论文部分内容阅读
在工程实际中,通常采用结构在空气中的自振频率乘以一个经验影响系数得出水中的自振频率,但是通过传统经验影响系数得出的结果与现实相比有很大的误差。本文选用能更加清楚表达水体对叶轮固有频率影响大小的下降系数进行研究。运用基于流固耦合的有限元方法对圆柱模型和两种离心泵叶轮进行模态计算,通过对结果的分析和比较发现:下降系数与结构的固有频率和振型有很大关系,采用分段取值更为合理,模态低阶取小值,高阶取大值,旋转振型取小值。最后对离心泵叶轮模型计算结果进行二次优化,得到更加符合实际的经验下降系数:模态前6阶除第3阶取0.05外,其余取0.15,第7—10阶取0.40。
In engineering practice, the natural frequency of natural air in the air is multiplied by an empirical coefficient of influence to obtain the natural frequency of water. However, the results obtained by the traditional empirical coefficient of influence are quite different from reality. In this paper, the descending coefficient which can more clearly express the influence of the water body on the natural frequency of the impeller is studied. The finite element method based on fluid-solid coupling is used to calculate the modal of the cylindrical model and the impeller of two kinds of centrifugal pumps. The analysis and comparison of the results show that the descending coefficient has a great relation with the natural frequency and mode shape of the structure, The value is more reasonable, the modal low order takes the small value, the high order takes the big value, and the rotation vibration mode takes the small value. Finally, the centrifugal pump impeller model calculation results for the second time to obtain a more realistic empirical decline coefficient: the first six modes in addition to the third order to take 0.05, the other to take 0.15, the first 7-10 to take 0.40.