Method for cleaning an internal area of ​​a turbomachine by water injection

Abstract

This method for cleaning an internal area (1) of a turbomachine (3) comprises the following steps: - Inserting a tool (5) into an endoscopic port (7) of the turbomachine (3), said tool (5) comprising an injection nozzle (17) for a mixture (21) comprising water in its liquid or vapor state, preferably in its vapor state; - Positioning the injection nozzle (17) of the mixture (21) opposite an internal area (1) of the turbomachine (3) to be cleaned; - Injecting the mixture (21) through the injection nozzle (17) onto the internal area (1) to be cleaned; and - Removing the tool (5) from said endoscopic port (7). Figure for the abbreviation: Fig. 2

Description

Title of the invention: Method for cleaning an internal area of ​​a turbomachine by water injection. Technical field

[0001] The invention relates to a method for cleaning an internal area of ​​a turbomachine, such as for example a turbojet or an aircraft turboprop.

[0002] In particular, the present invention relates to the cleaning of an area of ​​a distributor blade or of a moving blade of a low pressure turbine of the turbomachine.

[0003] Even more specifically, cleaning makes it possible to remove oxidation from the crevices and cracks in an area in order to facilitate its inspection. Previous techniques

[0004] A turbomachine conventionally comprises, from upstream to downstream in the direction of gas flow, a blower, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0005] The low-pressure turbine generally comprises several stages, each stage comprising a bladed rotor wheel and a ring of distributors located downstream of the bladed wheel. The distributor comprises an internal radially oriented platform and an external radially oriented platform connected by blades.

[0006] During maintenance operations, damage to several areas of the turbomachine is checked, either visually or using instruments. Areas to be checked that are external to the turbomachine can be easily accessed from the outside, whereas internal areas require the insertion of an endoscope through a specially designed endoscopic port. The endoscope allows visualization of areas located inside the turbomachine, particularly to check the condition of the distributors or the moving blades of the low-pressure turbine. Defects can thus be detected, these defects being generated, for example, by exposure to the environment, contact between parts, wear, or debris.

[0007] These defects considerably reduce the service life of the parts and can generate premature removal of turbomachinery when it is complex to resolve them.

[0008] The defects most often take the form of cracks, fissures regularly found in turbomachinery.

[0009] There is a method of crack repair called "boroblending" which consists of removing material in order to prevent the initiation and possible propagation of cracks. This method remains limited however because there are areas where this removal would reduce the lifespan of the part, which would then require repair or replacement.

[0010] Furthermore, detecting and identifying cracks and their dimensions is sometimes difficult, particularly during endoscopic inspection. This is mostly due to the presence of dust, sand, or oxidation that accumulates at the bottom of the cracks and on the surface, making inspection hazardous and ineffective. Other, more costly operations, such as dye penetrant testing, must then be carried out to properly inspect the turbomachine. However, in many cases, the presence of contaminants at the bottom of cracks and fissures also prevents the proper execution of dye penetrant testing.

[0011] The invention is not limited to the context of cleaning areas of the low-pressure turbine. Indeed, the invention can be applied to the maintenance of any internal part located, for example, in the aerodynamic duct of the turbomachine. Description of the invention

[0012] The present invention therefore aims to overcome the aforementioned disadvantages and to provide a method for removing dust, sand, oxidation and pollutants from the elements of turbomachines.

[0013] The present invention relates to a method for cleaning an internal area of ​​a turbomachine, the method comprising the following steps:

[0014] - A step of inserting a tool into an endoscopy port of the turbomachine, said tooling comprising an injection nozzle for a mixture comprising water in liquid or vapor state, preferably in vapor state.

[0015] - A step of arranging the mixture injection nozzle opposite an area internal cleaning of the turbomachine;

[0016] - A step of injecting the mixture through the injection nozzle onto the internal area to clean; and

[0017] - A step of removing the tooling from said endoscopy orifice.

[0018] Thus, water cleaning makes it possible to clean and strip surfaces, as well as cracks and crevices formed in hard-to-reach areas, without damaging the turbomachine material. Cleaning and deoxidizing the crevices also makes them easier to detect during endoscopic inspection and to identify their dimensions more easily. In particular, nickel oxides and coked oil can be removed using this process, as well as corrosion, soot, dust, and sand.

[0019] Furthermore, the presence of water prevents the generation of dust, unlike dry stripping. The mixture also requires no reagents or solvents and is environmentally friendly.

[0020] Advantageously, the water included in the mixture is demineralized water.

[0021] In a particular embodiment, the injection step is carried out with a mixture pressure between 0.1 and 0.8 MPa, preferably between 0.4 and 0.6 MPa.

