Cooling channel with internal threaded portion and turbine blade for aero-engine

Abstract

The invention relates to a cooling channel with an internally threaded portion and a turbine blade for an aero-engine. In the cooling channel with the internal thread part, the internal thread part is continuously and spirally arranged on the inner wall of at least one part of the cooling channel.

Description

Technical Field

[0001] The present invention relates to a cooling channel with an internal threaded portion, which can effectively suppress the formation of agglomeration of airflow in a recirculation zone formed after the airflow near the channel wall flows through the internal threaded portion. The present invention also relates to a turbine blade for an aircraft engine. The present invention belongs to the field of turbine blade design for an aircraft engine. Background Art

[0002] The aircraft engine is the "heart" of the aircraft. Increasing the temperature before the turbine of the aircraft engine is the most direct way to improve the engine's thrust-to-weight ratio and reduce fuel consumption. However, the increase in the temperature before the turbine will bring great challenges to the stable operation of key components such as turbine blades.

[0003] In order to ensure the stable operation of key components such as turbine blades in high temperature and high speed environments, the engine must take effective thermal protection measures to improve the heat resistance of the components. In the case of slow development of high-temperature alloys and ceramic materials, designing an efficient cooling structure is the key to improving the heat resistance of turbine blades.

[0004] There are two main directions of blade cooling technology at present: internal cooling and external cooling. Internal cooling mainly achieves the effect of cooling the blade by establishing a cooling channel inside the blade and passing cold air to remove the heat from the blade body. The amount of heat exchange between the blade and the cooling gas depends on the convection heat transfer coefficient and heat exchange area of ​​the channel.

[0005] The existing technical solutions for cooling channels inside blades mainly include impingement cooling, spoiler column cooling, spoiler rib cooling, etc. Figure 1 , schematically showing the complex cooling technology inside a turbine blade.

[0006] The technical solution of impact cooling is to use cold air from the outside to impact the inner wall of the blade at a certain speed, and achieve the cooling effect of the inner wall of the blade by enhancing the surface heat transfer coefficient. It is mainly used in the leading edge area of ​​the blade.

[0007] The technical solution of spoiler column cooling utilizes cylindrical spoiler to enhance turbulent heat transfer. The two ends of the spoiler column are fixedly connected to the pressure side wall and the suction side wall respectively, generating a turbulent wake zone at the trailing edge of the spoiler column to enhance the convective heat transfer effect. It is mainly used in the trailing edge area of ​​the blade.

[0008] The technical solution of spoiler rib cooling is to provide ribs roughly transverse to the flow direction on the inner wall of the cooling channel. The ribs form a strong disturbance to the fluid in the channel, increase the turbulence intensity of the fluid, destroy its heat transfer boundary layer, increase the heat transfer coefficient, and have a strong convective heat transfer effect.

[0009] However, the technical solution of the above-mentioned spoiler columns and spoiler ribs hinders the main flow of the cooling airflow in the cooling channel through the protrusions, converting part of the flow into turbulence. Although it can greatly enhance the degree of turbulence and strengthen the heat transfer effect, the secondary flow phenomenon it brings is more obvious.

[0010] See also Figure 2 , which schematically shows the temperature distribution pattern caused by the use of parallel transverse ribs. The secondary flow will form a recirculation zone, in which the agglomerated airflow prevents the cooling airflow from taking away the heat, which can easily cause local accumulation of heat, resulting in uneven distribution of heat transfer effects and excessive local thermal stress. In addition, the agglomerated airflow in the recirculation zone can easily lead to increased flow resistance.

[0011] Therefore, it is urgent to propose a cooling structure with simple structure, low flow resistance and uniform heat exchange effect distribution. Summary of the invention

[0012] In response to the above-mentioned problems in the prior art, the inventor provides a cooling channel with an internal threaded portion for use in turbine blades of aircraft engines. The cooling channel can effectively suppress the backflow of the airflow close to the channel wall after passing through the internal threaded portion, improve the local heat transfer deterioration, and to a certain extent reduce drag and pressure loss.

