Influence of impeller staggered arrangement on radial force and pressure fluctuation for a double-suction centrifugal pump

Influence of impeller arrangement on performance, radial force, and pressure fluctuation for a double-suction centrifugal pump is investigated. In comparison of the original impeller with staggered angle alpha of 0 degrees, the maximum improvement of pump efficiency is 2.19% for impeller with alpha of 30 degrees, and the maximum improvement of pump head is 1.76% for impeller with alpha of 20 degrees. The radial force vector on impeller is related to the staggered angle, and the phase angle of radial force vector is equal to the staggered angle. The staggered arrangement can effectively reduce the amplitude of radial force fluctuation. In comparison of case 0, the maximum amplitude of radial force fluctuation for case 30 reduces by 15.8%. The dominant frequencies of the radial force fluctuation for alpha = 0 degrees, 10 degrees, and 20 degrees are f(Bp), while the dominant frequency for alpha = 30 degrees is 2f(BP). An empirical formula is proposed to predict the radial fluctuation amplitude at specific staggered angle. For a point of the volute far from the exit volute, in comparison of case 0, the maximum amplitudes of pressure fluctuation for case 10, case 20, and case 30 are reduced by 13.1%, 49.8%, and 93.3%.