基于Fluent的外开式喷氢器射流特性数值模拟OA

As hydrogen energy application technology matures and national strategic policies provide support,hydrogen internal combustion engines(HICEs)experience rapid development.The hydrogen injector serves as a key actuator in the hydrogen supply system of in-cylinder direct injection HICEs,where its jet characteristics determine the formation of the combustible mixture in the cylinder and directly influence engine performance.The outward-opening hydrogen injector operates with a conical valve moving toward the cylinder during the opening phase,offering high flow rates suitable for gaseous fuels.During closure,the high in-cylinder pressure acts in the closing direction of the valve core,ensuring a more reliable seal.Based on a self-designed outward-opening hydrogen injector,numerical simulations of jet characteristics are conducted using ANSYS Fluent.The injector's mass flow rate is verified,and the macroscopic and entrainment characteristics of hydrogen jets under different pressure ratios are analyzed.The results indicate that under an injection pressure of 4 MPa,a background pressure ranging from 0.6 to 1.2 MPa,and an operating temperature of 450 K,the injector achieves a mass flow rate of 10.73 g/s,with precise hydrogen injection control enabled by adjusting the injection pulse width.The formation of the outward-opening injector jet undergoes three distinct stages:hollow cone jet,cone collapse jet,and single-core jet.The axial penetration distance,maximum width,and area exhibit a three-phase growth pattern and varying trends,increasing with injection pressure and decreasing with background pressure.The entrainment ratio along the jet development direction initially increases and then decreases,with the location of the maximum value shifting with the nozzle pressure drop.Additionally,lower injection pressures or higher background pressures result in a greater entrainment ratio.The investigation of the injector jet characteristics not only provides a basis for optimizing structural design and control strategies but also lays the foundation for improving the in-cylinder mixture formation and combustion characteristics of hydrogen internal combustion engines.