EXPERIMENTAL STUDY OF GAS-LIQUID FLOW THROUGH A MULTI-STAGE, MIXED-FLOW ELECTRIC SUBMERSIBLE PUMP

Laser Doppler velocimetry (LDV) and high-speed imaging techniques were used in a transparent model of a four stage, mixed-flow commercial electric submersible pump (ESP) to characterize the flow through a range of inlet gas volume fractions (GVF) from 0 to 30%. Measurements demonstrate the presence high turbulence levels in the wake of the impeller blades, and recirculation cells at low flow rates. In gas-liquid conditions, the bubble size varied within a pump stage, as break-up occurred at the impeller tip, and coalescence was dominant in the diffuser, especially at low flow rates because of recirculation. At moderate-to-high inlet GVF, the first impeller acted as a mixer and the flow patterns at the stage level alternated between bubbly and radially separated flows, as short gas slugs propagated through the stages. The flow patterns at the stage level did not depend on the pump inclination, but the inlet conditions did, with worse performance induced by slugging flows for the horizontal setup.