NNW-FSI软件静气动弹性耦合加速策略设计与实现

Design and implementation of coupling acceleration strategy in static aeroelastic module of NNW-FSI software

在国家数值风洞(NNW)工程的资助下,依托NNW-FSI流固耦合模拟软件平台,从气动载荷作用下飞行器结构静变形大小与收敛过程无关的物理机制出发,基于变形增量叠加的方式,设计和实现了一种静气动弹性耦合加速策略,通过松弛因子对耦合迭代的收敛过程进行调整。结合超大展弦比无人机和CHN-T1模型两种不同外形,开展了不同松弛因子下的静气动弹性耦合数值模拟,对耦合加速策略的参数影响和加速效果进行了测试和评估。从计算误差控制角度对松弛因子加速耦合迭代收敛的作用机制进行了理论分析,弄清3种类型静气动弹性耦合模拟过程中松弛因子发挥的作用,并给出了松弛因子选取范围的建议。静气动弹性耦合模拟和理论分析结果表明,针对不同类型的静气动弹性耦合问题,选取合适的松弛因子,能够达到抑制振荡并加速收敛的效果。

A coupling acceleration strategy was designed and implemented in the static aeroelastic module of the fluid-structure interaction software platform,NNW-FSI,with the support of the National Numerical Windtunnel(NNW)Project.The strategy was achieved based on a scheme of deformation increment superposition and used the relaxation factor to adjust the convergence process,inspired by the fact that the static structure deformation of aircraft under aerodynamic loads is independent of the convergence process.Then the parameter influence and acceleration effect of the strategy were tested and evaluated through the static aeroelastic simulation of the ultra-high respect-ratio unmanned aerial vehicle and the CHN-T1 model with different values of the relaxation factor.Finally,the effect of the relaxation factor in three types of static aeroelastic coupling simulation was clarified based on the theoretical analysis of the acceleration mechanism from the perspective of computational error control,and suggestions for the selection of the relaxation factor value were also given.Both the static aeroelastic simulation results and the theoretical analysis demonstrate that an appropriate selection of the relaxation factor value can suppress oscillation and accelerate convergence for a special type of static aeroelastic simulation problem.