Suppression of performance curve instability of a mixed flow pump by use of J-groove

In order to control and suppress performance curve instability characterize d by the positive slope of head-capacity curve of a mixed flow pump, a very simple passive method utilizing shallow grooves mounted on a casing wall p arallel to the pressure gradient (J-groove) is proposed. The optimum groove dimension and location for suppressing such an instability are determined experimentally. Results show that shallow grooves of adequate dimension and proper location can suppress such instability perfectly without decreasing the pump maximum efficiency. The remarkable effect of shallow grooves is t o decrease both the swirl strength and the propagation of reverse flow at t he impeller inlet region, through angular momentum absorption owing to mixi ng of groove reverse flow and swirl flow, yielding recovery of impeller the oretical head. [S0098-2202(00)02603-1].