Numerical Study on Unsteady Flow and Noise for a High Lift Configuration with Transition Effects

The boundary-layer transition effects on the flow and noise characteristics for a high lift configuration was investigated. Improved delayed detached eddy simulation (IDDES) is performed to resolve the turbulent structures and model the transition procedure by coupling k-ω-γ transition model. For comparison, IDDES coupled with shear-stress transport (SST) model is also performed. From the numerical results, IDDES coupled with transition model (IDDES-Tr) can simulate the boundary layer transition and thus exhibit a different distribution of flow variables such as the velocity and Cf. Therefore, the pressure fluctuations and the location of separation show significant differences. The far-field directivities are integrated for different integral surfaces by solving the Ffowcs Williams and Hawkings (FW-H) equation. At all angles, IDDES coupled with full turbulence model (IDDES-FT) indicates stronger noise and the maximum increase can reach 3.2 dB, due to the weaker fluctuations of IDDES-Tr on the main wing and flap surface which are the dominant noise sources in this study.