[0022] In an even more particular embodiment, the injection step is carried out at a mixture temperature between 120°C and 175°C, preferably between 130°C and 160°C, the water included in the mixture being in the vapor state.

[0023] Advantageously, the mixture comprises particles with a particle size between 50 and 500 microns, preferably between 125 and 255 microns.

[0024] Advantageously, the particles have a hardness between 2 and 5 on the Mohs scale, preferably between 2.5 and 3.5.

[0025] In one embodiment, the particles have a density between 1.3 and 1.7 g / cm3, preferably between 1.4 and 1.5 g / cm3.

[0026] In one embodiment, the method further includes a step of checking the internal area by dye penetrant testing after the tooling removal step.

[0027] Preferably, the method includes an endoscopy step by inserting an endoscope into the endoscopy orifice and visualizing the internal area before and / or during and / or after any of the steps of the cleaning process.

[0028] In particular, the internal area to be cleaned is an area of ​​a distributor blade or a moving blade of a low-pressure turbine of the turbomachine. Brief description of the drawings

[0029] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0030] [Fig.1] is a schematic view of the different stages of the cleaning process for an internal area of ​​a turbomachine according to the invention; and

[0031] [Fig.2] is a schematic cross-sectional view of a turbomachine surface on which a deposit has formed and is cleaned using tooling enabling the implementation of the process according to the invention.

[0032] Detailed description of at least one embodiment

[0033] The different steps implemented by the cleaning process of an internal zone 1 of a turbomachine 3 are schematically represented in [Fig.1].

[0034] Furthermore, a schematic cross-sectional view of an internal zone 1 of a turbomachine 3 and a tooling 5 enabling the implementation of the process has been represented on [Fig.2].

[0035] The internal zone 1 to be cleaned is for example an area of ​​a distributor blade or of a moving blade of a low-pressure turbine of the turbomachine 3. The internal zone 1 is therefore located inside the housing of the turbomachine 3 and is only accessible through endoscopy ports 7 previously formed in the housing.

[0036] In particular, [Fig. 2] illustrates a surface 9 of the turbomachine 3 on which a deposit 11 has formed and which needs to be cleaned, in other words removed, by implementing the present method. The deposit 11 includes, for example, dust, sand, corrosion, oxidation, for example nickel oxide, soot, or even coked oil. The surface 9 is, for example, a surface 9 including a crevice 13 that needs to be cleaned.

[0037] For the implementation of said method, a first step 15 is carried out of inserting the tooling 5 into an endoscopy orifice 7 of the turbomachine 3. For this purpose, the tooling 5 must be sufficiently thin, for example of a size similar to an endoscope used in aeronautics.

[0038] The tooling 5 includes an injection nozzle 17 and an injection channel 19 connecting said injection nozzle 17 to a pump and a reservoir (not shown) containing a mixture 21 intended to be injected onto the internal zone 1 via the injection nozzle 17. The injection nozzle 17 has, for example, an outlet section of the mixture 21 with a diameter between 1 and 10 millimeters, preferably between 1 and 5 millimeters.

[0039] Thus, a step 23 is then carried out of arranging the injection nozzle 17 of the mixture 21 in relation to the internal area 1 to be cleaned of the turbomachine 3.

[0040] Then, a step 25 is carried out of injecting the mixture 21 through the injection nozzle 17 onto the internal area 1 to be cleaned.

[0041] Preferably, the injection of the mixture 21 is direct from the injection nozzle 17 towards the internal zone 1, without being deflected by any obstacle. The injection nozzle 17 is, for example, positioned less than five centimeters from the internal zone 1 to be cleaned for the implementation of step 25 of injecting the mixture 21.

[0042] The mixture 21 comprises water in the liquid state or in the vapor state. For water in the liquid state, the mixture 21 will be described as cold, while for water in the vapor state, the mixture 21 will be described as hot.

[0043] In order for the injection step 25 to be more effective in cleaning the internal zone 1, a pressure injection is preferably applied, for example with a The mixing pressure should be between 0.1 and 0.8 MPa, preferably between 0.4 and 0.6 MPa. However, excessive pressure is not desirable to avoid damaging the internal zone 1 and the metal constituting the surface 9 to be cleaned.

[0044] Preferably, the mixture 21 comprises water in the vapor state because this hot mixture is faster than a cold mixture for cleaning the internal area 1.

[0045] In the latter case, the injection step 25 can be carried out at a mixture temperature between 120°C and 175°C, preferably between 130°C and 160°C, these temperatures being obtained with a pressure injection as described previously.

