The investigation on the flow characteristics during the continuous development of the tip leakage vortex cavitation in an axial pump-jet propulsion

Abstract

The continuous deterioration and development of tip leakage vortex (TLV) cavitation in the pump-jet propulsion significantly affect propulsion performance and operational stability. Larger eddy simulation and cavitation tunnel experiment are utilized to investigate the temporal and spatial evolution characteristics of TLV cavitation under varying cavitation conditions. The results reveal that the continuous development of TLV cavitation prompts the TLV to gradually move away from the blade suction surface due to increasing pressure difference at the blade tip surface. Furthermore, the development of TLV cavitation amplifies the effect of the radial outward Coriolis force and makes the TLV even more unstable. Under the influence of the tip leakage flow, primary generation of turbulent kinetic energy (TKE) persistently migrates to the TLV core center and subsequently travels downstream. Despite the large magnitude of TKE that occurs at the TLV core center, the TKE generation remains low. With the inception of TLV cavitation, the transport of TKE between the TLV core center and the surrounding flow gradually intensifies, followed by a subsequent weakening of this transport effect. It increases again as the breakdown of TLV becomes more severe.