Taking the inlet port for a reference system

the velocity equation was developed using the momentum theorem to describe the motion of the foreign object from the inlet port to the rotor blade of aeroengine. Correlations between impacting velocity and impacting direction were founded by taking the rotor blade as a reference system. A kind of airplane and its aeroengine were taken as example

the change rule of the motion velocity in inlet channel was studied at aeroengine 100% design speed when airplane took off the ground. It was found that the foreign object motion velocity related not only with the foreign object shape

dimension

location and material

but also with the aeroengine working state and the length of the inlet port. The impacting direction was nonvertical to the blade surface.