Oil return line, gas turbine engine and method of oil return

Abstract

The application relates to an oil return pipeline, a gas turbine engine and an oil return method. The oil return pipeline comprises an upper oil return pipeline section, a middle oil return pipeline section and a lower oil return pipeline section. The upper oil return pipeline section comprises an upper oil return pipeline section connector, an upper oil return pipeline section elbow and an upper oil return pipeline section stop ring. The upper oil return pipeline section stop ring is in contact with a casing, and the rest of the upper oil return pipeline section is outside the casing. One end of the upper oil return pipeline section is connected with an external pipeline, and the other end is connected with the middle oil return pipeline section. The middle oil return pipeline section comprises a middle oil return pipeline section flat tube inner tube, a middle oil return pipeline section flat tube outer tube, a middle oil return pipeline section flat joint, a middle oil return pipeline section transition section and a middle oil return pipeline section round joint. The lower oil return pipeline section comprises a lower oil return pipeline section elbow inner tube, a lower oil return pipeline section elbow outer tube, a lower oil return pipeline section round joint and a guide pipe cone surface connector. One end of the lower oil return pipeline section elbow inner tube and the lower oil return pipeline section elbow outer tube is connected with the middle oil return pipeline section round joint.

Description

TECHNICAL FIELD

[0001] The present application relates to an oil return pipeline, a gas turbine engine and an oil return method. BACKGROUND

[0002] A gas turbine engine often has multiple rotating shafts and multiple bearings arranged to support the shafts, and the bearings are filled with oil in the bearing cavities where the bearings are located. The oil lubricates the bearings and carries away heat generated by the bearings and seals to ensure stable operation of the bearing cavities. The oil in the bearing cavities flows out of the bearing cavities through an oil return pipeline and returns to an oil tank. The inventors have found that the oil in the oil return pipeline is prone to coking due to the connection of the bearing cavities to the engine.

[0003] After in-depth research, the inventors have found that the reasons include that the oil return pipeline passes through a high-temperature zone from the bearing cavities to the outside of the engine, and in this zone:

[0004] 1. Due to installation environment problems, the oil return pipeline is designed as a flat tube, and the characteristics of the flat tube result in uneven flow of the oil through the entire wall surface, with less oil flowing through some positions on the pipeline wall surface and higher wall surface temperature;

[0005] 2. To prevent the vibration of the engine case from threatening the stability of the pipeline, a stop ring at the connection of the oil return pipeline and the engine case uses direct contact connection, and the temperature at this position of the engine case is high, and the heat conduction of the solid is strong.

[0006] The above two positions have higher pipeline wall surface temperature, which is higher than the coking temperature of the oil, and the oil flowing through the pipeline at these positions is at high risk of coking and ignition.

[0007] Therefore, there is a need in the art for an oil return pipeline, a gas turbine engine and an oil return method to reduce the risk of oil coking. SUMMARY

[0008] An object of the present application is to provide an oil return pipeline.

[0009] Another object of the present application is to provide a gas turbine engine.

[0010] Still another object of the present application is to provide an oil return method.

[0011] According to the first aspect of the present application, an oil return pipeline comprises an upper oil return pipe section, a middle oil return pipe section, and a lower oil return pipe section. The upper oil return pipe section comprises an upper oil return pipe section connector, an upper oil return pipe section elbow, and an upper oil return pipe section stop ring. The upper oil return pipe section stop ring is used to contact a casing. One end of the upper oil return pipe section is connected to an external pipeline, and the other end is connected to the middle oil return pipe section. The middle oil return pipe section comprises a middle oil return pipe section flat tube inner pipe, a middle oil return pipe section flat tube outer pipe, a middle oil return pipe section flat tube connector, a middle oil return pipe section transition section, and a middle oil return pipe section connector. The middle oil return pipe section flat tube connector connects the middle oil return pipe section flat tube inner pipe, the middle oil return pipe section flat tube outer pipe, and the upper oil return pipe section stop ring. The middle oil return pipe section transition section connects the other end of the middle oil return pipe section flat tube inner pipe. The middle oil return pipe section connector connects the other end of the middle oil return pipe section flat tube outer pipe and the interface of the middle oil return pipe section transition section. The lower oil return pipe section comprises a lower oil return pipe section elbow inner pipe, a lower oil return pipe section elbow outer pipe, a lower oil return pipe section connector, and a guide pipe connector. One end of the lower oil return pipe section elbow inner pipe and the lower oil return pipe section elbow outer pipe is connected to the middle oil return pipe section connector, and the other end is connected to the lower oil return pipe section connector. The lower oil return pipe section connector is connected to the guide pipe connector. The flow direction of the oil in the oil return pipeline is from the lower oil return pipe section, through the middle oil return pipe section, to the upper oil return pipe section, and then to the external pipeline from the outlet of the upper oil return pipe section.

