The resulting high temperature exhaust gas is used to turn the power turbine and produce thrust when passed through a nozzle. The burner is arranged like an annulus , or a doughnut, as shown by the three burner configurations at the lower left. The central shaft that connects the turbine and compressor passes through the center hole. Burners are made from materials that can withstand the high temperatures of combustion. The liner is often perforated to enhance mixing of the fuel and air, as shown in the photo at the upper right.
Many modern burners have an annular design.
The burner in the middle is an older can or tubular design. The photo at the top left shows some actual burner cans. Each can has both a liner and a casing, and the cans are arranged around the central shaft. A compromise design is shown at the right. This is a can-annular design, in which the casing is annular and the liner is can shaped.