Investigation of Transient Flow and Cavitation Phenomenon in the Injector under Different Pump Speed

A numerical simulation was carried out to investigate fuel injection rate and cavitation phenomenon on different oil pump speed inside the injector. Simulation starts in steady flow at minimum needle lift, and then continues computing whole fuel injection process by unsteady method. Mixture and cavitation model were applied in description of two-phase flow in Fluent and self-made programs are added to set flow boundary, calculate needle valve´s speed and gather statistics. Simulation results were validated by experimental statistics from an injector test platform at 800 RPM pump speed. The results demonstrated needle lift, fuel injection rate and cavitation phenomenon during an injection event. Cavitation shifts from bottom to top of the nozzle orifice when injection started and reaches the peak range near the end of injection, then varnishes quickly in approximately one millisecond. Bubble clouds exist longer due to more opening time at high pump speed.