Assessment of Friction Drag Reduction on a Clark-Y Airfoil by Uniform Blowing

Aerodynamic Effects of Uniform Blowing and Suction on a NACA4412 Airfoil

“…(4) Uniform suction over the suction side in conjunction with uniform blowing over the pressure side is also beneficial for the aerodynamic efficiency, as expected, since both actuations are beneficial when applied separately. These results are qualitatively in agreement with those of recent experimental studies carried out at higher Reynolds number with similar configurations (Eto et al 2019;Kornilov et al 2019).…”

“…In particular, if the relative contribution of the pressure to the total drag remains nonnegligible, applying uniform blowing over the suction side will probably result in higher C d . This hypothesis is in agreement with the experimental results reported so far in the literature, up to Re c ≈ 1,600,000 (Eto et al 2019). Since uniform blowing applied over the suction side also reduces C l , this configuration appears to be the least promising.…”

“…For these reasons, the two following experimental works on the effects of blowing and suction on airfoils are of particular relevance. On the one hand, Eto et al (2019) considered blowing applied over the suction side of a Clark-Y airfoil at a Reynolds number based on the chord length of Re c = 1,600,000 ( Re c = U ∞ c∕ , where c is the chord length and the kinematic viscosity) and a blowing intensity of 0.14%U ∞ , and they observed a local reduction of the skin friction between ≃ 20 and ≃ 40% . However, they also reported that the total drag, estimated from the pressure measurements in the wake of the airfoil, increased.…”

Experimental investigation on friction drag reduction on an airfoil by passive blowing

“…5. Figure 6 shows the uncontrolled mean streamwise velocity profiles on the perforated metal plate and on the smooth surface in the present study, compared with the previous experimental result using a Clark-Y airfoil model (Eto et al, 2019) which is different from the one used in the present study, and the simulation result by means of RANS (Ohashi et al, 2019). The velocity profiles without blowing are measured at the angle of attack of α = 0 • and the Reynolds number based on the chord length of Re c = 1.55 × 10 6 .…”

“…Atzori et al (2018) confirmed the friction drag reduction effect of UB in an adverse pressure gradient turbulent boundary layer over a suction side of NACA 4412 airfoil by means of large eddy simulation (LES). Eto et al (2019) conducted a wind-tunnel experiment of UB at 0.14% free-stream velocity on an airfoil using air supply from an external compressor, i.e., active UB, and confirmed 20%-40% local friction drag reduction through a hot-wire measurement of velocity profiles and a quantitative assessment taking into account the pressure gradient. Although UB is generally known as an active control, Eto et al (2017) also attempted a passive blowing, which is driven by the pressure difference on a wing surface between suction and blowing region.…”