In-wall serpentine channel cooling structure and using method

Abstract

The invention discloses an in-wall serpentine channel cooling structure and a using method. The in-wall serpentine channel cooling structure mainly comprises a cooling wall and a serpentine channel. Cooling air enters the cooling wall from the cold air inlet, passes through the S-shaped channel in the cooling wall and then flows out from the cold air outlet, and an air film is formed on the outer wall face to protect the outer layer wall. By arranging the snakelike micro-channels in the wall surfaces, the internal cooling area and the cold air cooling stroke are increased, cross flow interference and cold air retention between new cold air and old cold air are avoided, the cold air cooling potential is fully explored, the laminate cooling effect is remarkably improved, and good application prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the field of gas turbine hot end component cooling, and in particular relates to an intra-wall serpentine channel cooling structure and a use method thereof. Background Art

[0002] Gas turbines are high-end power equipment widely used in the industry. The operating temperature of the current mainstream heavy-duty gas turbines exceeds 1200°C, and efficient cooling structures must be arranged on the hot end components such as the combustion chamber and turbine to protect the base material from risks such as high-temperature creep and melting.

[0003] Laminated plate cooling is currently the main cooling structure used for high-temperature components of gas turbines. It achieves a high comprehensive cooling efficiency by integrating impingement cooling, turbulence cooling, and air film cooling. However, with the continuous development of gas turbine technology, the shortcomings of laminated plate cooling technology have gradually been exposed: although impingement cooling has the advantage of high local heat exchange intensity at the impingement point, the direct stagnation of the jet will cause extremely high flow losses, and the sudden drop in jet velocity after the impingement will quickly lose its efficient cooling capacity; the effective cooling area of ​​turbulence cooling is limited to the surface of the turbulence column, and impingement holes and air film holes need to be arranged in the laminate, so the space for arranging turbulence columns is also limited, and the development potential for further improving the heat exchange of turbulence cooling is low; affected by the arrangement of impingement holes and turbulence columns, the pitch of air film holes is not easy to adjust.

[0004] The serpentine channel is the main air supply form used in turbine blades. It is characterized by low manufacturing cost and good air supply effect. However, it is a macroscopic structure relative to the characteristic length of the blade and its main function is air supply. In their research, scholars found that the high-speed turning of the cold air at the elbow of the serpentine channel generates secondary flow, which easily leads to an increase in the overall heat exchange level. In addition, since there is no significant flow separation, the flow resistance is generally low. Summary of the invention

[0005] The object of the present invention is to provide an intra-wall serpentine channel cooling structure and a method of use, so as to overcome the deficiencies of the serpentine channels in the above-mentioned prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A wall serpentine channel cooling structure is integrally formed using 3D printing technology, comprising a cooling wall with a hollow cavity, and a serpentine channel arranged in the hollow cavity of the cooling wall, two opposite wall surfaces of the cooling wall are respectively provided with a cold air inlet and a cold air outlet for being connected with the inlet and outlet of the serpentine channel.

[0007] A further improvement of the present invention is that the flow cross-sectional shape of the serpentine channel includes a circle, a polygon and a chamfered polygon.

[0008] A further improvement of the present invention is that the number N of U-bends of the serpentine channel ranges from 2 to 10.

[0009] A further improvement of the present invention is that the serpentine channel flow cross-sectional diameter D f The value range is 0.1~10mm.

[0010] A further improvement of the present invention is that the axis turning radius R of the serpentine channel p The value range is 0.1~10mm.

[0011] A further improvement of the present invention is that the U-bend height H of the serpentine channel ranges from 0.5 to 50 mm.

[0012] A further improvement of the present invention is that the U-bend flow direction distance P of the serpentine channel is p The value range is 0.5~50mm.

[0013] A further improvement of the present invention is that the distance T from the serpentine channel to the inner wall is i The value range is 0.1~10mm; Distance T from serpentine channel to outer wall o The value range is 0.1~10mm; Total thickness of cooling wall T w The value range is 0.1~50mm.

