Influences of Leading-Edge Tubercle Amplitude on Airfoil Flow Field

The influences of leading-edge tubercle amplitude on airfoil flow field have been analyzed at high angle of attack. The accuracy of a large eddy simulation (LES) research is validated through quantitative comparisons with corresponding experimental results. Then, a proper orthogonal decomposition (POD) analysis has been carried out based on the unsteady flow field and the fluid mechanisms of corresponding POD modes have been identified. Consequently, the influences of leading-edge tubercle amplitude have been uncovered. Since the streamwise vorticity is larger than that of small amplitude cases, the momentum transfer process at peaks is more obvious for large amplitude, leading to delayed flow separation. Both amplitude and wavelength play important roles in the generation of laminar separation bubble (LSB) at troughs. Moreover, the Karman vortex shedding process takes place at specific trough sections as pairs of periodic spatial structures exist in the dominant POD modes. The destruction of Karman vortex shedding process is strengthened along with the increase of amplitude.