[0046] Preferably, the water included in the mixture 21 is demineralized water, making it possible to avoid the deposition of impurities or limescale inside the turbomachine 3.

[0047] In order to increase the abrasiveness of the mixture 21, it is possible to add particles 27 with a particle size between 50 and 500 microns, preferably between 125 and 255 microns.

[0048] The particles 27 are, for example, mineral grains, such as grains of sand, so that the implementation of the process according to the invention is wet sandblasting or steam sandblasting.

[0049] Thanks to the water, no particle 27 penetrates the internal zone 1 and the cleaning finish is finer than dry stripping, forming a satin surface with a polishing effect.

[0050] In particular, the Arithmetic Mean Roughness, denoted Ra, of the surface 9 after cleaning is between 4 and 7 micrometers.

[0051] Preferably, the particles 27 have a hardness between 2 and 5 on the Mohs scale, preferably between 2.5 and 3.5.

[0052] Advantageously, the particles 27 have a density between 1.3 and 1.7 g / cm3, preferably between 1.4 and 1.5 g / cm3.

[0053] Finally, a step 29 is performed of removing the tooling 5 from the endoscopy orifice 7 once the internal area 1 has been cleaned.

[0054] Optionally, a step 31 of checking the internal zone 1 by dye penetrant testing is then carried out after step 29 of removing the tooling 5.

[0055] Dye penetrant testing includes the application of a colored or fluorescent liquid to the internal area 1, so that the liquid penetrates into the potential cracks 13. After surface washing of the internal area 1, and then drying, a developing product is applied to the internal area 1 in order to be able to easily identify the presence of the cracks 13 and their dimensions, for example by ultraviolet vision, or with an endoscope in the visible range.

[0056] In addition to the steps previously described, the method further includes an endoscopy step 33 by inserting an endoscope into the endoscopy port 7.

[0057] This step 33 allows visualization of the internal zone 1 before and / or during and / or after any of the steps in the cleaning process. Indeed, the endoscope can be introduced into the endoscopic port 7 at the same time as the tooling 5, or before, or after, once the cleaning has been carried out. Visualization of the internal zone 1 with the endoscope makes it possible to identify cracks 13 and determine their dimensions.

[0058] In addition to the steps described above, the process further includes a step 35 of repairing the cracks, according to a process known to those skilled in the art such as, for example, the application of a solder paste.

Claims

Demands

1. A method for cleaning an internal area (1) of a turbomachine (3), characterized in that it comprises the following steps: - A step of inserting (15) a tool (5) into an endoscopy port (7) of the turbomachine (3), said tool (5) comprising an injection nozzle (17) for a mixture (21) comprising water in the liquid or vapor state; - A step of positioning (23) the injection nozzle (17) of the mixture (21) opposite an internal area (1) to be cleaned of the turbomachine (3); - A step of injecting (25) the mixture (21) through the injection nozzle (17) onto the internal area (1) to be cleaned; and - A step of removing (29) the tool (5) from said endoscopy port (7).

2. A method according to claim 1, wherein the water included in the mixture (21) is demineralized water.

3. A method according to any one of claims 1 and 2, wherein the injection step (25) is carried out with a mixture pressure (21) between 0.1 and 0.8 MPa, preferably between 0.4 and 0.6 MPa.

4. A method according to claim 3, wherein the injection step (25) is carried out at a temperature of the mixture (21) between 120°C and 175°C, preferably between 130°C and 160°C, the water included in the mixture (21) being in the vapor state.

5. A method according to any one of claims 1 to 4, wherein the mixture (21) comprises particles (27) with a particle size between 50 and 500 microns, preferably between 125 and 255 microns.

6. A method according to claim 5, wherein the particles (27) have a hardness between 2 and 5 on the Mohs scale, preferably between 2.5 and 3.

5.

7. A method according to any one of claims 5 and 6, wherein the particles (27) have a density of between 1.3 and 1.7 g / cm3, preferably between 1.4 and 1.5 g / cm3.

8. A method according to any one of claims 1 to 7, further comprising a step (31) of checking the internal area (1) by dye penetrant testing after the step (29) of removing the tooling (5).

9. A method according to any one of claims 1 to 8, comprising an endoscopic step (33) by inserting an endoscope into the endoscopic orifice (7) and visualizing the internal area (1) before and / or during and / or after any of the steps of the cleaning method.

10. A method according to any one of claims 1 to 9, wherein the internal area (1) to be cleaned is an area of ​​a distributor blade or a moving blade of a low-pressure turbine of the turbomachine (3).

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