S形轴伸贯流泵装置效率改进方案

S形轴伸贯流泵广泛应用于沿江滨湖地区的防洪、除涝、灌溉、调水和供水、水生态环境改善等重要工程领域,但其装置的关键技术研究较涉后,运行效率较低。文中分析了目前S形轴伸贯流泵运行效率较低的主要原因,并从泵的装置结构、流道结构和叶片角度调节等3个方面提出最新改进方案,显著提高泵装置效率,同时对不同结构的适用场景提出建议,应用前景广泛。

扬州市安墩闸站S形轴伸泵装置选择及应用

分析原安墩闸站运行资料,并结合移址改建后安墩闸站的设计运行管理要求,选择S形轴伸泵装置,排涝标准为20年一遇。土建工程量减小,工程运行耗能显著降低,每年节省电量约960MWh,闸站运行管理更加便捷。同时应用CFX对安墩闸站S形轴伸泵装置性能进行预测,结果显示S形轴伸泵装置内部流态平顺,水流运动十分合理。水泵叶片最佳安放角为-2°,最高运行效率可达76%,设计工况下运行效率可达75%。

平面“S”形卧式轴伸泵在特低扬程条件下的应用

通过对苏州城市防洪工程中东风新、大龙港等平面"S"形卧式轴伸泵的运行工况分析,并与青龙桥潜水贯流泵等其它泵型的比较研究,肯定了平面"S"形卧式轴伸泵应用在特低扬程地区的显著优势,就相关问题提出了几点启示。

黄金坝泵站平面S形贯流泵装置物理模型试验分析

平面S形贯流泵装置是特低扬程泵站的重要装置形式之一,以黄金坝泵站为研究对象,通过对该贯流泵装置S形弯管和流道的优化设计,达到了提高泵装置能量性能的目的。经物理模型试验结果表明,在叶片安放角为2°时,平面S形轴伸贯流泵装置的最高效率达78.35%,此时泵装置的流量为244.21 L/s,装置扬程为2.003 m。在扬程1.5~2.0m范围内,泵装置的效率均在73%以上,泵装置高效区运行的流量范围较大。该优化方法为后续S形贯流泵装置的优化设计提供了有效的参考。

平面S形轴伸泵在苏州市城市防洪工程中的应用

在此介绍江苏省苏州市城市中心区防洪工程的概况,根据该工程的特点对常用的泵型进行比较,着重分析了潜水贯流泵、斜轴泵和平面S形轴伸泵三种泵型的装置特性、运行管理特点。并从数模计算和装置模型试验来分析、验证平面S形轴伸泵在该工程中应用的可行性。

汽车单叶片真空泵设计中的数学理论

探讨单叶片真空泵设计中的数学理论。以椭圆曲线为研究实例,得出了椭圆可以作为单叶片真空泵设计中的给定曲线,并提供了原体形线设计的一般计算公式。

汽车单叶片真空泵设计中的最优椭圆曲线

单叶片真空泵的设计主要是确定泵体内腔曲面,使同时作旋转运动和径向滑动的叶片的圆柱形端面和它保持相切。泵体内腔曲面的投影必须是一条封闭的光滑曲线。设计时,这条光滑曲线的一部分通常被提前选定,而剩余部分则根据几何约束产生。尽管一般的椭圆曲线可以满足参考曲线和生成曲线在连接点一阶可导,但在连接点通常是二阶不连续的。将找出一条最优的椭圆参考曲线,使得泵腔形线在连接点处不仅是一阶连续的而且是二阶连续的。这将使得泵的运转更加平稳并减小由于叶片径向加速度不连续产生的振动和噪声。

浅谈双向泵站的泵型选择及其应用

根据上海地区防汛排水和引清调水的要求,需建造具有双向引排水功能的泵站,目前双向泵站常选用的泵型主要有:立式轴流泵、卧式轴流泵、潜水轴流泵及贯流泵等.可根据经济要求、扬程、周边环境等的具体情况和需求合理选择泵型.

色彩在服装中的搭配与运用

就色彩配色与调和基本原理、服饰色彩的搭配组合进行分析与运用,旨在帮助为衣烦恼的女性了解和掌握服饰色彩的多样组合方法,以充分利用有限的服饰,穿出不同的风彩与品味。

Theoretical and Experimental Study on Ground Coupled Heat Pump with Vertical Spiral Coil

The numeric al simulation study on the temperature distribution of underground field for the ground coupled heat pump (GCHP) with vertical spira l coil was carried out by using finite element. The distribution and recovery of undergroun d field temperature under different operation ratio and the optimal operation ratio were simulated.The performance parameters, i.e. inlet and outlet temperature of the ground spiral coil in heating and cooling modes were tested, the heat extracted or emitted by the heat pump to the ground was calculated, and the coefficients of performance (COP) of GCHP at heat ing and cooling modes were analyzed.

Numerical simulation on heat transfer performance of vertical U-tube with different borehole fill materials

Heat exchange performance of vertical U-tube heat exchanger was studied with two different borehole fill materials and CFD software. Borehole surface temperature and water temperature distribution were simulated on the condition of continuous operation for 8 h in winter with inlet water temperature being 10℃. The results show that there is no obvious difference on heat exchanger performance between the two different borehole fill materials.

