Experimental investigation of suction flow enhancement in submerged jet pumps via perforated mixing chamber

Liquid–liquid jet pumps are essential in dredging, slurry transport, and submerged mixing applications, yet their suction performance remains constrained by the limited entrainment area in conventional solid-walled mixing chambers. This study experimentally investigates the geometric modification of using perforated mixing chambers that enable distributed radial suction driven by the hydrostatic pressure differential between the surrounding fluid and the low-pressure core induced by the motive jet. Seven perforated mixing chamber designs, differing in pore diameter, perforation density, spatial arrangement (aligned vs. staggered), and active perforated length, were tested against a non-perforated baseline in a fully submerged test rig. Performance was quantified primarily through the suction flow ratio ( M ) and specific energy consumption (SEC). All perforated configurations demonstrated superior entrainment compared to the conventional design. The optimal configuration was identified through parametric analysis and verified in a dedicated confirmation experiment. This configuration, at a dimensionless perforation ratio of τ ≈ 26.59 × 10 −3 , achieved a mean suction flow ratio of 6.97, corresponding to a 39.4% increase in the volumetric entrainment, while simultaneously reducing specific energy consumption by up to 39.45%. This configuration also shows a rise in the hydraulic efficiency from 7.8% (baseline) to 10.9% which overcomes the maximum theoretical efficiency value for conventional jet pump by 36.3%. A dimensionless perforation ratio ( τ , which is the ratio of the total open area of the perforations to the total surface area of the perforated section of the mixing chamber) was introduced to generalize the findings, revealing an optimal operating window. Below this range, suction is under-saturated; above it, excessive open area causes flow disturbances and pressure recovery that diminish returns. These results establish perforated mixing chambers as an effective, passive, and low-cost strategy for enhancing the suction capacity and energy efficiency of submerged jet pumps.