[0013] In the first example of the cooling channel with the internal thread portion, the internal thread portion is continuously spirally provided on the inner wall of at least a portion of the cooling channel.

[0014] In the second example of the cooling channel with the internal thread portion, the internal thread portion is continuously spirally provided on the entire inner wall of the cooling channel.

[0015] In the third example of the cooling channel with an internal thread portion, one or more of the first example and the second example may be optionally included, and a shape of a thread cross section of the internal thread portion includes at least one of a square wave, a sine wave, and a sawtooth wave.

[0016] In the fourth example of the cooling channel with an internal thread portion, one or more of the first to third examples may be optionally included, the internal thread portion includes a first surface facing the exit direction of the main flow of the cooling airflow in the cooling channel, and the internal thread portion is provided with an air outlet on the first surface, the air outlet leads to a recirculation zone located near the first surface, and the recirculation airflow group is dispersed by setting the air outlet.

[0017] In the fifth example of the cooling channel with an internal thread portion, one or more of the first to fourth examples may be optionally included, the internal thread portion includes a second surface facing the incoming direction of the main flow of the cooling airflow in the cooling channel, and the internal thread portion includes a through hole, the through hole forms an air outlet on the first surface, and an air inlet on the second surface, and by setting the through hole, a part of the incoming airflow is used as an airflow source for blowing away the reflow airflow group.

[0018] In the sixth example of the cooling channel with an internal threaded portion, one or more of the first to fifth examples may be optionally included, and the extension direction of the through hole is parallel to the flow direction of the main flow of the cooling airflow in the cooling channel, which facilitates design and processing and reduces resistance.

[0019] In the seventh example of the cooling channel with an internal threaded portion, one or more of the first to sixth examples may be optionally included, and the cross-sectional shape of the through hole may include at least one of circular, oval, racetrack, square, rectangular, rounded rectangular, hexagonal and octagonal.

[0020] In the eighth example of the cooling channel with an internal threaded portion, one or more of the first to seventh examples may be optionally included, and the air inlet is larger than the air outlet, so the air flow velocity out of the air outlet increases.

[0021] In the ninth example of the cooling channel with an internal threaded portion, optionally including one or more of the first to eighth examples, the cooling channel includes an airflow passage inside the channel wall, and the airflow passage is fluidly connected to each of the air outlets via a branch airflow passage.

[0022] The present invention provides a turbine blade for an aircraft engine, the turbine blade comprising a cooling channel with an internal threaded portion according to one or more of the first to ninth examples.

[0023] The technical solution for threaded wall cooling is to make the inner wall of the cooling channel into a threaded shape. The alternating appearance of wave crests and wave troughs will cause strong disturbances to the boundary layer flow field. Even at a very low flow rate, the flow can be quickly converted into turbulence, destroying the heat transfer boundary layer, thereby greatly improving the heat transfer coefficient. In addition, due to the presence of threads, the heat exchange area is significantly larger than that of smooth walls. A larger heat exchange area can bring a greater amount of heat exchange. The threaded wall is different from the spoiler ribs in the rib cooling technical solution. It does not cause obvious obstruction to the mainstream flow, and brings less flow resistance and flow loss.

