【作者】 杨帆；

【导师】 刘超；

【作者基本信息】 扬州大学 ， 水利水电工程， 2013， 博士

【摘要】 低扬程泵站是重要的水利基础设施,在跨流域调水工程、农田和区域抗旱、城市防洪排涝、城镇供水、污水排放等方面均起着关键性作用。随着国民经济的发展和国家对能源消耗的重视,人们对低扬程泵装置水动力性能的要求也越来越高,为了满足社会的需要同时推动低扬程泵装置研究的进一步发展,采用理论分析、数值模拟和物理模型实验相结合的方法对低扬程泵装置的水动力特性和多目标优化相关关键技术进行了研究,主要研究内容和取得的创造性成果有：(1)归纳分析了低扬程泵装置的分类及各类型泵装置水动力性能的优缺点,并从叶轮、导叶体、进水流道、出水流道及泵装置整体5个方面归纳分析了低扬程泵装置的研究进展概况。采用Matlab软件编制了自动求解泵装置水动力特性的程序,基于Visual Fortran和AutoCAD软件编制了对泵装置试验数据结果文件处理的自动绘图程序,为后续研究分析提供了技术支撑。分析了4种湍流模型、网格数量及网格类型在低扬程泵装置中的适用性问题,并将数值计算的预测值与物理模型试验值进行了对比。研究了叶顶间隙大小对低扬程泵装置内流场数值计算的影响,探讨了不同叶顶间隙对泵装置流量、扬程、轴功率及效率的影响,并成功捕捉到叶顶间隙泄漏涡结构。叶顶间隙在0.3mm以内时,对泵装置的能量性能影响较小,随着叶顶间隙增大,扬程和效率迅速下降,当叶顶间隙增大至1.0mm时,扬程降幅为10%～27%,效率降幅约10%,叶顶间隙作为低扬程泵装置数值计算固有的物理边界条件之一,在数值计算中应给予考虑。(2)基于CFD技术详细地分析了低扬程泵装置的进水流道与叶轮、导叶体与出水流道间的水力相干机理,进水流道出口断面的轴向速度分布均匀度和平均环量受叶轮旋转的影响较明显,叶轮旋转引起环量增加使进水流道水力损失有所减小。导叶体出口环量对出水流道的流场影响较大,导致隔墩两侧流量分配不均,大流量时隔墩两侧水流流态比较平顺,而小流量时隔墩右侧流道内出现螺旋状水流,两侧水流严重不均衡。无环量时出水流道的水力损失与流量成二次方关系,有环量时出水流道的水力损失增大,出水流道的内外特性与泵装置的运行工况有关系。针对双向立式低扬程泵装置的水动力性能特点,系统分析了导水锥对泵装置自流及抽水工况时进水流道水力性能的影响；借鉴灯泡贯流泵装置中扩散导叶的设计思路,研究了扩散导叶体对双向立式泵装置水力性能的影响及其在立式轴流泵装置中的适用性问题,通过物理模型试验分析了变转速变工况时双向立式泵装置内部水流脉动。(3)对斜15°轴伸贯流泵装置内流机理进行了全流道的三维数值计算,分析了在叶轮旋转条件下斜150进水流道出口断面的水力性能及其对叶轮进口断面相对位置高度的影响,给出了斜15°轴伸贯流泵装置的叶轮名义安装高度取值范围,分析了斜置安放叶轮受水流作用力的分布规律,探讨了其水力矩的变化规律及翼型附近相对流速的分布规律。针对城市防洪排涝泵站的特点,研发了两套超低扬程的双向潜水贯流泵装置,获得了双向潜水贯流泵装置的内流场,分析了灯泡体段对正、反向运行时泵装置水力性能的影响,包括灯泡体段的水力损失、导叶体内部流态及“S”形叶轮所受轴向力、叶顶间隙及叶片表面压力等。引入了单工况泵装置综合特性指标(C.P.I),分析了两套不同泵装置间水力性能的差异性,给出了双向潜水贯流泵装置的参考结构尺寸。为研究系列竖井型线的演变规律及其对泵装置水力性能的影响,在归纳分析竖井型线的基础上,采用一维水力设计方法设计了4种不同竖井贯流泵装置,并基于ANSYS CFX对其进行三维湍流场数值计算。采用多元线性回归方法建立了泵装置效率与流量、进水流道三个性能指标的函数关系式,表明进水流道的水力损失、轴向速度分布均匀度及速度加权平均角共同影响着泵装置的水力性能。在最优工况时各进水流道出口断面的轴向速度分布整体趋势相同,将各断面的轴向速度拟合成多项式数学模型,为叶轮的设计提供一定的参考。在泵装置三维定常数值计算的基础上,引入了泵装置的无因次动量参数和泵装置多工况性能加权评价指标(M.P.I),为解决不同泵装置水力性能的比较提供了参考方法。基于ANSYS CFX软件对前、后置竖井贯流泵装置进行三维定常流动数值模拟。引入平均涡角的概念,分析了前、后置竖井贯流泵装置内部流动的差异性,重点对不同形体的进、出水流道的水力性能及前、后置竖井贯流泵装置的外特性进行了分析比较。(4)在对泵装置进、出水流道水力性能的理论分析基础上,建立了泵装置进、出水流道的多目标多约束自动优化数学模型,并基于iSIGHT-FD优化软件构建了泵装置进、出水流道的自动优化平台,为泵装置流道的优化设计提供了全新的多目标多约束优化技术手段。以轴伸式贯流泵装置的进、出水流道为优化目标,在流道的几何数学模型描述的基础上采用多目标优化平台对其进行自动优化,优化后的进水流道水力损失减小了12.61%,轴向速度分布均匀度提高了1.86%,速度加权平均角提高了3.10°；优化后的出水流道水力损失减小了24.91%,动能恢复系数提高了6.65%,当量扩散角变为9.98°,从流道水力性能参数的定量分析可知,基于iSIGHT优化软件建立的多目标自动优化平台是可行性。在泵装置流道多目标优化设计基础上,提出了泵装置多目标优化的数学模型,并给出了泵装置多目标多约束自动优化的流程图。(5)基于泵装置三维定常数值计算,定性地分析了各工况时新型高效S形泵装置的叶轮表面静压分布及摩擦力线和导叶体内静压分布、漩涡情况,并定量分析了叶片出口的轴向速度分布规律及导叶体的回收环量能力和水力损失情况；分析了进水流道及出水流道的内部流动细节,包括流速分布、静压分布等,进水流道的轴向速度分布均匀度与速度加权平均角随着流量系数KQ的增大而增大,在最优工况KQ=0.490时,速度加权平均角为88.8°,轴向速度分布均匀度为97.51%,水力损失为3.89cm。因叶轮与导叶体的相对运动,泵装置内部流动实际是非定常流动,采用“瞬态冻结转子”技术对新型高效S形轴伸贯流泵装置进行了非定常数值模拟,定量分析了各过流部件内部的水力脉动情况、叶轮受力及扭矩的非定常特性,叶轮叶片及导叶片的最大与最小压力值的水压力脉动情况。针对新型高效轴伸S轴伸贯流泵装置,制作了泵装置物理模型并在江苏省水利动力工程重点实验室的高精度水力机械试验台进行性能试验,测试并分析了五个叶片安放角时新型S形轴伸贯流泵装置的能量性能、汽蚀性能及飞逸特性。在叶片安放角-2°时,新型高效S形泵装置的最高效率为83.55%,表明研发的新型高效S形轴伸贯流泵装置具有高效节能的突出优点。通过对模型泵装置阻力矩的计算分析,得出了在不同反向水头工况下相同叶片安放角时单位飞逸转速不是定值的原因,实际工程采用模型泵装置单位飞逸转速进行原型泵站飞逸转速换算是偏安全的。采用物理模型试验方法研究新型S形轴伸贯流泵装置的运行稳定性,在导叶体外壁布置两支电动式加速度传感器,分别测量了横向(X方向)与铅垂方向(Y方向)的振动位移。在额定转速1350r/min时,采用EN900采集分析仪对叶片安放角为+4°与-4°时不同运行工况的泵装置模型进行振动测试和分析。(6)开展了有涡入流条件下箱涵式轴流泵装置内部流动机理的研究,阐述了喇叭管悬空高及流道高度相关联时对箱涵式进水流道内流场及水力性能的影响,重点分析了有涡入流条件时叶轮所受轴向力及径向力情况,以及对叶轮进口处水力脉动的影响,采用定量的方法阐述了涡带在流道内部产生及逐步耗散的过程,通过3D-PIV测试技术和高速摄影技术验证了数值计算模拟的可靠性及有效性。(7)通过速度三角形分析了前置导叶对泵装置水动力性能的影响。依据前置导叶的设计要求,设计了可调前置导叶,开展了前置导叶不同调节角时泵装置的三维定常数值计算,分析了其对泵装置内、外特性的影响,重点分析了不同调节角时前置导叶对叶轮水力性能的影响,通过自编程序获取了可调前置导叶对泵装置影响的综合特性曲线,并建立了不同前置导叶片调节角时泵装置外特性预测的多元非线性回归预测数学模型。全面系统地探讨了可调后置导叶片对泵装置水动力性能的影响,重点分析了不同调节角时泵装置的内、外特性,基于数值计算结果建立了不同调节角时后置导叶对泵装置外特性预测的BP-ANN数学模型,并通过联合方法验证了该方法的可行性。更多还原

