An arcuate panel 52 for a thermal control assembly includes an arcuate panel base 58, at least one axially extending panel header 54 sealingly attached to a radially outwardly facing surface 62 of the panel base 58, a plenum 56 therebetween, one or more spray tubes or channels 60 depending radially inwardly from the panel base 58 and in fluid communication with the plenum 56, and radially outwardly biasing spring means 110 mounted on or attached to the radially inwardly facing surface of the panel base 58. The panel 52 may include at least one set of clockwise and counter-clockwise hinge wings 122, 124 attached to clockwise and counter-clockwise ends of the panel base 58, axial positioning means 180, and circumferential positioning means 144. The axial positioning means 180 may include a circular row of spring clips mounted on the panel base. A hoop of arcuate panels pivotably attached by hinges may encircle a portion of a casing 66 compressing leaf springs against rings of the casing 60.