Turbine center frame having a specifically designed annular space contour

Described is a turbine center frame for a gas turbine, in particular an aircraft gas turbine, the turbine center frame having a radially inner wall and a radially outer wall bounding an annular space through which hot gas flows and each having a contour facing the annular space, the contours describing an inner annular space curve along the inner wall and an outer annular space curve along the outer wall. At least one vane element extends in the radial direction through the annular space and has an axial leading edge and an axial trailing edge, the vane element having an outer axial width. The outer annular space curve or/and the inner annular space curve have at least one curve section having an inflection point of the respective annular space curve or/and a point of maximum slope of the respective annular space curve, the curve section being located in the region of the leading edge or trailing edge as considered with respect to the outer axial width or/and the inner axial width and having a length projected parallel to the axial direction which length is up to 20% of the respective axial width, and the curve section intersecting the piercing point where the leading edge or the trailing edge pierces the outer wall or the inner wall.