[0024] The cooling channel with an internal threaded portion of the present invention includes an air outlet on the internal threaded portion, which can effectively suppress the agglomeration of airflow in the recirculation zone formed after the airflow near the channel wall flows through the internal threaded portion, improve the excessive local thermal stress caused by local heat accumulation, and eliminate the agglomeration of airflow, which has the effect of reducing drag and pressure loss to a certain extent, and can further improve the heat exchange performance of the cooling channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to describe the implementation of the above and other features of the present invention, a more particular description of the invention briefly described above will be presented with reference to the exemplary embodiments of the invention shown in the accompanying drawings. It will be understood that these drawings only depict exemplary embodiments of the invention and should not be considered as limiting the scope thereof. The invention will be described and explained through the use of the accompanying drawings and with additional features and details. In the drawings:

[0026] Figure 1 is a cross-sectional view of a conventional turbine blade, showing the cooling technology inside it;

[0027] Figure 2 It is the temperature distribution pattern caused by the use of parallel transverse ribs;

[0028] Figure 3 is a perspective view of a cooling channel with an internal thread portion according to an embodiment of the present invention;

[0029] Figure 4 yes Figure 3 A three-dimensional view of a cooling channel with an internal threaded portion;

[0030] Figure 5A is a side cross-sectional view of a conventional cooling channel using transverse ribs;

[0031] Figure 5B is a side cross-sectional view of a cooling channel using transverse ribs according to an embodiment of the present invention;

[0032] Figure 5C is a side cross-sectional view of a cooling channel using transverse ribs according to another embodiment of the present invention;

[0033] Fig. 6A It is a side cross-sectional view of a conventional cooling channel using a threaded wall;

[0034] Figure 6B is a side cross-sectional view of a cooling channel using a threaded wall according to an embodiment of the present invention; and

[0035] Figure 6C 4 is a side cross-sectional view of a cooling channel with a threaded wall according to another embodiment of the present invention.

[0036] Figures 1 to 6CApproximately drawn to scale, however, the dimensions in the drawings are only schematic and do not necessarily conform to the scale, but are intended to be more clearly illustrated. In other embodiments, other relative dimensions may be used. Here and in all of the following, the same features appearing in different drawings are represented by the same or similar reference numerals.

[0037] List of reference numerals:

[0038] 1 Cooling channel

[0039] 10 Internal thread

[0040] 11 Page 1

[0041] 12 Side 2

[0042] 20 Air outlet

[0043] 30 Through hole

[0044] 40 Air Inlet

[0045] 50 Airflow path

[0046] 60 Branch air flow path DETAILED DESCRIPTION

[0047] First, the present invention mainly relates to structures related to the elimination of recirculation zones in any field of fluid mechanics. In particular, the present invention relates to the field of turbine blade design for aircraft engines, for example, the elimination of recirculation zones at the internal threaded portion of the cooling channel of the turbine blade, but is not limited to the elimination of recirculation zones in the cooling channel of the turbine blade.

[0048] The term "thread" as used herein is intended to describe a projection that is in the form of a continuous spiral so that a fluid can travel along the thread over the length of the thread.

[0049] Directional terms used herein, such as "top", "bottom", "upper", "lower", "inner", "inward", "outer", and "outward", are used to assist in describing the present invention according to the orientation of the embodiments shown in the drawings. Unless otherwise specified, such as "horizontal direction", "direction of gravity", etc., directional terms are not absolute up, down, horizontal, vertical, etc., and should not be interpreted as limiting the present invention to any particular direction.

[0050] As used herein, the terms "comprising," "having," "including," and variations thereof are intended to serve as open-ended transitional phrases, terms or words requiring the presence of specified elements / steps and also allowing for the presence of other elements / steps.

[0051] In the present invention, unless explicitly stated to the contrary, the terms "first", "second", etc. are not intended to indicate any difference in order, position, quantity or importance, but are merely used as labels to distinguish different positions and components, to distinguish one element, component, region and / or position from another element, component, region and / or position.

[0052] The present invention will be further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0053] In a non-limiting example, the cooling channel 1 of the present invention is used for a turbine blade of an aircraft engine. The overall shape of the turbine blade and the cooling channel 1 therein can be as follows: Figure 1 As shown, the cooling channel 1 includes a continuous spiral internal thread portion 10 on at least a portion of the inner wall.

