Moving blade for a turbomachine, the blade having a common cooling air feed cavity

Abstract

A moving blade for a turbomachine, the blade comprising an aerodynamic surface extending radially between a blade root and a blade tip, and at least one internal cooling circuit made up of at least one radial cavity, at least one air admission opening formed in the blade root and opening out into the cavity(ies), and a plurality of outlet orifices opening out from the cavity(ies) and leading to the outside of the blade, the blade root having lower swellings and upper swellings defining bearing surfaces for fastening the blade to a rotor disk. The air admission openings of the cooling circuit(s) open out into a common cavity that is formed in the blade root and that extends radially from the base of the blade root at least as far as the upper swelling of said root.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to the general field of cooling moving blades in a turbomachine, and in particular the moving blades of the high-pressure turbine.[0002]It is known to provide the moving blades of a gas turbine in a turbomachine, such as the high-pressure or the low-pressure turbine, with internal cooling circuits enabling them to withstand without damage the very high temperatures to which they are subjected while the turbomachine is in operation. Thus, for a high-pressure turbine, the temperature of the gas coming from the combustion chamber can reach values much higher than those that the moving blades of the turbine can withstand without damage, which has the consequence of limiting the lifetime of the blades.[0003]By means of such cooling circuits, air that is introduced into the blade via its root travels through the blade, following a path formed by a plurality of cavities formed in the blade, prior to being ejected through outlet...

AI Technical Summary

Benefits of technology

[0006]A main object of the present invention is thus to mitigate such drawbacks by providing a moving blade provided with internal cooling circuits that are simpler to fabricate by casting and in which the flow of air is facilitated.

[0008]The process of fabricating such a blade by casting is simplified. The ceramic core is consolidated by the presence of the location reserved for the common cavity for feeding air to the cavities of the cooling circuit(s). Furthermore, the presence of such a common cavity in the blade root avoids curving the cavities of the cooling circuit(s), thereby improving the flow of air therein. In addition, the presence of the common cavity makes it possible to make blades having a large cross-section—and thus an enlarged root—without thereby significantly increasing their weight (the purpose of using blades having a large cross-section is to reduce the total number of the moving blades in a given stage of a gas turbine).

Problems solved by technology

Thus, for a high-pressure turbine, the temperature of the gas coming from the combustion chamber can reach values much higher than those that the moving blades of the turbine can withstand without damage, which has the consequence of limiting the lifetime of the blades.

Fabricating a gas turbine moving blade having a cooling circuit of that type by a casting process presents drawbacks.

Unfortunately, the large number of cavities needed for cooling the blade makes it difficult to provide a ceramic core that is robust.

There is therefore a significant risk that such a core will break.

A result of this curvature of the cavities is that the flow of air in the cavities is disturbed, and that impedes cooling the blade.

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