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

다국어 초록 (Multilingual Abstract)

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.

목차 (Table of Contents)

• Abstract
• 1. Introduction
• 2. Theoretical background
• 3. Numerical simulation
• 4. Experimental design and setup
• 5. Results and analysis of the simulation and tests
• 6. Conclusion
• References

참고문헌 (Reference)

1 YANG G., "The Research of the Flow Field Cavitation inside Water Hydraulic Poppet Valve by CFD" 1 : 049-, 2007

2 Zhang L, "The CFD analysis of twin flapper-nozzle valve in pure water hydraulic" 31 (31): 220-227, 2012

3 Urata E., "On the torque generated in a servo valve torque motor using permanent magnets" 221 (221): 519-525, 2007

4 Chern M J, "Numerical Study on Cavitation Occurrence in Globe Valve" 139 (139): 25-34, 2013

5 Guoyi Peng, "Numerical Simulation of Unsteady Cavitation in a High-speed Water Jet" 한국유체기계학회 9 (9): 66-74, 2016

6 Sijun Wei, "Nozzle structure and flow coefficient of nozzle flapper" 8 (8): 21-25, 1989

7 Sijun Wei, "Nozzle structure and flow coefficient of nozzle flapper" 8 (8): 21-25, 1989

8 Wang T., "Modelling of a nozzle-flapper type pneumatic servo valve including the influence of flow force" 6 (6): 33-43, 2005

9 Khodaii z., "Modeling the effects of the external acceleration on the two stage flapper-nozzle servo electrohydraulic valves" 15 (15): 1-8, 2016

10 Merritt H E., "Hydraulic control systems" John Wiley & Sons 1967

11 Kagawa T., "Heat transfer effects on the frequency response of a pneumatic nozzle flapper" 107 (107): 332-336, 1985

12 Johnston D N., "Experimental investigation of flow and force characteristics of hydraulic poppet and disc valves" 161-171, 1991

13 Babic M., "Determination of Values for Flow Coefficients of First Stage Orifices in Two-Stage Electrohydraulic Servovalves" 5 (5): 27-30, 2002

14 Zhu Y, "Design criterion involving comprehensive performance characteristics of nozzle-flapper valves" 230 (230): 452-466, 2016

15 Desantes J M., "Characterization and prediction of the discharge coefficient of non-cavitating diesel injection nozzles" 184 : 371-381, 2016

16 Aung N Z., "CFD analysis of flow forces and energy loss characteristics in a flapper–nozzle pilot valve with different null clearances" 83 (83): 284-295, 2014

17 Chen Q., "CFD Simulation of a Hydraulic Servo Valve With Turbulent Flow and Cavitation" 27-30, 2004

18 Aung N Z, Li S., "A numerical study of cavitation phenomenon in a flapper-nozzle pilot stage of an electrohydraulic servo-valve with an innovative flapper shape" 77 (77): 31-39, 2014

19 Mchenya J M, "A Study of Flow-field Distribution between the Flapper and Nozzle in a Hydraulic Servo-valve" 658-662, 2011