模型可逆式水泵水轮机S区压力脉动测试

S区特性是影响可逆式水泵水轮机过渡过程工况运行稳定的重要影响因素,通过研究模型水泵水轮机S区压力脉动可以为准确预测真机过渡过程工况下的特性奠定基础,为设计和运行提供有效指导。本文在某模型水泵水轮机特性试验的基础上,对S区包括蜗壳进口、无叶区、尾水锥管和尾水肘管等测点的压力脉动进行了测试,获得了各测点压力脉动混频幅值的分布与频率成分变化情况。测试结果表明:在等开度线上,飞逸工况时各测点的压力脉动混频幅值达到最大;同一工况点,无叶区压力脉动大于蜗壳进口压力脉动;沿流道方向,无叶区、锥管0.4D2、锥管1.0D2和肘管压力脉动依次减小;S区部分工况点存在主频为0.63fR的旋转失速频率;0.18fR频率成分广泛分布于S区内各工况点和测点中,引起这方面的原因可能是尾水管中的低频涡带、低频振荡或装置固有频率。     

水泵水轮机泵工况下近设计点驼峰现象的流动机理研究*

中高比转速水泵水轮机泵工况下近设计点驼峰严重制约了其稳定运行范围,是制约抽水蓄能电站安全与经济运行的关键问题之一。作为流动问题的宏观表现,驼峰现象必然与水泵水轮机内部的非定常流动存在密切关系。为此,基于试验和数值模拟,对水泵水轮机泵工况下可调导叶流道内的非定常流动进行研究,探究模型机泵工况下的压力脉动特性、非定流动机理及与性能曲线稳定性之间的关系。结果表明：在设计和小于设计工况下,可调导叶流道内均存在两种显著的周期性压力脉动。模型机泵工况下的流量扬程曲线在0.45~0.75倍设计流量区间内出现驼峰,频域分析清晰地揭示了以上两种压力脉动是对该驼峰存在重要影响的流动参量。     

水轮机固定导叶的涡街模拟与振动分析

研究三峡右岸部分机组水轮机固定导叶出水边处的卡门涡街共振问题.根据机组的实际运行情况和产生异常噪声的特点,应用计算流体力学(Computational fluid dynamics,CFD)数值分析技术对固定导叶开展出水边处的涡街振动模拟,建立模拟涡街振动的CFD数值模型,采用Fluent软件实现对卡门涡街振动特性的定...     

基于奇异值分解的水轮机空化压力脉动调控方法

为了减小水轮机运行过程中空化、空蚀对效率和出力的影响,合理地分析和提取空化信号对指导水轮机的调控和运行有重要意义。文中提出了一种基于奇异值分解的水轮机空化压力脉动信号提取方法,采用奇异值辨识法对试验测得的压力脉动信号进行分离,分析水轮机产生空化时的压力脉动波形,以提高对空化工况分析的准确性,通过CFD仿真优化,模拟水轮机运行的工况,分析空化现象与压力脉动信号的关系。采用奇异值分解方法对水轮机压力脉动信号进行分离,实现脉动信号的降噪和特征提取。结合PID控制技术和远程检测技术,实现对流量、水位、补气阀开度的智能调控,保障了水轮机组的平稳运行。     

水轮机尾水管内部压力脉动试验研究

水轮机尾水管内部的水压力脉动是影响水轮机组运行稳定性和发电效益的重要因素之一。对水轮机模型,测取了从直锥段进口至尾水管出口8个截面共26个测点在6个稳定运行工况下的水压力脉动数据。通过水压力脉动数据的FFT频谱分析,研究了直锥段和尾水管内部在不同位置不同工况下的压力脉动在时域及频域上的变化规律。结果显示,尾水管内部的压力脉动在不同位置不同工况都有区别,直锥段内的压力脉动与转轮出口流态密切相关,尾水管肘管之后的压力脉动与尾水管本身的形状关系较大。这对改善尾水管设计、提高机组运行稳定性具有参考价值。     

