Effects of variable-speed operation on the tip leakage vortex and pressure pulsations in a vane-type multiphase pump

As a key component of oil–gas transportation systems, the off-design operating characteristics of multiphase pumps directly affect system stability and transport efficiency, while variable-speed transients are a key factor governing internal flow and energy conversion. This study numerically investigates the transient flow-field response of a vane-type multiphase pump under a prescribed variable-speed condition at a fixed inlet flow rate, focusing on the evolution of tip leakage vortex (TLV) and pressure pulsation characteristics. The results show that changes in rotational speed significantly affect the vorticity distribution within the impeller: during acceleration, the circumferential vorticity component strengthens and the axial and radial components extend over a wider region; during deceleration, the overall vorticity intensity decreases and the axial and radial components gradually weaken, with a delayed adjustment observed in the early deceleration stage. In the blade-tip region, the pressure-pulsation response varies markedly with monitoring position, with the strongest pulsations occurring near the pressure-surface inlet; the suction surface exhibits higher spectral amplitudes than the pressure surface. In the impeller passage, pressure-pulsation amplitude generally decreases along the flow direction, and the response exhibits a time lag relative to rotational-speed variation during both acceleration and deceleration. This study reveals the transient vorticity and pressure-pulsation characteristics of a multiphase pump under fixed-inlet-flow and prescribed variable-speed conditions, providing a reference for understanding the internal flow behavior of multiphase pumps during speed transients.