Cooling jacket for the hollow blade of the dispenser

Abstract

The present invention relates to a cooling jacket (26) for a turbine distributor of a turbine, comprising: - a body (30) including a central air inlet pipe (32) which defines a first ventilation air circulation area (34a) and at least two rows of holes (37) of two partition walls defining second and third ventilation air flow areas; - an outer plate (38) including a first hole (38a), a second hole (38b) and a third hole (38c) for allowing ventilation air to enter the first, second and third ventilation air flow areas respectively; and - an inner plate (40) including a central opening (40a) for discharging air from the first ventilation air flow area. Each of the inner plate and the outer plate is rigidly connected to the body by brazing to form an integral assembly having three ventilation air flow areas independent and sealed from each other, and then the integral assembly is assembled into a hollow blade of the distributor.

Description

Technical Field

[0001] The present invention relates to the general field of aviation turbines, and more particularly to aviation turbines such as turbojet engines and turboprop engines, and more specifically to a hollow airfoil of a nozzle of a gas turbine engine including a cooling jacket. Background Art

[0002] The turbine of a gas turbine engine conventionally includes one or more rows of moving turbine blades circumferentially spaced around the rotor of the turbine. It also includes nozzles, which typically include a plurality of fixed vanes or guide vanes that extend substantially radially between a radially outer coaxial annular platform and a radially inner coaxial annular platform and are circumferentially spaced relative to each other. These fixed nozzle blades are used to direct the flow path gas flow at an appropriate angle and speed towards the moving turbine blades located downstream of the nozzles, thereby rotationally driving the moving blades and the rotor of the turbine, and thus being in direct contact with the hot gas from the combustion chamber and exposed to high temperatures. Therefore, they need to be cooled and it is desirable to have an effective cooling device for the fixed nozzle blades, and it is desired to have a cooling device with high thermal efficiency to allow dissipation of high thermal power by using a medium air flow rate.

[0003] Furthermore, it is desired that the cooling device is airtight to ensure that the air in motion is only used for cooling the vanes. Specifically, the greater the airtightness of the cooling device, the higher its overall efficiency, and the latter is an increasing function of the airtightness and thermal efficiency of the cooling device.

[0004] For example, it is known from the application FR2976616 filed in the name of the applicant to employ a ventilation system including a tubular jacket made of a multi-perforated metal sheet to cool the hollow airfoil of the nozzle by the impact of cooling air passing through the holes formed in the wall of the jacket. This air entering upstream then flows downstream, where the air is discharged through the perforations provided along the wall of the trailing edge of the airfoil through the air flow path. It should be noted that, where applicable, the inner surface of the airfoil wall may be provided with fluid disturbing elements that promote heat exchange between the air circulating between the jacket and the airfoil wall.

[0005] After installation, the jacket that has been preformed and provided with an intake pipe and a closing plate to form an integral unit slides into the inner cavity of the hollow airfoil of the nozzle through an opening formed in the radially outer annular platform. The jacket is then fixed to the airfoil by welding or brazing along its edge in contact with the wall of the opening formed in the radially outer annular platform. The opposite parts of the jacket are simply guided through an opening formed in the radially inner annular platform of the airfoil, and the opening forms a sliding mechanism to allow relative movement between the airfoil and the jacket. These longitudinal displacements are due to temperature changes during the operation of the turbine, and the two components are different in terms of the nature of their constituent materials and their manufacturing methods.

[0006] While generally satisfactory, the robustness of the solution with respect to the correct air supply to the jacket holes located near the leading edge of the nozzle airfoil and to the air supply to the inter-disk cavities of the turbine is of little importance. Specifically, the inner side of the jacket consists only of a single cavity for all the holes supplying the jacket. In such a device, air preferentially flows towards the circuit and / or holes with the lowest pressure. Thus, once the air enters the jacket via the inlet pipe, the air will mainly flow towards the holes of the jacket located as close as possible to the perforations arranged along the wall of the trailing edge of the nozzle airfoil, thereby reducing the supply to the perforations located near the nozzle leading edge and the inter-disk cavities, resulting in a loss of robustness in terms of the airtightness and cooling of these same cavities. Summary of the Invention

