肘形进水流道优化设计与数值计算

为了提高泵站进水流道的设计水平,对应用最为广泛的肘形进水流道的型线进行了数学建模,并采用高级程序设计语言Visual Basic对工程图形处理软件AutoCAD进行二次开发,形成基于流道设计参数的优化设计软件,能够快速进行流道型线的绘制,并能使流道的型线自动符合流速渐变的原则.同时结合三维紊流数值模拟技术和流道的模型试验对流道的水力性能进行检验.通过工程实例说明,该流道设计方法快速、可靠,所设计的肘形进水流道具有出口流态较好、水力损失较小的优点.     

低扬程虹吸流道泵装置起动动态特性数学模型

从理论上分析了低扬程泵装置虹吸流道中空气动力学特性、泵机组暂态电气特性和动力学特性以及虹吸流道非恒定流、水泵动力性能，并结合水泵相似理论。提出了在低扬程虹吸流道泵装置起动过渡过程中泵机组动态特性以及虹吸流道内空气压力变化的数学模型。     

S形下卧式轴伸贯流泵装置叶片区压力脉动特性研究

为研究S形下卧式轴伸贯流泵装置叶片区压力脉动特性,采用非定常CFD方法对不同工况时泵装置进行了全流道三维非定常流场数值计算,通过在叶片区设置监测点以获得叶片区关键位置的压力脉动数据,并进行频谱分析。通过与实测泵装置扬程和效率对比,证明该方法能较准确地反映泵装置内部非定常流动特征。研究表明:高效工况和大流量工况时,转轮进口和出口的脉动幅值从轮缘向轮毂侧逐渐减小,小流量工况时未呈现该规律,各工况时转轮进口和出口脉动主频受叶频控制。流量系数KQ在(0.368~0.552)范围内转轮进口处同一监测点的压力脉动幅值随流量增大而降低,转轮与导叶体间的脉动幅值随流量的增加先减小后增大,在高效工况附近脉动相对最小。导叶体出口的压力脉动主频受叶频的影响较小,未与导叶体叶片数成规律。     

基于RNG紊流模型的立式轴流泵站三维流动数值模拟及性能预测

立式轴流泵站具有流量大、扬程低等特点,在农田排灌、调水工程等得到了广泛应用,目前在建的南水北调东线工程的泵站大多采用该形式.为深入研究立式轴流泵站内部流动和水力性能,采用考虑粗糙度的壁面函数的RNG紊流模型和SIMPLEC算法,基于多旋转坐标系模型,计算了采用钟型进水流道和蜗壳出水流道的低扬程立式泵站定常流动.通过计算获得了泵站整体流场结果,分析了在有转轮条件下进水流道喇叭管内断面轴向流速分布规律对泵站叶轮安装高程的影响,给出了参考的叶轮名义高度取值.通过计算预测了泵站水力性能,并与模型试验结果进行了比较,研究表明设计工况下数值预测与试验数据值吻合较好.三维数值分析和试验结果表明该泵站形式在南水北调东线工程中有一定的应用前景.     

用可调进口导叶调节特性的大型混流泵

阐述了大型混流泵采用可调进口导叶调节特性的原理、技术特点和结构设计 ,介绍了带可调进口导叶的SEZ2 0 0 0— 1 62 5VR型泵的具体结构和运行效果。     

叶轮进口宽度对液力透平性能的影响

针对叶轮进口宽度对液力透平性能影响规律的认识不足问题,建设了一开式液力透平实验台,对一单级液力透平进行了实验研究,得到了该比转速液力透平的外特性曲线。采用结构化网格技术对液力透平进行了全流场数值计算与分析,数值与实验相结合,验证了数值计算的准确性。对不同进口宽度透平叶轮的数值计算结果分析表明,随着透平叶轮进口宽度的增加最高效率点向大流量偏移,大流量时的效率逐渐增加;对于一定几何参数组合的液力透平,存在最佳叶轮进口宽度使液力透平最优工况点效率最高;透平的流量扬程曲线随叶轮进口宽度的增加变得更加平坦;透平的轴功率变化相对较小。     

Experimental study of the influence of flow passage subtle variation on mixed-flow pump performance

