Analysis And Research On Cavitation Of High Water-based Hydraulic Cone Valve

In the paper, using cone valve as special object, by the theory of fluid mechanics, fluid dynamics and bubble dynamics analysis combined with computational fluid dynamics software which is referred to as CFD, the cavitation of cone valve in different semi cone angle and different valve port opening have been researched. Based on the result of the numerical simulation, analyzed the main factors which affect the cavitation and speculated the most serious area where generates cavitation. Through the analysis and research, it is drawn a conclusion that cavitation phenomenon is mainly due to the internal flow field in the valve cavity where negative pressure is produced, and the serious damaged filed of cone valve is in the cone to cylinder junction.Compared the simulation results with the practical application of water hydraulic cone valve, the serious damage area are consistent which verify the rationality of the cavitation model simulation.According to the analysis result, the anti-cavitation structures of spool by cavitation damage serious positions are given: the arc transition between valve cone and cylinder and two-step throttle structure. At the same time, the stiffness characteristics and anti-cavitation characteristics of the two stage throttle are analyzed theoretically. And analyzed two anti-cavitation structures of flow field by numerical simulation. Compared with the original structure, the result of pressure distribution, velocity distribution, import and export of the valve port pressure and gas volume fraction were all improved to effectively reduce the cavitation damage. In particular, the two-step throttle structure can obviously inhibit the cavitation damage of the water hydraulic cone valve. The research of this paper provides a theoretical basis for the design of anti-cavitation structure of high water-based hydraulic cone valve, which has a certain guiding significance.The main contents of this paper are as follows:The first chapter, discusses the connotation and characteristics of water hydraulic transmission technology, and its research status and the key problems it faces; described in detail the research status and development situation of cavitation in water hydraulic components; and summarized the main research contents of this topic.The second chapter, based on the basic theory of bubble dynamics, fluid mechanics, fluid dynamics, analyze the formation of cavitation; and the essence of thebubble for generation, development and collapse; establish cavitation model of multiphase flow, preparing to cone valve cavitation flow field simulation.In the third chapter, established the three-dimensional channel model of water hydraulic poppet valve that spool semi cone angle is 30°, 45°, and 60°, and opening increase from 0.3mm to 0.8 mm. With FLUENT software, the cavitation model of flow field simulation have done. Then the pressure distribution, velocity distribution, gas volume fraction of flow channel are displayed with images, and related calculation results are output. Compared with the results, the effect of internal flow field characteristics on cavitation erosion is analyzed. Finally, according to the results, the most serious parts of the cavitation damage are found out.In the forth chapter, aimed at serious parts for cavitation of cone valve, put forward two kinds of the anti-cavitation structure of cone valve. Compared analysis of original structure with anti-cavitation structures on flow field distribution, three structures of cavitation inception number curves have been obtained and cavitation index of the structures are gained. Finally, the reduction degree of cavitation damage for anti-cavitation structures to the cone valve is obtained.