摘要
该文对商业软件ANSYS CFX进行二次开发,通过自定义函数求解角动量方程获取实时转速,建立了模拟离心泵事故断电过渡过程的三维瞬态数值计算方法,获得了离心泵外特性参数瞬变规律以及内部流场的动态特性。进一步采用熵产理论获得了离心泵事故断电停机飞逸过程中过流部件流场能量损失分布情况,并对流场内随时间变化的能量损失进行定量评估。结果表明:在整个事故断电飞逸过程中,熵产与离心泵外特性之间存在着明显的相关性,能量损失的产生与流场内部的流动分离、回流、漩涡等不良流动现象相关;叶轮、导叶与引水管的主要损失均是由湍流耗散引起的,其壁面熵产占总熵产的10%~15%左右,不可以忽略,而蜗壳区的损失则主要是由近壁面处的强壁面效应引起的;通过分析各部件流场局部熵产率分布随时间的变化情况,可以得出在制动工况中内流场的高损失区域最大。
In this paper,a transient numerical calculation method is established based on ANSYS CFX software and user-defined program,which can simulate the power-off runaway transient characteristics of a centrifugal pump.The variation rule of external characteristic parameters with time can be obtained through numerical calculations and compared with experimental data.The comparison of results show that the simulation results agree well with experimental results,the proposed numerical method has been therefore validated.During the power-off runaway transient process,the centrifugal pump system will successively undergo the pump condition,braking condition,turbine condition and runaway condition,with external characteristic varying significantly during the process.Internal flow structure is closely related to external characteristic and affects each other.The hydraulic loss due to friction and unstable flow patterns in the pump causes a drop in hydraulic efficiency.The traditional method for analyzing the hydraulic loss is by evaluating the total pressure drop,which has certain limitations and cannot determine the exact locations at which the high hydraulic loss occurs.In this study,entropy production theory has been adopted to obtain a detailed distribution of the hydraulic loss in the centrifugal pump.Through the use of the entropy production theory,the variation of the entropy production was obtained.The distribution of energy loss of flow components during this process is obtained by using the entropy generation theory,and the energy loss is analyzed.The results show that there is a clear correlation between the entropy production and the external characteristics of the centrifugal pump during the entire runaway process.The entropy production also undergoes dramatic changes at the moment of sudden changes in flow rate,rotational speed and torque.The main losses of the impeller,guide vanes and suction pipe are caused by turbulent dissipation,and the wall entropy production accounts for about 10%–15%of this total entro
作者
冯建军
张钰
朱国俊
李昀哲
李文锋
罗兴锜
Feng Jianjun;Zhang Yu;Zhu Guojun;Li Yunzhe;Li Wenfeng;Luo Xingqi(Institute of Water Resources and Hydro-electric Engineering,Xi’an University of Technology,Xi’an 710048,China;Zhejiang FINE Institute of Hydraulic Machinery,Hangzhou 311121,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2020年第4期10-17,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划资助(2018YFB1501900)
国家自然科学基金(51679195)
陕西省自然科学基础研究计划资助项目(2019JQ-044)
陕西省教育厅科研计划项目(19JK0570)。
关键词
离心泵
流场
数值模拟
断电飞逸
熵产
瞬态特性
能量损失
centrifugal pump
flow field
numerical simulation
power-off runaway
entropy production
transient characteristics
energy loss