【Abstract】 Low-lift pump system is an important modern water infrastructure, which plays a key role in many fields, such as inter-basin water transfer project, drought resistance of farmland and region, urban flood control and drainage, urban water supply, wastewater discharge and so on. With the development of national economy and energy consumption is emphasized by government, people hope the hydraulic performance of pump system become better and better. The hydraulic performance and multi-objective optimization design of pump system with low-lift based on the methods of theoretical analysis, numerical simulation and physical experiments. The main research contents and creative achievements are as follows:(1) The structure classification and characteristics of low-lift pump system were briefly introduced. The present results, progress and methods in its research were analyzed and summarized from four aspects, such as impeller, guide vane, inlet outlet passage and pump system. In order to offer technology support for further study, automatic solving program of hydraulic performance of pump system was implemented using the Matlab software, and combining traditional Visual Fortran with AutoCAD graphics software, the Bezier curve drawing program was developed which is human-computer interaction interface, to achieve the purpose of computer automated drawing of experimental data. A lot of numerical experiments have been done with the choices of turbulence model, mesh number and mesh type for studying the suitability of numerical simulation for low-lift pump system. The predicted data of numerical simulation and model test were compared for providing a reliable performance prediction method. Focusing on the effects of blade tip clearance on the numerical simulation of inner flow field of pump system, the effect of blade tip clearance on the flow rate, head, torque and efficiency of pump system were analyzed, and the structure of leakage vortex was captured and analyzed. When the tip clearance is not larger than0.3mm, blade tip clearance has little influence on the external performance of pump system. With the increase of blade tip clearance, head and efficiency drop quickly. When the blade tip clearance reaches to1.0mm, the decrease range is10%-27%and the efficiency is decreased by about10%. Blade tip clearance is one of physical boundary conditions for numerical simulation of pump system, which should be considered.(2) The Mutual coupling effect of inlet passage and impeller, guide vane and outlet passage analyzed in detail based on CFD. Outlet circulation of guide vane has great influence on flow pattern in the outlet passage. The flow distribution for both sides of the dividing pier is not symmetric, especially for small flow rate condition, the helical flow occurs at the right side of dividing pier. The effect of the residual circulation of outlet section on the outlet passage with and without pier was analyzed firstly based on the whole pump system. Under the condition of zero velocity circulation, the hydraulic loss of outlet passage is in proportion to the square of flow, and the hydraulic loss is larger than that with velocity circulation. The effects of flow guide cone on the hydraulic performance of inlet passage and the effects of guide vane on the performance of pump system were analyzed for reversible vertical pump system. According to the design method of diffusion guide vane of bulb tubular pump, the effects of diffusion guide vane on the reversible vertical pump system and applicability problem about it were analyzed. A physical model test was adopted to study the characteristics of pressure fluctuation of reversible pump system by performance and cavitation test. (3) The relation between hydraulic performance of outlet cross sections with rotating impeller and the relative height of outlet cross sections and the stress distribution of impeller were analyzed, as well as the relative velocity distribution near the airfoil cross sections under the designed condition. The hydraulic moments were calculated based on the numerical results under different conditions, and the changing features of hydraulic moment on blades with flow rates were analyzed firstly. The reference nominal height of pump system was given. According to the characteristics of urban flood protection and drainage pump system, two sets of dividing tubular pump systems with