消除小展弦比尾舵大舵偏非对称流动现象的方法研究

在前期的风洞试验结果中已经证实，跨声速条件下，俯仰舵偏角增大到一定程度时，呈开口布局的一对尾舵形成的翼尖涡会相互干扰，使得两侧的翼尖涡强度不同，形成非对称流动现象，进而使全弹产生较大的横侧向气动力，对尾舵的控制能力提出了挑战，需要开展消除非对称流动的方法研究。本文基于数值模拟方法对非对称流场随舵偏角的变化进行了研究，并对该非对称流动现象产生的机理进行了分析，基于此，在保持舵面效率不降低的情况下开展了消除非对称流动现象的方法研究。研究结果表明，随着舵偏角的增加，呈开口布局一对尾舵的翼尖涡距离逐渐减小，翼尖涡由弱的不对称性，逐渐发展直到其中的一侧翼尖涡消失，研究结果还表明通过尾舵前缘局部切角和降低尾舵根弦长的方法在保持尾舵效率不降低的情况下，能够有效消除非对称流动现象，对类似布局设计具有指导意义。

Investigation on the ways to eliminate the asymmetric flow on low-aspect ratio fins at large angles of pitch

It has been clarified in a recent wind tunnel test that the wingtip vortices generated from the leading edges of the pair of fins which is opening along the flow direction begin to interfere each other,and further make the formation of the asymmetric flow in transonic speed as the angle of pitch increases to some extent.The asymmetric flow generates large side force and rolling moment,and brings difficulties to the controllability of the fins.It is necessary to study the way to eliminate the asymmetric flow.This paper presents the changes of the asymmetric flow versus angles of pitch,and investigates the mechanism of the formation of the asymmetric flow based on numerical method.And then two ways to eliminate the asymmetric flow are proposed.The results show that as the angle of pitch is large enough,the interference of the asymmetry of the vortices becomes stronger generally till one of the vortices disappears.It is effective to eliminate the asymmetric flow,either through reducing the root chord length or cutting off the local area around the leading edge,and in the meantime the effectiveness of the fins is close with that of the base fin which has stable wingtip vortex formation.