Experimental Study of Churning Losses in Swash Plate Axial Piston Pump

The problem of the churning loss in swash plate axial piston machines is investigated through experimental measurement and theoretical analysis. Several works surrounding churning loss in hydraulic components have been proposed in the past, but few have conducted experimental studies and accounted for both dry and wet housing conditions. In this study,a specialized experimental setup is established, which includes a transparent test pump diligently designed for performing various functions of tests. The test pump can work as a real pump without losing any actual features of pump operation. The torque loss in both the dry housing pump and wet housing pump is measured in terms of the shaft speed and its predictive model is also developed analytically. The comparisons between measured and calculated torque loss are presented, showing how speed influences torque loss in both conditions. The advantage/disadvantages of the two cases are summarized. The significance of the test setup is highlighted by verifying the proposed model, which can advance the understanding of energy losses of high speed pumps in future.

Cross influence of discharge and circulation on head loss of conduit of pump system with low head

The relationship between the head loss and the discharge and circulation of the conduit of a pump system with low head is an important problem with an obvious influence on the improvement of its hydraulic performance. The velocity circulation from the pump guide vane makes the relationship more complicated, which has to be understood comprehensively. The results indicate that, under the condition of zero circulation, the head loss of the inlet and outlet conduits is in proportion to the square of discharge. Under the condition that the Reynolds number is satisfied with the resistant square area, the conduit loss is in proportion to the square of discharge for the similar working points with different speeds in a certain rotational speed range, indicating that the pump system efficiency is constant. The outlet conduit loss of design discharge for a pump system with low head depends on the velocity circulation from the guide vane exit, and the relationship between the loss and the circulation is an open curve with an upward direction, meaning that there is an optimal circulation for the loss. Under the condition of various working points for a pump system with low head, the head loss of the outlet conduit is under the cross influence of both the discharge and the circulation. As a result, the relationship between the head loss and the discharge is almost linear, and the mechanism needs to be further studied.

A Value Engineering Analysis of Head Loss in Pumping Mains

With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.

蝶阀在抽水蓄能电站尾水系统中的应用研究

为简化抽水蓄能电站尾水系统金属结构设备布置,提高电站防水淹厂房能力,提出了采用蝶阀作为尾水系统断流设备,并对其进行了可行性分析,同时还对蝶阀与事故闸门方案进行了对比研究。结果表明,尾水系统断流设备采用蝶阀方案切实可行,可提高防水淹厂房事故扩大的能力,简化设备的安装及减少土建施工。选定规格参数的蝶阀方案可降低建设成本,提高经济效益。研究结果可为类似工程的防水淹厂房事故扩大以及设备布置提供新的思路和技术参考。

基于熵产理论的水泵水轮机驼峰区内部水力损失特性研究

基于熵产理论,对水泵水轮机各个部件的水力损失进行了分析,并提出局部坐标系分析方法对转轮在多维度下的空间局部损失进行了定量分析。研究结果表明:在驼峰区工况下,间接熵产贡献的水力损失最高,占比71%;直接熵产贡献的水力损失最低,仅占比1%;壁面熵产贡献的水力损失占比27%;转轮进口叶片处流动分离现象发展成分离涡,引发靠近下环处回流产生,无叶区部分区域发生回流现象,导致了间接熵产显著增大;驼峰运行区内扬程的下降与水力损失的显著增加有关,受转轮进口以及无叶区的回流作用影响较大。

抽水蓄能电站上下库进出水口数值模拟分析研究

进/出水口是水电站引水建筑物的重要组成部分,其水力特性对于降低发电水头损失至关重要。为了降低进/出水口进流和出流时,因为吸气漩涡、逆向流等各种不利因素造成的水头损失对发电效益的影响,利用三维数学模型进行数值分析,以进/出水口流态、各流道分流比、拦污栅断面流速分布均匀性及水头损失等作为主要评价指标,对安徽省石台抽水蓄能电站上、下库进/出水口布置与体型进行了验证及优化,提出了推荐方案。结果表明:优化方案能有效改善进出水口的流态、流速不均匀系数和降低其水头损失,①推荐方案进/出水口进出流时各流道分流比为20.58%~30.45%,出流时为20.8%~27.91%,相邻边、中孔流道的流量不均匀程度均未超过10%,较为顺畅,未见吸气漩涡、强回流等不利流态,水流流态较好;②各孔流道内水流流速、流道间流量分配均匀性较好,进/出水口进流时拦污栅断面流速不均匀系数小于1.5,出流时小于2.0,满足相关规程要求;③进/出水口进流时水头损失系数0.28~0.30,出流时水头损失系数0.44~0.46,均符合规范要求。研究结果可供类似工程设计人员参考。

Performance Study Based on Inner Flow Field Numerical Simulation of Magnetic Drive Pumps with Different Rotate Speeds

Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researches on magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flow and high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magnetic drive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow field of magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According to analysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis of velocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating the power loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power loss between the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testing system. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head, while the pump efficiency could be got by calculating the power loss between the input power and the outlet power. The results of simulation and test were similar, which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magnetic drive pump.

