Experimental investigation on high-pressure methane jet characteristic single-hole injector

High-pressure gas direct injection (DI) technology benefits engines with high efficiency and clean emissions, and the gas jet process causes crucial effects especially inside an mm-size space. This study presents an investigation on the high-pressure methane jet characteristics from a single-hole injector by analysing jet performance parameters including jet impact force, gas jet impulse, and jet mass flow rate. The results show that the methane jet exhibited a two-zone behaviour along the jet direction in the spatial dimension induced by high-speed jet flow from the nozzle: zone 1 near the nozzle-the jet impact force and jet impulse increased consistently except for a fluctuation due to shock wave effects induced by the sonic jet and no entrainment occurs, and zone II farther away from the nozzle-the jet impact force and jet impulse became stable when the shock wave effects became weak and the jet impulse was conserved with a linear conservation boundary. The Mach disk height was exactly the turning point of two zones. Moreover, the methane jet parameters, such as the methane jet mass flow rate, jet initial jet impact force, jet impulse, and Reynolds number had a monotonous and linearly increasing correlation with injection pressure.