[0054] Figure 3 The schematic diagram shows a perspective view of a cooling channel with an internal thread according to an embodiment of the present invention. In the present invention, the internal thread 10 is continuously spirally arranged on at least a portion of the inner wall of the cooling channel 1, preferably on the entire inner wall, such as Figure 3 shown.

[0055] Preferably, the shape of the thread cross section of the internal threaded portion 10 may include at least one of a square wave, a sine wave and a sawtooth wave, but is not limited thereto and may be any shape suitable for fluid flow requirements and / or manufacturing requirements.

[0056] Before implementation, the basic size parameters of the thread channel must be determined. Generally, the heat transfer effect will increase first and then decrease with the ratio of the wave height to the wavelength H / L of the thread cross-sectional shape, so it is necessary to determine the optimal parameters through numerical calculation or experiment.

[0057] Numerical calculations or experiments can be performed on threaded channels with different H / L, the Reynolds number of the cooling gas inlet can be controlled, and the blade temperature field can be measured. Then, the heat transfer coefficient, resistance coefficient and comprehensive cooling efficiency of the inner surface of the channel can be calculated, and a curve diagram of the change of different cooling performance parameters with the H / L ratio can be established to find the optimal H / L ratio corresponding to different Reynolds numbers.

[0058] Figure 4 A perspective view of a cooling channel 1 with an internal thread portion 10 is schematically shown, wherein the thread cross section of the internal thread portion 10 is shown to be in a sine wave shape.

[0059] As mentioned above, the side of the transverse rib facing the direction of departure of the main flow of the cooling airflow in the cooling channel 1 is prone to generate a secondary flow and a recirculation zone. The thread surface of the continuous spiral internal thread portion 10 that is inclined relative to the main flow direction can effectively reduce the generation of secondary flows and recirculation zones. Therefore, it is more difficult for the internal thread portion 10 to generate a recirculation zone on the first surface 11 facing the direction of departure of the main flow of the cooling airflow in the cooling channel 1.

[0060] In a non-limiting example, the internal threaded portion 10 of the cooling channel 1 of the present invention may include an air outlet 20 .

[0061] The air outlet 20 is arranged on the first surface 11 and is designed to be able to lead to a recirculation zone generated near the first surface 11, so as to guide the tiny airflow leaving the air outlet 20 to disperse the clumped airflow in the recirculation zone, thereby further suppressing the recirculation zone that may be formed after the airflow near the wall of the cooling channel 1 flows through the internal threaded portion 10.

[0062] The air outlet 20 of the internal threaded portion 10 can improve the excessive local thermal stress caused by local heat accumulation, and eliminate the agglomerated airflow to a certain extent to reduce drag and pressure loss, which can further improve the heat exchange performance of the cooling channel.

[0063] In a non-limiting example, the internal threaded portion 10 of the cooling channel 1 of the present invention may include a through hole 30, which penetrates the second surface 12 of the internal threaded portion 10 facing the incoming direction of the main flow of the cooling airflow in the cooling channel 1 and the aforementioned first surface 11, specifically, an air outlet 20 is formed on the first surface 11, and an air inlet 40 is formed on the second surface 12.

[0064] Preferably, the extending direction of the through hole 30 may be parallel to the flow direction of the main flow of the cooling airflow in the cooling channel 1 .

[0065] In a non-limiting embodiment, for a straight cooling channel, in order to facilitate manufacturing, the continuous internal threaded portion 10 can be drilled so that the extension direction of the through hole 30 can be parallel to the cooling channel 1, and at this time, the cross-sectional shape of the through hole 30 is preferably a circular shape of the drill bit.

[0066] It can be understood that the extension direction of the through hole 30 is not limited to this, but can be optionally turned or extended straightly along the flow direction of the main flow of the cooling airflow in the cooling channel 1, so as to better lead to the recirculation zone located near the first surface 11, so as to guide the small airflow leaving the air outlet 20 to disperse the clumped airflow in the recirculation zone.

