Performance of liquid-gas ejector with curve diffuser in vertical flow

• A diffuser plays a role in converting energy from flow velocity to flow pressure. • The diffuser curve shape on the LGE affects the pressure recovery and efficiency. • Suction chamber design has a considerable impact on secondary fluid flow. • Froth flow in the LGE determines diffuser performance. • Flow pressure profiles follow a concave pattern along the diffuser curve. The Liquid-Gas Ejector (LGE) operates based on momentum transfer, especially in vertical flow configurations where high pressure is essential. The high pressure affects the buoyancy of the gas fraction, leading to increased flow resistance. To address this, a curved diffuser design is proposed to minimise the flow resistance caused by gas buoyancy. The experiment involved setting up a laboratory-scale test installation with transparent LGE specimens, where the curved diffuser geometry was modified. Pressure sensors were installed on the throat-and-diffuser to monitor pressure changes. The motive fluid pressure was adjusted to three different levels—204.74, 239.22, and 273.69 kPa—to analyse flow behaviour along the throat-and-diffuser. Measurements of pressure profile, pressure recovery ( C p ) and efficiency ( η ) were conducted, while flow visualisation was captured using a Canon 600D camera. The findings indicate that the curved diffuser enhances static pressure recovery by reducing gas buoyancy and flow resistance, resulting in concave pressure profiles influenced by suction and motive fluid pressures. The LGE demonstrated varying flow patterns—jet, froth, slug and bubbly flows—responsive to changes in motive fluid pressure. While the curved diffuser improves static pressure recovery, its impact is secondary to the influence of motive fluid pressure. Nonetheless, it delivers significant efficiency gains, up to 17.84 %, at high flow ratios, attributed to reduced gas buoyancy resistance and higher motive flow rates.