發(fā)布時(shí)間：2018-09-06 12:20

【摘要】：青海省鐵吾水電站HL220-WJ-71水輪機(jī)組采用的是截面等徑圓斷面彎管式鑄造尾水管,該尾水管中設(shè)有中隔板。加上隔板的目的是為了破壞渦帶的形成,降低水力損失及減輕尾水管振動(dòng)；但是由于隔板的存在,不僅增加了摩擦損失,水流撞擊隔板后還使得隔板嚴(yán)重受損。因此,本文通過CFD(Computational Fluid Dynamics)數(shù)值模擬技術(shù),對(duì)鐵吾電站等截面尾水管的隔板是否有存在的必要性進(jìn)行驗(yàn)證,并將一般彎肘型尾水管與等截面尾水管進(jìn)行性能對(duì)比。 通過計(jì)算可以得出,等截面無隔板尾水管與等截面有隔板尾水管的性能比較如下：在小流量下,等截面無隔板尾水管內(nèi)部流動(dòng)非常紊亂,有明顯的渦帶,二次回流以及滯流現(xiàn)象嚴(yán)重；而加上隔板后流動(dòng)狀態(tài)得到了一定程度的改善,盡管水流撞擊隔板會(huì)引起水力損失,但是整個(gè)水輪機(jī)組的效率還是得到了明顯的提升。在最優(yōu)工況以及大流量下,兩種尾水管的流動(dòng)狀態(tài)大致相同,速度以及壓力分布合理,流態(tài)較為穩(wěn)定,所以隔板基本沒有起到改善尾水管內(nèi)流動(dòng)狀態(tài)的作用,反而增加了摩擦損失,因此在最優(yōu)工況以及大流量下,增加隔板反而使得整個(gè)機(jī)組的效率有微小的下降趨勢(shì)。 對(duì)比分析彎肘型尾水管與等截面尾水管可以看出,無論在小開度、最優(yōu)開度還是大開度下,機(jī)組使用彎肘型尾水管的效率都要高于機(jī)組使用等截面尾水管的效率,說明彎肘型尾水管內(nèi)部流動(dòng)狀態(tài)更為合理,恢復(fù)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.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TK730.314

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