【作者】 朱强；

【导师】 陈松山； 万勇；

【作者基本信息】 扬州大学 ， 动力工程（专业学位）， 2017， 硕士

【摘要】 低比转速高速离心泵具有小流量、高扬程、结构紧凑等特点,被广泛应用于石油化工、航空航天等领域。但因其转速高,所以其内部流动与常见离心泵存在较大差异,如:在叶片吸力面易产生尾迹流,而压力面易出现射流等。高速泵的内外特性研究—直是流体机械领域重点研究课题。本文结合流量Qd=10m3/h、扬程H=410m、转速n = 8500r/min,比转速ns=18的高速泵的复合叶轮、蜗壳、诱导轮水力设计,利用三维湍流数值模拟方法,基于ANSYS CFX软件平台,对设计的高速离心泵进行全流道三维定常和非定常仿真计算,探索了高速离心泵内外特性的规律。研究得出了叶轮、蜗壳和诱导轮内的速度、压力分布特征,数值模拟预测水泵的外特性以及隔舌处的压力脉动特性。主要工作如下:(1)利用速度系数法和加大流量法,设计了流量Qd=10m3/h、扬程H = 410m、转速n = 8500r/min,比转速ns=18的高速泵的复合叶轮、蜗壳和等螺距诱导轮。(2)利用PRO/E和GAMBIT软件对离心泵的进水管、复合叶轮、蜗壳及等螺距诱导轮等过流部件进行三维建模,运用非结构化网格离散过流部件计算域。(3)为探求转速变化对离心泵内部流动影响,基于雷诺时均N-S控制方程和标准的k-ε湍流模型,利用ANSYSCFX软件,数值模拟了设计流量下6种不同转速的水泵内部流动,比较分析了转速对叶轮内静压和相对速度分布规律的影响。(4)针对设计转速n = 8500r/min,数值模拟离心泵高速运行在小流量0.4Qd、设计流量1.0Qd和大流量1.3Qd三种工况下的内外特性,研究得到了不同流量下复合叶轮内部压力场、速度场及蜗壳隔舌处的静压力场分布,数模预测高速泵的能量特性。(5)对带前置诱导轮的高速离心泵进行了三维定常数湍流值模拟,得出了小流量0.4Qd、设计流量1.0Qd和大流量1.3Qd三种工况的内外特性,对比了不同流量下诱导轮、叶轮的静压场和相对速度场分布;分析了前置诱导对水泵能量特性的影响。(6)数值模拟了带前置诱导轮的高速离心泵蜗壳与叶轮耦合非定常流动,得到了蜗壳隔舌处3个不同监测点,在小流量0.4Qd、设计流量1.0Qd和大流量1.3Qd三种工况下的压力脉动规律,对比分析了它们的时域特性和频域特性。(7)数值模拟了带前置诱导轮的高速离心泵叶轮叶栅及子午面上的空化情况,并就偏离设计点工况下诱导轮对泵汽蚀余量的影响进行了预测。更多还原

【Abstract】 The low-specific-speed high-speed pumps are used widely in petrochemical industry and aerospace field because of little rate of flux,high water-head,compact structure features.But because of its high rotational speed,so there is a big difference between its internal flow state and.the common centrifugal pump,for instance:wake flow is easy in the suction surface of the blade,but the pressure surface is prone to jet flow and so on.The research on the internal and external characteristics of high speed pump is the key research topic in the field of fluid machinery.In the paper,the hydraulic design of compound impeller,volute,inducer of the high speed pump is combined with Qd = 10m3/h,H= 410m,n=8500r/min and ns = 18.Based on ANSYS CFX software platform,using three dimensional turbulent numerical simulation method,three dimensional steady and unsteady simulation of the whole flow passage of the well designed high speed pump is carried out.The velocity and pressure distribution characteristics of the impeller with splitter blades,volute and inducer are obtained,numerical simulation is used to predict the external characteristics of the pump and the pressure pulsation of the tongue.Main work is as follows:(1)The impeller with splitter blades,volute,equal pitch inducer of high speed pump with Qd = 10m3/h,H 410m,n=8500r/min and ns = 18 are designed,using velocity coefficient method means of enlarging flow rate.(2)Using PRO/E and Gambit software to carry on three dimensional modeling of pipe,impeller with splitter blades,volute and equal pitch inducer of the centrifugal pump,using unstructured grids to discrete the computational domain of the over flow component.(3)In order to explore the influence of speed change on the internal flow of centrifugal pump,based on Reynolds averaged N-S equation and standard k-ε turbulence model,using ANSYS CFX software,numerical simulation of the flow state inside the pump with six different speeds in design flow working condition is carried out and influence of rotating speed on the distribution of static pressure and relative velocity is comparatively analyzed.(4)In the light of design velocity n=8500r/min,the internal and external characteristics of the centrifugal pump under the three conditions of little flux 0.4Qd,design flux 1.0Qd,and large flux 1.3Qd,the distribution of the pressure field,velocity field and the static pressure field in the volute tongue at different flow rates are obtained,energy characteristics of high speed pump are predicted in numerical simulation means.(5)Three dimensional steady turbulence numerical simulation of high speed pump with inducer is presented,the internal and external characteristics of three conditions of little flux condition 0.4Qd,design flux condition 1.0Qd and large flux condition 1.3Qd;Comparison of static pressure field and relative velocity field distribution of inducer and impeller with splitter blades is carried out;The influence of energy performance of pump with inducer is analyzed.(6)Numerical simulation of the coupled non-steady flow in the volute and impeller of high speed centrifugal pump with inducer is carried out,the pressure pulsation of three different monitoring points in the volute casing is obtained in three working conditions of little flux condition 0.4Qd,design flux condition 1.0Qd and large flux condition 1.3Qd,their time domain and frequency domain characteristics are compared and analyzed.(7)The cavitation of blades and meridian plane of impeller of centrifugal pump with inducer is numerically simulated,and the influence of inducer on NPSHr is predicted under the condition of deviation from design flow rate.更多还原