[0012] According to the second aspect of the present application, a gas turbine engine comprises the oil return pipeline of the first aspect.

[0013] According to the third aspect of the present application, an oil return method for oil is provided, which uses the oil return pipeline of the first aspect.

[0014] The beneficial effects of the present application include one or a combination of the following:

[0015] 1. In one aspect, the present application adds a guide plate, which can make the oil flow in the pipeline more uniform from the perspective of fluid mechanics. The oil can flow uniformly through the inner wall of the oil return pipeline, strengthening the heat exchange of the pipeline wall and making the temperature distribution more uniform, reducing the occurrence of high temperature points and the risk of oil coking and ignition.

[0016] 2. In another aspect, the present application also reduces the influence of external heat conduction on the oil return pipeline. The connection method of the stop ring at the connection between the oil return pipeline and the casing is a convex point connection method. This method can control the circumferential and radial displacement of the pipeline and reduce the influence of vibration on the pipeline, and from the perspective of heat transfer, it can greatly reduce the heat transfer from the casing to the oil return pipeline, reduce the local temperature of the oil return pipeline, and ensure the safe and stable operation of the oil system. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other features, properties, and advantages of the present application will become more apparent by describing in detail the following embodiments with reference to the accompanying drawings, in which:

[0018] Figure 1 This is a schematic diagram of the structure of a return oil pipeline according to one embodiment.

[0019] Figure 2 This is a schematic diagram of the return oil pipeline from another perspective of one embodiment.

[0020] Figure 3A as well as Figure 3B This is a schematic diagram of the structure of the stop ring in the return oil pipeline of one embodiment.

[0021] Figure 4 This is a cross-sectional structural schematic diagram of the middle section of the return oil pipeline in one embodiment.

[0022] Figure 5A as well as Figure 5B This is a schematic diagram of the structure of the circular joint in the middle section of the return oil pipeline in one embodiment.

[0023] Figure 6 This is a schematic diagram of the upper section of the return oil pipeline in one embodiment.

[0024] Figure label:

[0025] 1. Upper section of return oil pipe connector; 2. Upper section of return oil pipe bend; 3. Stop ring; 301. Stop ring round connector; 302. Stop ring flat connector; 303. Protrusion; 4. Middle section of return oil pipe; 401. Middle section of return oil pipe flat inner tube; 402. Middle section of return oil pipe flat outer tube; 403. Middle section of return oil pipe flat connector; 404. Middle section of return oil pipe transition section; 5. Middle section of return oil pipe round connector; 501. Middle section of return oil pipe round connector pipe wall; 502. Guide plate; 503. Guide plate opening; 6. Lower section of return oil pipe; 601. Lower section of return oil pipe round inner tube; 602. Lower section of return oil pipe round outer tube; 603. Lower section of return oil pipe round connector; 604. Conical connector of guide tube. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0027] Also, the use of "one embodiment", "an embodiment", "a further embodiment", "some embodiments", "one implementation", "an implementation", "some implementations", "one example", "an example", and / or "some examples" in the description, are not necessarily all referring to the same embodiment(s) and / or implementation(s) and / or example(s). Furthermore, certain features, structures, or characteristics of an embodiment or implementation can be combined in any suitable manner.