基于减小中间换热器[火用]损的自复叠热泵系统最佳工质循环配比分析及实验研究

从自复叠热泵系统的循环[火用]损出发进行分析,发现中间换热器[火用]损最大,进而对减小[火用]损的方法进行了理论分析,并以R290/R170、R600a/R1150两种不同沸点差的二元混合工质组合为例,深入研究了混合工质循环配比对中间换热器[火用]损的影响。通过实验测试,验证了不同循环配比下整机性能的变化。结果表明:中间换热器[火用]损大小取决于换热过程高压侧及低压侧的温度匹配程度,可通过热当量比来体现,热当量比越接近1,[火用]损越小;不同混合工质组合,存在各自的最佳循环配比,使得整机性能最佳,该最佳循环配比与理论分析得到的使中间换热器[火用]损最小的循环配比接近。

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.

Nozzle Optimization for Water Jet Propulsion with A Positive Displacement Pump

In the water jet propulsion system with a positive displacement （PD） pump, the nozzle, which converts pressure energy into kinetic energy, is one of the key parts exerting great influence on the reactive thrust and the efficiency of the system due to its high working pressure and easily occurring cavitation characteristics. Based on the previous studies of the energy loss and the pressure distribution of different nozzles, a model of water jet reactive thrust, which fully takes the energy loss and the nozzle parameters into consideration, is developed to optimize the nozzle design. Experiments and simulations are carried out to investigate the reactive thrust and the conversion efficiency of cylindrical nozzles, conical nozzles and optimized nozzles. The results show that the optimized nozzles have the largest reactive thrust and the highest energy conversion efficiency under the same inlet conditions. The related methods and conclusions are extended to the study of other applications of the water jet, such as water jet cutting, water mist fire suppression, water injection molding.

宿迁市刘老涧泵站加固改造工程水土保持效果评价

生产建设活动导致的人为水土流失是区域水土资源退化的主要原因之一,开展生产建设项目水土流失全过程监管对于提高我国水土保持治理能力现代化水平至关重要。采用遥感监测、调查监测与定点观测相结合的水土保持一体化监测方法,对刘老涧泵站加固改造工程在施工建设期和试运行期的水土保持效果实施全面评估。结果表明,各种水土保持防护措施的有效落实,不仅有效控制了建设区域内的水土流失,而且土壤侵蚀现象也未大面积出现,起到较好的水土保持效果。研究结果能够为类似水利工程建设项目水土保持方案制定和监督管理提供参考。

基于熵产理论的管道泵流动损失特性分析

为了揭示管道泵运行过程中的流动损失特性,基于熵产理论,采用数值计算方法对管道泵吸水室和叶轮内的总熵产以及局部熵产率进行了研究,并结合压力脉动及涡核分布对其产生流动损失的原因进行了分析。研究结果表明,叶轮总熵产和吸水室总熵产保持高度一致性,吸水室内部流动影响了叶轮内部流动。随着流量的增大,叶轮和吸水室总熵产先减小,随后增大,这与其内部监测点的压力脉动主频幅值变化规律基本一致。叶轮总熵产显著大于吸水室总熵产,偏工况下更为明显,前者至少是后者的4倍。湍流耗散熵产占据吸水室和叶轮总熵产的90%以上,构成了流动损失的主要部分。吸水室高熵产率区主要分布在第二弯道及出口处,小流量工况下的熵产率是其余工况下的数百倍,该位置的大尺度带核涡以及附壁涡是导致熵产率增加的主要原因。叶轮高熵产率区主要集中在叶轮进口和出口,在大部分区域,小流量下的熵产率是其余工况的6倍以上,小流量工况下叶轮进口预旋和出口失速涡以及大流量工况下叶轮中上游的分离涡是导致熵产率较高的主要原因。该研究可为管道泵局部流动损失识别以及开展针对性优化提供参考。