[0014] A further improvement of the present invention is that the serpentine channel cooling structure has a flow pitch P f The value range is 1~50mm; Spanwise pitch P of serpentine channel cooling structure s The value range is 1~50mm.

[0015] A method for using an in-wall serpentine channel cooling structure, based on the in-wall serpentine channel cooling structure, comprising: The cooling air enters the cooling wall from the cold air inlet, passes through the serpentine channel inside the cooling wall, and then flows out from the cold air outlet, forming an air film on the outer wall surface to protect the outer wall.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides an inner wall serpentine channel cooling structure and a method of use. Aiming at the shortcomings of the existing layer plate cooling technology, the present invention arranges a micronized serpentine cooling channel inside the cooling wall of the hot end components of the gas turbine such as the turbine blades, isolates the cooling space, isolates the cooling air jets from each other, avoids the mutual interference between the new and old cooling air, and increases the effective cooling area and flow stroke of the cold air. Since the diameter of the micro cooling channel is small, most of the cooling air can be placed in the thermal boundary layer, and the relative flow rate of the cooling air inside it is high, so that the heat exchange potential of the cooling air can be fully tapped, the heat of the wall surface can be effectively taken away, and the temperature of the inner wall can be reduced. The serpentine channel alternately passes through the outer wall surface and the inner wall surface, and while fully exchanging heat, it also improves the uniformity of the temperature distribution inside the cooling wall. According to calculations, the comprehensive cooling efficiency of the present invention is improved by 45% compared with the existing layer plate cooling technology, and the effective cooling area is increased by 7%. It can significantly enhance the cooling effect and cooling air utilization rate of the turbine blade layer plate cooling structure, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a three-dimensional stereogram of the present invention.

[0019] Figure 2 A diagram of a prior art structure for cooling a laminate.

[0020] Figure 3 (a) and (b) are a top view and an AA cross-sectional view of the present invention.

[0021] Figure 4 It is a three-dimensional stereogram of Example 2 of the present invention.

[0022] Figure 5 (a) to (c) are top views and AA and BB cross-sectional views of Example 2 of the present invention.

[0023] Figure 6 is a comparison chart of the Nusselt number between the prior art and this embodiment, where Figure 6 (a) is prior art, Figure 6 (b) and (c) are embodiments of the present invention.

[0024] Figure 7 is a comparison chart of the comprehensive cooling efficiency between the prior art and this embodiment, wherein Figure 7 (a) is prior art, Figure 7 (b) and (c) are embodiments of the present invention.

[0025] Description of reference numerals: 1. Cooling wall; 2. Serpentine channel; 3. Cold air inlet; 4. Cold air outlet; 5. Inner wall layer; 6. Outer wall layer; 7. Turbine column; 8. Impact hole; 9. Air film hole. DETAILED DESCRIPTION

[0026] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0032] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0033] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0034] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] Example 1 like Figure 1 The present invention provides an intra-wall serpentine channel cooling structure, which is integrally formed using 3D printing technology, and includes a cooling wall 1 having a hollow cavity, and a serpentine channel 2 arranged in the hollow cavity of the cooling wall 1, and two opposite wall surfaces of the cooling wall 1 are respectively provided with a cold air inlet 3 and a cold air outlet 4, which are used to communicate with the inlet and outlet of the serpentine channel 2.

[0036] Among them, the serpentine channel design can extend the flow path of the cooling medium (such as cold air) in the cooling wall, thereby increasing the heat exchange time between the cooling medium and the cooling wall and improving the cooling efficiency. The curved shape of the serpentine channel can also generate vortices and turbulence, enhance the disturbance of the cooling medium, further promote heat conduction, and make the cooling more uniform and efficient. The use of 3D printing technology in one piece makes the cooling wall and the serpentine channel an integral structure, avoiding the gaps and leakage problems that may occur in the traditional assembly process, and improving the sealing and reliability of the structure. 3D printing technology allows complex geometric shapes and internal structures such as serpentine channels to be implemented in the design, which may be difficult to achieve in traditional manufacturing methods. At the same time, by optimizing the structural design, the weight can be reduced while ensuring the strength, and lightweight can be achieved. The use of 3D printing technology makes the manufacturing of the cooling structure more flexible and can be customized according to specific application requirements. Whether it is the shape and size of the serpentine channel or the location of the cold air inlet and outlet, it can be adjusted and optimized according to actual needs. This design flexibility enables the cooling structure to better adapt to different working environments and cooling needs, improving its applicability and practicality.

