摘要:
对翼梢组合小翼构型和翼梢喷流控制翼尖涡进行了实验研究,在此基础上,提出组合小翼与翼梢喷流联合控制翼尖涡的方法,并对翼尖涡的控制效果进行了实验研究。实验在一低速直流式风洞中进行,基本模型为NACA0015二元截尖翼型,基于弦长和自由来流速度定义的雷诺数Re=5.3×104,喷流系数(喷流与自由来流的动量比)Cμ=0.017。研究结果表明:组合小翼构型能有效破碎主涡,改善翼尖部位的局部流动,并使最大升力系数提高12.3%;喷流可加剧涡核摆动,控制涡核位置,对翼尖涡的初始生成有一定的抑制作用;2种组合构型均达到了较好的翼尖涡控制效果,其中,喷流加强了组合小翼产生的同向涡之间的相互作用。在X/C=3时,瞬态涡量峰值的平均值相比单独用“+0-”构型控制时减小37%,比没有任何控制时减小79%。组合构型的控制效果取决于喷流控制能否促使翼尖涡主涡与小涡涡系尽早、尽快地相互作用以及主涡涡核的偏移方向。
Abstract:
The effects of multi-winglets and wingtip blowing on the wing tip vortex are exper-imentally studied.On the basis of those results,a wing tip vortex control strategy which com-bines multi-winglets and tip blowing is proposed and justified.The experiments have been con-ducted at a low speed wind tunnel.The basic wing model is a rectangular NACA 0015 airfoil. Reynolds number (Re)defined by the chord length of wing and the free flow speed is 5.3×104 . The blowing coefficient (Cμ)defined by the momentum ratio of blowing to free flow is 0.017. The results show that the multi-winglets divide the wing tip vortex into several co-rotating vorti-ces which decreases the effect of the downwash flow generated by wingtip vortex,and thus im-prove the quality of the local flow.The lift coefficient increases forα>4°.The maximum lift co-efficient increases up to 1 2 .3%.Blowing strengthens the “wandering”of vortex core to change the position of the tip vortex.Blowing suppresses the formation of the wingtip vortex to some ex-tent.The joint control strategies have achieved a well control effect,meanwhile,the blowing en-hances the interaction of the co-rotating vortices.The peak of mean instantaneous vorticity is de-creased by 37% compared with the individual “+0-”multi-winglets configuration,and by 79%compared with the basic wing.The control effect of the joint strategy is subjected to whether the blowing could enhance the interaction of the co-rotating vortices or not.The moving direction of wingtip vortex also has a substantial influence on the control effects.
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