[0007] Accordingly, a main object of the present invention is to mitigate these drawbacks by providing a cooling jacket for mounting in the hollow airfoil of a nozzle of a turbine, which cooling jacket enables a better distribution of the ventilation air flow allowed to enter the jacket. Thus, one object is to supply a portion of this ventilation air flow to other components of the turbine, in particular to the inter-disk cavities of the turbine, in order to make these inter-disk cavities airtight and to cool the turbine disks. Another object is to provide a method for assembling a turbine nozzle that is economically advantageous and has the lowest possible production cost.

[0008] These objects are achieved by a cooling jacket for a hollow airfoil of a turbine nozzle, the cooling jacket comprising:

[0009] - a body that extends in a radial direction between a radially inner end and a radially outer end and comprises a suction surface and a pressure surface as well as a central inlet pipe that defines a first ventilation air circulation region and is connected to these two surfaces by two partition walls that define second and third ventilation air circulation regions, the suction surface and the pressure surface each comprising at least two rows of drilled holes for discharging ventilation air from the second and third ventilation air circulation regions,

[0010] - an outer plate provided at the radially outer end of the body, the outer plate comprising first, second, and third holes for allowing ventilation air to enter the first, second, and third ventilation air circulation regions, respectively, and

[0011] - an inner plate provided at the radially inner end of the body, the inner plate comprising a central opening for discharging air from the first ventilation air circulation region, the outer plate and the inner plate being fixed to the body by welding to form an integral unit having three ventilation air circulation regions that are independent of each other and airtight, and then the integral unit is installed in the hollow airfoil of the turbine nozzle.

[0012] Preferably, the body as well as the outer plate and the inner plate are made by additive manufacturing, and the drilled holes are made by electrical discharge machining or by laser.

[0013] Advantageously, the first hole includes a section proportional to the number of airfoils, said section being greater than the sum of the sections of the injectors ensuring the ventilation air flow velocity downstream, and each of the second and third ventilation air inlet holes includes a section smaller than the sum of the sections of the drill holes respectively ensuring the discharge of the ventilation air from the second and third ventilation air circulation regions.

[0014] The invention also relates to a turbine nozzle of a turbine, which includes two coaxial annular platforms, between which extend substantially radial hollow airfoils, and each hollow airfoil includes a cooling jacket as described above.

[0015] The invention further relates to an aero turbine, such as a turbojet or turboprop engine of an aircraft, including the turbine nozzle as described above.

[0016] Finally, the invention relates to a method for assembling a cooling jacket of a hollow airfoil of a turbine nozzle of a turbine, characterized in that the method includes: manufacturing a body, the body extending between a radially outer end and a radially inner end along a radial axis and including a suction surface, a pressure surface and a central air inlet pipe, the central air inlet pipe defining a first ventilation air circulation region and being connected to the two surfaces through two partition walls defining the second and third ventilation air circulation regions; manufacturing an outer plate, the outer plate including first, second and third holes for respectively introducing ventilation air into the first, second and third ventilation air circulation regions; manufacturing an inner plate, the inner plate including a central opening for discharging air from the first ventilation air circulation region; machining at least two rows of drill holes on each of the suction surface and the pressure surface of the body to discharge the ventilation air from the second and third ventilation air circulation regions; and fixing the outer plate and the inner plate to the body by brazing to form an integral unit having three mutually independent and airtight ventilation air circulation regions, and then installing the integral unit into the hollow airfoil of the turbine nozzle.

[0017] Preferably, the suction surface and the pressure surface constituting the outer shape of the body are configured to fit the inner cavity of the hollow airfoil of the nozzle.

[0018] Advantageously, before fixing the contact surfaces between the body and each of the outer plate and the inner plate, as well as the outer surface and the inner surface of the body to the integral unit, they are also polished.

