Fluid–structure coupling analysis of deformation and stress in impeller of an axial-flow pump with two-way passage

Abstract

Axial-flow pump with a two-way passage has been widely employed in irrigation and drainage projects. Because of the shape of the two-way inlet passage, the impeller easily induces vibration due to unstable turbulent flow. This vibration results in structural cracks and even hinders the safe operation of the pump. Deformation and stress distributions in the impeller were calculated using two-way coupled fluid-structure interaction simulations, and a quantitative analysis of blade deformation and stress is carried out to determine the structure critical region. The results show that the values of deformation and stress significantly decrease with an increasing flow rate and a decreasing head, and the maximum total deformation can be found in the impeller rim, while the maximum equivalent stress can be obtained near the impeller hub. The total deformations in the blade rim decrease from blade leading edge to trailing edge, and the equivalent stress in the blade hub initially increases and then declines, and in the end, it rapidly increases from the blade outlet to inlet. These results reveal the deformation and stress in the impeller to ensure reliability and specific theoretical guidance for the structural optimization design of a pump device.

CFD-Rotordynamics Sequential Coupling Simulation Approach for the Flow-Induced Vibration of Rotor System in Centrifugal Pump

“…Compared with the two-way FSI study of the centrifugal pump made by Benra [16] and Pei [14,20], this work pays more attention on the vibration behaviors of the main shaft rather than the impeller, considering the commonly occurring shaft fracture failures. Furthermore, the Coriolis force and bearing characteristics have been included in the model of this work, which were ignored in previous research [14,16,20].…”

“…where α and β denote the mass and stiffness damping coefficients respectively. With references to research results of Pei et al [14,20], a stiffness damping coefficient was added into the rotordynamics model and its value was determined by trial-and-error method and engineering experiences. A trial operation was implemented under the flow rate of Q des , in which a relatively small stiffness damping coefficient (β = 0.001) was set firstly.…”

“…In this way, not only the required computational resources for both CFD and CSD solvers can be largely saved, but the information exchange (interface mesh deformation) and loads transfer (pressure from fluid domain and displacement on the solid surfaces) representing the FSI effect can be applied in an efficiency and stable way. In recent years, coupling simulation based on the partitioned method has been widely applied in the FSI problems of pump and other turbomachineries, either with the strong two-way coupling strategy or the one-way sequential coupling strategy, and most of the application cases achieved satisfactory prediction results in the deformation, oscillation, and orbit curves of the impeller [16][17][18][19][20].…”

“…It means that only influences of flow induced exciting force on the vibration behavior of the rotor system were considered, but interferences of the deformation and whirl orbits of impeller to the flow field are ignored. According to the calculation and experimental results of a centrifugal pump made by Pei et al [14,20], compared with the two-way coupling method with consideration of impeller deformation, the calculated radial force based on one-way coupling shows little differences in numerical values. In addition, the vibration displacements of impeller predicted by both one-way coupling and two-way coupling show very small errors with experimental results.…”

Transient flow analysis in axial-flow pump system during stoppage

“…The transient flow through a centrifugal pump during startup process with the 1 method of characteristics (MOC) was researched by C Issa et al 6 Nowadays, computational fluid dynamics (CFD) method is increasingly used to capture complex threedimensional (3D) features inside the fluid machinery. 7,8 Dedicated experiments for the validation of CFD codes applied in pump have already been performed by W-d Shi et al 9 J Feng et al 10 got the influence of the tip clearance in axial-flow pump using CFD method. The performance of axial-flow pump with adjustable guide vane was simulated by Z-d Qian et al 11 These studies enable us to improve our understanding of the flow characteristics in pump systems.…”