计及热效应的小展弦比机翼气弹稳定性分析

Analysison Aeroelastic Stability of Low-Aspect-Ratio Wing with Thermal Effect

以小展弦比机翼为例,分析其在超声速巡航过程中翼面的气动弹性稳定性。采用分层求解思路,按时间序求解超声速巡航过程瞬态热环境下的翼面温度分布、热模态和颤振边界。分析可知:在根部完全固支条件下,结构各阶固有频率在气动加热初期较常温时均有所提高,随着气动加热的进行,其各阶固有频率却不同程度上发生下降,特别是扭转模态频率;固有频率的下降直接降低气流中机翼弯、扭模态耦合频率,最终降低飞行器的颤振边界;不同的边界约束条件对机翼内部热应力的变化规律影响程度不同,边界约束越少,热应力的变化对结构刚度和颤振边界的影响也越小。

Aeroelastic stability of the wing is analyzed by taking a low-aspect-ratio wing during supersonic cruise as an example.A hierarchical solution was processed to solve the temperature filed in transient thermal environment,normal mode and flutter boundary in supersonic regime according to time sequence.For a low-aspect-ratio wing with fully-fixed supported conditions in the root chord,the natural frequency can be raised at the beginning of aerodynamics heating.However,the structural natural frequencies are lowered as the aerodynamics heating proceeds,especially the torsional mode frequency,which directly lowers the bending and torsion mode coupling frequency,subsequently lowering the aircraft's flutter boundaries.Different constraint conditions have different effects on the change of thermal stress;the fewer constraints are in the root,the less the overall structural stiffness or flutter boundaries change.