Effect of guide vane outlet angle on pump performance and impeller radial force in an axial-flow heart pump

To study the effect of guide vane outlet angle on pump performance and impeller radial force in an axial-flow heart pump, guide vane outlet angle/34 is considered to be 20°, 15°, 10°, 5° and 3° respectively. Based on ANSYS Fluent, numerical results of pump head and efficiency are validated by exper/ment results, in which Xanthan gum solutions are used with concentration of 0.06 wt. % as working fluid. Then, the effects of/34 on pump performance and impeller radial force are discussed, the errors of head and efficiency between test and simulation are within 5%. The results a/so indicate that the pump performance and efficiency are much better than those of other angles when guide vane outlet angle/34 is 10°, and the maximum variations in head and efficiency are 1.9% and 2.2%, respectively. With/34 increasing, the pulsation of radial force decreases firstly and then increases, when/34 is 10°, the minimum pulsation is 0. 0392N, which is about 80% of the maximum pulsation amplitude.

Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

Analysis of axial force of double circular arc helical gear hydraulic pump and design of its balancing device

In view of the axial force produced in the working process of double arc helical gear hydraulic pump,the theory of differential equation of curve and curved surface was utilized so that the calculation formula of axial force was obtained and the relationship between the axial force and structure parameters of gears was clarified.In order to balance the axial force,the pressure oil in the high pressure area was introduced into the end face of the plunger to press the plunger against the gear shaft,and the hydrostatic bearing whose type is plunger at the end of the shaft was designed.In order to verify the balance effect of axial force,the leakage owing to end clearance and volume efficiency of gear hydraulic pump before and after the balancing process was analyzed.This paper provides a new analysis idea and balance scheme for the axial force produced in the working process of the double arc helical gear hydraulic pump,which can reduce the leakage owing to end clearance caused by the axial force and improve the volume efficiency of the gear hydraulic pump.

Multi-objective Optimization Based on Unsteady Analysis Considering the Efficiency and Radial Force of a Single-Channel Pump for Wastewater Treatment

A multidisciplinary optimization was conducted to simultaneously improve the efficiency and reduce the radial force of a single-channel pump for wastewater treatment. A hybrid multi-objective evolutionary algorithm was coupled with a surrogate model to optimize the geometry of the single-channel pump volute. Steady and unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized using finite volume approximations and were then solved on tetrahedral grids to analyze the flow in the single-channel pump. The three objective functions represented the total efficiency, the sweep area of the radial force during one revolution, and the distance of the mass center of sweep area from the origin while the two design variables were related to the cross-sectional area of the internal flow of the volute. Latin hypercube sampling was employed to generate twelve design points within the design space, and response surface approximation models were constructed as surrogate models for the objectives based on the values of the objective function at the given design points. A fast non-dominated sorting genetic algorithm for local search was coupled with the surrogate models to determine the global Pareto-optimal solutions. The trade-off between the objectives was determined and was described in terms of the Pareto-optimal solutions. The results of the multi-objective optimization showed that the optimum design simultaneously improved the efficiency and reduced the radial force relative to those of the reference design.

A Numerical Investigation on the Characteristics of the Radial Force in a Cycloid Gerotor Pump

In order to improve the performances of a cycloid gerotor pump,the variations of the radial force induced by different rotating speeds and outlet pressures are analyzed numerically.Using the numerical simulations as a basis,an improved oil inlet and outlet groove structure is proposed.The results show that the radial force decreases with the decrease of the outlet pressure and of the rotor speed.Compared with the original model,the large-end oil inlet line and pressure line of the new oil groove are claw-shaped.This configuration can effectively weaken the pressure changes inside the gerotor pump and reduce accordingly the radial force on the inner rotor.

