微孔对翼型水力特性影响探讨
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摘要
应用ICEM、FLUENT、CFX(通过ISO认证的CFD模型)等软件,采用标准的k-ε模型,制成水力机械对称翼型叶片,并在其叶片的几何模型低压区断面上,布置种类为全通Ф28、Ф36、Ф63多微孔、半通单孔和全通单孔,进行绕流数值模拟分析。根据压强分布、升力系数、阻力系数和升阻比系数等变化因素判断了孔的数量及深度对翼型的空化性能和水力性能的影响关系。研究结果表明:在翼型的低压高速区工作面布置一定数量的微孔能有效增加压强,从而减小空化,且36孔翼型低压区范围最小、升阻比系数最大;在低压区打孔能够明显减小阻力,且1孔半、1孔全通模型阻力是无孔翼型阻力的39%和44%;微孔模型翼型升力有所下降;半通孔的阻力系数低于全通孔,且升力系数略高于全通孔。半通孔和全通孔的升阻比相对于无孔提高了2倍和1.7倍,进而改善翼型的水力特性,因此,孔采用半通方式优于全通方式。
In this paper the symmetrical airfoil of hydraulic machinery blade at low-pressure region was studied with the software of ICEM,FLUENT and CFX and using standard k-ε model. Different airfoils with 28,36,64 micropores of pass-through and semi-through holes were modeled. By analyzing the pressure distribution,lift coefficient,drag coefficient,lift drag coefficient and other factors,the influence of the number and depth of holes on the cavitation performance and hydraulic performance of airfoil was investigated. The results showed that configuring a certain number of micropores on the airfoil surface with high speed and low pressure can effectively increase the pressure and reduce the cavitation,and the airfoil with 36 holes has the smallest low pressure area and the highest lift drag coefficient. Drilling a hole in the area of low pressure can evidently reduce the resistance; the semi-through hole and the pass-through hole have only 39% and 44% of the resistance of the airfoil without hole,respectively. The lift,however,declines for the microporous airfoil. Compared to full-through holes,semi-through holes has lower drag coefficient,and slightly higher lift coefficient. Against the nonporous airfoil,the lift to drag ratio for the airfoils with semithrough hole and pass-through hole increases by 2 and 1. 7 times,respectively,indicating the improved hydraulic characteristics of the airfoil and the better performance of the semi-through hole.
In this paper the symmetrical airfoil of hydraulic machinery blade at low-pressure region was studied with the software of ICEM,FLUENT and CFX and using standard k-ε model. Different airfoils with 28,36,64 micropores of pass-through and semi-through holes were modeled. By analyzing the pressure distribution,lift coefficient,drag coefficient,lift drag coefficient and other factors,the influence of the number and depth of holes on the cavitation performance and hydraulic performance of airfoil was investigated. The results showed that configuring a certain number of micropores on the airfoil surface with high speed and low pressure can effectively increase the pressure and reduce the cavitation,and the airfoil with 36 holes has the smallest low pressure area and the highest lift drag coefficient. Drilling a hole in the area of low pressure can evidently reduce the resistance; the semi-through hole and the pass-through hole have only 39% and 44% of the resistance of the airfoil without hole,respectively. The lift,however,declines for the microporous airfoil. Compared to full-through holes,semi-through holes has lower drag coefficient,and slightly higher lift coefficient. Against the nonporous airfoil,the lift to drag ratio for the airfoils with semithrough hole and pass-through hole increases by 2 and 1. 7 times,respectively,indicating the improved hydraulic characteristics of the airfoil and the better performance of the semi-through hole.
引文
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[14]KRAVTSOVA A Y,MARKOVICH D M,PERVUNI KS,et al.High-speed visualization and PIV measurements of cavitating flows around a semi-circular leading-edge flat plate and NACA0015 hydrofoil[J].International Journal of Multiphase Flow,2014,119-134.
