﻿ 基于逆向工程的离心泵三维建模及数值模拟
 舰船科学技术  2016, Vol. 38 Issue (12): 94-97 PDF

Three-dimensional modeling and numerical simulation of centrifugal pump based on reverse engineering
ZHANG Yu, GONG Ya-jun, ZENG Bao-ping, WANG Qi
Wuhan Second Ship Design and Research Institute, Wuhan 430064, China
Abstract: Centrifugal pump is a crucial marine drive machinery equipment. With the development of computer technology, powerful 3D graphics software can be put into use to design the complex surface of the volute and impeller channel. In this paper, under the guidance of the concept of reverse engineering, combined with softwares, namely the laser scanner, scattered point cloud software and 3D CAD software will accurately construct 3D model of centrifugal pump to establish the 3D hydraulic model pump, using CFD method to analyze the internal flow phenomena and the basic rule for it. The predictive values and experimental values of the centrifugal pump working performance will be made comparison over and lead to the results that both are up to standards, and provide useful information for the structure optimization and performance enhancement of the pump.
Key words: reverse engineering     centrifugal pump     numerical simulation     computational fluid dynamics     computer-aid design
0 引 言

1 离心泵三维重构及水力计算模型提取 1.1 离心泵三维几何重构

 图 1 离心泵点云模型 Fig. 1 Point clouds model of centrifugal pump

 图 2 离心泵三维模型 Fig. 2 3D model of centrifugal pump
1.2 离心泵水力模型提取

 图 3 离心泵水力模型 Fig. 3 Hydraulic model of centrifugal pump
2 离心泵内流场的 CFD 分析

2.1 离心泵 CFD 模型建立 2.1.1 网格模型

 图 4 离心泵全流道网格模型 Fig. 4 Finite element model of centrifugal pump
2.1.2 边界条件

1）进口边界条件。如图 5 所示，采用速度进口（velocity inlet）。由质量守恒定律和无旋假设确定进口轴向速度，考虑叶轮与液流的相对运动，给出叶轮进口截面上的相对速度分布。假设在进口截面上压力为均匀分布。进口处的湍动能值 ${k_{in}}$，进口处湍动能耗散率 ${\varepsilon _{in}}$按下列公式计算：

 ${k_{in}} = 0.005u_{in}^2,$ (1)
 ${\varepsilon _{in}} = \frac{{C_\mu ^{3/4}k_{in}^{3/2}}}{l},$ (2)
 $l = 0.07{D_{inlet}}{\text {。}}$ (3)

2）出口边界条件。压力出口如图 5 所示，指定出口处的静压，当有回流时，使用压力出口边界条件代替自由出流边界条件会有比较好的收敛结果。

 图 5 边界条件 Fig. 5 Borndary condition

3）固壁条件。对于近壁区的流动，${R_e}$数较低，湍流发展并不充分，湍流的脉动影响不如分子粘性的影响大，这样在这个区域就不能使用前面建立的 $k-\varepsilon$模型。本文采用壁面函数法来解决这个问题。固壁上满足无滑移条件，即相对速度 $w = 0$；压力取为第 2 类边界条件，即 $\partial p/\partial n = 0$。湍流壁面条件采用壁面函数边界条件。在接近固体壁面区，壁面迫使流动产生较大的速度梯度，适应于湍流充分发展的 $k-\varepsilon$湍流模型在此区域需进行修正。设近壁点P 到壁面的距离为${y_p}$，则P 点处的速度 ${u_P}$ 和湍动能耗散 ${\varepsilon _P}$ 的值分别由下列壁面函数确定：

 $\frac{{{u_P}}}{{{u_\tau }}} = \frac{1}{\kappa }\ln \left( {Ey_p^ + } \right),$ (4)
 ${k_p} = \frac{{u_\tau ^2}}{{\sqrt {{C_u}} }},$ (5)
 ${\varepsilon _p} = \frac{{u_\tau ^3}}{{\kappa {y_p}}},$ (6)
 $y_p^ + = \frac{{\rho {u_\tau }{y_p}}}{\mu } = \frac{{\rho C_\mu ^{1/4}k_p^{1/4}{y_p}}}{\mu }{\text {。}}$ (7)

