www.tjprc.org editor@tjprc.org CFD APPROACH FOR OFF-DESIGN EFFICIENCY IMPROVEMENT OF DOUBLE SUCTION CENTRIFUGAL PUMP SHYAM NARAYAN SHUKLA 1 , RUCHI KHARE 2 & VISHNU PRASAD 3 1 Corporate Research and Engineering Development, Kirloskar Brothers Limited, Pune, India 2,3 Maulana Azad National Institute of Technology, Bhopal, India ABSTRACT The energy consumed by a large pump to transport the water has a dominant role in pumping system and hence the efficiency of the pump is of great concern to both manufacturer and customer in large size pumps. The pumps mostly operate at off-design conditions and hence at lower performance. A little improvement in the efficiency of pump will save huge amount of energy and money. In order to improve performance of double suction centrifugal pump, especially at off-design conditions, systematic and validated computational fluid dynamics (CFD) approach had been used to assess the flow behavior in suction casing, impeller and delivery casing of an existing pump for identification of geometrical locations for performance improvement. The head losses and flow pattern in the individual part of the pump were studied and identified the locations for performance improvement and accordingly, the geometry of pump components and surface roughness were modified. There was an increase of normalized head and efficiency by 4.5% and 3.1% respectively at duty point as compared to the CFD results of existing pump. The substantial increase in head and efficiency was also achieved at off-design conditions for both existing and smooth surfaces. KEY WORDS: Double Suction, Horizontal Split Case, Suction Casing, Delivery Casing & Pump Efficiency Received: Aug 22, 2017; Accepted: Sep 14, 2017; Published: Oct 03, 2017; Paper Id.: IJMPERDOCT201730 INTRODUCTION The double-suction centrifugal pumps are used for conveyance of a large quantity of water through long pipeline and have wide application due to its centrifugal structure with large flow rate, stable running operation and convenient maintenance. In double suction centrifugal pump, the curved flow passage with two suction intake and presence of rotating blades of impeller make the flow very complex. The designer has to make some assumptions to carry out the design and hence it becomes necessary to predict the pump performance. Computational Fluid Dynamics (CFD) has emerged as a cost effective tool for flow simulation in pumps for obtaining detailed flow behavior and derivation of pump performance. It has minimized the conventional physical pump model tests. The pressure and velocity distribution give a good insight of fluid flow behavior within the flow passage and helps to identify the defects in pump geometry. The Reynolds Averaged Navier Stokes (RANS) equations are solved using numerical techniques like the finite control volume method to obtain pressure and velocity distributions in the flow domain using CFD [Shah S.R. et al. (2013)]. The numerous commercial CFD codes are used for flow simulation. The accuracy of numerical flow simulation of commercial software depends on many parameters and selection of these parameters requires experience and the validation of CFD results with physical model test. CFD has been used for design improvement Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249-6890; ISSN (E): 2249-8001 Vol. 7, Issue 5, Oct 2017, 289-300 © TJPRC Pvt. Ltd.