Impact-rib combined cooling structure in turbine blade

Abstract

The invention discloses a turbine blade internal impact-rib combined cooling structure which comprises an impact target plate, an impact plate, a gas collection cavity, an impact cavity, a plurality of impact holes and a plurality of ribs, the impact target plate and the impact plate are arranged in parallel and are parallel to the flow direction of cooling gas, the semi-open gas collection cavity is formed above the impact plate, and the impact holes are formed in the impact plate. A semi-closed impact cavity is formed between the impact plate and the impact target plate, and an airflow outlet is formed in the impact cavity; the multiple impact holes are formed in the impact plate at intervals in the airflow flowing direction and the spanwise direction, and the multiple ribs are arranged on the impact target plate at intervals in the airflow flowing direction and the spanwise direction; cooling gas passes through the impact holes from the gas collection cavity, impacts on the impact target plate in a jet flow mode, exchanges heat with the impact target plate and then flows out of the impact cavity, and when the cooling gas flows in the impact cavity and passes through the multiple ribs, the cooling gas strides over the ribs to flow and generate vortexes to enable boundary layers to be separated. The heat exchanger has the advantages of being good in heat exchange performance and low in pressure loss.

Description

Technical Field

[0001] The invention belongs to the technical field of gas turbines, and in particular relates to an internal impingement cooling structure of a turbine blade. Background Art

[0002] In order to improve the efficiency of gas turbines and obtain a higher thrust-to-weight ratio, the inlet temperature of gas turbine turbines continues to rise. Nowadays, the inlet temperature of turbines of advanced aircraft engines far exceeds the maximum temperature that the blades can withstand, which makes the working environment of turbine blades increasingly harsh. In order to improve the working environment of turbine blades and extend the service life of turbine blades, efficient cooling technology is required to cool turbine blades. The back of turbine blades is generally equipped with an impingement cooling structure to enhance convective heat transfer. The cooling gas impinges on the inner surface of the blade and takes away the heat from the inner surface of the blade. However, the traditional impingement cooling structure will cause the downstream fluid to generate a boundary layer due to the cross flow in the impingement cavity, resulting in poor heat exchange. Therefore, a rib structure is set on the impact target surface to destroy the boundary layer of the fluid, thereby further enhancing the convective heat transfer of the impact target surface.

[0003] At present, most of the impact cooling structures are still traditional structures or combined structures with continuous straight ribs. The traditional cooling structure has poor heat transfer effect due to the boundary layer generated by the downstream fluid. Although the continuous straight ribs destroy the boundary layer of the fluid and have the effect of enhancing heat transfer on the impact target surface, they will also increase the pressure loss coefficient of the channel. Summary of the invention

[0004] An object of the present invention is to provide a turbine blade internal impingement-rib combined cooling structure, aiming to solve one of the technical problems of the related art at least to a certain extent.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A combined impact-rib cooling structure inside a turbine blade comprises an impact target plate, an impact plate, an air collecting cavity, an impact cavity, a plurality of impact holes and a plurality of ribs, wherein: the impact target plate and the impact plate are arranged in parallel and in parallel with the flow direction of the cooling gas, a semi-open air collecting cavity is formed on the impact plate, a semi-closed impact cavity is formed between the impact plate and the impact target plate, and an air flow outlet is provided in the impact cavity; a plurality of impact holes are provided on the impact plate at intervals along the air flow direction and the span direction, and a plurality of ribs are arranged on the impact target plate at intervals along the air flow direction and the span direction; the cooling gas passes through the impact holes from the air collecting cavity, the jet impacts the impact target plate, and after heat exchange with the impact target plate, flows out of the impact cavity, and in the process of the cooling gas flowing in the impact cavity, when passing through the plurality of ribs, the cooling gas flows across the ribs and generates vortices to separate the boundary layer.

[0007] Preferably, the rib is U-shaped or V-shaped.

[0008] Preferably, the ratio of the impact distance Z1 of the impact cavity to the rib height W1 is 3.

[0009] Preferably, the impact hole passes through the impact plate, and the hole axis of the impact hole is perpendicular to the impact plate and the impact target plate.

[0010] Preferably, the multiple impact holes are divided into 4 groups, and the multiple groups of impact holes are spaced apart on the impact plate along the airflow direction. Each group of impact holes includes multiple impact holes, and the multiple impact holes in each group of impact holes are spaced apart on the impact plate along the airflow direction.

[0011] Preferably, the ratio of the impact hole diameter to the rib width K is 1.8, the ratio of the impact hole flow direction spacing L1 to the rib width K is 16, and the ratio of the impact hole span direction spacing L2 to the rib width K is 8.

[0012] Preferably, the plurality of ribs are divided into a plurality of groups, and the plurality of groups of ribs are arranged on the impact target plate at intervals along the airflow direction, each group of ribs includes a plurality of ribs, and the plurality of ribs in each group of ribs are arranged at intervals along the airflow direction.