刘老涧泵站泵装置模型和水力性能等数据的检验对比研究

通过刘老涧泵站模型装置性能试验,得出能量、空化、飞逸特性、压力脉动试验及反向发电试验等数据,同时对机组试运行时的实际扬程、功率、流量、效率、温度、振动及泵房噪声等进行测定,对两种数据进行具体分析比较,得出水泵在不同角度下的效率与模型试验差值在-1.78%～+4.17%之间,基本能达到设计要求,实际运行的各项检测数据均满足设计和规范要求。     

1000 MW核主泵水力计算与压力脉动分析

本文以1000 MW核电轴流式核主泵为研究对象,首先对稳态条件下核主泵全流道流场进行计算,通过与试验值进行对比,验证了CFD数值计算准确性和精度。同时为了掌握核主泵全流道压力脉动特性,以稳态计算结果为初始条件,对核主泵非稳态数值计算,在计算中轴流泵设置了15个压力脉动监测点。计算结果表明:泵壳进口区域压力脉动为规则正弦波,主要频率为叶频;叶轮和导叶相互作用影响,压力脉动变化较复杂,脉动频率成分较多且脉动幅值较大;泵壳出口区域总体脉动较弱。     

基于支持向量机的水轮机特性建模

水轮机运行中要考虑空化问题和稳定性问题,因此,有必要建立水轮机空化特性和压力脉动特性的数学模型。针对经过试验得到的水轮机空化特性和压力脉动特性相对应的空间曲面比较复杂的特点,本文研究用支持向量机对水轮机空化特性和压力脉动特性进行建模,并应用于四川紫坪铺水力发电厂中的水轮机空化特性和压力脉动特性的建模中。建模结果表明,水轮机空化特性和压力脉动特性的支持向量机双输出模型,能真实的表达水轮机的空化特性和压力脉动特性,并具有较强的泛化能力,可以在控制水轮发电机组的运行等方面得到应用。     

叶轮形式对双吸离心泵压力脉动特性影响试验研究

双吸离心泵压力脉动是影响水泵机组运行稳定性的关键因素之一.为研究叶轮形式对双吸离心泵压力脉动的影响,对5种方案的叶轮进行压力脉动同台试验.通过在吸水室和压水室壁面布置压力脉动传感器,采集各个测试流量下的压力脉动信号,并进行混频幅值和频谱分析,得到吸水室和压水室的压力脉动分布规律.结果表明:双吸离心泵普遍存在叶片通过频率、泵轴旋转频率和低于轴频的低频脉动成分.相对于传统双吸叶轮,两侧叶片交错布置后可改善压力脉动特性;调整叶片出口边形状,增加叶片后盖侧的包角,可明显降低压水室叶片通过频率的脉动幅值,减轻动静干涉的危害;采用长短叶片形式可改善叶轮进口流态,降低吸水室的压力脉动,改善小流量工况下压水室的压力脉动特性.     

立式轴流泵装置叶片区压力脉动数值分析

压力脉动是影响轴流泵装置安全稳定运行的重要因素之一,为明确轴流泵装置叶片区压力脉动的变化规律,基于CFD软件对立式轴流泵装置全流道进行三维非定常数值计算,获得了轴流泵装置叶轮和导叶体区域的压力脉动时域数据,分析了最优工况时各监测点压力脉动特性,以及3个特征监测点的压力脉动随流量的变化规律。结果表明:最优工况时,叶轮进口压力脉动幅值从轮缘到轮毂逐渐减小;叶轮出口压力脉动幅值从轮缘到轮毂先减小后增大;导叶体出口处的压力脉动幅值从轮缘到轮毂先增大后减小。叶轮进口轮缘处压力脉动幅值随流量增大而减小;叶轮出口轮缘处压力脉动幅值随流量增大先减小后增大;导叶体出口轮缘处压力脉动幅值随流量增大而减小。小流量工况时各监测点的压力脉动主频幅值均大于最优工况和大流量工况。计算结果为分析轴流泵安全稳定运行提供了参考。     

Analysis of the Pump-turbine S Characteristics Using the Detached Eddy Simulation Method

Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.     

