Optimal cooling outer wall cavity type double-wall cooling structure and flat plate air film cooling device

Abstract

The invention discloses an optimal cooling outer wall cavity type double-wall cooling structure and a flat plate air film cooling device, and relates to the technical field of turbine blade air film cooling structures. The technical problem that an existing impact / air film cooling structure is poor in cooling effect when the cold air flow is small is solved. The cooling structure comprises a double-wall structure, and a plurality of outer wall cooling cavities, a plurality of air film holes and a plurality of impact holes which are formed in the double-wall structure, the double-wall structure comprises an outer wall, an inner wall and a plurality of inter-wall turbulent flow columns arranged between the outer wall and the inner wall; the outer wall cold cavity and the air film hole are formed in the outer wall; the outer wall cooling cavity is used for guiding airflow to flow and cooling the outer wall; the air film hole is located in the side of the outer wall cold cavity and penetrates through the outer wall in the thickness direction. A plurality of cold cavity outlet holes are formed in the side wall, close to the inner wall, of the outer wall cold cavity; the impact holes are used for guiding airflow to impact the outer wall cold cavity. The invention further provides a flat plate air film cooling device comprising the cooling structure.

Description

Technical Field

[0001] The present application relates to the technical field of turbine blade air film cooling structures, and in particular to an excellently cooled outer wall cavity type double-wall cooling structure and a flat air film cooling device. Background Art

[0002] As an advanced power device, gas turbines are widely used in power generation, aviation propulsion, chemical industry and other fields. The working efficiency of gas turbines is positively correlated with the total temperature before the turbine inlet. Therefore, increasing the turbine inlet temperature is one of the effective ways to improve the working efficiency of gas turbines.

[0003] The current turbine inlet temperature is already far higher than the tolerance temperature of the turbine blade material. Thermal protection is the key to the safe and efficient operation of turbine blades. Turbine blades are mainly cooled by cooling air drawn from the engine's compressor. The cooling methods are mainly divided into internal cooling and external cooling. Internal cooling is to allow the cooling air to conduct convective heat exchange inside the blades, mainly including impingement cooling and rib cooling. External cooling is to allow the cooling air to produce an insulating layer between the high-temperature combustion gas and the blades, reduce direct contact between the blades and the combustion gas, increase the thermal resistance between the two, and reduce the thermal radiation of the combustion gas to the blades. It mainly includes film cooling and divergent cooling.

[0004] In recent years, the double-wall cooling structure in turbine blades has developed rapidly. Figure 1 It is an existing double-wall cooling structure - impact / air film cooling structure. The cooling structure includes an outer wall 01 and an inner wall 02. The outer wall 01 and the inner wall 02 are connected by an inter-wall connection structure. A plurality of air film holes 03 are provided on the outer wall 01, and a plurality of impact holes 04 are provided on the inner wall 02. The air film holes 03 and the impact holes 04 are intersected and arranged periodically. Specifically, in the flow direction, 6 air film holes 03 are arranged on the outer wall 01, and 6 rows of impact holes 04 are also arranged on the inner wall 02. In the extension direction, there are 5 rows of air film holes 03 and 5 rows of impact holes 04.

[0005] When the cooling air flow is large, the impingement / film cooling structure can significantly reduce the temperature of the turbine blade surface and achieve better cooling effect than impingement cooling or film cooling alone. However, when the cooling air flow is small, the impingement / film cooling flow resistance coefficient is too small, and the film hole diversion causes the low-temperature impingement jet to flow out through the film hole before it fully exerts its cooling characteristics. Therefore, its cooling effect may not be as good as impingement cooling or film cooling alone. Summary of the invention

[0006] The embodiments of the present application provide a high-cooling outer wall cavity double-wall cooling structure and a flat air film cooling device, which solve the technical problem of the existing impact / air film cooling structure having poor cooling effect when the cold air flow is small.

[0007] To achieve the above-mentioned objectives, on the one hand, an embodiment of the present application provides a double-wall cooling structure with an outer wall cavity, comprising a double-wall structure and a plurality of outer wall cold cavities, a plurality of air film holes and a plurality of impact holes arranged on the double-wall structure; the double-wall structure comprises an outer wall, an inner wall and a plurality of inter-wall spoiler columns arranged between the outer wall and the inner wall; the outer wall cold cavity and the air film holes are both arranged on the outer wall; the outer wall cold cavity is used to guide the airflow and cool the outer wall; the air film holes are located on the side of the outer wall cold cavity and penetrate the outer wall along the thickness direction; a plurality of cold cavity outlet holes are arranged on the side wall of the outer wall cold cavity close to the inner wall; the impact holes are used to guide the airflow to impact the outer wall cold cavity.

