Simulation and Experimental Research on Fuel Spray Characteristics of a Self‑pressurized Injector

As a miniaturized direct injection (DI) solution, a self-pressurized injector is of great significance for small aviation piston engines, such as spark-ignited two-stroke heavy-fuel engines. The spray characteristics of DI injectors are an important application prerequisite. In this paper, the computational fluid dynamics (CFD) software AVL Fire is employed to study the spray characteristics. Two types of spray models are established based on the Han Sheet model and the KH-RT model, and simulation works are carried out according to two types of spray tests in the literature. The comparison results show that in the constant volume bomb test, the spray patterns obtained by simulation under the two sets of environmental pressures are similar to those in the experiment, and the simulation spray using the KH-RT model can fit the spray contraction of the near nozzle field and the vortex of the far nozzle field better. In the tube test, the spray patterns obtained by simulation under the five sets of flow velocity are similar to those in the experiment, and the simulation spray using the KH-RT model can fit the spray expansion and the vortex of the far nozzle field better. The RP-3 kerosene spray characteristics of the self-pressurized injector are also experimentally studied, and the results demonstrate that due to the higher viscosity of kerosene, the spray shrinks more easily, resulting in a smaller spray cone angle and larger penetration. Therefore, changes in environmental pressure have greater impact on the kerosene spray pattern.