Abstract: Improved operation can be achieved from an enhanced gas turbine engine having a segmented annular shroud which radially expands and contracts to match the expansion and contraction of engine rotor blades. The segmented annular shroud is supported by a structure which includes an annular ring having two radially outwardly extending flanges, and forward and aft annular segmented brackets which attach the segmented shroud to the forward and aft side of the ring respectively. In a preferred embodiment of the invention, two circumferentially extending separate and distinct air impingement manifolds surrounds each of the outwardly extending flanges. Each manifold is provided with a valve for controlling the amount and temperature of the airflow entering each manifold. The air from each manifold then impinges upon each of the outwardly extending flanges, thereby controlling the radial movement of the corresponding shroud segments and the associated clearances with the rotor blade tips.