[0013] Preferably, the spacing between any two adjacent groups of ribs is equal and is L3, and the ratio of L3 to the rib width K is 16; the spacing between each group of ribs is equal and is L4, and the ratio of L4 to the rib width K is 6.8; the ratio of rib height W1 to rib width K is 1, the rib angle α is 120°, there are two arcs inside and outside the rib respectively, the rib edge is tangent to the two arcs on the rib respectively, the two arcs on the rib are each part of a concentric circle, the ratio of the large arc radius R2 on the rib to the rib width K is 2, the ratio of the small arc radius R1 on the rib to the rib width K is 1, and the ratio of the rib side length L5 to the rib width K is 2.2.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0015] Under the same initial conditions, when the rib width, rib height, impact hole diameter and arrangement of the turbine blade internal impact-rib combined cooling structure of the present invention are the same as those of the straight ribs in the prior art, after computer simulation calculation and comparative analysis of the calculation results, the comprehensive heat transfer coefficient of the turbine blade internal impact-rib combined cooling structure of the present invention is improved by 15.5%. The pressure loss coefficient is reduced by 11.1%.

[0016] Therefore, the turbine blade internal impact-rib combined cooling structure of the present invention has the advantages of good heat exchange performance and low pressure loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 2 is a schematic diagram of the overall structure of the impact-rib combined cooling according to an embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of a partial structure of an impact-rib combined cooling structure according to an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the gas flow direction of the impact-rib combined cooling structure of an embodiment of the present invention;

[0020] Figure 4 is a layout diagram of an impact-rib combined cooling structure according to an embodiment of the present invention;

[0021] Figure 5 is a schematic structural diagram of a rib of an impact-rib combined cooling structure according to an embodiment of the present invention;

[0022] In the figure:

[0023] 101, impact target plate; 102, impact plate; S1, gas collecting cavity; S2, impact cavity; 1, impact hole; 2, rib; Z1, impact distance; W1, rib height; L1, impact hole flow spacing; L2, impact hole span spacing; L3, rib flow spacing;

[0024] L4, rib span spacing; L5, rib side length; D1, impact hole diameter; K, rib width; α, rib angle; R1, small circle radius on rib; R2, large circle radius on rib. DETAILED DESCRIPTION

[0025] The present invention will be further explained below in conjunction with the accompanying drawings.

[0026] like Figures 1 to 5 As shown, a turbine blade internal impact-rib combined cooling structure of the present invention comprises an impact target plate 101 , an impact plate 102 , an air collecting cavity S1 , an impact cavity S2 , a plurality of impact holes 1 and a plurality of ribs 2 .

[0027] like Figures 1 to 4 As shown, the impact target plate 101 and the impact plate 102 are arranged in parallel and parallel to the flow direction of the cooling gas. A semi-open gas collecting cavity S1 is formed above the impact plate 102, and a semi-closed impact cavity S2 is formed between the impact plate 102 and the impact target plate 101. The impact cavity S2 has an airflow outlet.

[0028] like Figures 1 to 4 As shown, a plurality of impact holes 1 are opened on the impact plate 102 at intervals along the airflow direction and the span direction, and a plurality of ribs 2 are arranged on the impact target plate 101 at intervals along the airflow direction and the span direction.

[0029] The rib 2 is non-linear, preferably, the rib 2 is U-shaped or V-shaped, such as Figure 2 , 4 and 5.

[0030] The cooling gas passes through the impact hole 1 from the gas collecting cavity S1, and the jet impacts the impact target plate 101. After heat exchange with the impact target plate 101, it flows out of the impact cavity S2. When the cooling gas flows in the impact cavity S2 and passes through multiple ribs 2, the cooling gas flows across the ribs 2 and generates vortices to separate the boundary layer. The ribs 2 increase the disturbance in the flow of the airflow, destroy the boundary layer, and thus enhance the heat exchange capacity between the cooling gas and the impact target surface 101.

[0031] like Figure 3 As shown, in one embodiment, the ratio of the impact distance Z1 of the impact cavity S2 to the rib height W1 is 3. The impact distance Z1 is the height of the impact cavity S2, that is, the distance between the impact plate 102 and the impact target plate 101, and the rib height W1 is the height of the rib 2.

[0032] like Figure 3 As shown, the impact hole 1 passes through the impact plate 102 , and the hole axis of the impact hole 1 is perpendicular to the impact plate 102 and the impact target plate 101 .

[0033] like Figure 4 As shown, in one embodiment, a plurality of impact holes 1 are divided into 4 groups, and the plurality of impact holes 1 are arranged at intervals on the impact plate 102 along the airflow direction, and each group of impact holes 1 includes a plurality of impact holes 1, and the plurality of impact holes 1 in each group of impact holes 1 are arranged at intervals on the impact plate 102 along the airflow span direction. The ratio of the diameter of the impact hole 1 to the rib width K is 1.8, the ratio of the impact hole flow direction spacing L1 to the rib width K is 16, and the ratio of the impact hole span direction spacing L2 to the rib width K is 8. Among them, the rib width K is the width of the rib 2, the impact hole flow direction spacing L1 is the distance between the hole axes of adjacent impact holes 1 in the airflow direction, and the impact hole span direction spacing L2 is the distance between the hole axes of adjacent impact holes 1 in the airflow span direction.

