适用于参数可调结构的非定常气动力降阶建模方法

摘要

基于计算流体力学(CFD)的非定常气动力降阶模型(ROM)可以极大提高气动弹性分析效率,然而现有的ROM只能针对固定参数结构,即只适合于固定模态振型,这使得现有ROM在气动弹性优化设计和不确定性分析等结构变参问题中应用受限.针对该问题,在文献[20]基础上提出了一种新的适用于任意模态振型的非定常气动力建模方法.首先将待设计/分析的结构进行参数化抽样和模态分析,之后通过主成分分析(PCA)得到若干基振型,再将这些基振型线性叠加即可拟合抽样空间内任何参数下结构的前若干阶振型.当结构参数改动时,仅仅是叠加系数发生变化.算例表明,仅用很少的基振型就能达到理想的拟合精度.经典的气动力降阶方法可用于基振型坐标下的气动力降阶,进一步变换可得到适用于不同结构的ROM,这意味着,结构参数可以在抽样空间内任意调节改动,而ROM却是通用的.该方法能广泛用于气动弹性优化设计和不确定性分析工作,可提高颤振分析精度和效率.%Computational fluid dynamics (CFD) based unsteady aerodynamic reduced-order model (ROM) can make significant improvement of efficiency of transonic aeroelastic analysis.However,the existing ROM is applicable only to structures with fixed parameters,namely prescribed model shapes (ROM-PMS).When structural parameters should be altered such as structure optimization and uncertainty analysis,ROM-PMS is no longer feasible.To settle the problem,a new unsteady aerodynamic modeling method for arbitrary model shapes is developed based on Ref.[20].Parametric sampling and modal analysis are conducted on the structure to be designed and analyzed.The basic mode shapes are then obtained through principal component analysis (PCA).Real model shapes of arbitrary structure in the sample space can be synthesized by linearly superimposing basic mode shapes with correct coefficients.The coefficients of superposition change with the alteration of structure parameters.The analysis shows that just small number of basic modes can reach desirable accuracy.Classical modeling method can be used to construct ROM in basic mode shape coordinate.The ROM applicable for various structures can be developed from ROM in basic mode coordinate,which means that structural parameters can be arbitrarily altered in the sample space,while ROM is universal.This method can be widely applied to aeroelastic optimization design and uncertainty analysis,with great improvement in computational efficiency.