CFD Analysis of Mixed Flow Pump

The study pertains to the CFD application for mixed flow hydraulic pumps. Authors have done CFD analysis of mixed flow pump (Nsq. = 46.00 Metric) at duty point and also at part load. The results of the study brought out following findings. 1. Head predicted by CFD analysis is 5 to 10 % higher at rated point as well as at part load, than the test result. The nature of Head versus Capacity curve is similar to that of standard mixedflow pump curve. 2. Power predicted by CFD analysis is 5 to 10% higher at rated point. Disc- friction power loss calculated using standard method and added to CFX generated power for estimating total power requirement. The nature of Power versus Capacity curve is similar to that of standard mixed flow pump curve. 3. Efficiency predicted by CFD analysis is higher than the test results. Leakage loss was predicted and volumetric efficiency was determined. Pump efficiency, considering disc-friction loss and leakage-loss was predicted and that is within + 5% range, at duty point. At off-design point, variation in efficiency was found. CFD analysis has clearly brought out the secondary flow/recirculation in stator at duty point which caused reduction in efficiency. This is improved by matching stator blade angle with respect to flow angle and changing hub-curve profile. The paper also includes the results of steady state analysis of original geometry and comparison of test result and CFD analysis result. The comparison of results of original and modified geometry was presented.

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