基于CFD流场计算的尾水管改进
发布时间：2018-09-06 12:20
【摘要】：青海省铁吾水电站HL220-WJ-71水轮机组采用的是截面等径圆断面弯管式铸造尾水管,该尾水管中设有中隔板。加上隔板的目的是为了破坏涡带的形成,降低水力损失及减轻尾水管振动；但是由于隔板的存在,不仅增加了摩擦损失,水流撞击隔板后还使得隔板严重受损。因此,本文通过CFD(Computational Fluid Dynamics)数值模拟技术,对铁吾电站等截面尾水管的隔板是否有存在的必要性进行验证,并将一般弯肘型尾水管与等截面尾水管进行性能对比。 通过计算可以得出,等截面无隔板尾水管与等截面有隔板尾水管的性能比较如下：在小流量下,等截面无隔板尾水管内部流动非常紊乱,有明显的涡带,二次回流以及滞流现象严重；而加上隔板后流动状态得到了一定程度的改善,尽管水流撞击隔板会引起水力损失,但是整个水轮机组的效率还是得到了明显的提升。在最优工况以及大流量下,两种尾水管的流动状态大致相同,速度以及压力分布合理,流态较为稳定,所以隔板基本没有起到改善尾水管内流动状态的作用,反而增加了摩擦损失,因此在最优工况以及大流量下,增加隔板反而使得整个机组的效率有微小的下降趋势。 对比分析弯肘型尾水管与等截面尾水管可以看出,无论在小开度、最优开度还是大开度下,机组使用弯肘型尾水管的效率都要高于机组使用等截面尾水管的效率,说明弯肘型尾水管内部流动状态更为合理,恢复性能更好。
[Abstract]:The HL220-WJ-71 turbine unit of Tiefu Hydropower Station in Qinghai Province adopts the cast draft tube with equal diameter and circular section, in which there is a middle partition. The purpose of adding the partition is to destroy the formation of vortex belt, reduce the hydraulic loss and reduce the vibration of the draft tube, but because of the existence of the diaphragm, not only the friction loss is increased, but also the diaphragm is seriously damaged after the water hits the partition. Therefore, this paper verifies the necessity of the existence of the partition plate of the equal-section draft tube in Tiegu power station by CFD (Computational Fluid Dynamics) numerical simulation technology, and compares the performance of the general curved elbow draft tube with the equal-section draft tube. Through calculation, it can be concluded that the performance of the iso-section non-partition draft tube is compared with that of the iso-section baffle draft tube as follows: under the small flow rate, the internal flow of the iso-section non-partition draft tube is very disordered, and there are obvious vortex bands. The secondary backflow and stagflation are serious, and the flow state is improved to a certain extent after adding the separator, although the hydraulic loss will be caused by the impact of the water flow on the separator, the efficiency of the whole turbine unit has been obviously improved. Under the optimal working condition and the large flow rate, the flow state of the two kinds of draft pipes is approximately the same, the velocity and pressure distribution is reasonable, and the flow state is relatively stable, so the baffle has no effect on improving the flow state in the tailings pipe. On the contrary, the friction loss is increased, so the efficiency of the whole unit decreases slightly with the increase of the partition plate under the optimal working condition and the large flow rate. By comparing and analyzing the bending draft tube and the equal section draft tube, it can be seen that the efficiency of the unit using the curved elbow draft tube is higher than that of the unit using the equal section draft tube, no matter under the small opening, the optimal opening or the large opening. The results show that the flow state of the elbow draft tube is more reasonable and the recovery performance is better.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK730.314
[Abstract]:The HL220-WJ-71 turbine unit of Tiefu Hydropower Station in Qinghai Province adopts the cast draft tube with equal diameter and circular section, in which there is a middle partition. The purpose of adding the partition is to destroy the formation of vortex belt, reduce the hydraulic loss and reduce the vibration of the draft tube, but because of the existence of the diaphragm, not only the friction loss is increased, but also the diaphragm is seriously damaged after the water hits the partition. Therefore, this paper verifies the necessity of the existence of the partition plate of the equal-section draft tube in Tiegu power station by CFD (Computational Fluid Dynamics) numerical simulation technology, and compares the performance of the general curved elbow draft tube with the equal-section draft tube. Through calculation, it can be concluded that the performance of the iso-section non-partition draft tube is compared with that of the iso-section baffle draft tube as follows: under the small flow rate, the internal flow of the iso-section non-partition draft tube is very disordered, and there are obvious vortex bands. The secondary backflow and stagflation are serious, and the flow state is improved to a certain extent after adding the separator, although the hydraulic loss will be caused by the impact of the water flow on the separator, the efficiency of the whole turbine unit has been obviously improved. Under the optimal working condition and the large flow rate, the flow state of the two kinds of draft pipes is approximately the same, the velocity and pressure distribution is reasonable, and the flow state is relatively stable, so the baffle has no effect on improving the flow state in the tailings pipe. On the contrary, the friction loss is increased, so the efficiency of the whole unit decreases slightly with the increase of the partition plate under the optimal working condition and the large flow rate. By comparing and analyzing the bending draft tube and the equal section draft tube, it can be seen that the efficiency of the unit using the curved elbow draft tube is higher than that of the unit using the equal section draft tube, no matter under the small opening, the optimal opening or the large opening. The results show that the flow state of the elbow draft tube is more reasonable and the recovery performance is better.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK730.314
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