Investigation of flow past a translatoric oscillating airfoil using detached eddy simulation

Wind turbine rotor blades in operation have been observed to undergo stall-induced lead-lag instabilities resulting in dramatic reduction of blade life, due to structural fatigue. Previous attempts to numerically simulate the flow past a translatoric oscillating airfoil have been few and feeble at the high angle of attacks often experienced by the individual rotor blade.

The present paper covers simulation of a translatoric oscillating NACA 0015 airfoil at a Reynolds number of 555,000, corresponding to avialable experimental data, using the newly adopted Detached Eddy Simulation (DES) approach. The DES method difines a hybrid method combining Reynolds Averaged Navier-Stokes (RANS) in the attached boundary layer with Large Eddy Simulation (LES) in the outer separated regions, thus resolving largescaled transient turbulent motion.

Comparison to existing unsteady k-w-SST RANS simulations and detailed experiments shows that DES improves the lift- and drag prediction along with improved realism in resolved flow fields.Results are presented for angel of attack of 15 eg. and translatoric oscillation angle of 5 deg. about the chord wise direction.See Figure 1.

Low-frequency vortex shedding, corresponding to Strouhal numer St=0.02, were found from the DES, which is comparable to numerical and experimental results obtianed by others.