The Influence of Radial Area Variation on Wind Turbines to the Axial Induction Factor

Improvements in the aerodynamic design will lead to more efficiency of wind turbines and higher power production. In the present study, a 3D parametric gas turbine blade geometry building code, 3DBGB, has been modified in order to include wind turbine design capabilities. This approach enables greater flexibility of the design along with the ability to design more complex geometries with relative ease. The NREL NASA Phase VI wind turbine was considered as a test case for validation and as a baseline by which modified designs could be compared. The design parameters were translated into 3DBGB input to create a 3D model of the wind turbine which can also be imported into any CAD program. Design modifications included replacing the airfoil section and modifying the thickness to chord ratio as a function of span. These models were imported into a high-fidelity CFD package, Fine/TURBO by NUMECA. Fine/TURBO is a specialized CFD platform for turbo-machinery analysis. A code-geomturbo was used to convert the 3D model of the wind turbine into the native format used to define geometries in the Fine/TURBO meshing tool, AutoGrid. The CFD results were post processed using a 3D force analysis code. The radial force variations were found to play a measurable role in the performance of wind turbine blades. The radial component of the blade surface area as it varies in span is the dominant contributor of the radial forces. Through the radial momentum equation, this radial force variation is responsible for creating the streamline curvature that leads to the expansion of the streamtube (slipstream) that is responsible for slowing the wind velocity ahead of the wind turbine leading edge, which is quantified as the axial induction factor. These same radial forces also play a role in changing the slipstream for propellers. Through the design modifications, simulated with CFD and post-processed appropriately, this connection with the radial component of area to the radial forces to the axial induction factor, and finally the wind turbine power is demonstrated. The results from the CFD analysis and 3D force analysis are presented. For the case presented, the power increases by 5.6% due to changes in airfoil thickness only.

Effects of the radial force on the static contact properties and sealing performance of a radial lip seal

The radial force is a critical factor to determine the sealing performance of radial lip seals.The effects of radial force produced by garter spring and interference on the static contact properties and sealing performance of a radial lip seal are investigated by numerical simulations and experiments.Finite-element analysis and mixed elastohydrodynamic lubrication simulation are used.Radial force,contact width,temperature in the sealing zone,the reverse pumping rate and friction torque are measured.A critical value of interference for a cost-effectively designed radial lip seal is found.Spring force is required to compensate the decrease of the radial force because of the interference and used as a possible way to obtain intelligent control of sealing performance.The quantitative results gotten in this study could provide guide for the seal design and improvement.

Influence of Cross-Sectional Flow Area of Annular Volute Casing on Transient Characteristics of Ceramic Centrifugal Pump

The annular volute is typically used in a slurry pump to reduce the collisions between solid particles and the volute tongue and to achieve a better resistance to blocking. However, only limited studies regarding annular volutes are available, and there is no systematic design method for annular volutes. In this study, the influence of volute casing cross-sectional flow area on the hydraulic loss, pressure pulsations, and radial force under varying working conditions in a centrifugal ceramic pump are discussed in detail. Experimental tests were conducted to validate the numerical results. The results indicated that, when the volute casing flow area increases, the hydraulic performance decreases marginally under the rated working conditions, but increases at the o-design points, specifically under large flow condition. However, the volute casing with a larger flow area has a wider high-e ciency region. In addition, the increase in the volute casing flow area will decrease the pressure pulsations in the volute, regardless of the working condition, and decrease the radial force on the shaft, therefore, providing an improved pump operational stability. It is anticipated that this study will be of benefit during the design of annular volutes.

Development and Application of a Surface High-pressure Injection Device Using a Submersible Electric Pump

Injection recovery is an important measure for increasing the oil recovery rate of an oil field. One way is that centrifugal pumps or plunger pumps are used in an injection station to responsible for injection over a large area under the same pressure. This method is ineffective for low-permeability layers. For the oilfields in dispersed distribution in the marginal areas of Daqing, the low water-absorbing section needs an injection with a high delivery pressure and a low discharge capacity; another way is to install the submersible electric pump upside down, but because the submersible electric pump and the motor are underground, it is difficult for installation and maintenance. Introduced in this paper is the development and application of a surface high-pressure injection device with a submersible electric pump. Bysuccessful resolving some problems, such as the axial force of the submersible electric pump, sealing, level regulation of the pump, coaxiality and vibration, the device has the good points of running smoothly, moving easily, installation and maintains quickly and long period of running. This device can effectively solve the injection of the low water-absorbing section and of oilfields in dispersed locations. The recovery rate of oilfields is also enhanced.

