Variation of Leading-Edge Suction at Stall for Steady and Unsteady Airfoil Motions
Variation of Leading-Edge Suction at Stall for Steady and Unsteady Airfoil Motions
复制标题
稳态和非稳态翼型运动失速时前缘吸力的变化
DOI：
10.2514/6.2016-1354
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发表时间：
2016
影响因子：
--
通讯作者：
J. Edwards
中科院分区：
文献类型：
--
作者：
S. Narsipur;Pranav Hosangadi;Ashok Gopalarathnam;J. Edwards
利用定常和非定常翼型运动的计算结果，研究了失速时前缘吸力的变化规律。采用非定常RANS代码对NACA 0012对称翼型和SD7003弧形翼型进行了计算，并对定常和非定常实验结果进行了验证。通过参数化研究确定了前缘吸力随螺距率和雷诺数变化的特性。结果表明，在一定的尾缘分离量下，非定常低俯仰率运动的流场结构与定常流场结构相似。升力系数和吸力系数的超调可归因于边界层对流滞后。对于前缘涡（LEV）主导的流动，无论运动参数如何，LEV启动后的流动形态都是相似的。然而，在低雷诺数和高雷诺数条件下，LEV起始点的时间瞬间和流场结构是不同的。虽然在低雷诺数模拟中，前缘吸力参数（LESP）值与运动运动学无关，但在高雷诺数情况下，情况并非如此。
Computational results for steady and unsteady airfoil motions are used to study the variation of leading-edge suction at stall. Computations were performed on the NACA 0012 symmetric airfoil and the SD7003 cambered airfoil using an unsteady RANS code that was validated against steady and unsteady experimental results. A parametric study was performed to determine the behavior of leading-edge suction with variations in pitch rate and Reynolds numbers. Results show that flowfield structures of unsteady low pitch rate motions are similar to steady results for a given amount of trailing-edge separation. The overshoot in lift and suction coefficients can be attributed to the boundary layer convection lag. For leading-edge vortex (LEV) dominated flows, it is found that flow morphology after LEV initiation is similar regardless of motion parameters. However, the time instant and flowfield structure at the point of LEV initiation vary for low and high Reynolds numbers. While leading-edge suction parameter (LESP) values at LEV initiation for low Reynolds number simulations are found to be independent of motion kinematics, the same is not true for the high Reynolds number cases.