一种CFD/CSD耦合计算方法

针对柔性大展弦比机翼气动弹性分析和主动弹性机翼(AAW)设计发展了一种计算流体动力学(CFD)和计算结构动力学(CSD)的耦合计算方法。其主要思想是采用在同一物理时间弱耦合求解CFD/CSD技术。气动力采用非定常N-S方程的双时间有限体积求解技术,结构响应则采用有限元数值求解技术。CFD和CSD耦合计算的边界信息(气动力和网格)由所设计的界面程序传输。网格信息传输采用守恒体积转换(CVT)方法将CSD计算结构响应位移插值到CFD网格点上。变形已有的CFD网格技术用以确定CFD的变形网格。以位移或载荷的迭代误差为判断耦合计算的收敛标准。最后得到了机翼在Ma=0.8395,α=5.06°时CFD/CSD耦合计算的收敛值。针对计算结果分析了机翼受静气动弹性过程中结构响应和气动特性随时间变化的效应。初步研究结果表明:这种弱耦合方法求解非线性气动弹性问题是可行的。

CFD/CSD Couping Numerical Computational Methodology

To model the nonlinear aeroelasticity of flexible high aspect ratio wings and design active aeroelastic wing (AAW), A CFD/CSD coupling numerical computational methodology is developed. In this study, an aeroelastic coupling procedure will perform with loosing coupling CFD/CSD at the same physics time step. Solving aerodynamic force employ Navier-Stokes discretized based cell-centered finite volume framework with LU-SSOR implicit time-marching second order accurate scheme and dual-time technology. Computational structural dynamics (CSD) are modeled using finite element equations. Matching the CFD grid displacements with the CSD or finite element model response maintains the accuracy in this loosely coupled approach. In the loosely coupled modular approach of two disciplines, boundary information between the CFD and CSD codes is exchanged through the developed codes’ interface mappings. The CSD code calculates the response of the structure. The resulting outputs, the displacements, are interpolated to the CFD grid using a displacement mapping of conservation volume transform (CVT). The CFD code calculates the flow field about this new CFD grid. CFD/CSD coupling procedure is converged after judged by error of the deformed displacements on the CSD in the iteration. Finally, the CFD/CSD coupling computational convergence solution is obtained for a swept wing at Ma=0.8395, α=5.06°using the developed nonlinear aeroelastic methodology. History of response of the structure and aerodynamic characteristic with time is analyzed. The study show it is important that structural inertia force must consider on static aeroelastic analysis and the developed CFD/CSD coupling procedure is abler to compute nonlinear aeroelastic analysis.