[0037] The one-piece manufacturing method simplifies the traditional multi-component assembly process, reduces processing steps and assembly time, and improves production efficiency. 3D printing technology can directly manufacture physical parts from digital models without molds and tooling, reducing manufacturing costs and cycles. The one-piece cooling structure reduces the connections and interfaces between components, reducing the risk of failures caused by poor connections or interface leakage. The serpentine channel design allows the cooling medium to be evenly distributed during the flow process, avoiding local overheating and thermal stress concentration, and improving the durability and service life of the cooling wall.

[0038] In this embodiment, the flow cross-sectional shape of the serpentine channel includes but is not limited to a circle, a polygon, and a polygon with a chamfered radius, and a circle is preferred in this embodiment.

[0039] The circular cross section has the smallest ratio of wetted area (i.e. the circumference of the fluid in contact with the solid) to area, which means that the fluid encounters the least resistance when flowing in the circular channel. The low resistance characteristic helps to reduce the energy loss of the cooling medium (such as cold air) during the flow process and improve the cooling efficiency. The circular cross section can maintain the stability of the fluid flow and reduce the generation of vortices and turbulence. This helps to ensure that the cooling medium flows evenly and stably through the serpentine channel and improves the consistency of the cooling effect. 3D printing adaptability: The circular cross section has a simple shape and is easy to use 3D printing technology for precise manufacturing. 3D printing technology can directly print out internal structures with complex geometric shapes, such as serpentine channels, with high precision. Compared with other complex cross sections, the processing and manufacturing of circular cross sections is simpler, reducing production costs and cycles. When the circular cross section is subjected to internal pressure, the stress distribution is uniform and stress concentration is not easy to occur. This helps to improve the structural strength and stability of the cooling wall and extend its service life. The circular cross section can adapt to different working pressure and temperature environments to ensure the reliability and safety of the cooling structure under various working conditions.

[0040] Under the same channel volume, the circumference of the circular cross section is relatively long, which helps to increase the heat exchange area between the cooling medium and the cooling wall. A larger heat exchange area means higher heat exchange efficiency, which can more effectively reduce the temperature of the cooling wall. The circular cross-sectional shape helps to optimize the heat conduction path, reduce thermal resistance, and improve the cooling effect.

[0041] Reduced pressure drop: The fluid in the circular cross-section channel flows more smoothly and has a smaller pressure drop. This helps reduce the energy loss of the cooling medium during the flow process and improves the overall efficiency of the system. Reduced leakage: The connection between the circular cross-section channel and the cooling wall is tighter, reducing the possibility of leakage and ensuring the sealing and reliability of the cooling system.

[0042] In this embodiment, the number N of U-bends of the serpentine channel ranges from 2 to 10, and is preferably 6 in this embodiment.

[0043] In this embodiment, the serpentine channel flow cross-sectional diameter D f The value range is 0.1~10mm, and 1mm is preferred in this embodiment.

[0044] In this embodiment, the axis turning radius R of the serpentine channel is p The value range is 0.1~10mm, and 1mm is preferred in this embodiment.

[0045] In this embodiment, the U-bend height H of the serpentine channel ranges from 0.5 to 50 mm, and is preferably 8 mm in this embodiment.

[0046] In this embodiment, the U-bend flow direction distance P of the serpentine channel is pThe value range is 0.5~50mm, and 3mm is preferred in this embodiment.

