الفهرس 
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Abstract
The present computational investigation aims to develop a numerical model to study the effect of trailing edge modification on centrifugal pump performance for pumps of very low specific speed (ns=9.5). Moreover, the current study compares between using unstructured and structured grid in pump modeling. The structured grid is used to model two domains, the first includes the liquid space within pump inlet, impeller, volute, and the outlet pipe, while the second domain extends to include the fluid between volute casing and both impeller sides. Seven blade trailing edge profiles are introduced into the centrifugal pump at three different rotational speeds. Steady simulation is used to solve the three-dimensional flow to predict the pump performance curves. Results show that changing the blade trailing edge profiles affect the pump performance significantly. V-cut, Circular edge (CE) and Ellipse on Pressure Side (EPS) profiles enhance pump efficiency remarkably, as vorticity distribution demonstrate that these profiles contribute to the vortex intensity reduction. Also, Ellipse on Pressure Side (EPS), Ellipse on Suction Side (ESS) and V-Cut profiles show positive impact on enhancing pump head. Moreover, when pump operating speed is increased, the effect of the introduced trailing edge profiles on pump performance is improved. Finally, the current study investigates the effect of domain size on the predicted pump performance. Losses due to fluid circulating to the impeller inlet and the disk friction losses on the impeller’s rear and front shrouds are considered in the extended domain model. Thus, the accuracy of the efficiency and power curves are increased significantly. However, losses included in the extended domain model do not depend on the trailing edge profile; therefore, it does not affect the results and conclusions derived concerning the effect of blade trailing edge profile on the pump performance.