某典型飞行器模型俯仰/滚转两自由度耦合动态气动特性

Unsteady aerodynamic characteristics of two-degree-of-freedom pitch/roll coupled motion for a typical vehicle model

先进飞行器在大迎角高机动飞行过程中,气动力复杂演化与运动姿态剧烈变化的相互作用,容易诱发俯仰拉起的滚转或侧偏等耦合运动,呈现出十分强烈的多自由度动态气动力特性。为此,选取某典型四代机修型设计模型,利用FL-26风洞专用的俯仰/滚转两自由度动态试验装置,开展了单自由度和俯仰/滚转两自由度耦合运动的动态气动力特性研究。结果表明,研究模型在迎角30°左右会出现滚转单自由度的侧偏和小振幅摇滚运动现象;俯仰单自由度振动条件下,模型法向力和俯仰力矩会出现明显的气动迟滞特性;在强迫俯仰/自由滚转(或强迫滚转)两自由度耦合运动情况下,模型的侧偏运动幅值得到了一定的抑制,但纵横向气动力都出现了迟滞现象,甚至是多个气动迟滞环结构,容易引发耦合失稳发散。

During high maneuvers at high angle of attack for advanced vehicles,coupled motions of pitch/roll or pitch/yaw may be induced by the interaction between the complex evolution of aerodynamic characteristics and the dramatic change of motion attitudes,displaying the strong multi-degree-of-freedom unsteady aerodynamic characteristics.Therefore,based on the dynamic test devices for two-degree-of-freedom pitch/roll in FL-26 wind tunnel,the unsteady aerodynamic characteristics of the one-degree-of-freedom motion and the two-degree-of-freedom pitch/roll coupled motion for a typical four-generation plane model are investigated.The results show that at around 30°angle of attack,the model occurs lateral deviation with for one-degree-of-freedom roll motion and wing rock of small amplitude.A significant dynamic hysteresis of normal force and pitch moment appears during one-degree-of-freedom pitch oscillation.During two-degree-of-freedom forced pitch/free roll coupled motion and forced pitch/forced-roll coupled motion,the amplitude of the sideslip angle decreases,but there are dynamic hysteresis with multiple hysteresis loops on longitudinal and lateral aerodynamic characteristics,which may induce instability and divergence.