设计工况下离心泵作液力透平内部流动耗散特性研究

离心泵反转作液力透平是一种能量回收装置,但缺点是即使在设计工况下的效率也相对较低。为揭示液力透平的流动耗散特性,文章首先通过流体动能方程构建了涡量与流动耗散之间的关系。随后,基于拟涡能耗散理论对设计工况下的流动耗散进行了定量计算。最后,对主要损失部件内的拟涡能耗散分布特性与局部主要流动特征进行了关联分析,进而揭示了透平内部流动耗散的发生位置和产生原因。结果表明:拟涡能耗散评估方法能够较为准确地计算透平的流动损失,设计工况下各部件损失占比大到小排列分别为:叶轮、蜗壳、腔体、出口段和进口段。叶轮内局部拟涡能耗散主要发生在吸力面的前缘下游及叶片尾缘附近,叶片前缘冲击、回流、旋涡等不稳定流动是导致叶轮内局部拟涡能耗散的主要原因。蜗壳的拟涡能耗散主要由出口回流、隔舌前缘及壁面处的附着旋涡粘性耗散引起,腔体的拟涡能耗散主要由前腔间隙射流所引起的旋涡耗散及壁面旋涡粘性耗散组成。出口管的流动耗散特性主要受叶轮出流条件的影响,前腔间隙射流会对出口管内的主流产生冲击并引起局部水力耗散。研究结果可为高性能液力透平的设计提供参考。

空间导叶式多级离心泵级间能量损失机理

为探究空间导叶式多级离心泵级间能量损失的原因,以1个单级和1个3级潜水泵为研究对象,通过试验和数值模拟相结合的方法,分析其级间能量损失的机理.对单级和3级潜水泵分别进行全流场外特性试验.基于ANSYS软件对3级潜水泵不同流量点进行数值模拟和内流场分析,着重对各级叶轮进口流态、内部旋涡结构和叶片载荷分析比较.结果表明:小流量工况下,3级潜水泵各级扬程接近且与单级扬程相差不大;额定流量工况和大流量工况下,3级潜水泵第1级扬程与单级扬程仍相差不大,但后2级扬程相比于第1级降低了6%~10%.随着流量的增大,首级叶轮来流稳定性不受影响,其后各级叶轮进流流态变差.后2级叶轮进口液体介质冲角变化使其对叶片进口边的冲击增大.后2级叶轮进口处的涡在流量较大时发展为流向涡,从而引起叶片载荷突变,削弱了叶轮做功能力,导致后2级能量损失.研究结果可为多级离心泵的设计提供理论依据.

径向剖分双吸式工业液力透平的内部流动损失特性分析

针对双吸式离心泵反转作液力透平运行区间狭窄、效率低等问题,对实际工程应用中的一台径向剖分双吸式离心泵反转作工业液力透平的内部流动损失特性进行了研究。首先,采用了数值模拟方法预测了液力透平在泵和透平典型工况下的水力性能,对比了透平在泵工况下的实验结果,验证了数值模拟的准确性和可靠性;然后,结合熵产理论,定量分析了透平工况下各过流部件对于总能量损失的权重以及熵产成分比重的分布情况;最后,结合局部流动特征进一步揭示了主要过流部件内流动损失的发生位置和产生原因。研究结果表明:壁面熵产是导致径向剖分双吸式工业液力透平内部流动损失的主要原因,在0.8Q_(b)、Q_(b)、1.2Q_(b)工况下,壁面熵产分别占总熵产的55.3%、69%、67.4%;导出室是透平内熵产占比最大的水力部件,局部回流、流动冲击等不良流动特征是导致湍流熵产增加的主要原因。该研究结果对离心泵反转作工业液力透平的优化设计、运行调控和推广应用有一定的借鉴意义。

一种用于微能量收集的升压电荷泵设计

开关电容直流-直流(Direct Current-Direct Current,DC-DC)变换器是电源管理系统中极其重要的一部分,升压电荷泵是其中的一个分支。在微能量收集的应用场景中,升压电荷泵的研究热点是实现低的泄漏电流和低的阈值电压损耗。多数升压电荷泵设计为了减少阈值电压损耗和电荷共享等非理想效应,使泄漏电流增大,或结构变得复杂,导致面积增大,不适用于微能量收集场景。Dickson电荷泵是早期的电荷泵结构,其结构简单实用,但较大的阈值电压损耗是其最大的缺点。为此,本文基于Dickson电荷泵进行分析,采用TSMC 250 nm工艺,使用中等阈值电压(Medium Threshold Voltage,MVT)型金属氧化物半导体场效应晶体管(Metal-Oxide-Semiconductor Field-Effect Transistor,MOS)代替二极管,降低阈值电压损耗,再利用体源二极管偏置技术,进一步降低阈值电压损耗。本文利用Positive MOS(PMOS)管与Negative MOS(NMOS)管级联的形式,减少泄漏电流,且NMOS管采用深N阱工艺,避免加入辅助电路。仿真结果表明,本文的升压电荷泵结构设计具有较好的性能表现,达到了设计要求。

