Optimization of Vane Diffuser in a Mixed-Flow Pump for High Efficiency Design

Optimization of Vane Diffuser in a Mixed-Flow Pump 

for High Efficiency Design

Abstract

This paper presents an optimization procedure for high-efficiency design of a mixed-flow pump. Optimization techniques based on a weighted-average surrogate model are used to optimize a vane diffuser of a mixed-flow pump.

Validation of the numerical results is performed through experimental data for head, power and efficiency. Three-level full factorial design is used to generate nine design points within the design space. Three-dimensional Reynoldsaveraged Navier-Stokes equations with the shear stress transport turbulence model are discretized by using finite volume approximation and solved on hexahedral grids to evaluate the efficiency as the objective function. In order to reduce pressure loss in the vane diffuser, two variables defining the straight vane length ratio and the diffusion area ratio are selected as design variables in the present optimization. As the results of the design optimization, the efficiency at the design flow coefficient is improved by 7.05% and the off-design efficiencies are also improved in comparison with the reference design.

Keywords: Mixed-flow pump, Impeller, Vane diffuser, Efficiency, Optimization, Weighted-average surrogate model.

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Optimization of Vane Diffuser in a Mixed-Flow Pump for High Efficiency Design

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Assessment Of A Mixing Plane Method For CFD Analysis

Multistage Centrifugal-Pumps: Assessment Of A Mixing Plane 

Method For CFD Analysis

Abstract

An accurate CFD investigation allows a thorough knowledge of the fluid dynamic field inside a multistage centrifugal pump but only a correct interpretation of its results grants a well-founded prediction of the machine performance curves. The paper introduces the assessment of an improved methodology to predict head-flow and efficiency characteristics of industrial pumps in real operating conditions. The described approach is based on standard CFD analysis and experimental tests.

 

The numerical procedure is built-up of three different steps:

· CFD investigation of the single impeller and diffuser domains;

· impeller-diffuser interaction analysis;

· evaluation of the whole multistage pump performance curves by pressure field

 

interpretation and taking into account real machine secondary phenomena. The stage computational model is made up of two 3D fluid domains with overlapping: one of them is aimed to simulate the diffuser and is related to a stationary reference frame while the other one models the impeller and is referred to a rotating system.

Moreover the impeller–diffuser interaction is studied by the employment of a mixing plane technique. Numerical results are then compared to the real pump performance test at the actual working conditions in order to validate the proposed methodology.

The paper will discuss all approach details and the main CFD features involved.

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Multistage Centrifugal-Pumps: Assessment Of A Mixing Plane Method For CFD Analysis
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