海上平台立式长轴消防泵转子静力学特性分析

Static analysis on rotor of vertical long-shaft fire pump used for offshore platforms

为了研究立式长轴消防泵转子的静力学特性,以XBC18-178-240LC3型号的立式长轴消防泵为研究对象.首先根据设计参数通过Creo建立了立式长轴消防泵内部流场的三维模型以及转子的物理模型,采用CFX对该泵在0.20Qd,0.65Qd,1.00Qd,1.20Qd,1.40Qd和1.50Qd这6种工况下进行3级泵内流场的定常数值模拟;然后把物理模型导入ANSYS Workbench中,并根据实际运行过程设置约束条件,根据模块耦合功能,将流场的模拟结果导入固体结构实现单向流固耦合,对转子模型进行了带预应力的静力学特性分析.结果表明:叶轮内部受到的流体载荷随叶轮级数增加而增大,随流量增大而减小;转子总变形量的最大值位于第3级叶轮后盖板的边缘处,等效应力与等效应变的最大值位于第3级叶轮后盖板边缘与叶片出口边的交点上,都随流量增大而减小;在0.20Qd,0.65Qd,1.00Qd和1.50Qd这4种工况下转子的最大等效应力为118.23 MPa,小于其许用应力250 MPa,符合强度要求;该泵的工作转速1485 r/min小于其0.85倍的一阶临界转速,符合动力学设计要求.

In order to investigate the static characteristics of the vertical long-shaft fire pump(VLSFP)rotor,the type XBC18-178-240LC3 VLSFP was chosen as the study object.First of all,a three-dimensional mathematical model of fluid flow in the VLSFP and a physical model for the rotor system of the VLSFP were generated by Creo according to design parameters and the flow fields of the VLSFP with three-stages were simulated numerically by CFX under six conditions of 0.20Qd,0.65Qd,1.00Qd,1.20Qd,1.40Qd and 1.50Qd.Then,the physical model was imported into ANSYS Workbench and constraints were added to it according to the actual running environment.Finally,the numerical simulation results of flow field were imported into the physical model of the structure to realize the unidirectional fluid-structure interaction and then the static characteristics on the rotor system of the VLSFP with the prestress were analyzed.It is demonstrated that the fluid pressure inside the impeller increases as the stage of the impeller increases and decreases as the flow rate increases;the maximum of the total deformation is located at the edge of the rear cover of the third-stage impeller and the maximums of the equivalent stress and equivalent strain are located at the intersection of the edge of the rear cover and the blade outlet in the third-stage impeller,which decrease with the increase of the flow rate;the maximum of equivalent stress of the rotor is 118.23 MPa under four conditions of 0.20Qd,0.65Qd,1.00Qd and 1.50Qd,which is smaller than its allowable stress(250 MPa)and meets strength requirement;the pump′s working speed of 1485 r/min is less than its first-order critical speed of 0.85 times,which meets the dynamic design requirement.