[0067] The cross-sectional shape of the through hole 30 is not limited thereto, but may be at least one of a circle, an oval, a racetrack, a square, a rectangle, a rounded rectangle, a hexagon, and an octagon.

[0068] The equivalent inner diameter of the through hole 30 may not be constant. Considering the Venturi effect, the air inlet 40 may be larger than the air outlet 20 . Therefore, the velocity of the tiny airflow leaving the air outlet 20 is faster and it is easier to disperse the agglomerated airflow in the recirculation zone.

[0069] Furthermore, the diameter, length, density and arrangement of the through holes 30 may also be optimized to achieve the best heat exchange and drag reduction effects.

[0070] In a non-limiting example, the cooling channel 1 of the present invention may include an air flow passage 50 inside the channel wall, the air flow passage 50 may have an air inlet (not shown) at the leading edge of the turbine blade, and the air flow passage 50 is fluidically connected to each of the air outlets 20 of the internal threaded portion 10.

[0071] Preferably, the interior of the internal threaded portion 10 includes a branch airflow passage 60 connecting the airflow passage 50 and the air outlet 20 of the internal threaded portion 10 .

[0072] After determining the basic size parameters of the turbine blade, the ceramic core casting method will be used to process the threaded cooling channel in the blade. The ceramic core is a key process component for forming the cooling channel inside the blade. The core made of special ceramic material can withstand temperatures exceeding 2000°C and can be dissolved in a special alkaline solution.

[0073] First, a threaded wall is machined on the surface of the ceramic core, the prepared ceramic core is accurately positioned in the wax mold, and injection molding is performed by a wax injection machine to prepare a wax model blade.

[0074] Next, the surface of the wax model blade is repeatedly coated with ceramic paint and special sand to form a ceramic shell.

[0075] Subsequently, the prepared shell is placed in a furnace for high-temperature treatment to completely melt the wax liquid inside, forming a blade cavity for casting.

[0076] Finally, after preheating, a high-temperature alloy is cast into the cavity in a vacuum melting furnace. After cooling, it is immersed in a high-temperature and high-pressure special alkaline solution to dissolve the outer ceramic shell and the inner ceramic core to obtain a blade blank with an internal threaded cooling channel.

[0077] Example 1

[0078] FIG. 5A to FIG. 5C 1 is a side cross-sectional view of a cooling channel 1 having an internal thread portion 10 in a square wave shape.

[0079] Figure 5A The diagram schematically shows an inner thread portion 10 having a square wave shape. Figure 5AThe cooling channel 1 in the embodiment is a substantially straight cooling channel, and the internal threaded portion 10 is provided over the entire length of the cooling channel 1 .

[0080] and Figure 5A compared to, Figure 5B The internal threaded portion 10 may include a through hole 30, an air outlet 20 is formed on the first surface 11, and an air inlet 40 is formed on the second surface 12. In addition, the extending direction of the through hole 30 is parallel to the cooling channel 1, and each through hole 30 extends substantially on the same axis.

[0081] and Figure 5A compared to, Figure 5C The cooling channel 1 includes an air flow passage 50 inside the channel wall, and the internal threaded portion 10 may include an air outlet 20 on the first surface 11, and a branch air flow passage 60 inside the internal threaded portion 10 connecting the air flow passage 50 and the air outlet 20 of the internal threaded portion 10.

[0082] Example 2

[0083] FIG. 6A to FIG. 6C is a side cross-sectional view of a cooling channel using transverse ribs.

[0084] Fig. 6A The diagram schematically shows an internal threaded portion 10 having a sinusoidal shape. Figure 5A The cooling channel 1 in the embodiment is a substantially straight cooling channel, and the internal threaded portion 10 is provided over the entire length of the cooling channel 1 .

