摘要
翼型的流场结构对地效飞行器气动特性有着重要影响,针对这一问题,该文介绍了在风浪槽中进行的近自由表面翼型的流场PIV试验测量及其试验结果。实验分别测量了翼型与自由表面不同间距的多种工况下,零攻角NACA0012翼型尾流速度场随时间的演化过程,并将同一间隙条件下连续采集的瞬态速度场结果进行时均统计分析,获得了尾流的时均速度场等信息,用于对比分析翼型与自由表面不同间隙时的流场结构特征。实验结果表明,随着翼型与自由表面间距的不同,翼型尾流场的流动结构和气流在翼型表面的分离特性发生明显的变化,进而可能引起作用于翼型的气动力的变化。而后将本征正交分解POD(Proper Orthogonal Decomposition)方法应用于PIV瞬态速度场的后处理,研究分析了翼型尾流各本征模态下的湍流结构。结果显示低阶本征模态中存在明显的相干结构,且大尺度的流动结构与流场中绝大部分的能量分布直接相关,而高阶本征模态代表了流动的小尺度结构。
The near wake flow structure of airfoils has significant influence to the aerodynamic characteristic of a Wing in Ground Effect Vehicle. In this paper, we introduce the PIV experimental results on the wake flow structure of a NACA0012 airfoil mounted above water surface. The experiment was carried out in a small-scale wind-wave tunnel. The diameter of wind-wave tunnel test section is 1.7m （long） ×0.4m （width）×0.4m （height）. We measured the wake flow of the airfoil in four different conditions by varying the gap between the airfoil and the water surface. The angle of attack of the airfoil keeps 0° during the experiment. For each experimental condition, the time series of particle images were captured to calculate the continuous evolution of the velocity fields and the velocity fields were ensemble averaged to get the statistic parameters, such as the mean vorticity, the turbulence intensity and the Reynolds Stress. The results indicate that the flow structures of the airfoil wake flow vary remarkably with the changing of the distance between the airfoil and free surface. And then the proper orthogonal decomposition （POD） was applied to the PIV data post-processing in order to analyze the turbulence structure. Each eigen-mode shows typical coherent structure in the airfoil wake flow.
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
2008年第2期196-203,共8页
Chinese Journal of Hydrodynamics
基金
国家自然科学基金(10572082)
上海市重点学科(Y0103)资助项目