[0019] Preferably, the metal material has a thickness of at least 0.5 mm. Description of the Drawings

[0020] Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings, which illustrate exemplary embodiments of the invention without any limiting features, wherein:

[0021] Figure 1 is a schematic perspective view of a turbine nozzle section for receiving a cooling jacket according to the present invention in each of its hollow airfoils.

[0022] Figure 2 is an external perspective view of a cooling jacket according to the present invention for installation in each hollow airfoil of the turbine nozzle of Figure 1.

[0023] Figure 3 details the upper and interior of the jacket of Figure 1.

[0024] Figure 4 details the lower and interior of the jacket of Figure 1, and

[0025] Figure 5 is a cross-sectional view of the cooling jacket installed in the inner cavity of the hollow airfoil of the turbine nozzle of Figure 1. DETAILED DESCRIPTION

[0026] Figure 1 shows a section 10 of a turbine nozzle of a turbine (such as a turbojet or turboprop engine of an aircraft), which includes two coaxial annular platforms, namely an inner platform 12 and an outer platform 14, which together define an annular air flow path, and between these annular platforms extend substantially radial hollow airfoils 16 (the number of airfoils can be about dozens). The outer platform 14 includes an upstream radially outer annular edge 18 and a downstream radially outer annular edge 20, and the upstream radially outer annular edge 18 and the downstream radially outer annular edge 20 include axial annular tongues 22 oriented upstream and adapted to engage in corresponding axial annular slots (not shown) of the turbine housing. The terms "outer" and "inner" should be understood with respect to the separation from the longitudinal axis of the turbine in the radial direction of the relevant elements, and the turbine nozzle extends around the longitudinal axis.

[0027] The hollow airfoils of the turbine nozzle include an inner cavity 24 in which a cooling jacket 26 (visible in Figure 2) is installed, and the cooling jacket 26 is used to ensure the circulation of ventilation air (see the input and output arrows for the input and output air respectively) from a supply chamber (not shown) radially outside the outer platform 14 in the hollow airfoil 16 (the air returns via the slots 28 in the trailing edge) and towards a supply chamber (not shown) radially inside the inner platform 12, and is used to supply air to the inter-disk cavity of the turbine.

[0028] According to the present invention, as shown in the external perspective views of Figures 2-4, the cooling jacket 26 includes the following elements:

[0029] - A hollow body 30, which extends in a radial direction between a radially outer end and a radially inner end and includes a suction surface 30a and a pressure surface 30b. The outer shape of the hollow body formed by these two surfaces is substantially adapted to the internal cavity 24 of the airfoil 16 of the nozzle, and the body is fixed to a central intake pipe 32. By means of two thick partition walls 36a, 36b provided on both sides of the central intake pipe, the central intake pipe 32 defines a first ventilation air circulation area 34a between the central intake pipe and each of the two surfaces 30a, 30b of the body, such that two separated upstream and downstream cavities are defined on either side of these walls, and the upstream and downstream cavities respectively define second and third ventilation air circulation areas 34b, 34c which are waterproof relative to each other and relative to the first ventilation air circulation area 34 and can be independently supplied with ventilation air. Each of the suction surface and the pressure surface of the body includes a plurality of rows of drilled holes 37 (usually at least two, one for each cavity) to allow cooling by the impact on the inner wall of the nozzle airfoil 16.

[0030] - An outer plate (first plate 38), which is for being fixed to the radially outer end of the body and is drilled with a first hole 38a, a second hole 38b and a third hole 38c. The first hole 38a supplies ventilation air to the central intake pipe 32 that encloses the first ventilation air circulation area 34a, the second hole 38b supplies ventilation air to the second ventilation air circulation area 34b, and the third hole 38c supplies ventilation air to the third ventilation air circulation area 34c, and

[0031] - An inner plate (second plate 40), which is for being fixed to the radially outer end of the body and is drilled with a single central opening 40a to allow the ventilation air circulating in the central intake pipe 32 to be directly guided to the inter-disk cavity of the turbine.

