Simulation of a Centrifugal Pump by Using the Harmonic Balance Method

Franco Magagnato,Jinfeng Zhang

doi:10.1155/2015/729140

Franco Magagnato, Jinfeng Zhang

Open Access

https://doi.org/10.1155/2015/729140

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Abstract

The harmonic balance method was used for the flow simulation in a centrifugal pump. Independence studies have been done to choose proper number of harmonic modes and inlet eddy viscosity ratio value. The results from harmonic balance method show good agreements with PIV experiments and unsteady calculation results (which is based on the dual time stepping method) for the predicted head and the phase-averaged velocity. A detailed analysis of the flow fields at different flow rates shows that the flow rate has an evident influence on the flow fields. At 0.6Qd, some vortices begin to appear in the impeller, and at 0.4Qdsome vortices have blocked the flow passage. The flow fields at different positions at 0.6Qdand 0.4Qdshow how the complicated flow phenomena are forming, developing, and even disappearing. The harmonic balance method can be used for the flow simulation in pumps, showing the same accuracy as unsteady methods, but is considerably faster.

Highlights

Flow in centrifugal pumps produces a complex threedimensional phenomenon involving turbulence, secondary flows, separations, and so forth (Brennen [1])
A detailed analysis of the flow fields at different flow rates shows that the flow rate has an evident influence on the flow fields
We apply the harmonic balance method (HBM) to a low specific centrifugal pump to demonstrate that these unsteady flows can be accurately calculated with substantially less computational effort than conventional time-accurate solution methods

Summary

Introduction

Flow in centrifugal pumps produces a complex threedimensional phenomenon involving turbulence, secondary flows, separations, and so forth (Brennen [1]). Because time does not appear explicitly, the harmonic balance equations can be solved very efficiently using the same numerical algorithms developed for steady-state flow problems using convergence acceleration techniques. We apply the harmonic balance method (HBM) to a low specific centrifugal pump to demonstrate that these unsteady flows can be accurately calculated with substantially less computational effort than conventional time-accurate solution methods. The method has some similarities to the dual time step method, used by Davis et al [19], Sayma et al [20], and others to compute unsteady flows in the time domain This approach has a number of important differences. The NS equations were solved, respectively, with the HB method and Figure 3: Flow and boundary condition domains. The number of time step is larger than the usually taken 300–400 time steps, to accurately resolve the physical effects in time

The Selection of the Harmonic Modes

Mesh Independence

Results

Flow Analysis at Different Flow Rates

Inner Flow Analysis at Different Positions

Conclusions