Methods, systems and apparatus relating to turbine engine exhaust diffusers

A method of operating a turbine engine, the turbine engine comprising a working fluid flowpath defined through a turbine section that is operably connected to a diffuser flowpath defined through a diffuser, wherein the diffuser comprises diffuser walls that define and enclose the diffuser flowpath between an inlet and outlet of the diffuser, the method comprising the steps of:

• providing at least one stationary diffuser wall of the diffuser walls;
• providing at least one adjustable diffuser wall of the diffuser wall, wherein the at least one adjustable diffuser wall is controllably movable between at least a first position and a second position relative to the at least one stationary diffuser wall, wherein the second position comprises a reduction in a flow area through the outlet of the diffuser compared to the first position;
• via one or more sensors, sensing a current value for an operating condition of the turbine engine;
• comparing the current value of the operating condition to a threshold value;
• in response to the comparison, moving the at least one adjustable diffuser wall from the first position to the second position.