Reynolds Number Effects on Regenerative Pump Performance

Abstract

Reynolds number effects on the performance of a conventional design regenerative pump were investigated, using glycerine-water mixtures, between an impeller tip speed Reynolds number, RT , of 5.0×103 (all glycerine) and 1.6×106 (all water). Results show that the maximum efficiency, nm , can be expressed in terms of an output to loss ratio, nm /1−nm , which varies as RT 0.203 for 2.0×104 < RT < 1.6×106 and as RT 1.156 for RT < 2.0×104 . These results are consistent with efficiency behavior reported in similar investigations on other types of turbomachines. Further, the design point flow coefficient increased over the range of Reynolds number investigated, while the design point head coefficient exhibited a maximum within this range. In addition, marked departure from scaling behavior occurred in the lower Reynolds number range. Finally, the correlation among torque coefficient, head coefficient, and flow coefficient previously established by the author was further verified and followed scaling behavior for the higher Reynolds number range.