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Research on transient characteristics of cavitation phenomena in pilot stage of jet pipe servo-valve
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作者 Wu Lin Chen Kuisheng Zhan Congchang 《High Technology Letters》 EI CAS 2020年第1期85-91,共7页
To obtain dynamic characteristics of cavitation and study the relationship between the cavitation and inlet pressure, large-eddy simulation(LES) is utilized to calculate unsteady flow field in the pilot stage. Lamb-Os... To obtain dynamic characteristics of cavitation and study the relationship between the cavitation and inlet pressure, large-eddy simulation(LES) is utilized to calculate unsteady flow field in the pilot stage. Lamb-Oseen vortex is observed. Simulation results show that vortex cavitation exists, and cloud cavitation begins to occur when inlet pressure reaches 7 MPa. Cavitation and cavitation-shedding are enhanced by the increment of inlet pressure. The main frequencies of the pressure oscillations of vortex cavitation and cloud cavitation increase with inlet pressure increasing. By comparing results of local cavitation and facet cavitation, it is known that cloud cavitation has a greater influence than vortex cavitation. Upon increasing the wedge length, the main frequency of vortex cavitation increases whereas that of cloud cavitation decreases, the volume fraction of the vapor phase and the energy efficiency decrease. Considering the above characteristics and the easiness of the process, the optimal wedge length is 0.03 mm. 展开更多
关键词 JET pipe servo-valve CAVITATION large-eddy simulation(LES) MULTIPHASE flow
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Analysis of pressure characteristics under laminar and turbulent flow states inside the pilot stage of a deflection flapper servo-valve:Mathematical modeling with CFD study and experimental validation 被引量:8
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作者 Bijan Krishna SAHA Songjing LI Xinbei LV 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2020年第3期1107-1118,共12页
Electro-hydraulic servo-valves are widely used components in the mechanical industry,aerospace and aerodynamic devices which precisely control the airplane or missile wings.Due to the small size and complex structure ... Electro-hydraulic servo-valves are widely used components in the mechanical industry,aerospace and aerodynamic devices which precisely control the airplane or missile wings.Due to the small size and complex structure in the pilot stage of deflection flapper servo-valves,accurate mathematical models for the flow and pressure characteristics have always been very difficult to be built.In this paper,mathematical models for the pilot stage of deflection flapper servo-valve are investigated to overcome some gaps between the theoretical formulation and overall performance of the valve by considering different flow states.Here,a mathematical model of the velocity distribution at the flapper groove exit is established by using Schlichting velocity equations for incompressible laminar fluid flow.Moreover,when the flow becomes turbulent,a mathematical model of pressure characteristics in the receiving ports is built on the basis of the assumption of the collision between the liquid and the jet as the impact of the jet on a moving block of fluid particles.To verify the analytical models for both laminar and turbulent flows,the pressure characteristics of the deflection flapper pilot stage are calculated and tested by using numerical simulation and experiment.Experimental verification of the theory is also presented.The computed numerical and analytical results show a good agreement with experimental data. 展开更多
关键词 Computational fluid dynamics(CFD) Deflection flapper servovalve Laminar flow Pressure characteristics servo-valve Turbulent submerged jet
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