Device for ventilation of a turbomachine turbine casing

Abstract

The invention relates to a ventilation device for a turbomachine turbine casing, comprising a plurality of line sets (16) configured to spray air over the turbine casing, the line sets being arranged next to one another, each line set comprising a main ring (161) in which air circulates, the main ring (161) comprising orifices (17) configured to spray a stream of air towards the turbine casing, the line set comprising a shield (162) configured to isolate the main ring (161) from a stream of air returning from the turbine casing towards the line sets after having been sprayed towards the turbine casing, the said shield (162) enveloping the main ring (161) and having orifices aligned with the orifices of the main ring (161).

Claims

1. A ventilation device for a turbine casing of a turbomachine comprising a plurality of manifolds configured to spray air onto the turbine casing, the manifolds being disposed side by side, each manifold comprising a main ring in which air circulates, the main ring comprising openings configured to spray an air flow toward the turbine casing, each manifold comprising a shield configured to isolate the main ring from an air flow reflected from the turbine casing toward the manifolds after having been sprayed toward the turbine casing, each shield surrounds the main ring by delimiting a cavity between the main ring and the shield, the shield comprising openings aligned on the openings of the main ring.

2. The ventilation device according to claim 1, wherein each shield extends tangentially from the openings of each manifold, the shield being in intimate contact with the main ring at the openings.

3. The ventilation device casing according to claim 1, wherein each shield extends tangentially from each manifold from an intimate contact zone, between each manifold and each shield, diametrically opposed to the openings.

4. The ventilation device according to claim 1, wherein the cross-section of each shield has the shape of an ellipse.

5. The ventilation device according to claim 4, wherein the ellipse has a major axis twice as large as the diameter of the cross-section of the manifold.

6. The ventilation device according to claim 1, wherein the cavity is filled with air or argon.

7. A turbomachine comprising a turbine which comprises the ventilation device according to claim 1.

Description

PRESENTATION OF THE FIGURES

(1) Other features, aims and advantages of the invention will be revealed by the description that follows, which is purely illustrative and not limiting, and which must be read with reference to the appended drawings in which, other than FIG. 1 which illustrates a schematic view of a turbomachine of the type already discussed:

(2) FIG. 2 illustrates a disposition of manifolds in a known type of ventilation device;

(3) FIG. 3 illustrates a disposition of manifolds in a ventilation device according to an embodiment of the invention;

(4) FIG. 4 illustrates a manifold of a ventilation device according to an embodiment of the invention.

(5) In all the figures, similar elements bear identical reference symbols.

DETAILED DESCRIPTION OF THE INVENTION

(6) Shown in FIG. 1 is a ventilation device of a known type comprising manifolds 16 which are typically in the form of rings perforated vertically above the turbine casing 7 so as to spray air onto the turbine casing 7.

(7) In relation with FIG. 2, the Applicant has observed that an air flow sprayed toward the turbine casing 7 will be heated by contact with the latter.

(8) For this reason, a stream of post-impact hot air F2 is reflected from the turbine casing 7 toward the manifolds so that it can heat the latter and therefore the flow of cold air F1 emerging from them.

(9) Thus, taking into account that several manifolds are disposed side by side, hot air derived from the impact of cold air on the turbine casing will heat the adjoining manifold(s), which reduces the cooling performance of the casing.

(10) In order to avoid this problem, the Application has modified the manifolds of FIG. 2 and of FIG. 1 (still positioned at the same location in the turbomachine of FIG. 1) in relation to FIG. 3 and proposes a ventilation device comprising a plurality of manifolds 16, each comprising a main ring 161 in which an air flow circulates, and a shield 162 configured to isolate the main ring from an air flow reflected from the turbine casing 7 toward the manifolds 16 after having been sprayed toward the turbine casing 7.

(11) The main ring 161 comprises openings 17 configured to spray an air flow toward the turbine casing 7.

(12) As can be seen in FIG. 3, an air flow F2 derived from the turbine casing 7 after having impacted the turbine casing is reflected toward the manifolds. By in comparison with the same air flow in the prior art configuration (see FIG. 2), it is farther away from the main ring.

(13) Thanks to this shield 162, dead zones inaccessible by the post-impact stream F2 are created around the main ring. These dead zones thermally isolate the main ring 161 reducing, with respect to the prior art, the temperature of the cold air flow F1 and improving the effectiveness of the cooling device.

(14) The shield can completely surround the main ring and comprises openings aligned on the openings of the main ring.

(15) Advantageously, the shield 162 extends tangentially from the openings of the manifold, the shield being in intimate contact with the main ring at the openings. Such contact makes it possible to limit the head loss during expulsion of air from the main ring toward the turbine casing 7.

(16) Likewise, advantageously, the shield extends tangentially from the manifold from an intimate contact zone, between the manifold and the shield, diametrically opposed to the openings. Such contact makes it possible to limit the external bulk and makes it possible to take advantage of the cold air which circulates in the secondary jet above and of the exchange by radiation with the nacelle which, for its part, is cold.

(17) In order to limit the radial bulk of the shields, the latter has the shape of an ellipse. It is also possible to provide a rectangular shape, or an oval one.

(18) In the case of an elliptical shape, as can be seen in FIG. 4, the ellipse has a major axis twice as large as the diameter D of the cross-section of the manifold.

(19) The shield 162 can be of the same material as the manifold, for example a chromium-nickel based alloy.

(20) The shield can be hollow, the cavity 163 defined between the shield and the manifold can be filled with air or argon. Air will however be preferred, as it is a better insulator and has a lower cost.