Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
PIV investigation of the flow field in a centrifugal rotor
Submission Author:
Edgar Ofuchi , PR
Co-Authors:
Edgar Ofuchi, Henrique Stel, Fabio Ernesto Mancilla Ramos, Rigoberto Morales
Presenter: Edgar Ofuchi
doi://10.26678/ABCM.ENCIT2022.CIT22-0463
Abstract
Centrifugal pumps are widely used in fluid transport in different areas such as in the oil and gas industry, medical application, and chemical plants in general. The flow developed inside a centrifugal pump is complex, highly turbulent and unstable at certain operating conditions. Understanding the complex flow pattern inside a centrifugal pump can contribute to a better design of it, for instance reducing vibration and hydraulic losses. In this sense, Particle Image Velocimetry (PIV) is used to measure the flow field inside a centrifugal rotor at four different planes and different operating conditions. The rotor prototype has equal inlet and outlet blade angles and is built to have a quasi-2D geometry. The PIV measurements were performed using the phase-locking technique, through which 500 samples were acquired in each experiment. Results for pressure rise show that the rotor obeys the pump affinity law. Moreover, velocity, turbulence kinetic energy and Reynolds shear stress profiles, taken at different radial positions, have shown that there is kinetic similarity for these variables, even at part-load operation. The analysis of the flow in different channels showed that, for the studied centrifugal rotor, the flow is periodic even at part-load conditions. From the analysis of the flow in different channels, it could be observed that only for 0.25∙QBEP the flow field was similar in all planes. For flow rates higher than 0.25∙QBEP the velocity magnitudes, turbulence intensities and Reynolds shear stresses were distinct in different planes. The difference in the flow fields in different planes is caused, mainly, by the change of the flow direction from the development pipe to the rotor channels. At part-load operations, rotational effect on the flow field is dominant. Stall cells were found in the impeller channels for 0.25∙ QBEP and 0.75∙ QBEP. Moreover, turbulence intensities and Reynolds shear stresses are higher in these cases than for BEP or over-load conditions. Therefore, increasing the flow rate reduced the rotational effects and the main flow inertia dominates the flow fields. In general, results from this work may help researchers to get a better understanding on how the flow field develops in a centrifugal rotor.
Keywords
centrifugal pump, PIV, Turbulence intensity, Reynolds shear stress
