基于跨声速非定常气动力求解的重叠场源法,开展了弹性飞机跨声速机动载荷计算方法研究,为现代飞机结构强度设计提供更加可靠和精确的临界载荷计算方法。首先通过采用重叠场源法求解关于62%根弦俯仰振荡的LANN机翼在马赫数为0.822的非定常气动力并与实验结果进行对比,验证了重叠场源法对跨声速激波效应预测和非定常气动力计算的能力;其次应用频域气动力有理近似技术拟合场源法计算得到的广义气动力系数矩阵,建立了机动载荷分析的状态空间模型;然后完成了某型民用飞机俯仰机动载荷分析,研究了俯仰机动飞行情况下飞机机体状态量及飞机部件载荷响应规律。计算结果表明:考虑机体弹性变形后,机翼和平尾气动载荷响应最大值分别减小了5.1%和10.6%,升降舵气动载荷响应最大值增大了16.2%,在飞机结构强度设计中必须考虑机体弹性效应对飞机部件载荷的影响。
Based on the overset field-panel method for computing unsteady aerodynamics in transonic flows, the calculation approach of maneuver load for flexible aircraft in transonic flows is developed, for the purpose of providing expedient and accurate critical loads for the design in structural strength of modern aircraft. The LANN wing in pitch mode about 62% root chord at Mach number 0. 822 is solved to validate the unsteady pressure coefficient with the experimental data, and excellent agreement shows the capability of the overset field-panel method in predicting the shock location and strength. State space model for analyzing maneuver loads is generated through rational aerodynamic approximations, then the transient load analysis of a transport aircraft in pitching is conducted to investigate the response of the airframe states and loads acting on the components of the aircraft. The results indicate that the peak loads acting on the wing and horizontal tail decrease by 5.1% and 10.6% respectively, while one on the elevator increases by 16.2%, due to the structural deformation. Therefore, the effect of structural deformation on loads must be considered in the design concerning structural strength of modern aircraft.