In the mixed-flow pump design, the shape of the flow passage can directly affect the flow capacity and the internal flow, thus influencing hydraulic performance, cavitation performance and operation stability of the mixed-flow pump. However, there is currently a lack of experimental research on the influence mechanism. Therefore, in order to analyze the effects of subtle variations of the flow passage on the mixed-flow pump performance, the frustum cone surface of the end part of inlet contraction flow passage of the mixed-flow pump is processed into a cylindrical surface and a test rig is built to carry out the hydraulic performance experiment. In this experiment, parameters, such as the head, the efficiency, and the shaft power, are measured, and the pressure fluctuation and the noise signal are also collected. The research results suggest that after processing the inlet flow passage, the head of the mixed-flow pump significantly goes down; the best efficiency of the mixed-flow pump drops by approximately 1.5%, the efficiency decreases more significantly under the large flow rate; the shaft power slightly increases under the large flow rate, slightly decreases under the small flow rate. In addition, the pressure fluctuation amplitudes on both the impeller inlet and the diffuser outlet increase significantly with more drastic pressure fluctuations and significantly lower stability of the internal flow of the mixed-flow pump. At the same time, the noise dramatically increases. Overall speaking, the subtle variation of the inlet flow passage leads to a significant change of the mixed-flow pump performance, thus suggesting a special attention to the optimization of flow passage. This paper investigates the influence of the flow passage variation on the mixed-flow pump performance by experiment, which will benefit the optimal design of the flow passage of the mixed-flow pump.     

Experimental study on two-way flow passages in pumping system

Based on the model test of pumping system with two-way flow passages, the flow characteristic and flow pattern in two-way outflow passage are specially observed and analyzed. The various schemes are compared by means of test and the measures for improving flow pattern in outflow passage are come up with by the authors. This research possesses reference value for pump selection and flow passages design of analogous pumping station. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

Numerical investigation of two-phase flow characteristics in multiphase pump with split vane impellers

Multiphase pump is a cost-effective option for subsea oil and gas field development. The ability to handle different inlet gas volume fractions (GVFs) especially high inlet GVF is critical to the development of pump performance. In this study, the two-phase flow characteristics in normal impeller and split vane impeller at different inlet GVFs were investigated by steady numerical simulations. The gas distribution on blade-to-blade plane and meridional flow channel at different inlet GVFs were analyzed and compared. Gas accumulation area and movement characteristics of the gas-liquid flow in impeller flow passage were also pointed out by unsteady simulations. Experimental results of the pump differential pressure were compared with the numerical simulation results, to validate the accuracy of numerical simulation method. The flow characteristics in pump with modified impeller and its performance at different inlet GVFs were both compared with that of the normal impeller. The steady simulation results of normal impeller in different inlet GVFs show that gas concentrating area in the flow passage increases as inlet GVF grows. The unsteady simulation results indicate that gas pocket firstly occurs on the pressure side of impeller, then moves to the suction side in the middle area of blade and finally transfers to outlet of impeller and disappears. The errors between numerical simulation results and experiment data are below 10 %, which validated the feasibility of the numerical simulation method. Simulation results on the split vane impeller demonstrate that the gas accumulation area in flow passage of the modified impeller is dramatically decreased compared to that of the normal impeller. The performance of the modified impeller is generally better than the normal impeller especially in high inlet GVF conditions.

     

凸轮转子泵抽送不同浓度非牛顿流体的流场分析及对性能影响

为了探讨摆线型凸轮转子泵抽送粪污介质的性能变化和针对非牛顿流体类抽送的优化设计,以三叶摆线型凸轮转子泵作为研究对象,选取清水和浓度为6.87%,9.20%,12.15%的猪粪作为抽送介质,对凸轮转子泵进行三维非定常数值模拟,分析内部流场瞬态特性,预测其外特性。分析结果表明:在抽送清水和不同浓度的猪粪时,从泵腔的进口区域到出口区域的压力逐渐升高,随猪粪浓度增大,独立工作腔室的压力增大;抽送非牛顿流体时,间隙处因挤压而产生的速度激增,转子泵腔内的速度分布更加均匀;出口的压力脉动主频均出现在2倍叶频处,压力脉动幅值随猪粪浓度增大而减小;随猪粪浓度增大,出口流量、容积效率及水力效率增大,流量脉动系数减小,其性能优于抽送清水介质。研究为凸轮转子泵输送非牛顿流体时的优化设计奠定了基础。     

平面叶栅周期性特性数值研究

为探索改善小角度进气条件下叶栅栅前流动周期性的试验控制方法,以某跨音速压气机平面叶栅试验件为研究对象,采用数值模拟方法研究了小角度进气条件下尾板偏移角度和端壁通道宽度对叶栅栅前周期性分布的影响。研究结果发现：叶栅在小角度进气时栅前周期性分布特性较差,调节下尾板角度对栅前周期性具有一定影响,调节上尾板对近端壁通道气流难以起到导流效果;采用全叶片式叶栅进气方案时,仅端壁附近流道的流动受到边界附面层影响,而中间测量通道内的周期性分布得到明显改善;改变近端壁两端通道宽度可以有效改善栅前流场周期性。     

