March 6 - 8, 2017 | Berlin
LEADING ENGINEERING SIMULATION CONFERENCE
In this work a reverse engineering (RE) procedure and a comparative CFD analysis using different software are presented. The three-dimensional flow in the semi-open impeller and volute of a centrifugal pump has been numerically simulated. This kind of impeller is less likely to clog with solid bodies (this is an important aspect in the case of slurry-processing) and for this reason is suitable for food, chemical and Oil & Gas industries. It is well known that the performance of a centrifugal pump drops when handling viscous fluids. Even so the pump behavior during the pumping of non-Newtonian fluids has not been investigated so far.
The RE procedure has been applied to a commercially available pump and the solid models of the impeller and volute have been reconstructed by means of a laser scanner. Simulations have been carried out using both open-source and proprietary software (OpenFOAM® and STAR-CCM+®). The challenges involved in this analysis are:
(i) The modelization of non-Newtonian fluid behavior and
(ii) The representation of the actual flow field inside a pump.
Automated conformal interface between stationary and rotating domains has been used in STAR-CCM+ allowing the representation of the flow leakage at the blade tip. The polyhedral grid provided with STAR-CCM+ allows the global number of elements to be reduced with respect to tetra, conserving accuracy and stability.
The performance of the machine handling both Newtonian and non-Newtonian fluids have been investigated. The slurries which are usually processed show a behavior which can be modeled according to a power law. Internal flow field, pressure distribution and pump performance have been obtained for both Newtonian and non-Newtonian fluids. Particular attention has been put on the apparent viscosity that drives the non-Newtonian model. By means of this analysis, the meridional flow channel and the cross-section of the outlet duct will be modified in order to improve the pump performance for different fluids.