[0047] In this embodiment, the distance T from the serpentine channel to the inner wall surface is i The value range is 0.1~10mm, and 4mm is preferred in this embodiment.

[0048] In this embodiment, the distance from the serpentine channel to the outer wall is T o The value range is 0.1~10mm, and 3mm is preferred in this embodiment.

[0049] In this embodiment, the total thickness of the cooling wall is T w The value range is 0.1~50mm, and 11mm is preferred in this embodiment.

[0050] In this embodiment, the serpentine channel cooling structure has a flow pitch P f The value range is 1~50mm, and 24mm is preferred in this embodiment.

[0051] In this embodiment, the spanwise pitch P of the serpentine channel cooling structure is s The value range is 1~50mm, and 4mm is preferred in this embodiment.

[0052] Example 2 This embodiment provides a method for using an inner wall serpentine channel cooling structure, comprising: The cooling air enters the cooling wall 1 from the cold air inlet, passes through the serpentine channel 2 in the cooling wall 1, and then flows out from the cold air outlet, forming an air film on the outer wall surface to protect the outer wall.

[0053] The differences from Example 1 are: 1. The serpentine channel of this embodiment is arranged in a horizontal direction, that is, the axial plane of the serpentine channel is parallel to the plane; 2. The number of elbows in each serpentine channel of this embodiment is 4, which is less than the 13 elbows in Example 1; 3. The flow cross-sectional diameter D of the serpentine channel in this embodiment is f 2mm, which is larger than 1mm in Example 1; 4. In this embodiment, the cooling structure is arranged evenly in the vertical and horizontal directions, and the flow pitch P f 12mm, spanwise pitch P s is 12 mm, and in Example 1, it is arranged in a horizontal row, and the flow pitch P f 24mm, spanwise pitch P s is 4mm.

[0054] Example 3 use Figure 2The prior art structure of the plate cooling shown in the figure is used as a comparison to perform numerical simulation on this embodiment, where 5 is the inner wall layer, 6 is the outer wall layer, 7 is the spoiler column, 8 is the impact hole, and 9 is the air film hole. The target surface comprehensive cooling efficiency and total pressure loss coefficient under the condition of the plate cooling blowing ratio of 1.0 (same flow conditions) are calculated. The blowing ratio is a dimensionless parameter used to measure the air film outflow state of the air film hole, and its definition is as follows: (1) Where: ρ is the fluid density, in kg·m 3 ; u is the fluid velocity, unit is m / s; subscript f represents the inlet position of the air film hole; subscript ∞ represents the incoming flow position.

[0055] The Nusselt number is a dimensionless parameter used to evaluate the internal cooling heat transfer coefficient and is defined as follows: (2) in: is the mainstream flow rate, in W / m 2 ; is the characteristic length of the cooling structure, in this embodiment, the unit is mm, and it is calculated based on the total wall thickness of 11 mm; is the total temperature of the mainstream inlet, in K; is the total temperature of the cooling air inlet, in K; is the thermal conductivity of air, with the unit of W / (m·K).

[0056] The comprehensive cooling efficiency is a dimensionless parameter used to measure the overall cooling performance including internal and external cooling structures. Its definition is as follows: (3) in: is the wall outer surface temperature, in K.

[0057] The total pressure loss coefficient is a dimensionless parameter used to evaluate the flow loss of the cooling structure. Its definition is as follows: (4) in: is the mainstream flow rate, in kg / s; is the cooling air flow rate, in kg / s; is the total pressure of the outlet gas, in Pa; is the total pressure of the mainstream inlet, in Pa; It is the total pressure at the cooling air inlet, in Pa.

[0058] It should be noted that, since external cooling will affect the heat entering the layer plate, when calculating the internal cooling parameters such as the Nusselt number and heat exchange, the constant wall temperature boundary condition is used, that is, the temperature of the internal cooling wall is set to the same as the mainstream gas temperature, and no solid domain is set. When calculating the overall aerodynamic and heat transfer parameters of the layer plate such as the blowing ratio, comprehensive cooling efficiency, and total pressure loss coefficient, the fluid-heat coupling boundary condition is used, that is, the internal cooling wall is set as the fluid-heat interface, and the solid domain is set to calculate the heat transfer equation.