屏蔽式离心泵浮动叶轮轴向力平衡方法

为了实现屏蔽泵离心叶轮轴向力平衡,设计浮动叶轮轴向力自平衡结构,借助全流道三维数值模拟手段,研究浮动叶轮的轴向力平衡作用机理和影响因素.在对数值模拟方法进行试验验证的基础上,开展针对不同工况下叶轮不同轴向位置轴向力的数值计算.数值模拟结果表明,在同一流量工况下,在叶轮浮动范围内,当叶轮向泵入口方向移动时,泵前腔泄漏量减小,扬程和效率增大,且越靠近入口,对泵的性能影响越显著.轴向力呈现先减后增的趋势,在远离入口时方向指向泵入口,在靠近入口时,叶轮轴向力迅速增大,实现反向,指向泵出口,帮助叶轮停止向入口移动,这种轴向力变化趋势可以使叶轮在工作时始终处于浮动状态,实现轴向力自平衡.

旋流泵叶轮流道固液两相流动不稳定性分析

由于结构的特殊性以及固液两相存在的密度差,旋流泵在输送固液两相介质过程中,内部会出现多方面的不稳定性特征,基于Particle模型,运用ANSYS CFX软件对额定转速下旋流泵在不同流量下输送不同固相体积分数的多种工况进行了非定常数值模拟,分析了叶轮流道内的固相分布、压力脉动和叶轮径向力,从而深入了解叶轮内部不稳定性。结果表明:在C_(v)=5%体积分数下,0.8 Q_(d)、1.0 Q_(d)流量下叶轮流道内固相体积分布均匀,1.2 Q_(d)分布不均匀;在C_(v)=10%体积分数下,0.8 Q_(d)流量下分布均匀,1.0 Q_(d)和1.2 Q_(d)流量下分布不均匀;在C_(v)=20%体积分数下,0.8 Q_(d)、1.2 Q_(d)流量下分布均匀,1.0 Q_(d)分布不均匀;在C_(v)=20%、1.0 Q_(d)工况的一个旋转周期内,叶轮内部始终存在一个条形固相分布区域,且其旋转速度滞后于叶轮旋转速度。在1.0 Q_(d)流量下,随着固相体积分数的增加,各监测点压力系数幅值波动逐步变大;后缩腔监测点叶频处的幅值基本不变,叶轮流道内监测点轴频处的幅值逐步变大;在C_(v)=20%体积分数下,随着流量的增加,各监测点压力系数幅值波动先增后减,后缩腔监测点叶频处幅值逐步增大,流道内监测点轴频处的幅值先增后减。相同固相体积分数下,随着流量的增加,径向力逐步增大;不同固相体积分数下,随着体积分数的增加,0.8 Q_(d)流量下径向力波动不大,1.0 Q_(d)流量下波动逐步变大,1.2 Q_(d)流量下波动逐步变小。

蜗壳断面形状对大型双吸泵性能影响的数值模拟

为研究蜗壳不同断面形状对大型双吸离心泵性能的影响,在确保其他因素不变的条件下,设计3种不同的蜗壳方案进行瞬态数值模拟。结果表明:3种蜗壳断面方案在设计工况下,圆形蜗壳的效率最高为90.7%,其次是梨形蜗壳,效率为90.2%,矩形蜗壳的效率最低为88.9%,且圆形蜗壳的高效区有所扩大;在各流量工况下圆形蜗壳能量损失率均为最少,在设计工况时圆形蜗壳的能量损失率为0.3%,矩形蜗壳的能力损失率为1.1%;在大流量和设计流量下,圆形蜗壳的叶轮所受径向力均最小,梨形蜗壳次之,矩形蜗壳最大;在设计工况下,3种蜗壳方案对蜗壳上的压力脉动均呈现周期性变化,圆形蜗壳在各检测点处压力脉动的振幅幅度均为最小。

