The effect of nozzle hole diameter on wall-impinged spray characteristics was investigated under the condition of a constant injection mass. Experiments were performed in a constant volume combustion chamber using a high pressure common-rail injector with a single-nozzle hole

the diameter of which could be changed. A high-speed camera and a Schlieren visualization set-up were used to capture the behavior of impinged liquid- and vapor-phase sprays respectively. Variation laws for the radiuses

heights

and areas of the impinged sprays in both liquid and vapor phases(RL and RV

HL and HV

as well as AL and Av) were obtained by analyzing the images captured in the experiments

and the comparison was made of the wall-impinged spray characteristics at and after the injection end time. The results show that for a constant injection mass

the rate of spray increase before the end of injection is higher than that after the injection. A larger nozzle hole diameter causes higher spray diffusion rate and shorter injection duration. Nevertheless

the diffusion rate of RV does not change with increased nozzle hole diameter after the injection has ended. At the injection end time

RL

RV

HV

AV and APV (pure vapor-phase impingement spray area) decrease with increased nozzle hole diameter

whereas HL and AL increase. Additionally

RV is close to RL

whereas HV is much higher than HL.