Cooling aft end of a combustion liner

A liner ( 18 ) installed in a transition region ( 16 ) between a combustion section ( 12 ) of a gas turbine engine ( 10 ) and an air discharge section ( 14 ) of the turbine. The liner has an air inlet ( 26 ) for admitting air into the liner, and an air outlet ( 28 ) by which air is discharged from the liner. Flow of air through the liner acts to cool air flowing through the transition region of the turbine between the combustion and air discharge sections thereof, so to lower the temperature from between 2800-3000° F. to around 1400-1550° F. The liner has at least one channel (C 1, C 2 ) formed in it for flow of air through the liner. The height of this channel uniformly decreases along the length of the channel from the liner's air inlet to its air outlet. This liner construction reduces the thermal strain occurring at the aft end of the liner, prolonging the useful life of the liner, while reducing the amount of air needed to flow through the liner to affect a desired level of cooling in the transition region.