Journal of Applied Fluid Mechanics, Vol. 9, No. 5, pp. 2475-2487, 2016. Available online at www.jafmonline.net, ISSN 1735-3572, EISSN 1735-3645. Experimental and Numerical Investigation of Coating Effect on Pump Impeller and Volute O. Kocaaslan 1 , M. Ozgoren 2 †, M. H. Aksoy 2 and O. Babayigit 3 1 Selcuk University, Huglu Vocational School, Huglu-Konya, Turkey 2 SelcukUniversity, Engineering Faculty, Mechanical Engineering Department, Konya, Turkey 3 Selcuk University Hadim Vocational School, Hadim-Konya, Turkey †Corresponding Author Email:mozgoren@selcuk.edu.tr (Received May 20, 2015; accepted December 2, 2015) ABSTRACT In this study, an impeller and volute of a centrifugal pump were designed and numerically analyzed in order to improve the pump efficiency. Before design, experimental and theoretical studies were performed on a centrifugal water pump taken as Model Pump (MP). Design parameters were taken as 100 m 3 /h for volume flow rate, 18m for head and 1480 rpm for rotating speed. After the inspection of the flow field in the MP, some geometrical modifications such as impeller inlet and outlet diameters, blade inlet and exit angles, blade wrap angle, blade thickness, blade inletand exit widthswere realized to design a new pump. Numerical analyses were performed for 8 different volume flow rates overlapping with experimental operation points by Ansys-Fluent Software. In numerical studies, k-ε turbulence model and standard wall function were utilized. The experimental and computational results were compared with the model pump. According to the analysis results at design flow rate, hydraulic torque value is decreased from 56.62 Nm to 51.05 Nm, while hydraulic efficiency is increased from 55.98% to 63.09%. In addition, in order to see the roughness effect and increase the pump efficiency, the wetted surfaces of the impeller and volute were coated with a polyurethane dye material. Later, performance curves of the coated and uncoated pumps were experimentally obtained which showed that the shaft power of the pump for the coated case was decreased around 10% and the hydraulic efficiency of the pump was increased approximately 18%. According to the economic analysis by basic payback period of the polyurethane coating is less than one year and the internal income ratio for ten-year life-cycle period is around %114. Keywords: Centrifugal pump; CFD; Coating; Hydraulic efficiency;k-ε turbulence model;Polyurethane coating;Turbulence kinetic energy. NOMENCLATURE A cross-section area C investment cost C1ε, C2ε , Cµ constants in the turbulence equations g gravitational acceleration Gk generation of turbulence kinetic energy (due to mean velocity) Gb generation of turbulence kinetic energy (due to buoyancy) Hm head I electric current i interest ratio k turbulent kinetic energy K constant of flow velocity ሶ rotating speed Ns specific speed P present value cosφ power factor ρ density CFD computational fluid dynamics Ps shaft power Q ሶ flow rate r internal income ratio S yearly total saving Sij strain rate tensor Sk, Sε user-defined source terms Th torque V voltage w angular velocity wηh uncertainty of hydraulic efficiency ηem electrical motor efficiency ηh hydraulic efficiency µt dynamic eddy viscosity σk, σε turbulent Prandtl number for k and ε DP designed pump IRR internal rate of return PBP basic payback period