Numerical simulations of turbulent flows in bulb tubular pump and performance predictions
Tang Xuelin1, Chen Xiongsheng1, Wang Fujun1, Yang Wei1, Wu Yulin2
1.College of Water Resources & Civil Engineering, China Agricultural University, Beijing 100083, China; 2.State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
Abstract:Owing to various characteristics of smooth flow pattern, less hydraulic losses and lower costs, tubular pumps are applied more and more widely in drainage and water diversion projects. Based on the standard k-ε and the Fluent software, the turbulent flows in a bulb tubular pump and the performance curves were investigated numerically. Under off-design operating cases, the streamline distributions inside the diffuser and the discharge passage indicate that there exist some secondary flows, which cause the hydraulic losses and the reduction in the tubular-pump efficiency. At large flow rates, there is a minimum of the static pressure near the inlet of the blade pressure surfaces due to the negative incidence angle. At small flow rates, the minimum of the static pressure happens near the inlet of the suction surfaces due to the positive incidence angle. At the best efficiency point(BEP), the minimum of the static pressure appears in the region behind the inlet of the suction surfaces. The calculated results show that the internal flow pattern is smooth at the BEP. Finally the overall performance curves including the head-discharge, power-discharge and efficiency-discharge curves were further obtained. The newly-designed pump model is validated by the comparisons between its predicted overall performance and the experimental data of the JGM-3 model. This research provides some important references for the design and optimization of a low-head bulb tubular pump.
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