symmetric aerofoil blade were developed. The effect of bulb section on the hydraulic performance was analyzed, which included the hydraulic loss of bulb section, the internal flow of guide vane and the hydraulic performance of "S" shape impeller vane. C.P.I (comprehensive performance index) is introduced firstly to analyze the difference between two sets of pump system. Structure size of pump system provided a reference for dividing tubular pump system. In order to study on the evolution law of shaft profile line and the influence relation between the hydraulic performance of pump system and shaft line,4different shaft inlet passages were designed with one-dimensional hydraulic design method based on the induction analysis of shaft profile lines. The CFD software ANSYS CFX was used to simulate the three-dimensional fluid flow of pump system. The expression of the functional relations between the efficiency of pump system, flow rate and three performance index of inlet passage were deduced based on the multiple linear regression analysis method. Due to the joint influence of the hydraulic loss, the axial velocity distribution uniformity and the velocity-weighted average swirl, the flow chart was put forward that is about multi-objective collaborative optimization of inlet passage. At the optimum operating condition, the distributions of axial velocity in different outlet section have same tendency, and polynomial mathematics model was used to fit out the distribution of axial velocity. Based on the three dimensional steady numerical simulation, dimensionless momentum parameter and the weighted performance of multiple operating conditions evaluation method (M.P.I) were solved to the hydraulic performance comparison of different pump systems. ANSYS CFX is applied to carry on the three-dimensional numerical simulation on the whole flow passage of the shaft tubular pump system of front-position, post-position. The hydraulic performance of different inlet and outlet passage and the external characteristic of two sets of pump system are compared and analyzed quantitatively in detail for introducing the average swirl angle.(4) Based on theoretical analysis of the hydraulic performance of inlet and outlet passage, Multi-objective optimization mathematical models of inlet and outlet passage were proposed firstly. In order to provide the new multi-objective and multi-constraint optimization techniques method for passage optimal design, automatic optimization platform of inlet and outlet passage were built firstly based on the optimization software iSIGHT-FD. In the paper, inlet and outlet passage of shaft extension tubular pump system were taken as optimization objects by using optimization platform, which were described by the geometric mathematical model. For optimized inlet passage, the hydraulic loss decreased by12.61%, the axial velocity distribution uniformity improved by1.86%, and the velocity-weighted average swirl angle increased by3.10°. For optimized outlet passage, the hydraulic loss reduced by24.91%, kinetic energy recovery coefficient improved by6.65%, and equivalent diffusion angle is9.98°. According to quantitative analysis of the optimization results, the automatic optimization platform is feasible. Based on the optimized design of passage, multi-objective optimized mathematic model of pump system was proposed firstly, and flow chart of automatic optimization was given.