[0085] and Fig. 6A compared to, Figure 6B The internal threaded portion 10 may include a through hole 30, an air outlet 20 is formed on the first surface 11, and an air inlet 40 is formed on the second surface 12. In addition, the extending direction of the through hole 30 is parallel to the cooling channel 1, and each through hole 30 extends substantially on the same axis.

[0086] and Fig. 6A compared to, Figure 6C The cooling channel 1 includes an air flow passage 50 inside the channel wall, and the internal threaded portion 10 may include an air outlet 20 on the first surface 11, and a branch air flow passage 60 inside the internal threaded portion 10 connecting the air flow passage 50 and the air outlet 20 of the internal threaded portion 10.

[0087] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution of the present invention is clearly and completely described above in combination with the specific embodiments of the present invention and the accompanying drawings.

[0088] Although various embodiments have been described above, it should be understood that the embodiments described are part of the embodiments of the present invention, rather than all embodiments, and they are presented in an exemplary rather than limiting manner. It is obvious to those skilled in the relevant art that the disclosed subject matter can be implemented in other specific forms without departing from its spirit and essential features.

[0089] In the process, various elements that are important to the present invention or are conducive to further developing the present invention will be mentioned in the content of the specific examples, but some of these elements can also be used to further develop the present invention when they are separated from the content of the corresponding examples and other features of the corresponding examples. Therefore, the embodiments described above are considered to be illustrative and non-restrictive in all aspects and are not used as a basis for any limitation of the present invention.

[0090] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The present disclosure also includes various modifications and modifications within the equivalent scope. In addition, various combinations and methods, further including only one element, more than one or less than one other combinations and methods also belong to the scope and scope of thought of the present disclosure.

Claims

1. A cooling channel with an internal threaded portion for a turbine blade of an aircraft engine, It is characterized in that The internal threaded portion (10) is continuously spirally arranged on the inner wall of at least a portion of the cooling channel (1).

2. The cooling channel with an internal thread portion according to claim 1, It is characterized in that The internal threaded portion (10) is continuously spirally arranged on the entire inner wall of the cooling channel (1).

3. The cooling channel with an internal thread portion according to claim 1, It is characterized in that The shape of the thread cross section of the internal thread portion (10) includes at least one of a square wave, a sine wave and a sawtooth wave.

4. The cooling channel with an internal thread portion according to claim 1, It is characterized in that The internal threaded portion (10) comprises a first surface (11) facing the exit direction of the main flow of the cooling airflow in the cooling channel (1), and The internal threaded portion (10) is provided with an air outlet (20) on the first surface (11), and the air outlet (20) leads to a reflow zone located near the first surface (11).

5. The cooling channel with an internal thread portion according to claim 4, It is characterized in that The internal threaded portion (10) comprises a second surface (12) facing the incoming direction of the main flow of the cooling airflow in the cooling channel (1), and The internal threaded portion (10) comprises a through hole (30), wherein the through hole (30) forms the air outlet (20) on the first surface (11) and forms an air inlet (40) on the second surface (12).

6. The cooling channel with an internal thread portion according to claim 5, It is characterized in that The extension direction of the through hole (30) is parallel to the flow direction of the main flow of the cooling airflow in the cooling channel (1).

7. The cooling channel with an internal thread portion according to claim 5, It is characterized in that The cross-sectional shape of the through hole (30) includes at least one of a circular shape, an oval shape, a racetrack shape, a square shape, a rectangular shape, a rounded rectangular shape, a hexagonal shape and an octagonal shape.

8. The cooling channel with an internal thread portion according to claim 5, It is characterized in that The air inlet (40) is larger than the air outlet (20).

9. The cooling channel with an internal thread portion according to claim 4, It is characterized in that The cooling channel (1) includes an air flow passage (50) inside the channel wall, and the air flow passage (50) is in fluid communication with each of the air outlets (20) via a branch air flow passage (60).

10. A turbine blade for an aircraft engine, It is characterized in that The turbine blade comprises a cooling channel with an internal threaded portion according to any one of claims 1-9.

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