A study of impeller - diffuser interaction in a centrifugal pump

ABSTRACT PhD THESIS A STUDY OF IMPELLER-DIFFUSER INTERACTION IN A CENTRIFUGAL PUMP Adnan OZTURK DEPARTMENT OF MECHANICAL ENGINEERING INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor Prof.Dr. Kadir AYDIN Year: 2004, Pages: 215 Jury Prof.Dr. Kadir AYDIN Prof.Dr. Beşir ŞAHİN Assoc.Prof.Dr. Osman BABAARSLAN Assoc.Prof.Dr. Ali PINARBAŞI Assist.Prof.Dr. Hüseyin AKILLI In this study, a centrifugal pump with a diffuser which has different radial gaps (20% of impeller radius) and a volute a thickness of 8 mm which is distinct from traditional pumps was investigated numerically with FLUENT package program using Finite Volume Method. Flow was assumed to be three dimensional, viscous, incompressible, turbulent steady and unsteady. The present centrifugal pump has an impeller with five backward curved blades and nine diffuser vanes. The impeller runs at 890 rpm. The centrifugal pump was modeled with various solid modeling programs. The investigations for three-dimensional geometry have been carried out lor 15 different volume flow rates, three different radial gaps and both steady and unsteady flows. The performance curves have been obtained for each gap to observe the effect of different radial gaps on the pump performance. The results were compared with the published experimental results obtained with PIV technique for five different flow rates for a 20% radial gap. On top of that, for the cases of 15% and 10% radial gaps, the flow mechanisms through the impeller and diffuser were numerically investigated. From the present results, it can be concluded that the 20% radial gap is most suitable for the pump and the flow in the pump is affected adversely by decreasing radial gaps and causing pressure fluctuations in the pump. Keywords: Centrifugal pump, Computational Fluid Dynamics (CFD), Finite Volume Method, Impeller-Diffuser interaction, Radial gap effect