[0032] Preferably, the cooling jacket is made entirely by additive manufacturing according to a metal 3D printing process, and the metal 3D printing process is carried out in the following stages.

[0033] First, in the first stage, on the same plate of an additive manufacturing machine (or 3D printer), without using any specific printing medium, preferably the body 30 (including its central intake pipe 32 and partition walls 36a, 36b), the upper plate 38 and the inner plate 40 are printed separately (to facilitate subsequent polishing steps). To avoid obtaining a surface deformed by the rollers of the 3D printer, in addition, a minimum material thickness of 0.5 mm is recommended. The printing of the body is completed vertically, starting from either its lower part (the bottom of the body) or its upper part (the top of the body) according to the choice. The material used is a metal material usually selected from type metal alloys.

[0034] Next, once the printing is completed, a second stage of machining the different drilled holes 37 on each suction surface and pressure surface of the body is continued, preferably machining of the EDM (or electrical discharge machining) type. However, laser drilling can also be envisaged.

[0035] In the third stage, a polishing operation of the functional surfaces of the different components (the contact surfaces between the body and the outer and inner plates of the jacket) is preferably carried out.

[0036] Finally, in the last stage, the operation of brazing the outer and inner plates to the body can finalize the jacket as an integral unit having three vented air circulation regions that are independent of each other and airtight before installing the jacket in the cavity 24 of the airfoil 16 of the nozzle, as shown in FIG. 5.

[0037] As is known, the cooling jacket thus obtained by additive manufacturing is then fixed and made waterproof relative to the inner wall of the nozzle by welding or brazing at the level of its outer plate 38 (see weld 42), and the inner plate 40 of the jacket itself is simply guided into the lower part of the nozzle, which forms a sliding part to allow relative movement between the airfoil 16 and the cooling jacket 26.

[0038] Therefore, the cooling jacket 26 installed and attached in the cavity 24 can perform the following functions:

[0039] - Impinge on the upstream part (near the leading edge) of the inner wall of the airfoil of the nozzle. The vented air enters through the second hole 38b to supply the upstream cavity 34b, and then is discharged through the first row of drilled holes 37, thereby impinging on the inner wall of the airfoil of the nozzle. Then, the air will circulate in the space defined by the inner wall of the airfoil of the nozzle and the outer wall of the jacket, and then is discharged through the discharge holes located on the trailing edge of the airfoil of the nozzle.

[0040] - Impinge on the downstream part (near the trailing edge) of the inner wall of the airfoil of the nozzle. The vented air enters through the third hole 38c to supply the downstream cavity 34c, and then is discharged through another row of drilled holes 37, thereby impinging on the inner wall of the airfoil of the nozzle. Then, the air will circulate in the space defined by the inner wall of the airfoil of the nozzle and the outer wall of the jacket, and then is discharged through the same discharge holes located on the trailing edge of the airfoil of the nozzle.

[0041] - Supply vented air to the inter-disk cavity. The air enters through the first hole 38a, circulates in the central intake pipe 32, and is discharged through the central opening 40a of the inner plate 40.

[0042] It should be noted that the second ventilation air inlet hole 38b and the third ventilation air inlet hole 38c may have a free form (rectangular, circular, oval, etc.), but must have a cross-section that allows for enhanced control of the respective flow rates in the upstream cavity 34 and the downstream cavity 34c. In other words, the cross-section of these holes must be smaller than the sum of the cross-sections of the drill holes that make up the respective cavities. Conversely, the first hole 38a, which may also have a free form (and the central opening 40a, which may have the same or a smaller size), must not have a cross-section that controls the downstream flow rate (this function is specifically transferred to the injector located in the inter-disk cavity), i.e., the sum of all cross-sections of the first hole 38a of the nozzle must be greater than the sum of the cross-sections of the injector that ensures the downstream ventilation air flow rate (therefore, the calculation of the flow rate for the holes must be proportional to the number of airfoils of the nozzle).

[0043] Therefore, the main advantages of the present invention resulting from the above structure are as follows:

[0044] - The supply of ventilation air to the upstream drill hole and the drill hole located downstream of the jacket is carried out separately.