[0008] Furthermore, the impact hole sequentially penetrates the inner wall and the corresponding inter-wall spoiler column and is connected with the outer wall cold cavity.

[0009] Furthermore, the impact hole is coaxially arranged with the inter-wall spoiler column.

[0010] Furthermore, the outer wall cold cavity is a rectangular cavity.

[0011] Furthermore, a plurality of the outer wall cold cavities are sequentially arranged along the flow direction of the outer wall, and are periodically arranged and extended along the span direction.

[0012] Furthermore, the cold cavity outlet holes are arranged alternately with the air film holes in the span direction, and the impact holes are arranged alternately with each other in the flow direction.

[0013] Furthermore, the air film holes and impact holes are equal in number and are periodically staggered.

[0014] Furthermore, the inter-wall spoiler column is a cylinder; and the air film hole and the impact hole are both circular holes.

[0015] Furthermore, the diameter of the air film hole is 1 to 3 times the diameter of the impact hole.

[0016] On the other hand, an embodiment of the present application further provides a flat-plate air film cooling device, comprising the above-mentioned superior cooling outer wall cavity type double-layer wall cooling structure.

[0017] Compared with the prior art, this application has the following beneficial effects:

[0018] 1. The embodiment of the present application has an excellently cooled outer wall cavity type double-wall cooling structure, by setting an outer wall cold cavity connected with the impact hole inside the outer wall, and then setting an air film hole on the side of the outer wall cold cavity, and the lower part of the impact hole is set on the inner wall, the middle part is coaxially set on the inter-wall spoiler column, and the upper part is set on the outer wall, so that the thickness of the impact wall is reduced without affecting the aspect ratio of the air film hole. At the same time, the outer wall makes full use of the internal cooling characteristics of the impact cooling, and the cold air fully cools the outer wall in the cold cavity, so that the cooling efficiency is improved.

[0019] 2. The embodiment of the present application has a double-wall cooling structure with a cavity on the outer wall. By coaxially arranging the middle part of the impact hole in the inter-wall spoiler column, the number of spoiler columns is increased compared to the existing typical double-wall structure, thereby enhancing the heat transfer effect of the cooling structure.

[0020] 3. The impact holes and air film holes in the double-wall cavity cooling structure of the preferred cooling outer wall of the embodiment of the present application are conventional round holes, which are much easier to process than special-shaped air film cooling holes, thus reducing the processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a structural schematic diagram of a double-wall cooling structure in the prior art;

[0023] Figure 2 This is a schematic diagram of the structure of the superior cooling outer wall cavity type double-wall cooling structure of the embodiment of the present application;

[0024] Figure 3 This is a left view of the superior cooling outer wall cavity type double-wall cooling structure of the embodiment of the present application;

[0025] Figure 4 This is a top view of the superior cooling outer wall cavity type double-wall cooling structure of the embodiment of the present application;

[0026] Figure 5 This is a schematic diagram of the three-dimensional structure of a periodic unit in an embodiment of the present application;

[0027] Figure 6 This is a schematic diagram of the decomposition structure of a periodic unit in an embodiment of the present application;

[0028] Figure 7 It is a graph of the airflow direction of a period unit in an embodiment of the present application;

[0029] Figure 8 It is a cooling efficiency distribution diagram of the double-wall cooling structure in the prior art;

[0030] Fig. 9 This is a cooling efficiency distribution diagram of the superior cooling outer wall cavity type double-wall cooling structure of the embodiment of the present application;

[0031] Fig.10 This is a comparison chart of the cooling efficiency of the superior cooling outer wall cavity double-wall cooling structure of the embodiment of the present application and the double-wall cooling structure of the prior art. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, they can understand the specific meanings of the above terms in this application according to specific circumstances.

[0035] 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. Thus, a feature defined as "first" or "second" can explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0036] Reference Figures 2 to 6 The embodiment of the present application provides a double-wall cooling structure with an excellent outer wall cavity, comprising a double-wall structure 1 and a plurality of outer wall cold cavities 2, a plurality of air film holes 3 and a plurality of impact holes 4 arranged on the double-wall structure 1. The air film holes 3 and the impact holes 4 are both circular holes with equal diameters.

[0037] The double-wall structure 1 comprises an outer wall 11, an inner wall 12 and a plurality of inter-wall spoiler columns 13 arranged between the outer wall 11 and the inner wall 12. The inter-wall spoiler columns 13 are cylindrical.

