基于流固耦合的导叶式离心泵强度分析

Strength analysis of a diffuser pump based on fluid-structure interaction

运用顺序耦合和双向流固耦合方法对导叶式离心泵进行了强度分析。通过顺序流固耦合方法,对叶轮进行了静应力强度分析,并与双向流固耦合方法得到的结果进行了比较。同时,对双向流固耦合结果中最大等效应力节点A和最大变形区域的节点B在叶轮旋转一周过程中的等效应力变化的时域图以及频域图进行了分析。结果表明,最大等效应力出现在叶轮前盖板、叶片背面和叶轮出口边的交界处(节点A);叶片进口边中部以及与前后盖板的交界处和叶片出口与后盖板的交界处这些地方有应力集中,可能发生强度破坏。后盖板出口处且正好在流道中部位置变形最大(节点B),可能发生刚度破坏。对于静力学分析,顺序耦合与双向耦合的结果基本一致。节点A的变形量小于节点B,但交变应力的幅值却远大于节点B。疲劳裂纹的扩展速度主要取决于交变应力幅值的大小,因此,在节点A处更易发生疲劳破坏。计算结果对导叶式离心泵叶轮结构优化设计提供了有效依据。

The sequential coupling method and the strong fluid-solid coupling one were used to analyze the strength of a diffuser pump. The static structural stress of an impeller was analyzed with the sequential coupling method, the results were compared with those using the strong fluid-solid coupling method. Then, the variations of equivalent stress in time domain and in frequency domain for the maximum equivalent stress node A and the maximum deformation node B were analyzed when the impeller rotated one revolution. The results indicated that the maximum equivalent stress appears at the junction of shroud, suction side of blade and outlet of the impeller; the streng failure may happen at the places with stress concentration, for example, in the middle of inlet side of blade, the junction of inlet or outlet side of blade, shroud and hub; stiffness damage may take place in the middle of the impeller passage＇s outlet side with the maximum deformation; although the deformation of the node A is less than that of the node B, the amplitude of the alternating stress of the node A is larger than that of the node B ; the expanding velocity of fatigue fracture depends on the amplitude of the alternating stress, so the fatigue failure is easier to happen at the node A. The results provided an effective reference for structural optimal design of impeller of a diffuser pump.