阀板尾迹对离心泵性能的影响

离心泵进水管路通常布置阀门供检修时切断水流,这会导致离心泵入流畸变。该研究旨在分析泵前检修阀所诱发的非定常尾迹特征及其对大流量工况离心泵运行特性的影响机理。试验对比了均匀来流和畸变来流条件下离心泵的外特性,数值模拟研究了阀板尾迹涡的流动特征及其对离心泵非稳态内流场的影响,分析了阀板尾迹涡诱发的叶轮径向力。结果表明:两种来流条件下数值模拟与试验得到的离心泵外特性误差在5%以内;对离心泵性能产生主要影响的尾迹涡主要来自阀门阀板一侧的边界层分离与卷吸,入流畸变导致大流量工况下离心泵效率相较于均匀入流下降9.15%,扬程降低1.2 m;阀板尾迹在离心泵入口产生1.9倍转频的脉动频率;尾迹涡的周期性入流导致两个叶片前缘的最大相对液流角由30°分别增大至43°和39°,这两个叶片的压力面脱流加剧,产生逐渐向下游耗散的失速团,叶片承受2倍转频的非稳态激振力;尾迹涡的周期性吸入导致叶轮上的时均径向力增大至均匀入流的4.5倍左右,最大径向力达到均匀入流的7倍左右,径向力矢量发生偏移,离心泵断轴风险加剧。研究结果可为工业现场中离心泵运行稳定性的改善提供理论依据。

大功率磁悬浮泵宽流道叶轮的水力性能分析

磁悬浮泵将磁悬浮电机与泵体结构一体化,利用磁场驱动叶轮旋转,并对其余5个自由度进行主/被动悬浮约束,从而实现完全无轴承的介质泵送,被广泛用于半导体制造等领域的电子化学品超洁净输送。目前,大功率磁悬浮泵产品存在泵送效率低的问题,同时随着功率的增加,磁悬浮泵的液压轴向力平衡问题越发突出。为此,设计了一种大功率磁悬浮泵的宽流道叶轮,并对其进行水力效率、液压轴向力及液压径向力分析。通过仿真研究,首先阐述了窄流道效应对大功率磁悬浮泵水力效率的影响,并对宽流道叶轮及窄流道叶轮进行水力效率对比分析;其次对宽流道叶轮的液压轴向力及径向力进行计算分析,表明宽流道设计对叶轮液压轴向力及径向力的影响,为大功率磁悬浮泵高效水力设计开发提供关键技术支撑。

大配合间隙下阀芯偏斜对水嘴性能的影响

水嘴作为配水器的核心组件,目前已被广泛应用于注水油田。然而,水嘴在实际应用中会遭遇卡阻,导致阀芯无法正常调节,影响注水的效果。并且在测试过程中,很难观察到阀芯卡阻的细节,并重现这种现象。为了揭示水嘴卡阻机理,对不同开度下大配合间隙、阀芯偏心及倾斜对水嘴性能的影响进行了研究。首先,利用了仿真计算方法,建立了水嘴流体域有限元模型,构建了水嘴理论流量特性计算模型,通过实验获得了流量特性,验证了有限元模型的准确性;然后,分析了不同配合间隙下水嘴的流量特性及阀芯表面压力特征,获得了水嘴关闭时的泄漏量、阀芯受到的轴向力和径向力以及表面流动特征;最后,利用了遗传算法,优化了配合间隙。研究结果表明:大配合间隙使流量调节率曲线明显偏离标准曲线,流量调节率明显降低;水嘴在零开度时的径向力与轴向力最大;当配合间隙为0.05 mm时,泄漏量比间隙为0.25 mm时减少了84.56%;配合间隙对泄漏量的影响最为显著,其次为径向力和轴向力;优化配合间隙能够降低泄漏量和径向力,增大偏心与倾斜角能够降低卡阻风险,提高水嘴运行的可靠性。

直线共轭内啮合齿轮泵集中参数法建模与激振源研究

直线共轭内啮合齿轮泵作为高效且静谧性能良好的动力元件,在电静压作动系统得到广泛应用。本文采用集中参数法建立直线共轭内啮合齿轮泵仿真模型。建立了实验平台,对直线共轭内啮合齿轮泵进出口压力脉动进行了测试。分析了直线共轭内啮合齿轮泵在吸排油区的压力脉动、齿腔内压力分布以及齿轮和齿圈在x轴和y轴方向的径向力等激振源。研究结果表明:所建立的直线共轭内啮合齿轮泵集中参数模型具有良好的精度和可靠性;齿轮和齿圈径向力随偏转角周期变化,在x轴方向,齿轮所受到的径向力指向低压区,齿圈受到的径向力指向高压区。在y轴方向,齿轮和齿圈所受到的径向力在正负之间波动。齿轮和齿圈所受径向力在x轴方向的基频幅值均小于其在y轴方向的基频幅值;困油现象会导致齿腔压力略微升高。研究结果为直线共轭内啮合齿轮泵的优化设计和振动噪声分析提供了参考。

