International Review of Mechanical Engineering (I.RE.M.E.), Vol. xx, n. x Design, Numerical Analysis and Manufacture of Radial Pump Impellers with Various Blade Geometries Michail D. Mentzos 1 , Angelos P. Markopoulos 2 , Nikolaos I. Galanis 2 , Dionissios P. Margaris 1 , Dimitrios E. Manolakos 2 Abstract – Impeller blade geometry plays a dominant role on the velocity profile of the fluid flowing through the pump. Although blades’ design is based on fluid dynamics considerations, it is sometimes limited by the available manufacturing methods, due to the required complexity in the geometry. In the present paper, the evolution of the velocity field in the blade passages of two anew designed radial pump impellers with different curvature and outlet blade angle is examined in order to verify their optimum design and characteristics. The numerical solution of the discrete three-dimensional, incompressible Navier-Stokes equations over a structured grid is accomplished with a commercial CFD finite-volume code. For each impeller, pressure and relative velocity distributions are presented and analyzed. The flow patterns in the blade passages are monitored and the mechanisms that dominate the flow field in the different regions of the impeller geometry are discussed. Furthermore, the new impellers that were tested numerically are manufactured in a CNC Milling Centre under the operation of sculptured surfaces; thus the feasibility of manufacturing the improved geometries is exhibited. Copyright © 2015 Praise Worthy Prize S.r.l. - All rights reserved. Keywords: CFD, Performance curves, Pump, Radial impeller, CAD, CNC Manufacturing I. Introduction An impeller is a rotating component of a centrifugal pump. Usually, it is composed of blades and a hub and is made of bronze or brass, with main function to transfer the energy from the motor to the fluid being pumped. A blade of an impeller is composed of a suction surface, a leading edge and a pressure surface. There are more than 120 varieties of impellers available on applications [1], [2]. Design, modeling and manufacturing of an impeller are composed of three separate yet equally important requirements. The first requirement is that the impeller provides an acceptable distribution of the relative velocity on both pressure and suction surfaces of the blade to minimize the possibility of flow separation and the accompanying loss in performance. In addition, the selected blade shape must be such that it can be manufactured accurately and economically on a CNC machining centre. Finally, the blade should be designed to keep the stress at a safe level, eliminating the possibility of excessive distortion or fracture during operation [3], [4]. The design of mixed flow impellers of high specific speed is a direct extension of the well established empirical methods of the design of radial flow impellers. The extension of similar methods serves for the design of mixed flow impellers, but the introduction of near diagonal flow layout at a still larger specific speed stimulated the incorporation of axial pump impeller [5]. The Computational Fluid Dynamics (CFD) analysis is a numerical method commonly used to solve and analyze fluid mechanics problems that involve fluid flows [6], [7]. With the aid of CFD, the complex internal flows in water pump centrifugal impellers can be well predicted, establishing computational simulations as a key tool for pump designers. Numerous studies are focused on the static performance of centrifugal pumps [8]-[11]. The steady-state characteristics of flow fields in impeller vanes are compared to experimental data, demonstrating the efficiency of the various turbulence models and numerical schemes considering the flow evolution in a large variety of pumps’ and impellers’ geometries. The most relevant studies to the present work are those of Westra et al [12] and Byskov, Jacobsen and Pedersen [13], who presented the flow field in a shrouded six bladed centrifugal pump impeller. The methodology relating the identification of the effects of the various forces acting on the fluid inside the blade passages is also used in the present study. However, in the present study, in contrast to the simple-arc based impeller blade, the impeller consists of five untwisted blades backward facing with an arc line based on a linear variation of angle β i , from the inlet β 1 =14 ο to the outlet, along the vane [14]. The present study refers to the computational Manuscript received December 2014, revised January 2015 Copyright © 2015 Praise Worthy Prize S.r.l. - All rights reserved