Flow field instability mechanism induced by cavitation inside the regulating valve

Cavitation poses a critical challenge to the performance for the regulating valve, severely degrading the service lifespan and operational reliability. Thus, a thorough understanding of cavitation influence mechanism is essential for developing effective mitigation strategies and improving the reliability of regulating valve. This paper proposes a coupled numerical model of flow resistance and cavitation characteristics based on the theory of the collaborative drag reduction theory, combining with the theory of vortex dynamics, reveals the dynamic coupling interrelationship between the cavitation flow field, flow resistance, and vortex structures, it fills the theoretical gap of the synergistic effect between gas–liquid phase transition process and vortex dynamics. The results show a strong connection between cavitation behavior, flow resistance, and the development of vortex structures. The initial development of cavitation aligns nearly perfectly with the first peak in flow resistance, with a maximum deviation of just 0.24%. Similarly, the end of cavitation development corresponds to the second peak in flow resistance, with a maximum deviation of 0.76%. Moreover, the initial stages of cavitation development coincide with the formation of characteristic vortices. The appearance of axial primary vortex rings hinders the downstream progression of cavitation. The flow resistance achieves the maximum at x = 62.68 mm as inlet pressure of 3.0 MPa, that is 4.18 × 102 W·cm−3, the vortex structure is also strongly affected the flow resistance. From the perspective of vortex dynamics, analyzing the internal cavitation flow fields of regulating valve under different operating conditions is helpful to reveal the cavitation mechanism.