Flow Control in Multiphase Pumps Based on Separated Trailing Edge Flap

Abstract

In developing and transporting significant oil fields in deep-sea environments, multiphase pumps are considered crucial energy conversion equipment. Ensuring their safe, efficient, and stable operation is currently a primary focus of research. The intermittent aggregation of the gas phase at the trailing edge flap of the impeller blades in multiphase pumps can lead to periodic and significant fluctuations in flow rate and outlet pressure, posing a threat to the overall operational safety of the pump system. Based on aerodynamic principles, this paper presents the design of a separate trailing edge flap for the impeller blades. The inner nodal method is applied to determine the design scheme of the trailing edge flap for the multiphase pump. A numerical approach is employed to analyze the impact of the flap deflection angle on the internal flow characteristics to provide theoretical guidance for the structural optimization of multiphase pumps. The results indicate that the influence of the deflection angle on the pump efficiency is complex and affected by a critical angle value. When the deflection angle is below the critical value, the trailing edge flap can effectively reduce the formation of energy dissipation vortices and radial pressure gradients within the impeller channel, enabling a significant improvement in the gas-phase aggregation phenomenon caused by gas–liquid separation. However, additional energy losses occur at the connection between the trailing edge flap and the main blade body for deflection angles exceeding the critical value. When the trailing edge flap length is 0.25 l and the deflection angle is 5°, the efficiency is improved by 3.4% compared to the original model. Consequently, the pressurization capacity of the pump is compromised. In the design and application of trailing edge flaps, a careful balance between various factors is required to ensure both the stability and high efficiency of the pump system.