Device for varying the section of the throat in a turbine nozzle

A device for varying the section of the throat of a turbine nozzle, the nozzle being made up of a plurality of stationary vanes extending radially between outer and inner annular platforms spaced apart from each other so as to define a flow passage for combustion gas passing through the turbine, the vanes being spaced apart from one another in order to define a throat presenting a minimum flow section, the device comprising an annular element having a coefficient of expansion that is less than that of the platforms of the nozzle, said annular element being secured to the outer platform and being suitable for occupying two positions:

• one position corresponding to no expansion of the platforms in which the element provides continuity for the profile of the flow passage, and another position corresponding to the platforms being expanded, in which position the element projects into the flow passage in such a manner as to reduce its section.