采用改进的延迟脱体涡仿真(IDDES)方法、双时间步LU-SGS方法、本征正交分解(POD)方法开展数值仿真,并分析吊窗的尾迹流动气动光学效应的非稳态特性。仿真流线与油流实验在总体上可比性较好,但二者的吊窗尾迹区流场结构存在一定差异。吊窗流动易分离,K-H不稳定波会使分离剪切层失稳并产生脱落涡街,涡街与颈项涡相互作用,在吊窗尾迹区产生复杂的非稳态流动。吊窗尾迹流动气动光学效应以稳态相差为主,占比达70%,稳态相差会弱化气动光学效应的非稳态特性;波前以低阶模态为主,阶数越高,模态包含越多小尺度结构。根据标度律,在海拔为10 km与吊窗直径为2 m条件下,方均根光程差的时均值约为0.48λ,气动光学效应将得到进一步加强,这会对高能激光**(ABL)性能带来不利影响。

In this study, a numerical simulation is conducted using the improved delayed detached eddy simulation (IDDES) method, the dual time-stepping LU-SGS method, and the proper orthogonal decomposition (POD) method, and the unsteady characteristics of aero-optical effects of the turret wake are analyzed. Although the simulated streamlines generally agree with oil flow test, some differences can be observed with respect to the flowfield structure of the turret wake. The flow around a turret can be easily separated. Further, the instability of the separated shear layer can be attributed to the K-H instability wave, resulting in the emergence of the shedding vortex streets. The unsteady complex flow in the turret wake area can be attributed to the interaction between the vortex streets and neck vortexes. The aero-optical effects of the turret wake are dominated by the steady-state aberration that accounts for 70% and can weaken the unsteady characteristics of the aero-optical effects. The wavefront is dominated by low-order modals, and the number of small-scale structures included in the modals will increase with the increasing order. According to the scaling law, the time mean value of the root-mean-square optical path difference is approximately 0.48λ under an altitude of 10 km and a turret diameter of 2 m; thus, the aero-optical effect will be further intensified, which can negatively affect the ABL performance.