Platform arrangement in an axial-throughflow gas turbine with improved cooling of the wall segments and a method for reducing the gap losses

Abstract

The invention relates to an arrangement of guide vane platforms forming the inner contour of the flow channel in an axial-throughflow gas turbine and to a method for reducing the gap losses and for the improved cooling of the wall segments. In order to avoid the disadvantages of the generic solutions, particularly to achieve reduced thermal stress on the stator housing and on the connected vane platforms and subsequently to introduce the cooling air expended for this purpose into the flow channel in such a way that the gap losses of the shrouds of the moving blades are reduced, it is proposed, according to the invention, by dispensing with heat shields, to form the inner contour of the flow channel at least predominantly by means of the guide vane platforms and and to arrange the transitional regions between the platforms and within the cavity formed by the continuous sealing ribs and of the shroud . For this purpose, the guide vane platforms possess, on both sides, prolongations , in the direction of the respectively adjacent moving blade row and extend into the region delimited by its sealing ribs and . According to a preferred embodiment, the guide vane carriers are designed as a hollow profile, and cooling air acts at least partially on the wall voids formed between the stator housing and platforms. In a particularly preferred embodiment of the invention, the cooling air is introduced at least from the wall void into the cavity of the shroud under a pressure which is above that in the surrounding flow channel