轴流泵参数化设计及应力与模态特征分析

以船用轴流式喷水推进泵为对象,探索了轴流泵参数化设计、水动力性能、静强度和结构声学特征分析的数值途径。轴流泵叶轮采用升力法设计,导叶采用流线法设计,叶片三维造型在NUMECA参数化设计平台中完成。轴流泵水动力性能校核由粘性CFD计算完成,CFD计算同时提取得到叶片分布式水动力载荷。叶片静强度校核由ANSYS有限元计算叶片应力和应变特征完成,应力分析时同时考虑水动力载荷、重力载荷和离心力载荷。叶片结构声学特征分析由NASTRAN有限元计算叶片模态振型和振型频率完成。计算结果表明,轴流泵扬程和功率满足设计指标,效率达87.13%;叶轮叶片形变相对于叶顶间隙来说为极小量,可忽略不计,叶片存在局部应力集中现象,最大应力小于许用应力,满足静强度要求;叶片前四阶振型特征与分析经验一致,且振型频率远离轴频、叶频及其谐频特征频率,能够避免共振产生。

Numerical design of an axial flow pump by means of parametric design, stress field and modal characteristics analysis

A numerical design method for axial waterjet pump of ship accounting for parametric design, hydrodynamics, static strength and structural acoustic characteristic has been developed.Impeller blade is designed by lifting line method, wherein the vane blade using streamline design method.The three-dimensional blade modeling is completed by NUMECA parametric design system.Viscous CFD calculation is used to validate the pump's hydrodynamics, including head, power and efficiency under design condition, and output the distributed hydrodynamic load on blades at the same time.Static strength analysis is focused on stress and deformation on blades by ANSYS finite element method (FEM) calculation accounting for the hydrodynamic load, gravity load and centrifugal force load.In addition, the modal deformation and frequency of the designed pump is calculated in NASTRAN software.Results show that, the head and power of the designed axial pump is acceptable compared with design value, and the efficiency up to 87.13%.The largest deformation of impeller blade is ignorable compared to the blade tip gap.Local stress concentration exists on impeller blade, but its amplitude meeting the requirement of static strength.The forth modal deformations shape well with engineering experience, and the frequencies are far away with axial passage frequency (APF), blades passage frequency (BPF) and their harmonics, which is beneficial to suppress the resonant phenomenon.