Flow characteristics around airfoils near transonic buffet onset conditions
| Autor: | Yuexi Xiong, Yanxiong Zhao, Zhixiong Dai, Yun Tian |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Shock wave
Airfoil 0209 industrial biotechnology Transonic buffet Separated bubbles Aerospace Engineering 02 engineering and technology 01 natural sciences 010305 fluids & plasmas Shock waves Physics::Fluid Dynamics Flow separation 020901 industrial engineering & automation 0103 physical sciences Trailing edge Supersonic speed Motor vehicles. Aeronautics. Astronautics Physics Shock (fluid dynamics) Mechanical Engineering TL1-4050 Mechanics Dynamic Mode Decomposition Boundary layer Transonic flow Transonic |
| Zdroj: | Chinese Journal of Aeronautics, Vol 33, Iss 5, Pp 1405-1420 (2020) |
| ISSN: | 1000-9361 |
| Popis: | In transonic flow, buffet is a phenomenon of flow instability caused by shock wave/boundary layer interaction and flow separation. The phenomenon is common in transonic flow, and it has serious impact on the structural strength and fatigue life of aircraft. In this paper, three typical airfoils: the supercritical OAT15A, the high-speed symmetrical NACA64A010, and the thin, transonic/supersonic NACA64A204 are selected as the research objects. The flow fields of these airfoils under pre-buffet and buffet onset conditions are simulated by Unsteady Reynolds Averaged Navier-Stokes (URANS) method, and the mode analysis of numerical results is carried out by Dynamic Mode Decomposition (DMD). Qualitative and quantitative analysis of the shock wave motion, shock wave intensity, shock foot bubble and trailing edge separation, and pressure coefficient fluctuation were performed to attain deep insight of transonic buffet flow features of different airfoils near buffet onset conditions. The results of DMD analysis show that the energy proportion of the steady mode of these airfoils decreases dramatically when approaching the buffet onset angle of attack, while the growth rate of the primary mode increases inversely. It was found that at the onset of buffet, there exist different degrees of merging behavior between shock foot bubble and trailing edge separation during one buffet cycle, and the instability of shock wave and separation induced shear layer are closely related to the merging behavior. |
| Databáze: | OpenAIRE |
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