Abstract: In order to study the influence of blade wrap angle on the performance of constant head pump, six impeller schemes with different blade wrap angle had been designed. Based on the Reynolds time-average N-S equation and the RNG k-ε turbulence model, the steady numerical calculation had been carried out, following the calculated results verified by experiments. The results show that before the cut-off flow, pump head decreases with the increase of the wrap angle. When the wrap angle of pump is 0 degree, the pump head is the largest. Under the schemes of 15 degrees, 30 degrees, and 45 degrees, the head of the pump is almost equal. When the wrap angle of pump is 60 degrees, pump has the smallest head, and the pump head decreases linearly with the increase of flow when the wrap angle is 75 degrees. The blade wrap angle has a significant influence on the efficiency of the pump. The pump efficiency in any scheme first increases and then decreases with the increase of flow, while the efficiency reaches its maximum value near the cut-off flow. Under the condition before the cut-off flow, the pump efficiency increases with the increase of the wrap angle, while after the cut-off flow, the larger the wrap angle is, the faster the efficiency decreases with the increase of the flow.

Key words: constant head, wrap angle, pumping chamber, cut-off flow, numerical calculation