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The main objective of this work is to use the computational fluid dynamics (CFD) technique in analyzing and predicting the performance of a radial flow-type impeller of centrifugal pump. The impeller analyzed is at the following design condition: flow rate of 528 m 3 /hr; speed of 1450 rpm; and head of 20 m or specific speed (N s ) of 3033 1/min in US-Units. The first stage involves the mesh generation and refinement on domain of the designed impeller. The second stage deals with the identification of initial and boundary conditions of the mesh-equipped module. In the final stage, various results are calculated and analyzed for factors affecting impeller performance. The results indicate that the total head rise of the impeller at the design point is approximately 19.8 m. The loss coefficient of the impeller is 0.015 when 0.6 < Q/Q design < 1.2. Maximum hydraulic efficiency of impeller is 0.98 at Q/Q design = 0.7. Based on the comparison of the theoretical head coefficient and static pressure rise coefficient between simulation results and experimental data, from previous work reported in the literature [Guelich, Kreiselpumpen, Springer, Berlin, 2004], it is possible to use this method to simulate the performance of a radial-flow type impeller of a centrifugal pump.

Results:The first stage involves the calculation of various dimensions such as the blade inlet and exit angle at hub and the mean and shroud positions to depict the meridional plane. The second stage deals with the CFD simulation. Various results were calculated and analyzed for factors affecting runner's performance. Results indicated that the head rise of the runner at the design point was approximately 39 m, which is lower than the specified head. Based on past experiences, the meridional plane was modified and blade inlet and lean angles were corrected. The process of meridional plane modification was repeated until the head rise was nearly equal to the specified head. Velocity vector and streamline should be a uniform stream. Conclusion/Recommendations: Results from calculating runner's performance were approximately 90% at design point. Existing absolute velocity component from CFD simulation pointed out that swirling flow occurred at the exit of runner. Based on the comparison of runner's performance between simulation results and experimental data from previous work reported in the literature, it is possible to use this method to simulate runner's performance of the Francis turbine.

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This study aims to analyze water flow through a centrifugal pump with straight radial blades double-acting impeller using computational fluid dynamics (CFD). The impeller analyzed was designed with the following conditions: a volume flow rate of 33.5 m3/h, head of 100 m, rotational speed of 2,950 rpm, and specific speed of 9. The first stage began with calculations for various dimensions of double-acting isolated impeller and impeller-collector assembly, followed by three-dimensional drawing and domain specification. In the second stage, grids for the isolated impeller and impellercollector assembly were generated. In the third stage, the initial conditions and boundary conditions were specified. Finally, the water flow through the isolated impeller and impeller-collector assembly was analyzed using the CFX 13 code to predict the water flow state. A fluid dynamic analysis of the isolated impeller and impeller-collector assembly reveals that the Q-H curve rises continuously toward shutoff as the flow rate is reduced. The results indicate that the total head rise of the isolated impeller is approximately 98.8 m for a 65 mm impeller inlet width and 99.89 m for a 70 mm impeller inlet width. This may be due to reduced circulation between blade passages of impeller. Similar to the isolated impeller, the Q-H curve of the impeller-collector assembly also rises continuously toward shutoff as the flow rate is reduced. The total head rise is reduced to approximately 98 m because of losses in the collector. Concerning the flow in the impeller-collector assembly when Q / Q design is or less than 1.0, the pressure distribution is high at the tongue of collector. Concerning the velocity distribution when Q / Q design is more or less than 1.0, there is circulation or a vortex at the top of the collector.