Turbulent intensity effect on low reynolds number airfoil wake

The work investigates the effect of turbulent intensity (T_u) on the force and wake of a NACA0012 airfoil at chord Reynolds number Re_c = 5.3 × 10³ and 2 × 10⁴. Lift and drag coefficients (C_L and C_D) on and flow fields around the airfoil were measured with T_u varied from 0.6 to 6.0%. Four Re_c regimes are identified based on the characteristics of the maximum lift coefficient (CL,_max), i.e., ultra-low (Re_c<10⁴), low (10⁴ ~ 3 × 10⁵), moderate (3 × 10⁵ ~ 5 × 10⁶), and high (>5 × 10⁶). It is noted that at Re_c = 5.3 × 10³ (ultra-low Re_c regime) the stall is absent for T_u = 0.6% but occurs for T_u = 2.6 and 6.0%. As Rec increases to low Re_c regimes, the T_u influence decreases. So does the critical Re_c, above which stall occurs. The effect of increasing Tu on flow bears similarity to that of increasing Re_c, albeit with a difference; the flowseparation point shifts upstreamwith increasing Re_c but downstream with increasing T_u.