Numerical Simulation and Experimental Research of the Flow Coefficient of the Nozzle-Flapper Valve Considering Cavitation

• Published in: International journal of fluid machinery and systems Vol. 10; no. 2; pp. 176 - 188
• Main Authors: Li, Lei, Li, Changchun, Zhang, Hengxuan
• Format: Journal Article
• Language: English
• Published: Tokyo 한국유체기계학회 01.01.2017; Japan Science and Technology Agency
• Subjects: Cavitation; Computer simulation; Design parameters; Flow coefficients; Inlet pressure; Mathematical models; Nozzles; Pneumatics; Simulation; Throttles; 기계공학; Nozzle-flapper valve; Numerical simulation; Flow coefficient; Cavitation; Servo valve
• ISSN: 1882-9554; 1882-9554
• DOI: 10.5293/IJFMS.2017.10.2.176

The nozzle-flapper valves are widely applied as a pilot stage in aerospace and military system. A subject of the analysis presented in this work is to find out a reasonable range of null clearance between the nozzle and flapper. This paper has presented a numerical flow coefficient simulation. In every design point, a parameterized model is created for flow coefficient simulation and cavitation under different conditions with varying gap width and inlet pressure. Moreover, a new test device has been designed to measure the flow coefficient and for visualized cavitation. The numerical simulation and test results both indicate that cavitation intensity gets fierce initially and shrinks finally as the gap width varies from small to large. From the curve, the flow coefficient mostly has experienced three stages: linear throttle section, transition section and saturation section. The appropriate deflection of flapper is recommended to make the gap width drop into the linear throttle section. The flapper-nozzle null clearance is optionally recommended near the range of DN/16. Finally through simulation it is also concluded that the inlet pressure plays a little role in the influence on the flow coefficient.