In-wall rotational flow cooling laminate

Abstract

The invention discloses an in-wall rotational flow cooling laminate, and relates to the technical field of turbine blades. The in-wall rotational flow cooling layer plate is integrally formed through the 3D printing technology and comprises a cooling wall, a rotational flow cavity inlet, a rotational flow cavity and a rotational flow cavity outlet. Wherein one or more stages of rotational flow cavities are distributed, and each group of rotational flow cavities are relatively closed. According to the turbine blade cooling wall, the rotational flow cavity structure is arranged in the turbine blade cooling wall, the internal cooling space is isolated, cooling air jet flows are isolated from one another, mutual interference between new cooling air and old cooling air is avoided, and the effective cooling area of cold air is remarkably increased. And meanwhile, the stroke of cooling air can be prolonged through the arrangement of the multi-stage rotational flow, and the heat exchange potential of the cooling air is fully excavated. Through calculation, the comprehensive cooling efficiency can be improved by 61% compared with the prior art of laminate cooling, the cooling effect and the cooling air utilization rate of the turbine blade can be remarkably improved, and the method has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of turbine blades, and particularly to an internal-wall swirling cooling lamella. Background Art

[0002] Gas turbines are representative products of the high-end equipment manufacturing industry. Turbine blades are the core hot-end components for realizing the thermal power conversion of gas turbines and operate in an ultra-high temperature environment. Currently, the inlet temperature of the turbines of mainstream heavy-duty gas turbines has exceeded the melting point of the blade matrix material. It is necessary to arrange an efficient and precise cooling structure to achieve the design goals of reducing the blade temperature and extending the blade life.

[0003] The traditional cooling forms of turbine blades mainly include impingement cooling, rib turbulators, film cooling, lamella cooling, etc. Among them, lamella cooling is a cooling form with relatively strong cooling ability that combines impingement cooling, rib turbulators, and film cooling in the form of a double-layer wall, and is generally used in positions with high heat loads such as the blade leading edge and blade end wall.

[0004] Lamella cooling usually uses a simple cylindrical turbulator structure to connect the inner and outer walls to form an impingement cavity space. Cooling air generally enters the impingement cavity through the impingement holes on the inner wall. After completing the impingement cooling, it flows out of the lamella through the film holes and forms a film on the outer surface of the outer wall to protect the outer surface of the lamella from direct heating by high-temperature gas. In actual applications, there is significant non-uniformity in the pressure field outside the outlet of the film holes, and the impingement cavity space is interconnected, which makes it difficult to design the flow rate distribution and prone to the phenomenon of uneven flow rate distribution of the cooling air in the film holes. The cooling air inside the film holes with difficult outflow will stagnate and accumulate, forming a cross-flow towards the film holes with easy outflow, which will seriously weaken the cooling effect of the impingement jet along the way. This phenomenon is called cross-flow interference. In addition to cross-flow interference, another disadvantage of the traditional lamella cooling structure is the insufficient effective cooling area. Limited by the investment casting process, the impingement holes, turbulator columns, and film holes are all relatively simple cylindrical structures, and the cooling air can only perform forced convection heat transfer on the holes, columns, and the surface of the lamella. A considerable part of the cooling air is discharged from the lamella without sufficient heat transfer activities. With the development of metal 3D printing technology, more ingenious structures can be explored for the lamella cooling design of turbine blades to avoid cross-flow interference and tap the heat transfer potential of the cooling air.

[0005] Swirling cooling is a cooling form applied to the leading edge of turbine blades. When the cold air enters the swirling chamber, a shear layer and a Görtler vortex pair will be generated at the edge of the nozzle jet, which has a strong destructive effect on the thermal boundary layer, and thus has a strong cooling effect on the curved wall surface. However, since the swirling chamber must be circular, swirling cooling is generally applied to components with a large curvature. Summary of the Invention

[0006] In view of the problems existing in the above-mentioned existing internal-wall swirling-flow cooling laminated plates, the present invention is proposed.

