论文部分内容阅读
针对模拟双自由度(2DOF)运动的“PQR”强迫振荡试验装置,通过坐标变换,将机构运动转化为空间欧拉角进行表示,实现对机构俯仰/偏航、俯仰/滚转和偏航/滚转等3种耦合运动的统一描述,采用预定运动轨迹的动网格计算技术,构造了基于非定常雷诺平均Navier-Stokes(URANS)方程的飞行器双自由度振荡数值模拟方法。围绕某复杂构型飞行器低速流动,在模型迎角10°、滚转角±40°、偏航角±40°振荡预设条件下分别对单自由度偏航、滚转振荡和双自由度偏航/滚转振荡进行了模拟,得到的气动系数迟滞回线在形态和量值上与风洞试验结果吻合,证明当前方法可以作为飞行器复杂耦合运动的一种有效研究手段。针对偏航/滚转耦合振荡,从运动形式和气动特性上与单独偏航、滚转运动进行了对比分析,结果表明,耦合运动在气流角、绕体轴的旋转角速度等方面与单自由度叠加效果不同,力矩系数迟滞回线存在曲线交叉的现象,表现出与单自由度振荡不同的阻尼特性。在当前模拟状态下,偏航/滚转振荡流场以横向分离涡运动为主要特征,可以推测大迎角情况下纵横向分离涡流动结构更加复杂,耦合作用更强,需要进一步在分离流模拟方法上开展研究。
Aiming at the “PQR” forced oscillation test device simulating two degrees of freedom (2DOF) motion, coordinate transformation is used to transform the movement of the mechanism into the Euler angles of space, which can be used to represent the pitch / yaw, pitch / roll and bias Flight / roll and other three kinds of coupled motions, the numerical simulation method of two-degree-of-freedom oscillations of an aircraft based on unsteady Reynolds-averaged Navier-Stokes (URANS) equations is constructed by moving grid computing technology with predetermined trajectories. Around a complex configuration aircraft low speed flow, the model of the angle of attack 10 °, roll angle ± 40 °, yaw angle ± 40 ° oscillation under the preconditions for single degree of freedom yaw, roll oscillation and two degrees of freedom yaw / Tumbling oscillations were simulated. The hysteresis loop of the aerodynamic coefficient obtained was in good agreement with wind tunnel test results in form and magnitude, which proves that the current method can be used as an effective research method for complex coupled motions of aircraft. For the yaw / roll coupled oscillation, it is compared with single yaw and roll motion separately from the motion form and the aerodynamic characteristic. The results show that the coupling motion has the same effect with the single degree of freedom The effect of superposition is different, the curve of hysteresis loop of moment coefficient has the phenomenon of crossover, which shows the damping characteristics different from those of single degree of freedom oscillation. Under the current simulation conditions, the yaw / roll oscillating flow field is mainly characterized by the lateral separation vortex movement. It can be inferred that the vertical and horizontal separation vortex flow structures are more complicated and the coupling effect is stronger at the high angle of attack, which needs to be further studied in the separation flow simulation Methods to carry out research.