[0045] - The supply of ventilation air to the inter-disk cavity and the supply to the drill hole are carried out separately, and there is no heating during the process of passing through the central intake pipe of the jacket.

[0046] - The manufacturing cost of the components is reduced.

Claims

1. A hollow airfoil cooling jacket for a turbine nozzle of a turbine, comprising: - A body that extends in a radial direction between a radially outer end and a radially inner end, and includes a suction surface, a pressure surface, and a central air inlet pipe that defines a first ventilation air circulation area, and two partition walls are connected to the two surfaces, the partition walls define a second ventilation air circulation area and a third ventilation air circulation area, and each of the suction surface and the pressure surface includes at least two rows of drilled holes, wherein one row of drilled holes discharges ventilation air from the second ventilation air circulation area, and one row of drilled holes discharges ventilation air from the third ventilation air circulation area. - An outer plate provided at the radially outer end of the body, the outer plate includes a first hole, a second hole, and a third hole to enable ventilation air to enter the first ventilation air circulation area, the second ventilation air circulation area, and the third ventilation air circulation area respectively, and - An inner plate provided at the radially inner end of the body, the inner plate includes a central opening to discharge air from the first ventilation air circulation area. The inner plate and the outer plate are fixed to the body by welding to form an integral unit having the first, second, and third ventilation air circulation areas that are independent and airtight from each other.

2. The cooling jacket according to claim 1, wherein, The body, the outer plate, and the inner plate are made by additive manufacturing, and the drilled holes are made by electrical discharge machining or by laser.

3. The cooling jacket according to claim 1, wherein, The first hole includes a cross-section proportional to the number of airfoils, and the cross-section is larger than the sum of the cross-sections of the ejectors that ensure the ventilation air flow velocity downstream.

4. The cooling jacket according to claim 1, wherein The second hole and the third hole each include a cross-section, and the cross-sections are each smaller than the sum of the cross-sections of the drilled holes that respectively ensure the discharge of ventilation air from the second ventilation air circulation area and the third ventilation air circulation area.

5. A turbine nozzle of a turbine, comprising two coaxial annular platforms, and substantially radially hollow airfoils extend between the annular platforms, and each of the airfoils includes the cooling jacket according to claim 1.

6. An aero turbine, comprising at least one turbine nozzle according to claim 5.

7. A method for assembling a hollow airfoil cooling jacket of a turbine nozzle of a turbine, wherein, The method includes: manufacturing a body that extends in a radial direction between a radially outer end and a radially inner end and includes a suction surface and a pressure surface, and a central intake pipe that defines a first ventilation air circulation area and is connected to the two surfaces by two partition walls that define a second ventilation air circulation area and a third ventilation air circulation area; manufacturing an outer plate that includes a first hole, a second hole, and a third hole for taking in ventilation air in the first, second, and third ventilation air circulation areas, respectively; manufacturing an inner plate that includes a central opening for discharging ventilation air from the first ventilation air circulation area; machining at least two rows of drilled holes on the suction surface and the pressure surface of the body, with one row of drilled holes discharging ventilation air from the second ventilation air circulation area and one row of drilled holes discharging ventilation air from the third ventilation air circulation area; and fixing the outer plate and the inner plate to the body by brazing to form an integral unit having the first, second, and third ventilation air circulation areas that are independent of each other and airtight, and then installing the integral unit into the hollow airfoil of the turbine nozzle.

8. The method according to claim 7, wherein The suction surface and the pressure surface that form the outer shape of the body are configured to fit the inner cavity of the hollow airfoil of the nozzle.

9. The method according to claim 7, wherein Before fixing the contact surfaces between the body and each of the outer plate and the inner plate, as well as the outer surface and the inner surface of the body, to the integral unit, the contact surfaces, the outer surface, and the inner surface are also polished.

10. The method according to claim 7, wherein, The body, the outer plate, and the inner plate are printed from a metal material with a thickness of at least 0.5 millimeters.

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