Surging parametrization for gas-liquid centrifugal pumps

Abstract

The present work investigates the dimensional and similarity representations of two-phase flows in centrifugal pumps. A new parametrization scheme is advanced for the capacity (ϕ=Q/ωD3) and head (ψ=gH/ω2D2) coefficients in terms of the non-dimensional parameters β (no-slip volume gas fraction) and Ω (= ωD/UM, UM = mixture velocity in the inlet pipe). The new parametrization yields universal performance curves that capture the positions of performance degradation (ϕcr and ψmax) and the appearance of surging. The new expressions are supported by a comprehensive set of experiments carried out for volume gas fractions up to 12% and four rotational speeds. The experimental conditions cover the four different flow patterns commonly described in the literature. The experiments are conducted with water and air. The flow parameters are characterized through global parameters (pressures, flow rates). The work confirms the rotation speed as a relevant parameter in the performance determination of gas–liquid systems and shows its relation to bubble breakup and the definition of the four observed flow patterns. The particularly introduced parametrization equations are limited to the geometry of the pump that is tested. The developed methodology, however, is expected to be extendable to pumps of different geometries.