Study on Internal Flow Mechanism and Performance of Double-suction Annular Jet Pumps

This paper adopts the theory of jet energy transfer analysis and computational fluid dynamics (CFD) technology to improve annular jet pump (AJP). The nozzle of AJP is improved so that the annular nozzle is wrapped by the suction nozzles on both sides, which creates a double-suction annular jet pump (DAJP). The primary flow injected into suction chamber is surrounded by the secondary flow. The energy loss caused by direct contact of the primary flow with the wall is reduced. CFD was used to analyze the flow mechanism and performance in order to optimize its structure. Simulation results show that: the performance of the jet pump with a nozzle distance of 8mm from the wall is better than that of the other three DAJPs and the prototype pump. Its maximum efficiency can reach 51.77%. When the flow rate ratio is less than 0.4, the turbulent kinetic energy (TKE) is larger. It causes instability and irregular fluid motion, which ultimately leads to fluid energy loss and flow resistance increase. The smaller the flow ratio, the larger the backflow area in the suction chamber. The backflow area disappears when the flow ratio is greater than 0.4. The prototype pump only appears the backflow area near the axis of the suction chamber, while the DAJP also has a backflow area near the wall where the nozzle connects with the suction chamber. © 2024, Turbomachinery Society of Japan. All rights reserved.