Study on the performance degradation mechanism of hydraulic pressure recovery turbine under two-phase conditions based on a gas-liquid mean kinetic energy transport loss model

The Hydraulic Pressure Recovery Turbine (HPRT) is a key device for industrial waste energy recovery. In many applications, the working medium exists as a gas–liquid mixture, making the internal flow more complex than under single-phase conditions. To investigate the performance degradation of the HPRT under gas–liquid two-phase conditions, this study proposes an energy loss model based on the mean kinetic energy equation within the Euler–Euler framework and analyzes the energy dissipation mechanism using the Liutex method.The results show that as the inlet gas volume fraction (IGVF) increases, the recovery pressure difference and shaft power decrease nonlinearly. The impeller and guide vane are identified as the main regions of energy loss. With increasing IGVF, turbulent dissipation and interfacial dissipation become the dominant loss mechanisms. Further analysis reveals that a higher IGVF enhances vortex structures within the flow passage, intensifies shear effects, and consequently increases energy dissipation. Based on the rigid enstrophy transport equation, the Coriolis force term, the pseudo Lamb vector curl term, and the baroclinic moment term are identified as the main drivers of vortex generation, and their contributions are significantly amplified at higher IGVF.