CFD on-board high-pressure pneumatic vacuum pneumatic valve flow field is introduced. 1

by using CFD (computational fluid dynamics method and software Gambit and Fluent was used to study the pneumatic valve cavity internal pressure field and velocity field distribution, abstract: level of a hydrogen energy vehicles two high pressure pneumatic vacuum pneumatic valve on the flow field analysis. First analyzed the on-board two levels of the working process of the high pressure pneumatic relief valve. Analyses the two pneumatic valve decompression effect, velocity analysis results indicate the pneumatic valve inside the highest velocity in pneumatic valve accessories and the position of partial downstream.
keywords: pneumatic; Reduced pressure pneumatic valve; The flow field. 计算流体动力学; Hydrogen energy vehicles

in the preface by reaction of gaseous hydrogen and oxygen in the air, producing water, hydrogen energy vehicles often adopts the high pressure gas hydrogen storage method. Achieve zero emission, no pollution using chemical reactions occur at the same time the power to move the car. In order to ensure the car after a hydrogenation of continuous driving distance from achieve km above, onboard hydrogen system cylinder pressure to ask achieve MPa above [ ] Hydrogen energy vehicles requirements for proton exchange membrane fuel cell in the normal work of the hydrogen pressure is provided. MPa
implementation car carrying a hydrogen pressure control system. In this paper, based on this, [ ] In the proposed two-stage relief way. Research in the process of two-stage decompression, pneumatic valve cavity flow field and its distribution.
car two stage high pressure pneumatic vacuum pneumatic valve
figure for a hydrogen energy vehicles used on the two levels of high-pressure pneumatic relief valve hydrogen system principle.

the primary vacuum pneumatic valve and secondary vacuum pneumatic valve are straight moving cone vacuum pneumatic valve, the hydrogen energy vehicles used by the two levels of high pressure pneumatic relief valve by pneumatic seat, level of vacuum pneumatic valve, pneumatic valve, secondary stress thin slender orifice throttling orifice and other parts. And through the cartridge connection device in pneumatic seat. Work, high pressure gas by the gas source after the entry into the pneumatic valve, decompression after decompression pneumatic valve and thin section flow hole hydrogen system of relief for the first time, at this time of high pressure gas pressure by the MPa to MPa; After secondary vacuum pneumatic valve and elongated second decompression orifice complete hydrogen system, then, by the MPa pressure relief to the pressure force. MPa through the throttle to the mass exchange membrane fuel cell. Work, in the process of pneumatic seat two chamber should have the effect of air capacity, dynamic can adjust the hydrogen system.

calculation model. Gambit modeling and meshing
take car two stage high pressure pneumatic relief valve half symmetry structure as the research object, for the study of modeling and convenient. Before using the Fluent software, the software Gambit to two-dimensional modeling. As shown in figure for simulation model in this paper. As shown in figure a two stage high pressure pneumatic pressure pneumatic valve interior flow fluid planar map, including reduced pressure pneumatic valve for pneumatic valve mouth open. Mm, secondary vacuum pneumatic valve pneumatic valve mouth open mouth is. Mm, two slender throttle aperture are. Mm as shown in figure b for meshing figure, due to the throttle opening size, pressure gradient is large, in order to ensure the precision of the pneumatic valve port and slender orifice at the grid partial encryption.

。 Border conditions and solving model
set into the mouth border condition and entry the border pressure imported form and entry form, respectively, considering the recommend suite and compressible gas flow. Using uncoupled segreg solving the model, and considering viscous heating dissipative term and activation energy equation; Turbulence model adopts the single equation model. Calculation conditions for MPa inlet pressure, temperature K, inlet pressure. MPa, K
temperature. Basic equations
flow field was divided into many control body, through the mesh. For each control body, has the following basic equation. Mass conservation equation