2023年离心泵压力脉动的特性分析和测试.docx

Abstract Centrifugal pump produces static pressure components and produces dynamic pressure components，that is，pressure pulsation. Pressure pulsation is superimposed on static pressure components just like AC signals. Most of the spiral volute centrifugal pump，volute ring distortion and asymmetry of the tongue caused by impeller exit flow，especially in the non design condition，the distortion is more violent，so in the design of the spindle，the pressure must be due to the unbalanced distribution of fluctuation caused by considering. The pressure pulsation in the centrifugal pump is extremely complex，and the pressure pulsation of the same pump is different in different working conditions. Pump internal flow field and unsteady turbulent characteristics，the impeller and the water inlet pipe of the rotor stator interaction，eddy current and reflux may cause pressure pulsation，mechanical vibration of the pressure pulsation excitation pump and pipeline，affect the normal operation of the pump，reduce the service life of the pump； if the excitation frequency is close to the frequency of the pump. The resonance vibration will occur，will produce pressure fluctuations in the ambient medium adjacent，have a great noise. It can be seen that the pressure pulsation in the pump is an important factor affecting the stability of the pump operation，and is also an important cause of noise pollution. Therefore，it is one of the important tasks to study the pressure pulsation in the pump and reduce the vibration noise of the pump. This paper first applies CFD technology FLUENT software to monitor the pressure pulsation in impeller and volute simultaneously under multiple conditions，so as to reveal the relationship between pressure pulsation and centrifugal pump performance，and provide a basis for further prediction of unsteady flow induced pressure pulsation in centrifugal pumps. In order to study the centrifugal pump under different working conditions and the variation of pressure fluctuation between different locations and their relationship，standard k- turbulence model and sliding mesh model based on the application of FLUENT software on the internal flow field of centrifugal pump has steady and unsteady three-dimensional simulation，get the pressure pulsation of internal flow characteristics and monitoring points of the roughly. The calculation results show that under the condition of small flow rate，the pressure pulsation at each monitoring point is large and uneven due to the unstable internal flow field，and the pressure pulsation near the impeller outlet is significantly higher than that in other regions of impeller passage. Under the large flow condition，there will be a certain reflux in the tongue and outlet of the volute，which results in the instability of the pressure fluctuation near the worm shell. Because of the complex pressure pulsation at the location of the basin，the fluctuation of the outlet of the volute is very gentle，which is mainly due to the buffering and steady flow of the outlet section of the volute. On the other hand，on the design of the measurement system，we fully understand the parameters of the pressure transmitter and data acquisition module，and complete the hardware selection of the two parts and the construction of the wiring diagram. Then we use LabVIEW software to write the upper machine interface. We set up sampling frequency，sampling data points and collecting ranges to complete the 8 channel data collection and curve display，and save data. Keywords：centrifugal pump, pressure fluctuation, Constant simulation, Unsteady simulation, Unsteady simulation 目录 I Abstract II 第一章 绪论 1 1.1 课题的研究背景及意义 1 1.2 国内外研究现状 2 1.2.1 国外研究现状 2 1.2.2 国内研究进展 3 1.3 论文工作的主要内容 4 第二章 泵内流动数值计算方法及压力脉动的相关理论 5 2.1 离心泵的三维建模 5 2.1.1 叶轮实体模型的建立 5 2.1.2 蜗壳实体模型的建立 6 2.1.3 进水管实体模型的建立 7 2.1.4 元件的装配 8 2.2 数值计算方法概述 9 2.2.1 流动控制方程 10 2.2.2 旋转区域中流动问题的建模 12 2.2.3 湍流模型 13 2.2.4 求解控制 14 2.3 离心泵的网格划分 15 2.3.1 网格相关问题的概述 15 2.3.2 网格划分 16 2.4 离心泵压力脉动的分类 18 2.5 离心泵压力脉动的产生 19 2.5.1 动静干扰引起的压力脉动 19 2.5.2 二次流引起的压力脉动 20 2.5.3 汽蚀引起的压力脉动 21 2.6 压力脉动的分析方法 21 2.6.1 时域法 21 2.6.2 频域法 22 2.7 本章小结 23 第三章 离心泵内三维数值特性分析 24 3.1 定常数值模拟 24 3.1.1 网格检查 24 3.1.2 设置求解器与计算模型 25 3.1.3 设置边界条件 25 3.1.4 设置检测器与计算 26 3.1.5 不同工况下数值模拟结果分析 27 3.2 非定常数值模拟 31 3.2.1 计算方法 31 3.2.2 压力脉动特征参数确实定 32 3.2.3 压力脉动监测点位置的设定 32 3.2.4 时间步长及采样频率确实定 33 3.2.5 不同工况下数值模拟结果分析 34 第四章 测量系统的方案设计 44 4.1 系统要求 44 4.1.1 总体要求 44 4.1.2 系统功能要求 45 4.1.3 系统技术指标 45 4.2 硬件设计 46 4.2.1 变送器 46 4.2.2 信号调理模块 47 4.2.3 数据采集卡 48 4.2.4 电路接线图 49 4.3 软件设计 50 4.4 USB数据通信 51 4.5 界面设计和程序打包 53 第五章 结论与展望 55 5.1 结论 56 5.2 展望 57 第1章 绪论 离心泵主要用来在某一流量下产生一个稳定的压力差以到达输送介质的目的 ，理想的流量与扬程曲线给人的感觉是在某一流量点扬程是静态的。事实上，泵在产生静态压力分量的同时还产生动态压力分量，也就是压力脉动。压力脉动象交流信号一样叠加在静态压力分量上。 离心泵内的压力脉动是极其复杂的，不同的离心泵可能表现不同种类的压力脉动，即使对同一台离心泵，当处于不同工况时也可能呈现不同性质的压力脉动。因此，离心泵内压力脉动的定义必须包含随机脉动和周期脉动两种。设p为离心泵内某点的压力， 假设对于任意的时间t和充分大的周期T，有平均压力根本不随时间而变化。 令，那么即为离心泵内某点的压力脉动。这些压力脉动是由叶轮进出口回流、 汽蚀等非期望的