Cavitation Characteristics and Structure Optimization of Two-Dimensional Valve Based on Entropy Production Theory

In addition to noise and vibration, cavitation also lowers the efficiency, performance, and working lives of two-dimensional valves. To study the effect of cavitation on the flow characteristics of two-dimensional valves, standard turbulence model and an energy equation model were selected, and the local entropy production rate was defined using the custom field function. The entropy production theory was introduced to numerically simulate the cavitation flow in a two-dimensional valve, and based on this, the structure of the pilot stage of the valve was optimized. The results showed that there was a distinct correlation between the entropy production and the flow characteristics of the valve. When the mass flow rate changed, the entropy production also changed. The turbulent dissipation entropy production always accounted for more than 50% of the total entropy production in the flow field. In the valve sleeve chute area downstream of the valve throttling port, turbulence dissipation entropy production was concentrated; and the energy loss was large. According to the optimization of the structure of this area, the total entropy production of the side-V-slot valve sleeve structure was 7.46% lower than that of the unslotted valve sleeve structure for different valve openings, while the total entropy production of the rear-V-slot valve sleeve structure was 14.31% higher. The energy loss caused by cavitation could be better reduced using a V-shaped groove on the side of the valve sleeve.