Effects of Water-Admission on the Performance of a Centrifugal Pump

In order to improve the centrifugal pump performance at off-design operation condition, water-admission is introduced at the upstream of impeller inlet. This paper treats a centrifugal condensate pump with the specific speed of 216 min⁻¹·m³/min·m. Both hydraulic and cavitation performance have been experimentally tested for the pump. For analysis, the three-dimensional cavitating turbulent flows are simulated based on RANS method and a homogeneous cavitation model for several water-admission cases. The results indicated that with the water-admission, the pump head and hydraulic efficiency increase with the water-admission pressure up to 70kPa. However, with the water-admission pressure larger than 70kPa, the pump performance drops due to a large flow rate induced upstream the pump impeller. It is also noted that the water admission is unfavorable for cavitation inception. According to the numerical result, there is a sudden increase of accumulated cavity volume inside the impeller with the water-admission pressure larger than 70kPa. Thus, the water-admission should be further studied to improve the cavitation performance.