(5) For new S-shaped shaft extension tubular pump system, the distribution of static pressure, skin friction line of the blade surface, and the distribution of static pressure and vortex in the guide vane were analyzed qualitatively, based on the steady numerical simulation. The distribution law of axial velocity of impeller outlet, recovery circulation and hydraulic loss of guide vane outlet were analyzed quantitatively. The paper pay attention to the detail of the flow field in the inlet and outlet passage includes the distribution of velocity and static pressure. With the increase of flow coefficient, the axial velocity distribution uniformity and the velocity-weighted average angle increase gradually. The velocity-weighted average angle is88.8°, the axial velocity distribution uniformity is97.51%and the hydraulic loss is3.89cm at the optimum operating condition KQ=0.490. Because of the relative motions between impeller and guide vane, the technology of the transient rotor stator (TRS) was applied to simulate the pressure fluctuation of interior flow in the new high efficient S-shaped shaft extension tubular pump system and maximum and minimum static pressure on the blades of the impeller and guide vane.A physical model experimental research on energy performance, cavitation performance and runaway characteristics of the pump model system has been conducted on the high precision hydraulic machinery test stand of Jiangsu province. The highest efficiency of the new S-shaped extension pump system is83.55%at the blade angle-2°, which has significant advantages of high efficiency and energy-saving. The comprehensive hydraulic performance of the new S-shaped extension pump system reaches international leading level. Through the calculation of resistance torque, the variable factor of a unit runaway speed with same blade angle is analyzed under different working conditions of reverse-water-head. The unit runaway speed obtained from model pump system is applicable and safe for conversion to prototype pump system.Two electro acceleration sensors were set on the outer wall of guide vane for studying the operation stability of new S-shaped shaft extension pump system, and the vibration displacement of X direction and Y direction were analyzed at the rotation speed1350r/min. Signal collecting analyzer EN900is used to study the operation stability of model pump system at blade angle+4°and-4°.(6) The internal flow mechanism of cube-type axial-flow pump system was studied under vortex inflow for the first time. The influence of bottom clearance of flare tube is related with the passage height on the internal flow and hydraulic performance of cube-type inlet passage was analyzed. The axial force and radial force of the impeller were mainly analyzed under vortex inflow. The influence of submerged vortex on the pressure fluctuation of impeller inlet in different operating conditions was mainly analyzed. The evolution process of submerged vortex generation and the gradual dissipation was studied by the quantitative method. The3D-PIV measurement technique and high-speed camera were adopted in experiments. By compared testing data with computational results, it is found that the results of numerical simulation are in satisfactory agreements with experimental data, which validates the numerical results to be reasonable.(7) The effects of inlet guide vane on the hydraulic performance of pump system were analyzed by the method of velocity triangle. According to the design requirements of inlet guide vane, adjustable inlet guide vane was designed, and3D steady numerical simulation of pump system was simulated in different adjustable angle of inlet guide vane. This paper mainly studies on the effects of inlet guide vane on the external and internal characteristics of pump system and the hydraulic performance of impeller. Synthetic characteristic curve of pump system with inlet guide vane was obtained by self-compiling program. By establishing mathematical model of multivariate nonlinear regression model, the external characteristic data can be obtained in the different adjustable angle. The effects of adjustable outlet guide vane on the performance of pump system and the internal flow pattern of guide vane were analyzed based on CFD. BP-ANN mathematic model was established for predicting the external performance, and the combined method was used to verify the feasibility of adjustable outlet guide vane.更多还原