CFD结合降阶模型预测阵风响应

GUST RESPONSE PREDICTION WITH CFD-BASED REDUCED ORDER MODELING

传统的阵风响应主要在频域内进行分析,气动载荷基于线性方法计算,不能考虑黏性和跨声速流动影响.飞机设计需考虑不同频率和不同形状阵风的响应,基于CFD的阵风响应预测由于计算工况太多,工作量巨大.本文发展了一种CFD结合非定常气动力ARMA(autoregressive-moving-average model)降阶模型的阵风响应分析方法,CFD只要针对给定频率和形状的一种阵风响应进行计算,对获得的气动力时间历程运用线性最小二乘法参数辨识ARMA降阶模型的系数,则对任意频率和形状的阵风,代入降阶模型即可确定该阵风的响应,大大提高了计算效率.为效验发展的方法,先计算NACA0012翼型在低马赫数0.11的阵风响应,通过对比CFD、ARMA降阶模型及早期发展的不可压阵风响应预测方法的结果,验证了方法的有效性.再对比CFD、ARMA在跨声速马赫数0.8的阵风响应预测结果,证实所发展的方法对跨声速阵风响应预测亦是有效的.

Traditional gust responses are mainly analyzed based on linear aerodynamic load calculations in frequency-domain, which is unsuitable for and the viscous and transonic flows. Since gust response for aircraft design needs to be calculated for the many gust cases with various frequencies and shapes, direct CFD-based gust response predictions are huge time-consuming. In the paper, a new gust response method is developed based on CFD method coupled with ARMA reduced order model. CFD is only used once for a special gust to identify coefficients of ARMA model. The computational efficiency of gust response analysis for any shaped gust can be improved significantly based on the determined ARMA model compared with the direct CFD method. To validate the new developed method, first, for NACA0012 airfoil at Mach number of 0.11, the gust responses are analyzed through the comparisons of the results of CFD, ARMA model and an early incompressible analytic resolution. Then, the method is also testified to be valid for transonic flows.