17 volume create an obstruction in the hot gas flow that the combustor shell contains the hot gas is therefore forced to follow the path of the corrugations as it would a row of stationary vanes as is common with other annular combustors a second shell liner 18 amp 19 encompasses the main combustor shell that envelops the combustion process this liner may have constant radii or variable radii in the longitudinal and or circumferential directions this liner creates an annular volume inside and outside the annular combustion region compressor discharge air is passed through these regions with the intent of removing heat from the combustor shell 14 amp 15 additionally the outer cooling region is open to the 1st stage turbine at the downstream end therefore the flow is pressure driven and exits at this end of the combustor in this outer annulus region the discharge air travels downstream and through the outside of the corrugations 21 removing heat from that material as well before entering the first stage turbine this outer liner 18 must attach to the outer combustor shell 14 by establishing a surface contact between 14 and 18 at the end of the combustor the surface contact will begin at the combustor exit and end slightly upstream establishing this type of mounting joining of the two liners 14 amp 18 creates an enclosed corrugation channel 21 on the cooling flow side this allows for the cooling flow to become more developed before entering the turbine inlet in this example the inner cooling region does not enter the 1st stage turbine instead dilution holes placed in.