[0059] The comparison results of Nusselt number and comprehensive cooling effect are shown as follows: Figure 6 , 7 It can be seen that the Nusselt number and the comprehensive cooling efficiency of the two embodiments of the present invention are significantly improved compared with the prior art.

[0060] According to calculations, compared with the prior art, the effective cooling area of ​​Example 1 is increased by 4%, the Nusselt number is increased by 139%, the heat exchange is increased by 150%, the blowing ratio is increased by 0.68, the comprehensive cooling efficiency is increased by 45%, and the total pressure loss coefficient is increased by 80%. This can meet the needs of more efficient layer plate cooling technology.

[0061] Compared with the prior art, the effective cooling area of ​​Example 2 is reduced by 19%, the Nusselt number is increased by 27%, the heat exchange is increased by 3%, the blowing ratio is reduced by 0.36, the comprehensive cooling efficiency is increased by 25%, and the total pressure loss coefficient is reduced by 28%. It can meet the needs of more efficient layer plate cooling technology.

[0062] The above comparison results show that both the longitudinally arranged and horizontally arranged serpentine channel structures can effectively improve the comprehensive cooling efficiency. Even the simple serpentine channel with 4 elbows and large diameter has better internal cooling and heat exchange capacity than the existing layer plate cooling technology. The significant enhancement of internal cooling and heat exchange can be easily achieved by reducing the aperture and increasing the number of elbows. Under the condition of the same flow loss, the cooling area, heat exchange intensity, heat exchange amount, comprehensive cooling efficiency and cold air utilization rate of the present invention are better than the existing technology.

[0063] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0064] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A wall serpentine channel cooling structure, characterized in that: The structure is integrally formed using 3D printing technology, and includes a cooling wall with a hollow cavity, and a serpentine channel arranged in the hollow cavity of the cooling wall. Two opposite wall surfaces of the cooling wall are respectively provided with a cold air inlet and a cold air outlet for connecting with the inlet and outlet of the serpentine channel.

2. The wall serpentine channel cooling structure according to claim 1, characterized in that: The flow cross-sectional shapes of the serpentine channel include a circle, a polygon and a polygon with a chamfer.

3. The wall serpentine channel cooling structure according to claim 1, characterized in that: The number N of U-bends in the serpentine channel ranges from 2 to 10.

4. The wall serpentine channel cooling structure according to claim 1, characterized in that: Serpentine channel flow section diameter D f The value range is 0.1~10mm.

5. The wall serpentine channel cooling structure according to claim 1, characterized in that: The axis turning radius R of the serpentine channel p The value range is 0.1~10mm.

6. The wall serpentine channel cooling structure according to claim 1, characterized in that: The U-bend height H of the serpentine channel ranges from 0.5 to 50 mm.

7. The wall serpentine channel cooling structure according to claim 1, characterized in that: The U-bend flow distance P of the serpentine channel p The value range is 0.5~50mm.

8. The wall serpentine channel cooling structure according to claim 1, characterized in that: Distance T from serpentine channel to inner wall i The value range is 0.1~10mm; Distance T from serpentine channel to outer wall o The value range is 0.1~10mm; Total thickness of cooling wall T w The value range is 0.1~50mm.

9. The wall serpentine channel cooling structure according to claim 1, characterized in that: Serpentine channel cooling structure flow pitch P f The value range is 1~50mm; Spanwise pitch P of serpentine channel cooling structure s The value range is 1~50mm.

10. A method for using an inner wall serpentine channel cooling structure, characterized in that: The method is based on an in-wall serpentine channel cooling structure according to any one of claims 1 to 9, comprising: The cooling air enters the cooling wall from the cold air inlet, passes through the serpentine channel inside the cooling wall, and then flows out from the cold air outlet, forming an air film on the outer wall surface to protect the outer wall.

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