Wind tunnel experiments are carried out on a 3D wing-in-ground effect at pre- and post-stall angles of attack at a relatively low Reynolds number, Re ≈ 8.8 × 104. The rectangular wing, aspect ratio, AR = 6.4 used in the present work has a symmetric airfoil section, NACA0012 and is studied at different ranges of ground proximity and also compared to a wing of cambered airfoil section, NACA4415 not in ground proximity. Unsteady and time-averaged six-component aerodynamic characteristics, coefficients of Lift, Drag, Side forces, Pitch, Roll, Yaw moments at several angles of attack in the range – 8° < α < 18° are reported. Aerodynamic efficiency and drag polars are studied in lieu of ground proximity at several angles of attack. Effect of ground proximity on the occurrence of stall and is studied. Numerical calculations using steady-state CFD are also made for quantitative comparison. The effect of ground proximity on span-wise pressure distribution and induced velocity in the vicinity of the wing is also discussed in detail.
HalloranMO’MearaS. Wing in ground effect craft review. Melbourne:DSTO Aeronautical and Maritime Research Laboratory Melbourne, 1999.
2.
KimDHChangJW. Low-reynolds-number effect on aerodynamic characteristics of a naca 0012 airfoil. Aerospace Sci Technology2014; 32: 162–168. DOI: 10.1016/j.ast.2013.08.018.
3.
PatilBSThakareHR. Computational fluid dynamics analysis of wind turbine blade at various angles of attack and different reynolds number. Procedia Eng2015; 127: 1363–1369, DOI: 10.1016/j.proeng.2015.11.495.
4.
WinslowJOtsukaHGovindarajanB, et al.Basic understanding of airfoil characteristics at low reynolds numbers (104–105). J Aircraft2017; 55: 1–12. DOI: 10.2514/1.C034415.
5.
WorasinchaiSIngramGDominyR, et al.A low-reynolds-number, high-angle-of-attack investigation of wind turbine aerofoils. Proceedings Institution Mechanical Engineers, Part A: J Power Energy2011; 225: 748–763. DOI: 10.1177/0957650911405411.
6.
LaitoneEV. Wind tunnel tests of wings at reynolds numbers below 70 000. Experiments in Fluids1997; 23: 405–409.
7.
MizoguchiMKajikawaYItohH, et al.Aerodynamic characteristics of low-aspect-ratio wings with various aspect ratios in low reynolds number flows. Transactions Japan Society for Aeronautical Space Sciences2016; 59: 56–63. DOI: 10.2322/tjsass.59.56.
8.
AnandaGSukumarPSeligM, et al.Measured aerodynamic characteristics of wings at low reynolds numbers. Aerospace Sci Technology2015; 42: 392–406, DOI: 10.1016/j.ast.2014.11.016.
9.
AhmedMSharmaS. An investigation on the aerodynamics of a symmetrical airfoil in ground effect. Experimental Thermal Fluid Sci2005; 29(6): 633–647, DOI: 10.1016/j.expthermflusci.2004.09.001.
10.
DjavareshkianMEsmaeliAParsaniA, et al.Aerodynamics of smart flap under ground effect. Aerospace Sci Technology2011; 15(8): 642–652, DOI: 10.1016/j.ast.2011.01.005.
11.
GhadimiPRostamiABJafarkazemiF, et al.Aerodynamic analysis of the boundary layer region of symmetric airfoils at ground proximity. Aerospace Sci Technology2012; 17(1): 7–20, DOI: 10.1016/j.ast.2011.02.008.
12.
LiSZhouDZhangY, et al.Aerodynamic investigation of rae2822 airfoil in ground effect. Procedia Eng2015; 126: 174–178, DOI: 10.1016/j.proeng.2015.11.208.
13.
AhmedMRTakasakiTKohamaY, et al.Aerodynamics of a naca4412 airfoil in ground effect. AIAA J2007; 45: 37–47. DOI: 10.2514/1.23872.
14.
Martínez-ArandaSGarcia-GonzalezAParrasL, et al.Comparison of the aerodynamic characteristics of the naca0012 airfoil at low-to-moderate reynolds numbers for any aspect ratio. International J Aerospace Sciences2016; 4: 1–8. DOI: 10.5923/j.aerospace.20160401.01.
15.
JungJHKimMYoonH, et al.Endplate effect on aerodynamic characteristics of three-dimensional wings in close free surface proximity. International J Naval Architecture Ocean Eng2012; 4: 477–487. DOI: 10.3744/JNAOE.2012.4.4.477.
LuoSChenY. Ground effect on flow past a wing with a naca0015 cross-section. Experimental Thermal Fluid Sci2012; 40: 18–28. DOI: 10.1016/j.expthermflusci.2012.01.014.
18.
Tavakoli DakhrabadiMSeifM. Influence of main and outer wings on aerodynamic characteristics of compound wing-in-ground effect. Aerospace Sci Technology2016; 55: 177–188, DOI: 10.1016/j.ast.2016.06.002.
19.
AbramowskiT. Numerical investigation of airfoil in ground proximity. J Theoretical Applied Mechanics2007; 45: 425–436.
20.
FinkMLastingerJAeronauticsUSN, et al.1961.Aerodynamic characteristics of low-aspect-ratio wings in close proximity to the ground. Washington, DC: NASA technical note, National Aeronautics and Space Administration.
21.
OhtakeTNakaeYMotohashiT, et al.Nonlinearity of the aerodynamic characteristics of naca0012 aerofoil at low reynolds numbers. J Japan Society for Aeronautical Space Sciences2007; 55(644): 439–445. DOI: 10.2322/jjsass.55.439.
22.
RoyAMukherjeeR. Three dimensional rectangular wing morphed to prevent stall and operate at design local two dimensional lift coefficient. Aerospace Sci Technology2020; 107: 106312, DOI: 10.1016/j.ast.2020.106312.
23.
EastmanJShermanA. 1937.Airfoil section characteristics as affected by variations of the Reynolds number. Washington, DC: NACA R-586, National Advisory Committee for Aeronautics.