[0007] Therefore, the object of the present invention is to provide an internal-wall swirling-flow cooling laminated plate, and the object is: creatively arrange the swirling-flow cavity with a rounded rectangular cross-section inside the laminated plate, and utilize the shear layer and Görtler vortices generated when the cooling air scours the curved wall surface to weaken the thermal boundary layer to fully cool the inner wall of the laminated plate. At the same time, increase the internal cooling area, avoid the cross-flow interference and cold-air retention between the new and old cold air, reduce the flow resistance, so as to fully explore the cooling potential of the cold air.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: The internal-wall swirling-flow cooling laminated plate is integrally formed by 3D printing technology, and includes a cooling wall, a swirling-flow cavity inlet, a swirling-flow cavity and a swirling-flow cavity outlet;

[0009] Among them, the swirling-flow cavity is distributed in one or more stages, and each group of the swirling-flow cavities is relatively closed;

[0010] The cross-sectional shape of the swirling-flow cavity in the spanwise direction includes a circle, a polygon or a polygon with rounded corners.

[0011] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the flow direction length Li of the swirling-flow cavity inlet ranges from 0.1 to 10 mm.

[0012] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the spanwise length Wi of the swirling-flow cavity inlet ranges from 0.1 to 10 mm.

[0013] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the spanwise length Wf of the swirling-flow cavity outlet ranges from 0.1 to 10 mm.

[0014] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the flow direction length Lf of the swirling-flow cavity outlet ranges from 0.1 to 10 mm.

[0015] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the flow direction length Lm of the connecting hole of the swirling-flow cavity ranges from 0.1 to 10 mm.

[0016] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the height Hm of the connecting hole of the swirling-flow cavity ranges from 0.1 to 10 mm.

[0017] As a preferred scheme of the internal-wall swirling-flow cooling laminated plate of the present invention, among them: the spanwise length Wm of the connecting hole of the swirling-flow cavity ranges from 0.1 to 10 mm.

[0018] As a preferred embodiment of the internal-wall swirling-flow cooling lamina of the present invention, wherein: the flow length Lc of the swirling cavity ranges from 0.1 to 50 mm.

[0019] As a preferred embodiment of the internal-wall swirling-flow cooling lamina of the present invention, wherein: the flow length Ls of the two-stage swirling cavity ranges from 0.1 to 100 mm.

[0020] Advantages of the present invention: By arranging a swirling cavity structure inside the cooling wall of the turbine blade, the present invention isolates the internal cooling space, isolates the cooling air jets from each other, avoids the mutual interference between the new and old cooling air, and significantly increases the effective cooling area of the cold air. Compared with the existing technology of lamina cooling, which can only maintain a high heat transfer area near the impact point, swirling cooling can maintain a high heat transfer coefficient throughout the swirling cavity. The arrangement of multi-stage swirling can also extend the travel of the cooling air and fully exploit the heat transfer potential of the cooling air. Through calculation, the comprehensive cooling efficiency of the present invention can be increased by 61% compared with the existing technology of lamina cooling, which can significantly enhance the cooling effect of the turbine blade and the utilization rate of the cooling air, and has good application prospects. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0022] Figure 1 It is a schematic diagram of the swirling cooling mechanism.

[0024] Figure 2 It is a schematic diagram of the overall structure of the internal-wall swirling-flow cooling lamina in Embodiment 1 of the present invention.

[0025] Figure 3 It is a top view and cross-sectional views A-A, B-B, and C-C of the internal-wall swirling-flow cooling lamina in Embodiment 1 of the present invention.

[0026] Figure 4 It is a schematic diagram of the overall structure of the internal-wall swirling-flow cooling lamina in Embodiment 2.

[0027] Figure 5 It is a top view and cross-sectional views A-A, B-B, and C-C of the internal-wall swirling-flow cooling lamina in Embodiment 2 of the present invention.

[0028] Figure 6 It is a schematic diagram of the overall structure of the cooling lamina in Comparative Example 1 of the present invention.

[0029] Figure 7(a) is a graph of the Nusselt number results in Embodiment 1 of the present invention;

[0030] Figure 7(b) is the Nusselt number result diagram of Embodiment 2 of the present invention;

[0031] Figure 7(c) is the Nusselt number result diagram of Comparative Example 1 of the present invention.