基于OpenFOAM的导叶式离心泵数值模拟研究

针对目前有关OpenFOAM对带导叶这种特殊结构的离心泵的计算研究较少且没有形成系统性研究的现状,为了验证OpenFOAM开源软件在导叶式离心泵数值计算方面的可靠性,分别对0.6Qd～1.4Qd流量工况下的导叶式离心泵进行外特性试验以及稳态和瞬态的数值计算.结果表明:OpenFOAM计算得到的外特性结果贴近试验数据,最...     

高压叶片泵流量脉动CFD模拟

高压泵是液压系统中的核心设备,流量脉动是影响其输出稳定性的重要参数。针对液压系统双作用高压叶片泵,采用CFD方法对其内部流场进行了三维瞬态模拟,分析了不同工况对出口流量脉动及其性能的影响规律。结果表明：排油初期高压差的作用使得工作腔内会出现明显的回流现象,产生较高的流量脉动;随着叶顶间隙的增大,泵的流量脉动减小,但容积效率明显下降,间隙值为30μm时,容积效率仅为61.1%;流量脉动幅度随叶片数的增多而减小;吸液压力为0.1 MPa时的流量脉动率为0.2 MPa时的4.4倍,容积效率增大了5.6%。因此,提高吸液压力可以有效改善泵的流量脉动和容积效率。     

新型轴流导叶可调液力变矩器设计与分析

采用“两圆弧+直线”的设计方法设计了有效直径370 mm的新型轴流导叶可调液力变矩器循环圆;运用等倾角射影法设计了新型轴流导叶可调液力变矩器各叶轮叶片的叶形,并给出了其总体结构。为了实现导轮叶片的转动,设计了导叶调节机构和导轮内外环结构,阐述了实现导轮叶片转动的过程,并定义了导叶开度的变化范围。运用CFD方法对所设计的新型轴流导叶可调液力变矩器进行数值模拟计算,获得了其原始特性,并对其特性进行了分析。由分析可知,通过调节导叶开度的变化能够实现轴流导叶可调液力变矩器能容的连续可控。由于其连续可控的能容特性,在与发动机共同工作时能够实现动态匹配,进而提高整机性能。     

Hydraulic design and performance analysis on a small pump-turbine system for ocean renewable energy storage system

Korea has a myriad of islands in the south western coast that extensively rely on diesel generators for power production, which increase cost and environment pollution. The small hydro pump-turbine system for ocean renewable energy storage system is a kind of hybrid system that can reduce the usage of diesel generators and help to contribute to the environment in a positive manner by helping to reduce carbon emissions. The study focuses on initial hydraulic design and numerical analysis of a 30 kW-class pump-turbine system for energy independent islands in South Korea. The purpose of the study is to propose an ocean renewable energy storage system using a small pump-turbine system working with seawater. A 30 kW-class pump-turbine does not require a large head; approximately 30 m is sufficient for the design and application. Several other renewable energy systems like wind turbines, tidal turbines, wave energy converters and solar energy could be used to make a hybrid system with pump-turbine. The initial design achieved more than 85 % efficiency in both pump and turbine modes. However, further optimizations of the impeller blade shape and number of guide vane and stay vanes could improve the overall efficiency of the system.     