[0028] The following embodiments introduce the oil return pipeline, which is applied to a gas turbine engine, specifically a turbofan engine, and the fluid transported in the oil return pipeline is oil, but not limited to this, for example, it can also be a marine gas turbine, a ground gas turbine, etc.

[0029] Reference Figures 1 to 6 As shown, in some embodiments, the oil return pipeline for the oil system of an aero-engine includes an upper oil return pipe section, a middle oil return pipe section, and a lower oil return pipe section. The oil flow direction is from the lower oil return pipe section, through the middle oil return pipe section, to the upper oil return pipe section, and from the upper oil return pipe section outlet to the external pipeline.

[0030] The upper oil return pipe section contacts the case with the rest of the section outside the case; one end is connected to the external pipeline, and the other end is connected to the middle oil return pipe section.

[0031] The upper oil return pipe section is composed of an upper oil return pipe section connector 1, an upper oil return pipe section elbow 2, and an upper oil return pipe section stop ring 3: the upper oil return pipe section connector 1 is connected to the external pipeline, one end of the upper oil return pipe elbow is connected to the upper oil return pipe section connector 1, and the other end is connected to the upper oil return pipe section stop ring 3.

[0032] The middle oil return pipe section passes through the inside of the case support plate and has no direct contact with the case support plate; one end is connected to the upper oil return pipe section, and the other end is connected to the upper oil return pipe section.

[0033] As shown Figure 4 The middle oil return pipe section 4 is composed of a middle oil return pipe section flat tube inner tube 401, a middle oil return pipe section flat tube outer tube 402, a middle oil return pipe section flat connector 403, a middle oil return pipe transition section 404, and a middle oil return pipe section round connector 5: the middle oil return pipe section flat connector 403 connects the middle oil return pipe section flat tube inner tube 401, the middle oil return pipe section flat tube outer tube 402, and the upper oil return pipe section stop ring 3 mentioned above, the middle oil return pipe transition section 404 connects the other end of the middle oil return pipe section flat tube inner tube 401, and the middle oil return pipe section round connector 5 connects the other end of the middle oil return pipe section flat tube outer tube 402 and the round interface of the middle oil return pipe transition section 404.

[0034] The lower oil return pipe section 6 is located inside the case and outside the case support plate; one end is connected to the middle oil return pipe section, and the other end is connected to the bearing oil return pool.

[0035] As shown in Figure 6 The lower section of the oil return pipe 6 is composed of the lower section of the oil return pipe elbow inner tube 601, the lower section of the oil return pipe elbow outer tube 602, the lower section of the oil return pipe round joint 603 and the guide pipe cone interface nozzle 604. The lower section of the oil return pipe elbow inner tube 601 and the lower section of the oil return pipe elbow outer tube 602 are connected with the above-mentioned middle section of the oil return pipe round joint 5 at one end and connected with the lower section of the oil return pipe round joint 603 at the other end. The lower section of the oil return pipe round joint 603 is connected with the guide pipe cone interface nozzle 604. The guide pipe cone interface nozzle is connected with the bearing cavity.

[0036] The connection mode between the inner tube, the joint, the nozzle and the stop ring of the oil return pipe is all welded connection.

[0037] The connection mode between the outer tube and the joint of the oil return pipe does not adopt welding but direct contact connection. The outer tube of the oil return pipe is divided into two parts along the circumference. The two parts are connected by welding method and are sleeved outside the inner tube of the oil return pipe. The function of the outer tube of the oil return pipe is to greatly reduce the heat radiation generated by the high temperature case and the support plate to the inner tube of the oil return pipe.

[0038] The thickness of the inner tube and the outer tube of the oil return pipe is 1mm. The inner tube and the outer tube are separated by 1mm. The inner diameter of the round tube of the oil return pipe is 16mm. The length of the straight wall surface of the flat tube of the oil return pipe is 19mm. The diameter of the wall surface of the round tube is 8mm.