[0032] Figure 8(a) is the comprehensive cooling efficiency result diagram of Embodiment 1 of the present invention;

[0033] Figure 8(b) is the comprehensive cooling efficiency result diagram of Embodiment 2 of the present invention;

[0034] Figure 8(c) is the comprehensive cooling efficiency result diagram of Comparative Example 1 of the present invention.

[0035] Figure 8(d) is a schematic diagram for comparing the comprehensive cooling efficiency results of the present invention. Detailed implementation manners

[0036] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention with reference to the accompanying drawings of the specification.

[0037] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0038] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is separate or selectively mutually exclusive with other embodiments.

[0039] Thirdly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally out of the general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0040] The swirl cooling mechanism of the present invention refers to the reference: Ligrani P M, Oliveira M M, Blaskovich T. Comparison of heat transfer augmentation techniques[J]. AIAA Journal, 2003, 41(3): 337 - 362.]

[0041] Embodiment 1

[0042] Reference Figure 1-3 , for the first embodiment of the present invention, a wall-internal swirl cooling lamina is provided. The wall-internal swirl cooling lamina is integrally formed by 3D printing technology and includes a cooling wall, a swirl chamber inlet, a swirl chamber, and a swirl chamber outlet; the cross-sectional shape of the swirl chamber in the spanwise direction includes a circle, a polygon, or a polygon with rounded corners; the swirl chamber is relatively enclosed.

[0043] This embodiment is a wall-internal single-stage single-hole swirl chamber design, that is, only one stage of swirl chamber is provided, and each swirl chamber has only one inlet, and the cross-sectional shape of the swirl chamber in the spanwise direction is a rounded rectangle.

[0044] During use, the cooling air enters the swirl chamber from the swirl chamber inlet, completes forced convection heat transfer in the swirl chamber in a swirling form, and then flows out from the swirl chamber outlet to form a gas film to protect the outer wall. The single-chamber design helps to reduce the flow resistance, and the single-hole design helps to increase the cooling area. By dividing the space between the laminas into relatively enclosed swirl chambers and replacing the impinging form of the prior art with a swirling form with more sufficient and uniform heat transfer, the internal cooling area is increased, the cross-flow interference and cold air retention between the new and old cold air are avoided, the flow resistance is reduced, and the cooling effect of the lamina is significantly improved.

[0045] Embodiment 2

[0046] Reference Figure 1-5 , for the second embodiment of the present invention, the difference between this embodiment and the first embodiment is:

[0047] Compared with Embodiment 1, this embodiment is a wall-internal two-stage multi-hole swirl chamber design, that is, two stages of swirl chambers are provided, and each swirl chamber has multiple inlets. Since the rest of the design is basically the same as that of Embodiment 1.

[0048] During use, the cooling air enters the first-stage swirl chamber from the swirl chamber inlet, completes forced convection heat transfer in the swirl chamber in a swirling form, and then enters the second-stage swirl chamber through the swirl chamber connection hole. After completing a similar heat transfer process in the first-stage swirl chamber, it flows out from the swirl chamber outlet to form a gas film to protect the outer wall. The multi-hole design helps to give full play to the high heat transfer coefficient of swirl cooling, and the multi-stage design helps to fully explore the heat transfer potential of the cold air and improve the utilization rate of the cold air.

[0049] Comparative Example 1

[0050] Reference Figure 5, which is a comparative example of the present invention, referring to the public literature: Zhou WL, Deng QH, Feng ZP. Conjugate heat transfer analysis for laminated cooling effectiveness: Part A–effects of surface curvature[C]. ASME Paper GT2016-57243, 2016. (EI: 20164302940710)

[0051] During operation, the cold air passes through the impact holes in the form of a columnar jet and impacts the target surface (the inner wall surface of the outer layer wall). After the impact, it is disrupted by the turbulator columns, forming a turbulent secondary flow to cool the turbulator columns and the inside of the laminated plate. After bypassing the turbulator columns, it leaves the laminated plate under the suction of the film holes, and isolates the laminated plate from the high-temperature gas in the form of a film on the outer wall surface of the outer laminated plate, completing the cooling process.