基于卷积神经网络的抽油机故障诊断

抽油机故障诊断对于保障油气田的稳定运行至关重要.针对已有基于深度学习的故障诊断模型参数量大导致应用范围受限的问题提出一种基于空洞卷积和惩罚机制的卷积神经网络模型.该模型在浅层神经网络部署不同空洞卷积率的空洞残差模块高效获取示功图轮廓特征的同时降低了模型参数量.其次将惩罚机制融入Softmax损失函数增强模型诊断气体影响等难分样本的故障准确率.采用抽油机实况数据集进行实验验证结果表明该模型参数量为0.94 M浮点型计算量为165.24 M.与MobileNetV3相比改进后的算法模型在准确率同为96.6%的前提下参数量减少了3.30 M浮点型计算量减少了52.22 M更易部署在资源受限的故障诊断平台.

小型压水堆屏蔽泵的屏蔽套涡损计算方法及应用

屏蔽泵是小型压水堆一回路的核心设备,对整个反应堆的安全性与经济性有重要影响。屏蔽泵解决了轴封泵的泄漏问题,但屏蔽套使屏蔽泵的电涡流损耗更大,且热量难以带出,因此计算屏蔽套的电涡流损耗对屏蔽泵的设计和分析十分重要。常用屏蔽泵屏蔽套涡流损耗计算经验公式是基于两极千瓦级屏蔽泵提出和修正的,对于百千瓦级小型压水堆屏蔽泵计算偏差较大,有必要对其开展研究。文章首先针对常用屏蔽泵电机屏蔽套的电涡流损耗开展有限元计算,与实验结果对比,验证了有限元计算方法的精确性;其次,在考虑小型压水堆屏蔽泵特殊设计结构对屏蔽套电涡流损耗影响的基础上,修正了经验公式,使其适用于百千瓦级小型压水堆屏蔽泵;最后,基于修正后的经验公式提出了半有限元-经验公式结合算法的初步设计算法,应用于某小型压水堆屏蔽泵的结构设计。该方法使屏蔽电机的初步设计更加便捷。

旁路电流对全钒液流电池库伦效率的影响

为提高全钒液流电池(VRB)系统中电池的性能和效率,根据VRB的组成及原理,建立了包括电化学、流体力学、温度、旁路电流、钒电池多堆等效损耗电路模型,并探究全钒液流电池管道系统中的泵送损耗与旁路电流对钒电池的影响。通过建立泵送损耗和泵损电流之间关系、旁路电流模型、多堆串联的钒电池等效电路模型,将各模型“化零为整”,阐述了计及动态响应的钒电池的内核机理。详细探讨了VRB建模中涉及的关键因素,包括泵送损耗、旁路电流,并分析了电池性能和效率的影响因素。研究表明,管道的长度与横截面积等参数影响着管路电阻,较长的主管与支管会减小旁路电流,但会增大泵损电流;较长和较粗的管道有利于同时减小旁路电流和泵送损耗,提高了电池的能量效率,这为厂家管路设计提供了思路。

大型变速抽水蓄能发电电动机不同转速下三维端部电磁场和损耗研究

大型变速抽水蓄能发电电动机端部区域漏磁和构件损耗较高,为了研究不同转速时大型变速抽水蓄能发电电动机三维端部电磁场和端部构件损耗的变化规律,本文建立326 MW变速抽水蓄能发电电动机三维端部瞬态电磁场的数学模型,研究变速抽水蓄能电机在发电机工况下不同转速时定转子端部构件磁密的变化规律,确定变速抽水蓄能电机端部构件涡流密度的分布情况,探究变速抽水蓄能电机在发电机工况下不同转速时定子压圈、定子环板、转子护环以及转子齿压板等端部构件损耗的变化规律。采用相同的计算方法对小容量10 MW变速抽水蓄能发电电动机进行研究,通过试验测试和计算结果的对比验证了本文计算方法的可行性。