导叶叶片数对LNG四级潜液泵轴向力及首级叶轮流场的影响研究

应用CFD技术研究了导叶叶片数对LNG潜液泵首级叶轮压力和轴向力分布的影响,对一、三级导叶同时设计7、8、9三种叶片数,采用K-epsilon湍流模型进行了多工况数值模拟,并采用液氮工质进行了相关外特性试验验证,得到LNG泵内部首级叶轮压力分布以及轴向力特性。结果表明:潜液泵所受总轴向力在导叶数为8时最小,泵的整体效率最优。作用在首级叶轮上后盖板的轴向力大于前盖板。其中,导叶数为8时首级叶轮前后盖板轴向力最小,压力分布最均匀;而导叶数为9时,与叶轮叶片数9相同,运转时会有共同的倍频出现,在相同的倍频上振动累加,并诱发共振,导致前后盖板的轴向受力最大,叶轮前盖板所受轴向力相对于其他方案平均增加了3.45%;后盖板轴向受力绝对值平均增加1.88%。综上,导叶数为8时潜液泵的水力效率最优。

双排平衡式盘配流径向柱塞泵的设计与仿真

柱塞泵是液压系统的主要动力元件。针对单排径向柱塞泵工作时存在主轴径向力的受力不平衡问题,提出了一种双排转子-定子交错布置的平衡式盘配流新型径向柱塞泵结构。基于双排平衡式盘配流径向柱塞泵的工作原理,建立AMESim仿真模型,通过仿真分析其流量特性,确定选用双排九柱塞径向柱塞泵进行研究,分析柱塞泵系统压力、柱塞直径以及排角(两排相邻柱塞之间夹角)对主轴所受径向力的影响规律及影响机理。结果表明,系统压力和柱塞直径的变化,对径向力幅值影响较小,但会出现径向力突变,造成主轴变形;随着排角的增大,主轴所受径向力的突变频率和瞬时突变幅值会降低,逐渐趋于光滑曲线。

大型立式多级离心泵轴向力平衡装置研究

针对多级离心泵轴向力平衡问题,对大型立式多级泵轴向力平衡装置展开了研究,并分析对比了其在不同流量和泵级数下的轴向力平衡效果。通过数值模拟和试验研究,对立式多级泵轴向力和平衡装置推力进行了计算与分析,比较了不同工况下轴向力和推力的变化趋势及轴向力平衡效果。结果表明,多级泵轴向力、平衡装置推力与流量呈负相关,而轴向力平衡效果随着流量增大而加强;随着泵级数增加,多级泵轴向力呈现上升趋势,并且立式多级泵轴向力与泵级数呈非线性倍数关系,六级泵轴向力约为三级泵的2.5倍,推力装置的轴向力平衡效果随着泵级数增加而弱化;该轴向力平衡装置能够有效平衡大型立式多级离心泵轴向力,在各工况下能够平衡多级泵50%以上的轴向力;基于扬程估算推力与试验结果相近,可作为平衡装置推力快速估算方法。研究结果可为多级离心泵的设计及应用提供参考。

双吸离心泵变频调速过程中叶轮的径向力特性

为研究离心泵在变频调节过程中叶轮的受力特性,以某一单级双吸泵离心泵为研究对象,对其在“线性”及“非线性”2种变转速调节规律下泵内流场进行数值模拟,分析变转速过程中叶轮所受径向力及其流道内压力变化.结果表明:不同的变转速过程,转速变化率对径向力变化出现差异起主导作用;2种变转速过程中径向力在圆周方向的矢量分布呈现略微差异,非线性变化时各方向受力更加均匀,更利于设备稳定运行;相比不同时刻所对应的定转速工况,变速工况下径向力均偏大,在0.11 s时刻最为明显,且非线性变化过程径向力值增幅更大,达到534 N;在变频调节过程中,径向力的脉动频率以低频为主;相比于其他部位,叶轮出口的压力变化较明显,引起叶轮出口受力变化,是影响径向力大小的直接因素.