Turbofan engine comprising a system for blocking the flow path of the bypass stream comprising veils

A turbofan engine having a longitudinal direction and comprising an engine and a nacelle surrounding the engine which comprises a fan casing, in which a path of a bypass air stream is delimited between the nacelle and the engine and in which an air stream circulates from front to rear of the turbofan engine, said nacelle comprising:

• a fixed structure fixed to the fan casing,
• a movable cowl which is movable in translation on the fixed structure in a direction of translation between an forward position, in which the movable cowl is positioned such that the movable cowl is close to the fan casing, and a rearward position, in which the movable cowl is positioned such that the movable cowl is away from the fan casing to define between them an open window between the flow path and the outside of the nacelle,
• a set of actuators ensuring a displacement of the movable cowl between the forward position and the rearward position, and vice versa,
• a plurality of flexible veils, each veil having a first edge either directly or indirectly attached to the movable cowl and a second edge opposite the first edge, in which said veil can alternately assume a folded position in which said veil is housed in the movable cowl or a deployed position in which said veil is extended between the first edge and the engine across the flow path, and
• a pneumatic system arranged to displace the second edge of each veil to displace said veil from the folded position to the deployed position and to displace the second edge of each veil to displace said veil from the deployed position to the folded position, in which the pneumatic system comprises:
• a rigid main roll fixed inside the movable cowl to the rear of the window,
• for each veil, at least one extendable secondary roll secured to the main roll and in which the inside of each secondary roll is in fluidic continuity with the inside of the main roll, in which the second roll of said veil is fixed to each of said secondary rolls, and
• a pressurization and depressurization system which, alternately, generates a pressure in the main roll and, therefore, in each secondary roll, to inflate them in a transition from the forward position to the rearward position, or depressurizes the main roll and, therefore, in each secondary roll, to deflate them in the transition from the rearward position to the forward position.