[0052] Perform numerical simulation on this comparative example, compare it with Examples 1-2, and calculate the comprehensive cooling efficiency of the target surface and the total pressure loss coefficient under the condition of the cooling blowing ratio of 1.0 (under the same flow rate condition) of the laminated plate. The blowing ratio is a dimensionless parameter used to measure the film outflow state of the film holes, and its definition is as follows:

[0053]

[0054] where: ρ is the fluid density, with the unit of kg·m 3 ; u is the fluid velocity, with the unit of m / s; the subscript f represents the inlet position of the film hole; the subscript ∞ represents the oncoming flow position.

[0055] The Nusselt number is a dimensionless parameter used to evaluate the internal cooling heat transfer coefficient, and its definition is as follows:

[0056]

[0057] where: q is the mainstream flow rate, with the unit of W / m 2 ; L is the characteristic length of the cooling structure. In this example, the unit is mm, calculated according to the total wall thickness of 11 mm; is the total mainstream inlet temperature, with the unit of K; is the total cooling air inlet temperature, with the unit of K; k is the air thermal conductivity, with the unit of W / (m·K). The comparison results of the Nusselt number are shown in Figure 7.

[0058] The comprehensive cooling efficiency is a dimensionless parameter used to measure the overall cooling performance of the internal and external cooling structures, and its definition is as follows:

[0059]

[0060] Where: T w is the temperature of the outer surface of the wall, with the unit of K. The comparison results of the comprehensive cooling effect are shown in Figure 8.

[0061] The total pressure loss coefficient is a dimensionless parameter used to evaluate the flow loss of the cooling structure, and its definition is as follows:

[0062]

[0063] Where: is the mainstream flow rate, with the unit of kg / s; is the cooling air flow rate, with the unit of kg / s; is the total pressure of the outlet gas, with the unit of Pa; is the total pressure at the mainstream inlet, with the unit of Pa; is the total pressure at the cooling air inlet, with the unit of Pa.

[0064] The parameter values and common ranges used in the comparative calculation are shown in Table 1.

[0065]

[0066]

[0067] Data simulation calculations were performed on the comprehensive cooling effects of Examples 1 to 2 and Comparative Example 1, and the results are shown in Table 2. The Nusselt number is a dimensionless parameter used to measure the internal cooling heat transfer coefficient. The internal heat transfer amount is generally used to measure the actual cooling capacity of the internal cooling structure, that is, it includes the overall cooling benefit brought by the cooling performance and the cooling area. The external cooling performance will affect the heat entering the wall surface. Therefore, an isothermal wall boundary condition is adopted when calculating the Nusselt number and the internal heat transfer amount, that is, the internal cooling surface temperature is set to 1480K. The blowing ratio is used to measure the momentum strength of the film efflux. The higher the blowing ratio, the easier the film is to lose the cooling effect due to detaching from the wall surface. However, when the blowing ratio is too low, it indicates that the flow rate of the film cooling air is low, which may lead to insufficient coverage effect. Generally, it is preferably about 0.5 to 1. The comprehensive cooling efficiency is used to measure the overall cooling performance. Therefore, a fluid-thermal coupling boundary condition is adopted during the calculation, that is, the calculation domain includes both the fluid and solid parts, and the two are connected by a fluid-solid interface. The total pressure loss coefficient is a parameter that measures the flow losses of the internal and external cooling parts. Generally, it is desirable that this value be as low as possible on the premise of meeting the cooling performance requirements. The blowing ratio and the total pressure loss coefficient are also calculated according to the fluid-thermal coupling boundary condition.

[0068] Table 2

[0069]

[0070]

[0071] It can be seen from Table 2 that:

[0072] In Example 1 of the present invention, the effective cooling area is increased by 153%, the Nusselt number is decreased by 23%, the internal heat transfer amount is increased by 49%, the blowing ratio is decreased by 0.4, the comprehensive cooling efficiency is increased by 61%, and the total pressure loss coefficient is decreased by 28%.

[0073] In Example 2 of the present invention, the effective cooling area is increased by 43%, the Nusselt number is increased by 26%, the internal heat transfer amount is increased by 62%, the blowing ratio is increased by 0.4, the comprehensive cooling efficiency is increased by 41%, and the total pressure loss coefficient is increased by 40%.

