三角翼大幅度俯仰运动非定常测压实验洞壁干扰研究

The Research of Wall Interference on Unsteady Pressure Tests for Dalta Wing Undergoing Large Amplitude Pitching Motions

用两个几何相似大小不同的前缘后掠角 70°三角翼模型在闭口风洞中进行正弦俯仰振荡实验 ,测量三角翼模型吸力面动态压力以及风洞洞壁上最佳测压点的非定常压力。实验表明 ,三角翼模型在正弦俯仰振荡时 ,其吸力面动态压力以及洞壁上最佳测压点的非定常压力与三角翼模型上的法向力一样呈现迟滞环现象。模型展宽比 (翼展 /洞宽 )增大 ,迟滞环幅度增大 ,动态压力绝对值增大。无论上仰或下俯 ,模型展宽比 (翼展 /洞宽 )增大 ,三角翼模型吸力面涡破碎位置离前缘较远。风洞顶壁上最佳测压点非定常压力迟滞环方向与风洞底壁上对应最佳测压点非定常压力迟滞方向相反。风洞洞壁上最佳测压点非定常压力变化频率与模型正弦俯仰振荡频率一致 ,各最佳测压点间呈现时间延迟现象。

Unsteady experiment for two geometry similar delta wing models undergoing a cosinoidal pitching oscillation was performed in closed wind tunnel. The two delta wing models having 70° leading edge sweep differ from one another in their linear dimensions. Dynamic pressure on the suction surface of delta wing and unsteady wall presure at the optimum measuring pressure point were measured. Expriments show that dynamic pressure on the suction surface of delta wing and wall pressure at the optimum measuring pressure point would exhibit the hysteresis loop phenomenon similar to that of unsteady arodynamic load of wing model. The larger the wing model, the larger the hysteresis loop and the bigger the absolute value of unsteady pressure. The larger the wing model, the farther the vortex breakdown location from leading edge leaves, whether in pitch up or in pitch down. The hysteresis direction at the optimum measuring pressure point on top wall is opposite to that on bottom wall. The frequency of unsteady wall pressure at the optimum measuring pressure point is in agreement with frequency of delta wing model undergoing a pitching oscillation. The time lag phenomenon among optimum measuring pressure points is presented.