Broadband Vibrational Cooling of Cold Cesium Molecules： Theory and Experiments

The use of a broadband, frequency shaped femtosecond laser on translationally cold cesium molecules has recently demonstrated to be a very efficient method of cooling also the vibrational degree of freedom. A sample of cold molecules, initially distributed over several vibrational levels, has thus been transfered into a single selected vibrational level of the singlet X^1∑g ground electronic state. Our method is based on repeated optical pumping by laser light with a spectrum broad enough to excite all populated vibrational levels but limited in its frequency bandwidth with a spatial light modulator. In such a way we are able to eliminate transitions from the selected level, in which molecules accumulate. In this paper we briefly report the main experimental results and then address, in a detailed way by computer simulations, the perspectives for a ＂complete＂ cooling of the molecules, including also the rotational degree of freedom. Since the pumping process strongly depends on the relative shape of the ground and excited potential curves, ro-vibrational cooling through different excited states is theoretically compared.

Optimal rotor wear design in hypotrochoidal gear pump using genetic algorithm

The wear rate between the rotors of a hypotrochoidal gear pump is characterized.Using the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated through the calculation of the Hertzian contact stress.Based on the above results and the sliding velocity between the rotors,a genetic algorithm (GA) was used as an optimization technique forminimizing the wear rate proportional factor (WRPF).The result shows that the wear rate or the WRPF can be reduced considerably,e.g.approximately 12.8%,throughout the optimization using GA.

Effect of blade tip geometry on tip leakage vortex dynamics and cavitation pattern in axial-flow pump

A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.

Performance Enhancement of a Pump Impeller Using Optimal Design Method

This paper presents the performance evaluation of a regenerative pump to increase its efficiency using optimal design method. Two design parameters which define the shape of the pump impeller, are introduced and analyzed. Pump performance is evaluated by numerical simulation and design of experiments(DOE). To analyze three-dimensional flow field in the pump, general analysis code, CFX, is used in the present work. Shear stress turbulence model is employed to estimate the eddy viscosity. Experimental apparatus with an open-loop facility is set up for measuring the pump performance. Pump performance, efficiency and pressure, obtained from numerical simulation are validated by comparison with the results of experiments. Throughout the shape optimization of the pump impeller at the operating flow condition, the pump efficiency is successfully increased by 3 percent compared to the reference pump. It is noted that the pressure increase of the optimum pump is mainly caused by higher momentum force generated inside blade passage due to the optimal blade shape. Comparisons of pump internal flow on the reference and optimum pump are also investigated and discussed in detail.

Flow Structure Around the Intake of a Vertical Pump

The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their installation area is demanded to be minimum without losing the high performance. We concentrate our attention on the expansion ratio of the intake as a representative characteristic of the shape of the pumps and investigate the effect of the expansion ratio on pump performance. It is concluded that the optimum expansion ratio ranges in 1.1-1.2 if we take into consideration that the area needed for the installation of the pump should be minimum.

Experimental Study of the Viscous Pump with a Helical Channel Rotor:Torsion Effect of the Channel

The viscous pump,which has a rotor with a helical square channel,is studied experimentally.The non-dimen-sional channel curvature is taken to be about 0.1.Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics.We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump.We also observe the secondary flow at a cross-section of the channel.Some of the results obtained are shown as follows:The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation,and becomes small when the favorable rotation of the rotor to the flow is applied.As for the secondary flow in a cross-section,there appear several types of vortex.When there is no rotation,the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex,but it changes to a four-vortex type when the flux is large.The secondary flow becomes asymmetric as the rotation is applied.We have unsteady flow patterns at large flux and rotation.

Fluid-solid strong-interaction model of mechanical seals in reactor coolant pumps

The studies on the mechanisms and performances of the mechanical seals in reactor coolant pumps are very important for the safe operations of the pressurized water reactor power plants. Based on the hydrostatic mechanical seal in reactor coolant pumps, an analytical fluid-solid strong-interaction model is proposed in this paper. According to the design features and operafional principles of the seal, an analytical method to calculate the mechanical deformation of the seal assembly is developed based on the ring deformation theory. A strong-interaction algorithm combining the analysis of the mechanical deformation of the seal assembly and flow field between the seal faceplates is utilized, in which the three kinds of equations including the fluid domain, solid domain and coupling action are constituted in the same equations set and all the variables are solved simul- taneously. So the analytical fluid-solid strong-interaction model used for the seal is built. Moreover, the model is verified by the experimental results. Based on the model, the design parameters of the seal are studied. Two different conditions of the general case and fixed seal leakage rate are discussed respectively, and the regularities that the seal behaviors are affected by the parameters of the holding screws on the clamp rings and seal faceplates are obtained. The research results can provide a theoretical basis for performance analysis, design and assemblage of the seal. Compared to the numerical methods, the proposed model has the unique advantages of high efficiency, convenience and easy application of constraints.