[0074] This shows that the single-stage single-hole swirl cavity design in Example 1 can improve the cooling effect by significantly increasing the cooling area, and since the swirl cavity structure itself does not contain flow disturbing elements, it also has obvious advantages in reducing the flow resistance. However, the single-hole design causes the swirl to be greatly affected by the boundary layer shear effect of the swirl cavity side wall, and the Nusselt number is relatively lower than that of the comparative example, which weakens the cooling effect of the swirl to a certain extent. The two-stage multi-hole swirl cavity design in Example 2 can not only increase the cooling area but also retain the advantage of a high Nusselt number of the swirl. However, the connecting holes between the two-stage swirls have a relatively small flow-through area, resulting in significant throttling losses, so the overall flow resistance increases. In addition, the design of the two-stage swirl reduces the layout space of the film holes, causing an increase in the blowing ratio when the aperture size remains the same, weakening the film cooling effect, and it is easy to further improve by increasing the aperture size.

[0075] However, although different in-wall swirl design schemes are adopted in Example 1 and Example 2, they both demonstrate excellent capabilities in improving the cooling effect of the lamella, providing new ideas for the next-generation lamella cooling design, and having excellent application prospects and rich design spaces.

[0076] Importantly, it should be noted that the construction and arrangement of the present application shown in multiple different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who refer to this disclosure should easily understand that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter described in this application (e.g., changes in the dimensions, scales, structures, shapes and proportions of various elements, as well as parameter values (such as temperature, pressure, etc.), installation arrangements, use of materials, colors, orientations, etc.). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature, number or position of discrete elements may be altered or changed. Accordingly, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be altered or reordered according to alternative embodiments. In the claims, any clause of "means plus function" is intended to cover the structures that perform the recited function herein, and not only structural equivalents but also equivalent structures. Other substitutions, improvements, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0077] In addition, in order to provide a concise description of the exemplary embodiments, all features of the actual embodiments may not be described (i.e., those features that are not relevant to the currently considered best mode of carrying out the present invention or those features that are not relevant to implementing the present invention).

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A wall-internal swirl cooling panel, characterized in that: The internal-wall swirling cooling lamina is integrally formed by 3D printing technology, and includes a cooling wall, a swirling cavity inlet, a swirling cavity, and a swirling cavity outlet; Among them, the swirling cavities are distributed in one or more levels, and each group of the swirling cavities is relatively enclosed; The shape of the cross-section of the swirling cavity in the spanwise direction includes a circle, a polygon, or a polygon with rounded corners.

2. The internal-wall swirling flow cooling lamella according to claim 1, wherein: The flow length Li of the swirling cavity inlet ranges from 0.1 to 10 mm.

3. The internal-wall swirling cooling lamellar plate according to claim 2, wherein: The spanwise length Wi of the swirling cavity inlet ranges from 0.1 to 10 mm.

4. The internal-wall swirling flow cooling laminated plate according to claim 3, wherein: The spanwise length Wf of the swirling cavity outlet ranges from 0.1 to 10 mm.

5. The internal-wall swirl cooling laminated panel according to any one of claims 1 to 4, wherein: The flow length Lf of the swirling cavity outlet ranges from 0.1 to 10 mm.

6. The internal-wall swirling cooling lamella according to claim 5, characterized in that: The flow length Lm of the connection hole of the swirling cavity ranges from 0.1 to 10 mm.

7. The internal-wall swirling cooling laminated plate according to claim 6, wherein: The height Hm of the connection hole of the swirling cavity ranges from 0.1 to 10 mm.

8. The internal-wall swirling flow cooling lamella according to claim 7, characterized in that: The spanwise length Wm of the connection hole of the swirling cavity ranges from 0.1 to 10 mm.

9. The internal-wall swirling cooling lamella according to claim 8, wherein: The flow length Lc of the swirling cavity ranges from 0.1 to 50 mm.

10. The internal-wall swirling flow cooling laminated plate according to claim 9, wherein: The flow length Ls of the two-stage swirling cavity ranges from 0.1 to 100 mm.

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