Numerical study of free stream turbulence effects on dynamic stall of pitching tubercled wings

Abstract

The feasibility of a tubercled leading-edge in dynamic stall control has been validated, and the impacts of an upstream cylinder wake have already been discussed in the previous research. However, the influences of wake coherent characteristics on the dynamic stall process are inevitable. To this end, the synthetic turbulence method was adopted in the present study to generate incoming turbulence. The suppression of dynamic stall could be observed according to the shrink of hysteresis loop of aerodynamic lift. Then, the dynamic stall mechanisms have been analyzed with the help of mode decomposition method. The emergence and development of the leading-edge vortex indicate the increase in aerodynamic lift, while he detachment of dynamic stall vortex leads to the lift degradation during the onset of dynamic stall. Eventually, the influence of turbulence intensity (TI) has also been discussed through the comparison of TI = 5% and TI = 10% cases. It turns out that flow separation is more remarkable at both peak and trough sections in the case of TI = 5%, which is intrinsically caused by the suppression of resistance of adverse pressure gradient.