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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。
The unsteady aerodynamic order reduction model (ROM) based on computational fluid dynamics (CFD) can greatly improve the efficiency of aeroelastic analysis. However, the existing ROM can only deal with the fixed parameter structure, which is only suitable for the fixed mode shape, which The existing ROM is limited in the application of aeroelastic optimization design and uncertainty analysis. Aiming at this problem, a new unsteady aerodynamic modeling method for arbitrary mode shapes is proposed based on the literature [20]. Firstly, parametric sampling and modal analysis of the structure to be designed / analyzed are performed, and then a number of fundamental vibration modes are obtained by principal component analysis (PCA). Then, these vibration modes are linearly superposed to fit the structure under any parameter in the sampling space The first number of order mode. When the structural parameters change, only the superposition coefficient changes. The example shows that the ideal fitting accuracy can be achieved with only a few fundamental modes. Classical aerodynamic reduction methods can be used to reduce the aerodynamic force in the fundamental mode coordinates. Further transformations can be made for ROMs of different configurations, which means that the structural parameters can be arbitrarily adjusted within the sampling space while ROM is generic. This method can be widely used in aerodynamic elastic optimization design and uncertainty analysis, which can improve the accuracy and efficiency of flutter analysis.