2.2 数值模拟计算方法 2.2.1 数学模型

2.2.2 主要设计参数

2.3 数值模拟计算结果与分析 2.3.1 压力分析

 图 6 压力分布 Fig. 6 Pressure distribution
2.3.2 速度分析

 图 7 速度分布 Fig. 7 Velocity distribution
2.3.3 离心泵性能曲线

 图 8 扬程—流量曲线 Fig. 8 Head-flow curve

 图 9 效率—流量曲线 Fig. 9 Efficiency-flow curve
3 结 语

 [1] 金涛, 童水光. 逆向工程技术[M]. 北京: 机械工业出版社, 2003 . JIN Tao, TONG Shui-guang. Reverse engineering[M]. Beijing: China Machine Press, 2003 . [2] 李琦, 胡义刚, 朱建军, 等. 基于逆向工程的叶轮叶片建模[J]. 轻工机械 , 2015, 33 (4) :76–80. LI Qi, HU Yi-gang, ZHU Jian-jun, et al. Impeller blade modeling research based on reverse engineering[J]. Light Industry Machinery , 2015, 33 (4) :76–80. [3] 柯映林, 肖尧先, 李江雄. 反求工程CAD建模技术研究[J]. 计算机辅助设计与图形学学报 , 2001, 13 (6) :570–575. KE Ying-lin, XIAO Yao-xian, LI Jiang-xiong. Study of CAD modeling for reverse engineering[J]. Journal of Computer Aided Design & Computer Graphics , 2001, 13 (6) :570–575. [4] 周小东, 成思源, 杨雪荣. 面向创新设计的逆向工程技术研究[J]. 机床与液压 , 2015, 43 (19) :25–28. ZHOU Xiao-dong, CHENG Si-yuan, YANG Xue-rong. Study of reverse engineering technology oriented to innovative design[J]. Machine Tool & Hydraulics , 2015, 43 (19) :25–28. [5] 胡大超, 张洪宝. 逆向工程技术及应用[J]. 上海应用技术学院学报(自然科学版) , 2014, 14 (3) :204–208. HU Da-chao, ZHANG Hong-bao. Technology and application of reverse engineering[J]. Journal of Shanghai Institute of Technology (Natural Science) , 2014, 14 (3) :204–208. [6] ASUAJE M, BAKIR F, TREMANTE A, et al. 3D quasi-unsteady flow simulation in a centrifugal pump:comparison with the experimental results[C]//Proceedings of ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. Charlotte, North Carolina, USA:ASME, 2004:1081-1090. [7] 杜喆华, 姜勇, 赵俊涛. 基于模态分析和CFD的船用离心泵减振[J]. 舰船科学技术 , 2012, 34 (10) :109–114. DU Zhe-hua, JIANG Yong, ZHAO Jun-tao. Reduce vibration measures for ship centrifugal pump based on modal analysis and CFD simulation[J]. Ship Science and Technology , 2012, 34 (10) :109–114. [8] 王福军. 计算流体动力学分析-CFD软件原理与应用[M]. 北京: 清华大学出版社, 2004 . [9] MAJID K. Numerical study of unsteady flow in a centrifugal pump[J]. Journal of Turbomachinery , 2005, 127 (2) :363–371. DOI:10.1115/1.1776587 [10] GOTO A, NOHMI M, SAKURAI T, et al. Hydrodynamic design system for pumps based on 3-D CAD, CFD, and inverse design method[J]. Journal of Fluids Engineering , 2002, 124 (2) :329–335. DOI:10.1115/1.1471362 [11] 姚玉英. 化工原理[M]. 天津: 天津大学出版社, 2005 .