The Effect of Inlet Swirl on the Rotordynamic Shroud Forces in a Centrifugal Pump

Abstract

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

Cálculo das velocidades angulares críticas da linha de eixo de turbinas hidráulicas com ênfase no comportamento estrutural dinâmico do gerador.

“…De acordo com GUINZBURG et al [19], este efeito é causado principalmente pelas forças tangenciais e tende a ser mais intenso em condições de pouca vazão ou com pequenas folgas radiais dos labirintos.…”