A turbine includes a combustion chamber with deflectors generating vortices in a secondary gas flow into the combustion chamber, thereby confining the flame front from penetrating into the cold region of the chamber under variable operating conditions, simplifying cooling of the chamber walls. The turbine further includes devices for decoupling vibrations between the high- and low-speed shafts, including a loosely mounted spline coupling the high-speed shaft to the step-down system and disk dampening means coupling the step-down system to the low-speed output shaft.