论文部分内容阅读
为了研究叶轮机叶片的失速颤振特性,发展了一种计算流体力学与计算结构力学(CFD/CSD)时域耦合方法。该方法通过每一物理时刻CFD和CSD的循环迭代实现了耦合计算。在CFD分析中,采用鲁棒性较好的空间离散格式AUSM+-UP,并基于延迟脱体涡模型(DDES)模拟了带分离流动。在结构分析中,通过模态法构建了旋转叶片动力学方程并运用杂交多步方法进行求解。以孤立转子Rotor37为例,计算了不同工况下流场总体与细节参数,与实验结果的对比验证了CFD算法的精度。对某转子叶片进行了颤振特性研究,计算所得的广义位移时间响应曲线表明该叶片在近失速工况下会发生失速颤振,其表现形式为一阶弯曲模态发散且各阶模态之间不耦合。分析表明,流场不稳定和非定常效应是引起失速颤振的关键因素,同时折合频率的降低也会导致原本气动弹性稳定的叶片发生失速颤振。
In order to study the characteristics of stall flutter in impeller blades, a CFD / CSD time-domain coupling method is developed. The method achieves the coupling calculation through the cyclic iteration of each physical moment of CFD and CSD. In the CFD analysis, AUSM + -UP, a robust robust spatial dispersion format, was used and the separation flow was modeled based on the delay stripping vortex model (DDES). In structural analysis, the kinetic equations of rotating blades were constructed by modal method and solved by hybrid multi-step method. Taking rotor isolated Rotor37 as an example, the overall and detail parameters of the flow field under different operating conditions are calculated. The comparison with the experimental results verifies the accuracy of the CFD algorithm. The flutter characteristics of a rotor blade is studied. The calculated generalized displacement time response curve shows that the flutter of stall occurs in the near stall condition, which is characterized by the first-order bending mode divergence and the different modes Do not couple between. The analysis shows that the instability and unsteady flow field are the key factors causing the flutter of stalling, and the reduction of the equivalent frequency also leads to the occurrence of stall flutter in the aeroelastic stable blade.