Experimental Investigation of the Boundary Layer and Pressure Measurements on Airfoils with Laminar Separation Bubbles

Validating the URANS shear stress transport γ −Reθ model for low‐Reynolds‐number external aerodynamics

“…Test case 4 is resimulated using a free-stream turbulence intensity of 1.00%, that is, at the threshold of natural and bypass transition. The calculated pressure coefficients are displayed in Figure 7a and compared with the results at T u 1 = 0.11% and the experimental data of Wahidi and Bridges [50]. The agreement between the new results and the published results is much better.…”

“…At 0 ı angle of attack and at AoA = 4 ı and Re D 5.0 10 4 , an LSB does not form. Most of these trends were also observed by several authors [1,6,8,16,49,50] at similar Reynolds numbers and angles of attack. It should be noted that the XFLR5 results (not shown) fail to capture separation at Re D 2.5 10 5 and incorrectly indicate transition and reattachment at 0 ı angle of attack.…”

“…In this section, the chosen numerical method is tested against published DNS and experimental data at Re = 5.0 ×10 4 , AoA = 5°(Case 2), Re ≈ 5.0 ×10 4 , AoA = 6°(Case 3), and Re = 2.5 ×10 5 , AoA = 4°(Case 4). Table displays the time‐averaged LSB characteristics along with the turbulence intensity values around the airfoil ( Tu ∞ ).…”

“…On the other hand, the SST Re ™ model at Re D 5.0 10 4 , AoA = 5 ı predicts a larger LSB than the one calculated by Jones et al [13], while at Re D 5.0 10 4 , AoA = 6 ı the SST Re ™ model predicts a smaller LSB than the one experimentally measured by Kim et al [49] at a slightly lower Reynolds number (Re D 4.8 10 4 /. Finally, for Case 4, the calculated LSB is larger than what was previously measured by Wahidi and Bridges [50].…”

“…The boundary layer also thins with increasing Reynolds number or decreasing angle of attack (see also Figure 17). Figure 21 displays the average lift coefficients compared to DNS [13] and experimental [50,61] results. The experimental data at Re D 2.5 10 5 [50] exhibit negative lift at the lower angles of attack despite the fact that the experimental data at Re D 1.0 10 5 [61] indicate positive lift throughout.…”