翼型近尾迹流动的PIV研究—运动学特性
A PIV STUDY OF NEAR WAKE FLOW OF AIRFOIL PART Ⅰ-KINEMATIC CHARACTERISTICS
-
摘要: 利用在线式PIV系统(ParticleImageVelocimetry),在低速风洞中对NACA0012翼型在雷诺数2.39×105,0°和4°攻角下的近尾迹流动进行了实验研究。实验结果表明,在较高的雷诺数下翼型近尾迹流动是一种以旋涡的运动学和动力学特性为主导的湍流剪切流。在测量范围内,翼型的尾缘处是近尾迹涡街的形成区;尾缘后0.5倍弦长的区域存在类似于卡门涡街的有序结构,是旋涡发展区域,旋涡具有较好的稳定性;距翼型尾缘0.5倍弦长至1倍弦长的区域,是翼型近尾迹流动由有序走向无序区域,旋涡开始破裂。翼型表面边界层对翼型近尾迹湍流剪切流的演化有重要影响。实验结果还给出了近尾迹流动的平均速度、湍流强度和剪切应变变化率,以及速度脉动量的二阶关联量u'u',u'v'和v'v' 的分布。Abstract: Detailed 2D velocity fields obtained from on-line PIV (Particle Image Velocimetry) measurements in a low speed wind tunnel are used to investigate flow structures in the turbulent near wake flow of a NACA0012 airfoil.The Reynolds number on chord length is 2.39×105,the angles of attack are 0° and 4°.The experimental results indicate that the turbulent near wake flow is dominated by the dynamic and kinematic characteristics of vortices at relatively high Reynolds number.According to the flow structures identified from instantaneous velocity fields,the vortex street is created at the airfoil tail region.Structures in the vortex developing region (within 0.5 chord length) are similar to those for the Karman vortex street and structures in the vortex break-up and dissipation region (between 0.5 and 1.0 chord length) change from organized to non-organized.The results also show that the boundary layer of the airfoil affects the structures in the near wake flow.The fields of mean velocity,turbulence intensity,strain rate and correlation coefficients of EMBED Equation are also obtained.
-
Key words:
- Airfoil /
- Wakes /
- Kinematics
点击查看大图
计量
- 文章访问数: 1825
- HTML浏览量: 3
- PDF量: 409
- 被引次数: 0