Gas turbine sealing joint having lamellar structure

The jet engine has a sealing system for insulating a cavity from a vein of primary flow. The system has a joint (50) mounted at periphery of an upstream portion (12a) of an external case (12) of a diffuser grid. Blades of the joint (50) are in support on a free end of a spoiler (71). Another joint (60) is situated upstream of the joint (50), and whose blades are in support on an upstream end of a spoiler (72) and on a spoiler (76).