Effects of tip clearance on the internal flow characteristics of a multiphase pump under gas–liquid two‐phase cases

As a critical piece of equipment for offshore oil and gas transportation, the multiphase pump has been widely applied in engineering practice. However, the existence of tip clearance not only deteriorates the internal flow pattern but also reduces the overall efficiency of the unit. To reveal the effect of tip clearance on the internal flow characteristics of a multiphase pump, the numerical approach was employed to investigate the flow behaviour under different tip clearances (Rtc = 0, 0.5, 1.0, and 1.5 mm). The results indicate that the low‐pressure region near the inlet of the impeller S2 stream surface gradually extends toward the impeller outlet, accompanied by increasingly evident pressure contour deflection, which is particularly pronounced at Rtc = 1.5 mm. On the guide vane S2 stream surface, the number of vortices decreases gradually, indicating a more stable flow pattern, and the vortices correspond well to the low‐pressure regions. Tip clearance reduces the gas volume fraction in the impeller and suppresses its axial fluctuation. It mainly affects the gas–liquid slip velocity in the impeller, while its effect in the diffuser is relatively weak. Moreover, gas accumulation near the impeller hub is significantly alleviated by the presence of tip clearance.