[2]赵亚萍,廖伟丽,李志华,等.轴流式水轮机叶片进水边形状对其性能的影响[J].农业工程学报,2012,28(13):94-99.ZHAO Ya-ping,LIAO Wei-li,LI Zhi-hua et al.Influence of water inlet shape of axial flow turbine on its performance[J].Transactions of the Chinese Society of Agricultural Engineering,2012,28(13):94-99.
[3]于凤荣,张立翔.多孔翼型流场数值模拟研究[J].固体力学学报,2014,35(10):59-63.YU Feng-rong,ZHANG Li-xiang.Numerical simulation of the flow field of a porous airfoil[J].Acta Mechanica Solida Sinica|Acta Mech Solid Sin,2014,34(10):59-63.
[4]张德胜,施卫东,陈斌,等.轴流泵叶轮汽蚀两相流的数值模拟与分析[J].流体机械,2013,04:16-20.ZHANG De-sheng,SHI Wei-dong,CHEN Bin,et al.Numerical simulation and analysis of two-phase flow in axial flow pump impeller[J].Fluid Machinery,2013,04:16-20.
[5]朱冬生,毛玮,蓝少健,等.多孔介质模型在板翅式换热器数值模拟中的应用[J].流体机械,2012,04:63-67.ZHU Dong-sheng,MAO Wei,LAN Shao-jian,et al.Application of porous media model in numerical simulation of plate fin heat exchanger[J].Fluid Machinery.,2012,04:63-67.
[6]王惠敏,韩喜莲,孙三祥.空化数与雷诺数关系的确定[J].西华大学学报,2008,27(6):9-12.WANG Hui-ming,HAN Xi-lian,SUN San-xiang.Determination of the relationship between cavitation number and Reynolds number[J].Journal of Xihua University(Natural Science Edition),2008,27(6):9-12.
[7]容亮湾.水轮机叶片水动力分析及翼型优化[D].哈尔滨:哈尔滨工程大学,2006.RONG Liang-wan.Hydrodynamic analysis of turbine blade and optimization of airfoil[D].Harbin:Institute of Technology,2006.
[8]韩中合,贾亚雷,李恒凡,等.风力机分离式尾缘襟翼气动性能[J].农业工程学报,2014,30(20):58-64.HAN Zhong-he,JIA Yal-ei,LI Heng-fan et al.Aerodynamic performance of discrete trailing edge flaps of wind turbine[J].Transactions of the Chinese Society of Agricultural Engineering,2014,30(20):58-64.
[9]PRITCHARD R E.Base drag effects on maximum lift-to-drag ratio airfoils at moderate supersonic speeds[J].Journal of Optimization Theory and Applications,1969,3(2):115-136.
[10]LI Shi-bin,HUANG Wei,WANG Zhen-guo,et al.Design and aerodynamic investigation of a parallel vehicle on a wide-speed range[J].Science China Information Sciences,2014,57(12):1-10.
[11]冯俊,郑源.基于CFD的轴流泵三维湍流数值模拟[J].流体机械,2012,11:33-36+88.FENG Jun,ZHEN Yuan.Numerical simulation of three dimensional turbulent flow in axial flow pump based on CFD[J].Fluid Machinery,2012,11:33-36+88.
[12]武建国,陈超英,王延辉,等.水下滑翔其浮力驱动效率分析[J].机械工程学报,2009,45(4):172-176.WU Jian-guo,CHEN Chao-yin,WANG Yan-hui et al.Analysis of the buoyancy driven efficiency of underwater gliding[J].Journal of Mechanical Engineering,2009,45(4):172-176.
[13]LEROUX JB,COUTIER-DELGOSHA O,ASTOLFI J A.A joint experimental and numerical study of mechanisms associated to instability of partial cavitation on two-dimensional hydrofoil[J].Physics Of Fluids,2005.
[14]KRAVTSOVA A Y,MARKOVICH D M,PERVUNI KS,et al.High-speed visualization and PIV measurements of cavitating flows around a semi-circular leading-edge flat plate and NACA0015 hydrofoil[J].International Journal of Multiphase Flow,2014,119-134.