Influence of inlet velocity condition on unsteady flow characteristics in piping with a short elbow under a high-Reynolds-number condition
Influence of inlet velocity condition on unsteady flow characteristics in piping with a short elbow under a high-Reynolds-number condition
复制标题
高雷诺数条件下入口速度条件对短弯管管道非定常流动特性的影响
DOI：
10.1299/mej.16-00217
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
H. Kamide
中科院分区：
文献类型：
--
作者：
A. Ono;Masaaki Tanaka;J. Kobayashi;H. Kamide
在日本先进钠冷快堆的设计中，冷却剂在直径为1.27 m的主热段（H/L）管道中的平均速度约为9 m/s。在H/L管中的雷诺数达到4.2 × 107。此外，在H/L管道中使用Rc/D = 1.0（Rc：曲率半径，D：管道直径）的短弯头，以实现紧凑的工厂布局并降低工厂建设成本。在H/L管道中，由于短弯管内的压力波动引起的激振力，流激振动（FIV）是一个值得关注的问题。在以前的研究中，流动分离和压力波动之间的关系，在短弯管的特定的入口条件下的时间平均轴向速度的平坦的速度分布和相对较低的速度波动强度进行了研究。然而，由于反应器容器（R/V）中的复杂几何形状，反应器中的H/L的入口速度条件可能是高度湍流的非均匀轮廓。本文研究了进口速度条件对短弯管内非定常速度特性的影响。虽然R/V中H/L入口周围的流动无法完全模拟，但通过安装适当堵塞流动孔的多孔板来控制入口速度条件。然后，在手肘进口上游2D处建立受控流型.通过粒子图像测速仪观察到的流动结构表明，进口速度分布影响周向二次流，然后影响手肘处的流动分离区域。在手肘上游观测到的低频分量的速度脉动，虽然强度有所减弱，但在手肘下游仍能保持。先进的H/L周围的流动模式表明，由模型R/V的几何形状引起的偏转流动影响手肘和管道中的流动分离，他们表明，与传统的平坦速度剖面相比，在具有偏转速度剖面的入口条件下，压力波动的幅度增加。采用激光多普勒测速仪（LDV）的平均速度剖面不能显示入口条件如何影响手肘内的流动结构，因为它们的入口条件非常复杂，包含统一的非定常流态。为了研究短弯管内进口条件与分离区的相互影响，
In the design of the Advanced Sodium-cooled Fast Reactor in Japan, the mean velocity of the coolant is approximately 9 m/s in the primary hot leg (H/L) piping, which has a diameter of 1.27 m. The Reynolds number in the H/L piping reaches 4.2 × 10 7 . Furthermore, a short elbow, which has R c /D = 1.0 ( R c : curvature radius, D : pipe diameter), is used in the H/L piping to achieve a compact plant layout and reduces plant construction costs. In the H/L piping, flow-induced vibration (FIV) is a concern due to the excitation force caused by pressure fluctuation in the short elbow. In a previous study, the relation between flow separation and pressure fluctuations in the short elbow was investigated under the specific inlet condition of a flat velocity profile of time-averaged axial velocity and relatively low velocity fluctuation intensity. However, the inlet velocity condition of the H/L in a reactor may be a highly turbulent non-uniform profile owing to the complex geometry in the reactor vessel (R/V). In this report, the influence of inlet velocity condition on the unsteady velocity characteristics in the short elbow was studied. Although the flow around the inlet of the H/L in the R/V could not be simulated completely, the inlet velocity conditions were controlled by installing a perforated plate, which appropriately plugged the flow holes. Then, controlled flow patterns were established at a position 2 D upstream of the elbow inlet. Observed flow structures by particle image velocimetry indicated that the inlet velocity profiles affected a circumferential secondary flow, which then affected an area of flow separation at the elbow. It was also found that the velocity fluctuation at low frequency components observed upstream of the elbow could remain in downstream of the elbow though its intensity was attenuated. the flow pattern around the H/L the Advanced showed the deflected flow caused by the geometry of the modeled R/V affected the flow separation in the elbow and pipe in they showed that the amplitude of pressure fluctuation increased under an inlet condition with a deflected velocity profile condition in comparison to that under a conventional flat velocity profile Their experimental of the one-dimensional time-averaged velocity profile using Laser Doppler Velocimetry (LDV) could not show how the inlet condition affected the flow structure in the elbow since their inlet condition was highly complex and contained unified unsteady flow patterns. In order to interaction between the inlet condition and separation region in the short elbow, an