In order to resolve the problem of determining the injection parameters when spraying to wash a certain type of turbofan engine from the inlet lip for the long distance of inlet and the irregular flow passage

the droplet size and motion trajectory were taken as the optimization goal

and the droplet on the airflow inlet face of the engine and the penetrating ability were taken as the effect target to carry out numerical simulation by using linearized instability sheet atomization（LISA）and Spalart-Allmaras（S-A）models.The nozzle design parameters were determined by optimized selection so that the commissioning workload and trial cost were reduced. Trial run of aircraft inlet combined with engine flow passage online washing was conducted to further measure and evaluate performance of the injection parameters predetermined nozzles. The trial run validation results showed that engine was washed in cold operation state and the injection parameters were determined as spray cone angle of 18°

installation upward offset angel of the nozzle on the spray frame of 7°30′and the washing vehicles feed liquid pressure of 1MPa. The optimal injection parameters

including nozzle type

injection pressure

spray angle and installation angle

for engines cold start or idle condition

were effective

making the washing droplet not only cover the entire engine entrance section and penetrate the whole blade cascade

but also not cause accessional blade erosion.