[0038] The outer wall cold cavity 2 and the air film hole 3 are both arranged on the outer wall 11. The impact hole 4 passes through the inner wall 12 and the corresponding inter-wall spoiler column 13 in sequence and then communicates with the outer wall cold cavity 2. Specifically, the impact hole 4 includes an upper section of the impact hole, a middle section of the impact hole and a lower section of the impact hole. The upper section of the impact hole is located on the side wall of the outer wall cold cavity 2, the middle section of the impact hole is located on the inter-wall spoiler column 13 and is coaxially arranged therewith, the lower section of the impact hole passes through the inner wall 12 along the thickness direction, and the outer wall cold cavity 2 is located directly above the impact hole 4, so that the impact hole 4 can guide the airflow to impact the outer wall cold cavity 2. At the same time, since the inter-wall spoiler column 13 can increase the turbulence of the fluid and promote heat transfer, the embodiment of the present application sets the impact hole 4 in the inter-wall spoiler column 13, which not only improves the structural strength of the impact cooling, but also increases the number of spoiler columns per unit area compared to the existing typical double-wall structure, thereby enhancing the heat transfer effect of the cooling structure.

[0039] Reference Figure 3 and Figure 4 , the equivalent diameter D of the air film hole 3 is 2 mm, and the diameter of the impact hole 4 is equal to that of the air film hole 3. The impact holes 4 and the air film holes 3 are arranged in a periodic staggered manner. Specifically, in the span direction, the number of columns of the impact holes 4 is the same as the number of columns of the air film holes 3, both of which are 5 columns. In the flow direction, the number of rows of the impact holes 4 is also consistent with the number of rows of the air film holes 3, both of which are 6 rows. It should be noted that the number of impact holes 4 and air film holes 3 can be adjusted according to actual conditions, and is not limited here.

[0040] The thickness of the outer wall 1 and the inner wall 2 and the distance between the outer wall 1 and the inner wall 2 are both 1.5D. The spanwise spacing P and the flowwise spacing S between two adjacent air film holes 3 and two adjacent impact holes 4 are both 7.5D. The diameter of the inter-wall spoiler column 13 is 2D. The spanwise spacing Z and the flowwise spacing Y between the air film holes 3 and the impact holes 4 are both 3.75D.

[0041] The outer wall cold cavity 2 is a rectangular cavity. Multiple outer wall cold cavities 2 are arranged in sequence along the flow direction of the outer wall 11, and are periodically arranged and extended along the span direction. In this way, the outer wall cold cavity 2 can guide the airflow and cool the outer wall 11. The air film hole 3 is located on the side of the outer wall cold cavity 2 and penetrates the outer wall 11 along the thickness direction, that is, the air film hole 3 does not overlap with the outer wall cold cavity 2. The depth H2 of the outer wall cold cavity 2 is 0.5D, the groove width W is 4D, and the distance H1 from the outer side and the distance H3 from the inner side of the outer wall 1 are both 0.5D.

[0042] A plurality of cold cavity outlet holes 5 are sequentially arranged on the side wall of the outer wall cold cavity 2 close to the inner wall 12 along the flow direction. The number of the cold cavity outlet holes 5 is equal to the number of the impact holes 4. The axis of the cold cavity outlet hole 5 and the axis of the air film hole 3 are located in the same horizontal plane in the span direction, and the axis of the cold cavity outlet hole 5 and the axis of the impact hole 4 are located in the same horizontal plane in the flow direction. The cold cavity outlet hole 5 is preferably a circular hole for easy processing. In addition, the diameter of the cold cavity outlet hole 5 is equal to the diameter of the impact hole 4. In this way, the small-sized structure is conducive to the inter-cavity jet to fully cool the outer wall and then pass into the double-layer wall.

[0043] Figure 5 and Figure 6 The diagram shows the position relationship of a periodic unit on the inner wall 1 and the outer wall 2. The air film hole 3, the cold cavity outlet hole 5 and the impact hole 4 form a periodic unit.

[0044] Figure 7 A periodic unit airflow direction curve diagram is shown.

[0045] The airflow cooling process and principle are as follows:

[0046] The airflow enters from the lower end of the impact hole 4, and is impact-cooled through the impact hole 4 to form an impact jet C1. Since the outer wall cold cavity 2 is located directly above the impact hole 4, the impact jet C1 is injected into the outer wall cold cavity 2 and directly impacts the top of the outer wall, and then forms an inter-cavity jet C2 in the outer wall cold cavity 2. At this time, the airflow can effectively impact and cool the outer wall 1. Subsequently, under the guidance of the outer wall cold cavity 2 and the cold cavity outlet hole 5, the inter-cavity jet C2 is ejected in an orderly manner through the cold cavity outlet hole 5, and an inter-wall turbulence C3 is formed in the double-wall region formed between the inner wall 2 and the outer wall 1. After heat exchange in the double-wall region, the inter-wall turbulence C3 enters the air film hole 3 to form an air film cold flow C4. The air film cold flow C4 is ejected from above the air film hole 3, forming a cooling air film on the hot flow side of the outer wall 1, forming low-temperature protection for the outer wall 1.

