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首页> 外文期刊>The Aeronautical Journal >Aerodynamics of an aerofoil in transonic ground effect: numerical study at full-scale Reynolds numbers
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Aerodynamics of an aerofoil in transonic ground effect: numerical study at full-scale Reynolds numbers

机译:跨音速地面效应中的翼型的空气动力学:全尺寸雷诺数的数值研究

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The potential positive effects of ground proximity on the aerodynamic performance of a wing or aerofoil have long been established, but at transonic speeds the formation of shock waves between the body and the ground plane would have significant consequences. A numerical study of the aerodynamics of an RAE2822 aerofoil section in ground effect flight was conducted at freestream Mach numbers from 0.5 to 0.9, at a range of ground clearances and angles of incidence. It was found that in general the aerofoil's lifting capability was still improved with decreasing ground clearance up until the point at which a lower surface shock wave formed (most commonly at the lowest clearances). The critical Mach number for the section was reached considerably earlier in ground effect than it would be in freestream, and the buffet boundary was therefore also reached at an earlier stage. The flowfields observed were relatively sensitive to changes in any given variable, and the lower surface shock had a destabilising effect on the pitching characteristics of the wing, indicating that sudden changes in both altitude and attitude would be experienced during sustained transonic flight close to the ground plane. Since ground proximity hastens the lower surface shock formation, no gain in aerodynamic efficiency can be gained by flying in ground effect once that shock is present.
机译:长期以来,地面接近对机翼或机翼的空气动力学性能产生了潜在的积极影响,但在跨音速下,机体与地面之间形成冲击波将产生重大后果。在地面距离和入射角范围内,自由流马赫数从0.5到0.9进行了RAE2822机翼截面在地面效应飞行中空气动力学的数值研究。人们发现,总体上,直到降低地面冲击波的形成点(最常见的是最低间隙),机翼的提升能力仍会随着离地间隙的减小而得到改善。该部分的临界马赫数在地面效应中比在自由流中要早得多,因此,自助边界也在较早阶段达到。观测到的流场对任何给定变量的变化都相对敏感,并且较低的表面冲击对机翼的俯仰特性产生了不稳定作用,表明在持续的跨音速飞行中,接近地面的高度和姿态都会突然发生变化。飞机。由于靠近地面会加速下表面震动的形成,一旦出现震动,就无法通过飞入地面来获得空气动力学效率的提高。

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