【作者】 王银平；

【导师】 练继建； 郭祺忠；

【作者基本信息】 天津大学 ， 水利工程， 2018， 硕士

【摘要】 为了克服水电站纯一维计算无法准确描述关键部件动态特性以及全三维计算浪费计算资源的弊端,对水电站水力系统进行一维三维耦合模拟计算有很大的必要性。本文依托雅砻江某水电站,首先在现场对水轮机内压力进行了测试,然后基于课题组对该水电站调压室水位波动的数据进行了以下研究:(1)通过Visual Basic6.0实现了对FLUENT的二次开发,建立了一维三维耦合模拟模型,实现FLUENT打开、读取case以及date文件、更改边界条件、计算、输出耦合面数据等自动化操作。(2)利用耦合模型和传统的一维模型对雅砻江某水电站引水隧洞、调压室系统进行单机甩负荷过程计算。与实测数据对比发现:一维模型计算大室、升管1、升管2的水位振幅为56.84m、57.95m、57.95m,与实测数据差值为-0.23m、1.71m、0.58m;耦合模型计算振幅为57.20m、55.50m、57.69m,与实测数据差值为0.13m、-0.74m、0.32m。在描述各部位水位差方面,一维模型最大误差4.16m,耦合模型最大误差1.06m,耦合模型能够更好模拟各部位水位差以及调压室内水流的振荡特性。分析2#机组蜗壳进口压力频率为0.002Hz与调压室相同,调压室水位波动会对机组产生影响。对溢流堰高度、升管面积、大室底部阻抗孔面积对调压室水力特性的影响进行了研究,结果表明,溢流堰高度越高、升管面积越小、大室底部阻抗孔越小,波动周期和振幅越小。(3)在雅砻江某水电站开展原型试验,对水轮机蜗壳入口及尾水管出口脉动压力数据进行测试。建立水轮机模型进行稳态计算,将计算所得蜗壳进口压力、末端压力与尾水管进口压力与实测数据对比,误差分别为3.70%、4.58%、7.18%。真机试验满负荷下蜗壳入口压力脉动主频为0.38Hz;尾水管进口脉压主要为0.3-0.9Hz,数值计算频率为0.73Hz、0.38-0.76Hz。利用耦合模型对雅砻江某水电站引水管道水轮机系统进行了飞逸过渡过程计算。计算结果显示:飞逸过渡过程中水轮机蜗壳压力以及导叶压力上升,压力下降梯度减小;转轮内水流流向恶化,发展为冲击水轮机叶片。分析飞逸计算末时刻蜗壳和尾水管入口脉压频率分别为0.78Hz及0.78-1.56Hz,蜗壳入口脉动由尾水涡带引起,故尾水涡带频率增加,不利于水轮机运行。更多还原

【Abstract】 In order to overcome the shortcomings of hydropower station pure one-dimensional calculation can not accurately describe the dynamic characteristics of key components and the waste of computational resources in full three-dimensional calculation,it is necessary to carry out one-dimensional three-dimensional coupled simulation calculation of hydropower system.Based on a hydropower station in Yalong River,this paper first tests the internal pressure of the turbine at the site,and then based on the data of the research group on the water level fluctuation of the hydropower station:(1)Through Visual Basic 6.0,the secondary development of FLUENT is realized,and a one-dimensional three-dimensional coupled simulation model is established to realize automatic operations such as opening and reading case and date files,changing boundary conditions,calculating and outputting coupling surface data.(2)The coupling model and the traditional one-dimensional model were used to calculate the single-machine load shedding process for the diversion tunnel and surge tank system of a hydropower station in Yalong River.Compared with the measured data,it is found that the water level amplitudes of the large chamber,riser 1,and riser 2 are 56.84 m,57.95 m,and 57.95 m,and the difference from the measured data is-0.23 m,1.71 m,0.58 m.The calculated amplitude of the model is 57.20 m,55.50 m,57.69 m,and the difference from the measured data is 0.13 m,-0.74 m,0.32 m.In describing the water level difference of each part,the maximum error of the one-dimensional model is 4.16 m,and the maximum error of the coupling model is 1.06 m.The coupling model can better simulate the water level difference of each part and the oscillation characteristics of the water flow in the pressure regulating room.Analysis of the 2# unit volute inlet pressure frequency is 0.002 Hz and the same as the surge chamber,the water level fluctuation of the surge chamber will have an impact on the unit.The effects of overflow weir height,riser area,and impedance hole area at the bottom of the chamber on the hydraulic characteristics of the surge tank were studied.The results show that the higher the weir height,the smaller the riser area,and the lower the impedance hole at the bottom of the chamber.Small,the fluctuation period and amplitude are smaller.(3)Prototype test was carried out at a hydropower station in Yalong River,and the pulsation pressure data of the turbine volute inlet and the draft tube outlet were tested.The turbine model was established to calculate the steady state.The calculated inlet pressure,end pressure and draft tube inlet pressure of the volute were compared with the measured data.The errors were 3.70%,4.58% and 7.18%,respectively.The true frequency of the volute inlet pressure pulsation at full load is 0.38 Hz;the inlet pressure of the draft tube is mainly 0.3-0.9 Hz,and the numerical calculation frequency is 0.73 Hz and 0.38-0.76 Hz.The coupling model was used to calculate the flyover transition process of the water turbine system of a hydropower station on the Yalong River.The calculation results show that the pressure of the turbine volute and the pressure of the vane rise during the transition period,and the pressure drop gradient decreases.The flow direction of the runner deteriorates and develops into the impact turbine blade.The pulse pressure frequencies at the entrance of the volute and the draft tube at the end of the calculation are calculated to be 0.78 Hz and 0.78-1.56 Hz,respectively.The vortex inlet pulsation is caused by the tail water vortex,so the frequency of the tail water vortex increases,which is not conducive to the turbine operation.更多还原