【摘要】 抽水蓄能电站在水电中扮演着极其重要的角色,其机组水泵水轮机的"S"特性区流动情况是研究的重点。以自主研发的某水泵水轮机为研究对象,根据模型试验结果的"S"特性曲线,选取其中小导叶开度的"S"特性曲线,结合SST k-w湍流模型,运用ANSYS-CFX软件对曲线上部分工况点进行了数值分析。数值分析工况包括水轮机工况、飞逸工况、制动工况和反水泵工况,通过计算得到了单位流量和单位转速的关系曲线,所得曲线与模型试验曲线较为吻合。计算结果表明:在制动工况和反水泵工况时,固定导叶、活动导叶和转轮区域内均存在较多的旋涡性回流,为较为不稳定的工况。转轮区域内流动速度极低,叶片中间位置有无规则性回流,相邻的两个叶片头部之间形成横向流动的水环,水环在离心力的作用下阻挡水流进入流道,从而大大减小了转轮的过流能力,这可能是导致水泵水轮机在制动工况下单位转速降低的重要原因。更多还原

【Abstract】 Pumped storage power stations play an important role in hydropower. The flow condition in "S" characteristics zone of pump-turbine is an important research issue in hydraulic machinery industry. Taking a self-developed pump-turbine as the research object, based on "S" characteristics curve from model test and selecting the "S" characteristics curve with small openings, we analyzed some partial operation points on the curve by ANSYS-CRX software and turbulent flow model. The numerical analysis operation cases included turbine condition, runaway condition, braking condition and reverse pump condition. The relation curve of unit discharge and unit rotating speed were obtained, and they were in good agreement with model test curve. The analysis results showed that in braking and reverse pump cases, vortex back flow existed in the zones of stationary blade, moving blade and runner, which were unstable. The flow velocity in runner zone was very low. The irregular back flow existed in the middle of the blade, and the transversal flow-ring formed in the zone between two blade heads, which would resist flow entering flow channel under the action of centrifugal force and greatly reduce the flow capacity of runner. This may be the important cause of unit rotating speed falling of pump-turbine under braking condition.更多还原