[0047] In addition, since the inter-wall spoiler column 13 is coaxial with the impact hole 4, it not only strengthens the flow heat exchange between the inter-wall spoiler C2 and the outer wall 2, but also improves the structural strength of the impact cooling. Compared with the prior art, the number of inter-wall spoiler columns 13 is increased, so that the cooling efficiency is further improved.

[0048] In order to further verify the cooling effect of the embodiment of the present application, the applicant conducted numerical simulation experiments in FLUENT with an air flow rate of 0.0012 kg / m3 on the cooling structure of the embodiment of the present application and a cooling structure of the prior art.

[0049] It should be noted that, refer to Figure 1A cooling structure of the prior art includes an outer wall 01 and an inner wall 02. The outer wall 01 and the inner wall 02 are connected by an inter-wall connection structure. A plurality of air film holes 03 are provided on the outer wall 01, and a plurality of impact holes 04 are provided on the inner wall 02. The air film holes 03 and the impact holes 04 are intersected and arranged periodically. The number and arrangement of the air film holes 03 and the impact holes 04 in the cooling structure are exactly the same as those in the cooling structure of the embodiment of the present application.

[0050] Figure 8 The cooling efficiency distribution diagram of the prior art cooling structure is shown. Fig. 9 The cooling efficiency distribution diagram of the cooling structure of the embodiment of the present application is shown. It can be seen from the figure that the cooling efficiency of the cooling structure of the embodiment of the present application is higher than that of the technical cooling structure.

[0051] Fig.10 A comparison chart of the cooling efficiency of the cooling structure of the embodiment of the present application and the technical cooling structure is shown. It can be seen that the comprehensive cooling efficiency of the center line of the air film hole 3 in the cooling structure of the embodiment of the application is improved by 11.5%.

[0052] On the other hand, an embodiment of the present application further provides a flat-plate air film cooling device, comprising the above-mentioned superior cooling outer wall cavity type double-layer wall cooling structure.

[0053] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A double-wall cooling structure with a cavity-type cooling outer wall, characterized in that: It includes a double-wall structure and multiple outer wall cold cavities, multiple air film holes and multiple impact holes arranged on the double-wall structure; the double-wall structure includes an outer wall, an inner wall and multiple inter-wall spoiler columns arranged between the outer wall and the inner wall; the outer wall cold cavity and the air film holes are both arranged on the outer wall; the outer wall cold cavity is used to guide the airflow and cool the outer wall; the air film holes are located on the side of the outer wall cold cavity and penetrate the outer wall along the thickness direction; multiple cold cavity outlet holes are arranged on the side wall of the outer wall cold cavity close to the inner wall; the impact holes are used to guide the airflow to impact the outer wall cold cavity.

2. The excellently cooled outer wall cavity type double-wall cooling structure according to claim 1 is characterized in that: The impact holes sequentially penetrate the inner wall and the corresponding inter-wall spoiler columns and are communicated with the outer wall cold cavity.

3. The excellently cooled outer wall cavity type double wall cooling structure according to claim 2 is characterized in that: The impact hole is coaxially arranged with the inter-wall spoiler column.

4. The excellently cooled outer wall cavity type double wall cooling structure according to claim 1 is characterized in that: The outer wall cold cavity is a rectangular parallelepiped cavity.

5. The excellently cooled outer wall cavity type double wall cooling structure according to claim 4 is characterized in that: The plurality of outer wall cold cavities are sequentially arranged along the flow direction of the outer wall and are periodically arranged and extended along the span direction.

6. The excellently cooled outer wall cavity type double wall cooling structure according to claim 5, characterized in that: The cold cavity outlet holes are arranged alternately with the air film holes in the span direction, and the impact holes are arranged alternately in the flow direction.

7. The excellently cooled outer wall cavity type double wall cooling structure according to claim 1, characterized in that: The air film holes and impact holes are equal in number and are periodically staggered.

8. The excellently cooled outer wall cavity type double wall cooling structure according to claim 1, characterized in that: The inter-wall spoiler column is a cylinder; the air film hole and the impact hole are both circular holes.

9. The excellently cooled outer wall cavity type double wall cooling structure according to claim 8, characterized in that: The diameter of the air film hole is 1 to 3 times the diameter of the impact hole.

10. A flat film cooling device, characterized in that: It comprises the excellently cooled outer wall cavity type double-wall cooling structure as described in any one of claims 1 to 9.

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