中文摘要：

以DG85-80五级节段式离心泵作液力透平,采用N-S方程和标准k-ε湍流模型,选择Mixture多相流模型和SIMPLE算法,用CFD软件对不同体积含气率的气液两相介质的液力透平进行数值试验,分析其外特性和内部流动规律.结果表明：气体膨胀作功对液力透平能量特性的影响较大,透平进口含气率增大时,最优工况的压头和功率增大,水力效率和质量流量减小,各级导叶与叶轮交界面压力损失的总和变大;叶片背面压力小于工作面压力,叶片背面流体速度大于工作面,随透平进口含气率变大,叶轮各流道压力分布不均匀性加剧,叶片工作面进口附近的漩涡区域减小;叶片背面含气率比工作面的大,从导叶进口到叶轮出口含气率增大,从第一级到第五级,随级数增加,导叶-叶轮流道内体积含气率减小.

英文摘要：

The DG85-80 five-stage segmental centrifugal pump was used as a hydraulic turbine. In order to analyze the external characteristic and the internal flow pattern of this pump-as-turbine, its numerical test with gas-liquid two-phase media of different gas volume fractions was conducted by using CFD soft- ware, Narier-Stokes equations, standard κ-ε turbulent mode, Mixture multiphase flow model, and SIM- PLE algorithm. The result indicated that the work done by gas expansion would have a large influence on the energy characteristics of the hydraulic turbine. As the gas volume fraction at the inlet of turbine in- creased, its head and power under optimal operating conditions would be increased, while its hydraulic ef- ficiency and mass flow rate decreased, the sum of pressure loss at the interface between stage guide vane and impeller increased, the pressure on the blade suction surface lower than that on pressure surface, and the fluid velocity on the blade suction surface higher than that on the pressure surface. When the gas vol- ume fraction at turbine inlet increased, the non-uniformity of pressure distribution in each channel of im- peller would become larger and the whirlpool area near the inlet of impeller blade would be reduced. The gas volume fraction on the blade suction surface would be higher than that on the pressure surface. From the inlet of guide vanes to the outlet of the impeller, the gas volume fraction would be raised. From first stage to fifth stage the gas volume fraction in the flow passage of guide vanes and impeller would become lower with the stage progression.