Geometrically-exact unsteady model for airfoils undergoing large amplitude maneuvers
Geometrically-exact unsteady model for airfoils undergoing large amplitude maneuvers
复制标题
经历大幅度机动的机翼的几何精确非定常模型
DOI：
10.1016/j.ast.2014.09.021
复制
发表时间：
2014
影响因子：
5.6
通讯作者：
M. Hajj
中科院分区：
文献类型：
--
作者：
Zhimiao Yan;Haithem E. Taha;M. Hajj
建立了翼型作大幅度机动时的半解析、几何精确、非定常势流模型。为此，重新讨论了经典的Theodorsen非定常理论，放松了一些主要假设，如(1)平坦尾迹，(2)小迎角，(3)对平均流分量的小扰动，以及(4)时不变的自由流。对尾迹涡的运动学进行了数值模拟，同时解析地确定了尾迹和束缚环流的分布以及相应的压力分布。用实验和计算结果验证了模型的定常和非定常行为。然后利用该模型确定了不同平均迎角下的升力频率响应。得到的频率响应与Theodorsen在大迎角下的频率响应存在定性和定量的差异。
A semi-analytical, geometrically-exact, unsteady potential flow model is developed for airfoils undergoing large amplitude maneuvers. For this objective, the classical unsteady theory of Theodorsen is revisited relaxing some of the major assumptions such as (1) flat wake, (2) small angle of attack, (3) small disturbances to the mean flow components, and (4) time-invariant free-stream. The kinematics of the wake vortices is simulated numerically while the wake and bound circulation distribution and, consequently, the associated pressure distribution are determined analytically. The steady and unsteady behaviors of the developed model are validated against experimental and computational results. The model is then used to determine the lift frequency response at different mean angles of attack. Both qualitative and quantitative discrepancies are found between the obtained frequency response and that of Theodorsen at high angles of attack.