An assembly includes an injection system and an injector for an aircraft turbomachine combustion chamber. The system includes an aerodynamic bowl including a first end widening toward the downstream end and centered on a central axis of the injection system, this also including a central body along which a film of fuel is intended to flow in the downstream direction. The central body includes a second end widening toward the downstream end, the first and second widening ends between them delimiting an air through duct and the system includes motion inducing a device allowing a relative movement between the first widening end which is stationary and the second widening end, along the central axis of the injection system, by moving the central body relative to the injector.