立式轴流泵装置流道内部流动特性及消涡试验

采用数值计算和高速摄影技术研究分析了立式轴流泵装置的箱涵式进水流道水力特性,数值预测的附底涡与高速摄影捕捉到的附底涡均发生于喇叭管正下方,各工况时附底涡的运动轨迹较为一致,表明了数值计算的有效性。相比无消涡锥的进水流道,有消涡锥时进水流道出口断面的轴向速度分布均匀度平均提高了0.423%,速度加权平均角平均提高0.397°。设计的复合型消涡短锥可消除各工况运行时箱型进水流道附底区的涡带,提高泵装置运行的安全可靠性。对于箱涵式进水流道,为保证泵装置的安全稳定运行,需在流道附底区设置消涡装置。     

拉瓦尔式燃料流量调节阀流量特性分析

燃料供给的实时、精确调节是冲压发动机技术研究的重点,对提高发动机的效率、改善发动机的工作性能具有重要的意义。为实现冲压发动机气态燃料在高温下流量的精确调节,提出了一种新型的拉瓦尔式燃料流量调节阀,以对流入发动机燃烧室的高温气态燃料进行流量调节。首先,开发了一种用于燃料供应的高温流量调节阀,然后通过采用有限元分析方法,分析了流经主阀阀口的气态燃料速度及压力的分布,从而找出了流量变化规律。研究结果表明,采用拉瓦尔管状阀口的流量调节阀,在不改变阀芯位移量以及一定入口压力条件下,流经阀口的燃料流量保持不变,且与出口压力无关。     

Softness abrasive flow method oriented to tiny scale mold structural surface

Tiny scale mold structural surface finishing is of high difficulty. In allusion to the problem, a new no-tool precision finishing method based on solid–liquid two-phase softness abrasive flow (SAF) is brought forward. By setting restrained component for the structural surface machined, the restrained flow passage is constructed. Using the wall effect of SAF, no-tool precision finishing for tiny scale structural surface can be realized. According to the Nikuradse’s experimental principles, the motion regulars of SAF are studied, and the friction coefficient formulas suited for SAF finishing are obtained. Taking U-shaped restrained flow passage as instance, standard k-ε model and Euler multiple-phase model are used to describe the SAF flow field, and the kinetic model of SAF is established based on discrete phase model. Then, the variation trends of SAF turbulent parameters and flow passage pressure distribution with different inlet velocities are acquired by semi-implicit method for pressure-linked equations consistent algorithm. Numerical simulation results derived that pressure attenuation of solid phase in flow passage is inversely proportional to inlet velocity, and the motion trails are disordered and stochastic, which are the sufficient conditions of SAF finishing. By analyzing pressure distribution and turbulent characteristics of SAF, the best finishing area in restrained flow passage is gained. Observational experiment of particles motion had been carried out; experimental results showed particles’ motion satisfied requirements of SAF finishing, and feasibility of SAF could be proved theoretically. SAF experimental platform oriented to module structural surface finishing is constructed, and the nano-level finishing can be realized. Experiment results show that SAF method can increase mold structural surface precision more than ten times, and the roughness machined in Ra value is less than 62?nm.     

大型立式轴流泵叶片进口流场及其对水泵影响研究

分析各因素对大型立式轴流泵叶片进口流态的影响,研究该断面流场的形成机理。提出叶栅对进口流态反作用和相互自动调整的观点,即如果叶栅来流非均匀轴向,叶栅过流特性会反过来影响来流流态并调整达到平衡。结果表明,立式轴流泵叶片进口流场既非轴向,又非均匀,不符合常规假设。用五孔探针实测叶轮直径D=1.64m轴流泵叶片进口流场,证明了理论分析的正确性。分析叶片进口流态对水泵性能、导轴承偏磨和间隙气蚀的影响,提出改善流态的方法。成果对改进轴流泵及其进水流道设计理论和方法,提高运行性能具有重大意义。     

Simultaneous internal/external flow calculation of a solid fuel ramjet projectile: a design analysis

SFRI has been regarded as a prime mode of secondary propulsion which enables the projectile to achieve a higher terminal velocity. Geometry of SFRJ is quite simple due to the lack of turbomachinery that conventional jet engines need. The complete internal/external flow field of an SFRJ-TGTR projectile at a cruising Mach number is calculated by an unstructured triangular compressible RANSE solver. To complete the analysis, single-component fuel combustion is added in the combustor flow calculation. A commercial CFD package is used with structured rectangular meshes for such computation. The results from the two computations are compared with existing computational and experimental data for validation. The design parameters like thrust, total pressure loss, inlet and nozzle efficiencies and drag coefficient are derived from the detailed flowfield data. Different values of cruising Mach number and nozzle throat area have been tried as a preliminary design procedure. Change in the nozzle throat area directly affects the inlet flow, because the internal flow is mostly subsonic and is linked directly to the nozzle flow.     