直接空冷机组排汽管道内加装导流片的流场的数值模拟

研究直接空冷机组排汽管道的重点是均衡各蒸汽分配管内的流量和降低压降。利用计算流体力学软件FLU-ENT,在典型工况下对某600MW直接空冷汽轮发电机组排汽管道内的蒸汽流场进行了数值模拟,然后在管道内增加和调整导流片进行模拟来得出最佳的导流片布置方式。结果表明:在最佳导流片布置的情况下,蒸汽在蒸汽分配管道内流量均衡,流动阻力减少。     

Entropy production analysis for hump characteristics of a pump turbine model

The hump characteristic is one of the main problems for the stable operation of pump turbines in pump mode.However,traditional methods cannot reflect directly the energy dissipation in the hump region.In this paper,3D simulations are carried out using the SST k-ω turbulence model in pump mode under different guide vane openings.The numerical results agree with the experimental data.The entropy production theory is introduced to determine the flow losses in the whole passage,based on the numerical simulation.The variation of entropy production under different guide vane openings is presented.The results show that entropy production appears to be a wave,with peaks under different guide vane openings,which correspond to wave troughs in the external characteristic curves.Entropy production mainly happens in the runner,guide vanes and stay vanes for a pump turbine in pump mode.Finally,entropy production rate distribution in the runner,guide vanes and stay vanes is analyzed for four points under the 18 mm guide vane opening in the hump region.The analysis indicates that the losses of the runner and guide vanes lead to hump characteristics.In addition,the losses mainly occur in the runner inlet near the band and on the suction surface of the blades.In the guide vanes and stay vanes,the losses come from pressure surface of the guide vanes and the wake effects of the vanes.A new insight-entropy production analysis is carried out in this paper in order to find the causes of hump characteristics in a pump turbine,and it could provide some basic theoretical guidance for the loss analysis of hydraulic machinery.     

基于数值模拟的新型轴向导叶性能分析

由于塑料具有成本低、轻巧、表面光洁等优点已获得广泛的工程应用。但传统扭曲空间导叶由于叶片几何边界复杂,很难通过注塑工艺进行生产,而应采用圆柱叶片。因此,本文通过125QJ20型塑料泵的研发,设计出新型轴向导叶。为分析该导叶的性能,结合自主开发的导叶设计软件DLSJ,根据参数设计出另一径向导叶模型,并将同一叶轮分别与两个导叶进行匹配。再通过Fluent软件,采用标准k-ε模型、SIMPLEC算法对这两组模型分别进行了全流场数值计算,并对导叶内部内流场进行对比分析,结果表明轴向导叶外特性明显优于径向导叶。通过流场分析,该新型轴向导叶能改善导叶内部流动,提高井泵水力性能。同时,新导叶具有注塑简单的特点,可有效降低成本,有着较好的市场前景。     

Thermo-hydraulic characteristics of Hybrid mixing vanes in a 17×17 nuclear rod bundle

The lateral flow in the sub-channel of a nuclear rod bundle increase turbulent mixing and enhance heat transfer rate and safety. Various types of mixing vanes have been investigated to produce more lateral flow. In this study, the thermal-hydraulic characteristics of Hybrid mixing vane in a 17×17 rod bundle were calculated. Hybrid mixing vane has bended root part and split stem part. The computation was performed using a supercomputer due to the high number of grid meshes. The characteristics of Hybrid mixing vane were compared to Split mixing vane. The Hybrid mixing vane showed higher values of secondary intensity, cross-sectional turbulence intensity and Nu number and lower values of maximum temperature and standard deviation of temperature. Meanwhile, The Hybrid mixing vane has higher invariance because small vortexes travel, stretch and are connected with main stream.     

大型混流式模型机组动应力及压力脉动测试研究

最近几年在若干水力工程中,由于设计及机组运行调度的不合理,一些电站的机组,尤其是转轮叶片出现了局部裂纹问题,这引起了业界的高度关注。为此,东方电机在模型机组和真机上开展了叶片表面的动应力及表面压力脉动的测试。呈现模型机组测试的结果,通过这种测试发现最大的压力脉动幅值出现在转轮进口边区域,叶片表面上的压力脉动幅值明显大于转轮与活动导叶动静干涉所在的无叶区诱发的压力脉动幅值以及尾水涡所在的尾水管区域诱发的压力脉动幅值。叶片表面的压力脉动对应的主频和动应力对应的主频一致,主要为叶片数通过频率。动应力表现为类转频、尾水涡频率和动静干涉频率的叠加。