典型钝体断面大攻角下的颤振自激力特性

Characteristics of self-excited forces in flutter of typical blunt body under large attack angles

基于三自由度强迫振动装置,真实模拟了实际结构大攻角下的弯曲振动形态,并以矩形和H型截面为研究对象,对比分析了竖向振动方式对H1*、H4*、A1*、A4*等4个气动导数的影响。试验研究发现,弯曲振动形态对H1*、H4*、A1*三个气动导数存在明显影响,对导数A4*影响较小,且对气动导数的影响程度与风攻角和截面形式有关;不过,振动形态不影响各导数随无量纲风速的变化规律。分析表明,大攻角下采取与实际结构一致的竖弯振动方式来识别气动导数是完全必要的。

Based on a forced vibration device with three degrees of freedom, the actual bending vibration modes of a real structure at large attack angles were simulated, and the influence of vertical vibration on aerodynamic derivatives H1*, H4*, A1*, A4*, was further investigated through a series of wind tunnel tests on structures of rectangular and sections. The results show that vertical vibration modes have obvious effect on aerodynamic derivatives H1*, H4*, A1*, and the influence degree is relevant with the wind attack angle and the shape of cross section. However, the variation rule of aerodynamic derivatives versus the non-dimensional wind speed is not affected by vibration modes. Contrastive analysis shows that in identification of flutter derivatives under large attack angles of wind, it is necessary to adopt the vertical bending vibration modes consistent with those of the actual structure.