| The replacement of diesel engines with natural gas engines is an effective solution to the increasingly severe environmental pollution and energy problems.The gas accuracy and timing of natural gas engine determine the performance of the engine.In particular,high-power natural gas engines require large gas flow and high control precision.Therefore,higher requirements are imposed on the gas injection valve.The performance of the gas injection valve directly affects the performance of the engine's gas supply system.Therefore,This article aimed at gas injection valves of natural gas engine,investigating the flow characteristics of the flow,which provides a theoretical basis for system matching and flow control of gas injection valves.Firstly,Proposing a straight-through externally guided gas injection valve.According to the working characteristics of the gas injection valve,The structural parameters of the spool and the seat rings and the drive components are determined.and the theoretical gas injection valve flow equation is derived according to the fluid continuity equation and the steady flow energy equation,The fluid simulation model is established by ICEM CFD and FLUENT software.Secondly,unfolding the research of stability and dynamic characteristics of the gas injection valve.the influence of the gas inlet pressure and temperature and the lift on the mass flow rate of the gas is studied,and the law of change of physical quantities are obtained under different opening degrees of the valve core.According to the dynamic characteristics of the gas injection valve,the flow condition and velocity propagation characteristics of the gas in the valve cavity are analyzed by using dynamic mesh technology.It is found that the pressure disturbance has a significant influence on the outlet flow velocity when the subsonic flow is performed.Different valve core motion curves were established,and jet law in different jet pulse widths and pressure were obtained.Finally,for the multiple injection characteristics of the gas injection valve,the variation of the injection law under multiple jet cycles and the influence of the length of the diversion chamber on the gas fluctuation are analyzed.The results show that the reduction of the length of the diversion chamber can reduce the amplitude of the gas fluctuation but the frequency of fluctuation will also increase.By changing the gas inlet angle,the variation of the outlet mass flow rate with different inlet angles under different lengths of the diversion chamber is obtained.When the gas leakage into the valve cavity,the gas diffusion condition of the reflux gas is analyzed.It is found that the voltage regulator cavity structure can increase the hysteresis of the gas outflow and reduce the instantaneous leakage amount,which can be reduced by 1.54g/s at the maximum.At the same time,the variation of reflux gas in the stable chamber gas injection valve was analyzed.The research indicates that the gas concentration stratification during reflow is the main reason for the step change of gas leakage. |
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