[0039] As shown in Figure 5A and Figure 5B The middle section of the oil return pipe round joint 5 is provided with a tube wall 501 and a guide plate 502. The function of the guide plate 502 is to prevent a large amount of oil from flowing through the curved wall surface of the flat tube. Most of the oil will flow uniformly through the entire flat tube wall surface, so that the internal oil flow is more uniform.

[0040] The thickness of the guide plate 502 of the oil return pipe is 1-3mm. It is located in the middle section of the oil return pipe round joint 5. The position is within 5mm from the center of the middle section of the oil return pipe round joint 5.

[0041] The guide plate 502 of the oil return pipe guides the oil flow in the guide pipe and prevents the oil from flowing along the original flow trend, i.e. mainly along the curved wall surface of the flat tube. The fluid passing through the guide plate can flow more uniformly through the flat tube, which can effectively reduce the occurrence of local high temperature.

[0042] The guide plate 502 of the oil return pipe has a plurality of openings 503 on the guide plate 502. The oil flowing through the guide plate will flow out of the openings. Due to the surface tension, the oil will gradually accumulate on the curved wall surface of the flat tube. When the oil flows through the guide plate, the oil will flow uniformly along the straight wall surface of the flat tube due to the flow through the openings.

[0043] The openings 503 of the flow guide plate are not uniformly distributed on the whole plane, and the openings are concentrated in the direction perpendicular to the direction of the flat tube. The oil will not flow down along the curved wall of the flat tube, but will flow along the straight wall of the flat tube.

[0044] The openings 503 of the flow guide plate have different diameters, and the diameters gradually decrease from the center to the outside, and the diameters become smaller as they get closer to the wall. The effect is to control the turbulent oil-gas mixture and the air in the pipe, reduce the air flow through the wall, and guide the oil-gas mixture to flow down from the straight wall of the flat tube.

[0045] As shown in Figure 3A and Figure 3B , the stop ring 3 is an arc-shaped cylindrical ring, and the two sides are respectively a circular interface 301 and a flat interface 302. The reason for designing the arc shape is to prevent circumferential displacement. At the same time, the stop ring is directly connected with the casing, which can ensure the connection of the pipeline with the casing. The outer surface of the stop ring has a protrusion 303. The inside of the stop ring is a circular pipeline for conversion with the flat pipeline. The thickness of the stop ring is 3-5 mm.

[0046] The protrusions 303 on the stop ring are arranged at the oil return pipe stop ring 3. The protrusions 303 are directly connected with the casing. The protrusions 303 are located at the central position of the cylindrical stop ring and are arranged along the circumference of the stop ring 3. There are 10-12 protrusions 303 on the stop ring 3, which are arranged at an interval of about 30°-40°. The size of the protrusions 303 is slightly smaller than the thickness of the stop ring, and the diameter is about 2 mm. The height of the protrusions 303 is 0.5-1 mm.

[0047] If the stop ring 3 is not connected with the casing by using the protrusions 303, the contact area is about 500 mm 2 . After the stop ring is connected with the casing by using the protrusions 303, the contact area between the stop ring and the casing is about 60 mm 2 . The contact area is greatly reduced, the heat transfer strength is reduced, and the risk of high temperature in the pipe is greatly reduced

[0048] As introduced above, the application also provides an oil return method of lubricating oil, which adopts the oil return pipeline introduced in the above embodiments. The flow direction of the lubricating oil of the oil return pipeline structure is: from the lower section of the oil return pipe, through the middle section of the oil return pipe, to the upper section of the oil return pipe, and then flows to the external pipeline from the outlet of the upper section of the oil return pipe.