汽油机进气歧管数值计算方法研究

针对两种数值计算方法（四口全通、三闭一通）影响进气歧管的流场特性和进气均匀性计算结果的问题,分别采用这两种数值计算方法对某四缸汽油机的两款进气歧管进行了CFD计算,分析了两种数值方法获得的进气阻力和进气均匀性计算结果。同时,建立了相应的发动机试验白架,通过分析两款进气歧管对发动机的动力性、经济性及运行平稳性的试验数据来验证数值计算方法的可靠性。研究结果表明：采用“四口全通”和“三三闭一通”这两种数值计算方法获得的进气阻力变化趋势一致,两者都适用于进气阻力仿真分析;两种数值计算方法的进气均匀性计算结果差异很大;“三闭一通”数值计算方法更加适用于进气歧管进气均匀性分析。     

旋流泵内盐析两相流场的计算及试验研究

为研究流体机械内部伴有盐析的液固两相流动情况,自行设计了旋流式模型泵,采用双流体模型计算了该泵在最优工况下的氯化钠盐析两相流场,并采用先进的激光相位多普勒粒子测速仪测量了泵无叶腔及叶轮内部盐析两相流的三维速度场。将试验结果与计算结果进行对比,验证了计算模型的适用性,并给出了误差分析。通过对试验测得的周向、轴向、径向速度及其对应的脉动速度分布曲线讨论,初步揭示了该型泵内盐析两相流动特征。在整个流道内,盐析晶体颗粒大部分集中于无叶腔,且分布较均匀;进入叶轮后向叶片工作面靠拢;颗粒浓度最低处是在叶轮进口叶片背面靠近叶轮后盖板附近;液固两相在叶轮与无叶腔中的周向速度分布差异明显;两相间速度及脉动速度有滑移,但差异总体上并不显著。     

Comparison of cavitation prediction for a centrifugal pump with or without volute casing

Cavitation may not only cause head and efficiency breakdown of hydraulic machines but also generate other unfavorable phenomena such as noise and vibration. Therefore, the accurate prediction of cavitation development is important for various pump applications. In this paper, two numerical models, namely, models A and B, are applied to simulate the turbulent cavitating flows inside a centrifugal pump to investigate the effect of calculation domain on the prediction accuracy of cavitation performance for hydraulic machines. Model A has a calculation domain with volute casing, whereas model B has a single blade-to-blade flow passage without volute casing. Steady simulations of cavitating flow in the pump have been conducted based on the shear stress transport k-ω turbulence model and the homogeneous cavitation model. Both models A and B predicted that the pump performance decreases with decreasing cavitation number. Experimental results show that model B can predict better the critical cavitation number at the best efficiency point compared with model A, which is the full flow passage model. Internal flow investigations indicate that an asymmetrical feature of cavitating flow exists when the calculation domain with volute casing is applied. The asymmetrical cavitation development in different blade-to-blade flow passages for model A results in an over-estimation of the decrease in pump performance because of the interaction between the impeller blade and the tongue of the volute casing. A simple calculation domain without volute casing is preferred for steady cavitation prediction in pumps rather than the full flow passage with volute casing because the former has better convergence, less resource requirements, and lower time consumption.     

某医院住院楼地源热泵热水系统性能测试与研究

简单介绍了某医疗建筑的能耗情况和医院的工程概况,并对本医院的供热水系统——地源热泵系统的运行情况进行测试和性能研究,包括对机组冷冻水的进/出温度的测试、土壤换热器吸热效率的测试、机组的能效测试等,并分析冷冻水的进/出温度、流量及其他因素对系统能耗产生影响情况,并得出系统冷冻水流量在4.3～4.8kg/s范围内为最佳流量段,此时土壤换热器的吸热效率较高,土壤换热器单位管长换热量在35.5W/m左右,机组的能效比值达4.0及以上,系统的能效比达3.7及以上;最后对本系统进行了节能计算及效益分析,可看出此系统节能效益非常可观。