Abstract: When the aircraft is maneuvering at high angle of attack and fast pitch, the flow field contains large-scale and unsteady vor-tices. The traditional RANS model can not accurately simulate the flow field structure. According to the development trend of international research, the hybrid RANS/LES model is needed to accurately simulate the complex separated flow. In this paper, the dual RANS/LES hybrid computational model based on zonal mixing and turbulence scale mixing is further devel-oped and applied. Through the static and dynamic turbulent large separation flow of typical simplified models, DES-based methods are tested and validated. The correctness and validity of IDDES model in the application of dynamic problems are emphatically studied. The reliability, robustness and accuracy of the numerical simulation method and corresponding calcula-tion software are tested and verified. Typical examples include supersonic cylindrical bottom flow, pitch oscillation of NACA0012 airfoil and deep stall separation eddy simulation of NACA0015 airfoil. The requirements of three flow types for turbulence simulation methods are given: steady separated flow, static unsteady separated flow and dynamic unsteady sepa-rated flow. The results show that SA and SST models can give ideal results for static separated flows, DES, DDES and IDDES models are equivalent for static unsteady separated flows, and IDDES models are needed for dynamic unsteady separated flows.

Key words: unsteady flow, the hybrid RANS/LES model, separated flow, IDDES model