[0049] In summary, the beneficial effects of the oil return pipeline, the gas turbine engine and the oil return method of lubricating oil introduced in the above embodiments include one or a combination of the following:

[0050] In one aspect, the present application adds a guide plate, from the perspective of fluid mechanics, can make the internal sliding oil of the pipeline flow more uniformly, the sliding oil can uniformly flow through the inner wall of the oil return pipeline, strengthen the heat exchange of the pipeline wall, make the temperature distribution more uniform, reduce the occurrence of high temperature point, reduce the risk of sliding oil coking and ignition;

[0051] On the other hand, the present application also reduces the influence of external heat conduction on the oil return pipeline, the connection method of the stop ring at the connection between the oil return pipeline and the casing is a convex point connection method, while controlling the circumferential and radial displacement of the pipeline and reducing the influence of vibration on the pipeline, from the perspective of heat transfer, the heat transfer of the casing to the oil return pipeline can be greatly reduced, the local temperature of the oil return pipeline is reduced, and the safe and stable operation of the sliding oil system is ensured.

[0052] Although the present application is disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical scheme of the present application, falls within the protection scope defined by the claims of the present application.

Claims

1. A return oil pipeline, characterized in that, include: The upper section of the return oil pipe includes an upper section return oil pipe connector, an upper section return oil pipe bend, and an upper section return oil pipe stop ring. The upper section of the return oil pipe has a stop ring for contacting the casing. One end of the upper section of the return oil pipe is connected to an external pipeline, and the other end is connected to the middle section of the return oil pipe. The return oil pipe mid-section includes a mid-section flat inner tube, a mid-section flat outer tube, a mid-section flat connector, a return oil pipe transition section, and a mid-section connector. The mid-section flat connector connects the mid-section flat inner tube and the mid-section flat outer tube to the aforementioned upper section stop ring of the return oil pipe. The return oil pipe transition section connects to the other end of the mid-section flat inner tube. The mid-section connector connects the other end of the mid-section flat outer tube and the return oil pipe transition section interface. The lower section of the return oil pipe includes an inner tube of the lower section bend, an outer tube of the lower section bend, a round joint of the lower section, and a conduit nozzle; one end of the inner tube of the lower section bend and the outer tube of the lower section bend are connected to the aforementioned middle section joint of the return oil pipe, and the other end is connected to the round joint of the lower section, which is connected to the conduit nozzle; The flow direction of the lubricating oil in the oil return pipeline is as follows: from the lower section of the oil return pipeline, through the middle section of the oil return pipeline, to the upper section of the oil return pipeline, and from the outlet of the upper section of the oil return pipeline to the external pipeline.

2. The return oil pipeline as described in claim 1, characterized in that, The connection between the inner tube of the return oil pipe, the joint, the nozzle, and the stop ring is all welded.

3. The return oil pipeline as described in claim 1, characterized in that, The connection between the outer pipe of the return oil pipe and the joint is not a direct contact connection without welding.

4. The return oil pipeline as described in claim 1, characterized in that, The return oil pipe has a pipe wall and a guide plate in the middle section of the circular joint. The guide plate blocks the lubricating oil from passing through the flat pipe wall.

5. The return oil pipeline as described in claim 4, characterized in that, The guide plate is located in the circular joint in the middle section of the return oil pipe, within 5mm of the center of the circular joint in the middle section of the return oil pipe.

6. The return oil pipeline as described in claim 4, characterized in that, The guide plate has several openings so that lubricating oil can flow out from the openings after passing through the guide plate.

7. The return oil pipeline as described in claim 1, characterized in that, The stop ring is an arc-shaped columnar ring with a circular interface and a flat interface on each side, and the stop ring is in direct contact with the casing.

8. The return oil pipeline as described in claim 7, characterized in that, The protrusions of the stop ring are arranged circumferentially on the stop ring, and the protrusions of the stop ring are in direct contact with the casing.

9. The return oil pipeline as described in claim 8, characterized in that, The number of protrusions is 10-12, and they are evenly distributed in the circumferential direction.

10. A gas turbine engine, characterized in that, Including the return oil pipeline as described in any one of claims 1-9.

11. A method for returning lubricating oil, characterized in that, The lubricating oil is returned through the return oil pipeline as described in any one of claims 1-9, wherein the flow direction of the lubricating oil in the return oil pipeline is as follows: from the lower section of the return oil pipeline, through the middle section of the return oil pipeline, to the upper section of the return oil pipeline, and from the outlet of the upper section of the return oil pipeline to the external pipeline.

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