Compressor casing

In a compressor section of a gas turbine engine, a double wall casing is provided wherein a nonstructural inner wall is removably attached to a thin, structural outer casing. The inner wall isolates the thin stator outer casing during transient turbine operations of throttle burst and throttle chop. During throttle burst and chop, the nonstructural inner wall delays rapid heating and cooling of the relatively thin-walled outer casing, and reduces radial misalignment between the stator casing and rotor due to uneven thermal expansion and contraction. The nonstructural inner wall evens-out thermal expansion and contraction of the stator casing with respect to the rotor. To fine tune the actual clearances between stator and rotor and prevent the casing outer wall from overheating, thermal insulation material is used between the nonstructural inner wall and outer casing.