numerical method to simulate the coupled oscillations of flexible structures in flowing fluids显示文摘A numerical method is developed to simulate the coupled phenomena in a fluid-flexible-structure system.Specifically,a two-dimensional panel method is used to calculate the hydrodynamic forces and a modal superposition method is adopted to solve the governing equation of an Eulerian beam.The stability boundary of a single flexible beam in a uniform flow is calculated and compared with previous results to verify the validity of the code.The flow-induced flapping of a single and two flexible bodies for S=1.0,U=7.0 are investigated.For the flow-induced vibration of a single beam,the oscillation frequency is close to the secondary natural frequency of a cantilever.For two parallel flexible beams,they oscillate in phase when the non-dimensional separating distance H<0.25.When H>0.25,the out-of-phase mode occurs with a jump in frequency.When H>1,the interaction between the two beams decouples and the frequency and forces of each beam revert to behavior associated with a single beam in the same flow.Simulations of coupled-flapping of two tandem flexible structures proved that the drag acting on the upstream body is reduced while for that downstream drag is obviously increased when the structures are closely arranged.The numerical results obtained in the present work are qualitatively consistent with early experimental results. | WANG SiYing YIN XieZhen | 2010 | Chinese Science Bulletin2010，55，34： | 6 |
| 3 | 周期性扰动对鱼鳍波动推进性能影响数值研究显示文摘在鱼鳍的推进性能的研究中,鱼鳍波状运动产生推进力使鱼类具有很高的机动性,可以在复杂的水下环境中穿梭自如,可以实现精确的位置和姿态控制,且运动更具连续性和平稳性。针对上述问题,建立了鱼鳍摆动和波动的运动学方程,并借助于流体动力学软件比较分析了鱼鳍在没有前端扰动和加入前端扰动两种情况下的波动推进力和升力产生的机理,分析前后缘涡产生、脱泻、相互作用的过程,揭示前端周期性扰动对鱼鳍波动推进性能的影响及其规律。仿真结果显示:波动鳍对前端周期性扰动形成的尾迹反卡门涡街进行重新调制,可以从中获取能量用于提高自身波动推进性能。研究为研制高性能的多鱼鳍协调控制推进的仿鱼鳍推进器提供理论依据。 | 章永华 何建慧 | 2012 | 计算机仿真2012，29，10： | 2 |
| 4 | 波动鳍刚度对尾迹区域摆动翼推进性能的影响显示文摘为了弄清波动鳍刚度对位于其尾迹区域摆动翼推进性能的影响,基于计算流体动力学(CFD)原理,首先研究了摆动翼前端有无波动鳍干扰流动对其推进力产生的影响,进而分析波动鳍在四种不同鳍面刚度相同运动学参数下对摆动翼推进性能的影响情况,最后给出某一刚度下不同运动学参数对摆动翼推进性能的影响,并从涡动力学角度解释内在规律。通过计算发现:前端波动鳍产生的反卡门涡街与位于其后的摆动翼前缘涡旋转方向相反,使前缘涡强度减弱或消失;相同运动学参数下随着波动鳍刚度的增加,摆动翼的推进力随之降低;另外,摆动翼推进力随波动鳍的频率和摆幅的增大而减小。 | 何建慧 贾来兵 | 2015 | 系统仿真技术2015，11，2： | 0 |
| 5 | Spiral forces established by optical phase singularities显示文摘The spiral forces of phase singularities are demonstrated experimentally and numerically by presenting the generation and propagation dynamics of multiple optical vortices embedded in a Gaussian beam.The results reveal that the energy flow established by certain phase singularity will perform the characteristics of force on other singularities whose direction is determined by the sign of the topological charge.The force is confirmed by the fluid-like motions of multi-vortex beams,i.e.singularities undergo rotation(annihilation) with each other when they involve identical(opposite) topological charges.This force mechanism may help develop an intuitive understanding of multi-vortex motion and presents a new viewpoint from which to study the dynamics of singularities. | FANG Xiang DING ZhaoJun FENG YanLi ZHANG JianPeng | 2010 | Chinese Science Bulletin2010，55，35： | 0 |
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