Determination of Pump Impeller Deflections: Comparison of FSI-Simulations to Measurements

Abstract

The determination of pump rotor oscillations induced by exciting hydrodynamic forces requires both a solution of the flow field in the pump and an analysis of the structural mechanics of the pump rotor. In the present contribution, simulations which accomplished different coupling methods between the fluid dynamic solution and the structural analysis were carried out for a single-blade pump. In a first approach a one way coupling was used to determine the oscillations of the pump impeller during operation. The forces calculated from the transient flow field were treated as a load acting at the impeller. A comparison of the computed oscillations to measurements showed that in the present case the strong physical interaction between the flow and the impellers structure requires the feedback of the structural analysis to the flow solution to give more meaningful results. In a second approach a simulation was carried out, which accomplished a full coupling of the fluid dynamics and the structural dynamics. Both physics were solved alternating and at least two iterations, one for each physics, were needed to achieve the required coupled response. The calculations were coupled by passing loads across the physics field interfaces. In the present example, for each regarded time step during one impeller revolution, the pressure field acting at the impeller surface was transferred from the CFD solver to the structural solver as the load on the impeller and the computed deflection of the impeller was transferred back deforming the computational grid of the fluid volume.

Numerical Analysis of Stress on Pump Blade by One-Way Coupled Fluid-Structure Simulation

“…Coupling methods between fluid and structure dynamics should be selected depending on a strength of coupling mechanism between flow patterns and solid behaviors. Details of coupling methods for performing an accurate fluid-structure simulation were discussed by using a physical feature of a fluid-structure interaction (1) .…”

Computational Fluid Dynamics of Cavitating Flow in Mixed Flow Pump with Closed Type Impeller

“…When the high cycle fatigue of the structural strength is evaluated, the fluctuating stress needs to be predicted. A two-way coupled fluid and structure simulation is needed to predict the fluctuating stress [2].…”

Investigation of unsteady flow-induced impeller oscillations of a single-blade pump under off-design conditions

“…In the research area of fluid machinery, some numerical research was conducted with a coupled method, but only a few studies considered the vibration problems of pump machinery in which water was the operational medium, such as the works by Benra (2006), Benra et al (2006), Benra and Dohmen (2007), Campbell and Paterson (2011), Gnesin and Rzadkowski (2002), Kato et al (2005), Langthjem andOlhoff (2004), andMuench et al (2010). These numerical and experimental studies offer insight on flow-induced vibration and noise phenomenon in fluid machinery; however, only a few considered the integrated interaction between the fluid and solid with a strongly coupled analysis.…”