[0034] like Figure 4 As shown, in one embodiment, the plurality of ribs 2 are divided into a plurality of groups, and the plurality of groups of ribs 2 are arranged on the impact target plate 101 at intervals along the airflow direction, and each group of ribs 2 includes a plurality of ribs 2, and the plurality of ribs 2 in each group of ribs 2 are arranged at intervals along the airflow direction. The spacing between any two adjacent groups of ribs 2 is equal and is L3, and the ratio of L3 to the rib width K is 16; the spacing between each group of ribs 2 is equal and is L4, and the ratio of L4 to the rib width K is 6.8.

[0035] like Figure 5As shown, in one embodiment, the ratio of the rib height W1 to the rib width K is 1, the rib angle α is 120°, and the rib angle α is the opening angle of the rib 2. There are two arcs inside and outside the rib (at the bend of the rib 2), respectively, the rib edge is tangent to the two arcs on the rib, the two arcs on the rib are respectively part of concentric circles, the ratio of the radius R2 of the large arc on the rib to the rib width K is 2, the ratio of the radius R1 of the small arc on the rib to the rib width K is 1, and the ratio of the rib side length L5 to the rib width K is 2.2.

[0036] It should be noted that, under the same initial conditions, the width and height of the ribs, the diameter and arrangement of the impact holes in the impact-rib combined cooling structure of the present invention are the same as the width and height of the straight ribs, the diameter and arrangement of the impact holes in the prior art, and the cooling performance of the straight ribs and the cooling structure of the present invention are evaluated by the comprehensive heat transfer coefficient, and the comprehensive heat transfer coefficient formula is as follows:

[0037]

[0038] Among them, Nu is the average Nusselt number of the impact target surface with ribs, Nu0 is the average Nusselt number of the impact target surface of the traditional impact cooling plane, f is the pressure loss coefficient of the channel with ribs, and f0 is the pressure loss coefficient of the traditional impact cooling channel. The calculation methods of the above parameters are consistent with the common understanding and calculation methods of relevant practitioners. The results calculated under the same boundary conditions are shown in Table 1:

[0039] Table 1

[0040] Straight ribs The present invention Nu 31.3 34.78 <![CDATA[Nu0]]> 25.084 25.084 f 2.69 2.39 <![CDATA[f0]]> 2.17 2.17 Comprehensive heat transfer coefficient 1.16 1.34

[0041] It can be seen that the comprehensive heat transfer coefficient of the impact-rib combined cooling structure of the embodiment of the present invention is higher than that of the straight ribs, and the pressure loss coefficient is lower than that of the straight ribs, and the comprehensive heat transfer coefficient is increased by 15.5% and the pressure loss coefficient is reduced by 11.1%.

[0042] Therefore, the turbine blade internal impact-rib combined cooling structure of the present invention can not only achieve a higher comprehensive heat transfer coefficient than that of straight ribs, but also greatly reduce the pressure loss coefficient of the channel.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A turbine blade internal impingement-rib combined cooling structure, characterized in that: The invention comprises an impact target plate (101), an impact plate (102), an air collecting cavity (S1), an impact cavity (S2), a plurality of impact holes (1) and a plurality of ribs (2), wherein: the impact target plate (101) and the impact plate (102) are arranged in parallel and parallel to the flow direction of the cooling gas; a semi-open air collecting cavity (S1) is formed on the impact plate (102); a semi-closed impact cavity (S2) is formed between the impact plate (102) and the impact target plate (101); and the impact cavity (S2) is provided with an air flow outlet; the plurality of impact holes (1) The impact plate (102) is provided with gaps along the airflow direction and the span direction, and a plurality of ribs (2) are arranged at intervals along the airflow direction and the span direction on the impact target plate (101); cooling gas passes through the impact hole (1) from the gas collecting cavity (S1), and the jet impacts the impact target plate (101), exchanges heat with the impact target plate (101), and then flows out of the impact cavity (S2); when the cooling gas flows in the impact cavity (S2), when it passes through the plurality of ribs (2), the cooling gas flows across the ribs (2) and generates vortices to separate the boundary layer.

2. A turbine blade internal impingement-rib combined cooling structure according to claim 1, characterized in that: The rib (2) is U-shaped or V-shaped.

3. The turbine blade internal impingement-rib combined cooling structure according to claim 1, characterized in that: The ratio of the impact distance Z1 of the impact cavity (S2) to the rib height W1 is 3.

4. The turbine blade internal impingement-rib combined cooling structure according to claim 1, characterized in that: The impact hole (1) passes through the impact plate (102), and the hole axis of the impact hole (1) is perpendicular to the impact plate (102) and the impact target plate (101).

5. A turbine blade internal impingement-rib combined cooling structure according to claim 1 or 4, characterized in that: The plurality of impact holes (1) are divided into four groups, the plurality of groups of impact holes (1) are arranged at intervals on the impact plate (102) along the airflow direction, each group of impact holes (1) comprises a plurality of impact holes (1), and the plurality of impact holes (1) in each group of impact holes (1) are arranged at intervals on the impact plate (102) along the airflow direction.

6. The turbine blade internal impingement-rib combined cooling structure according to claim 5, characterized in that: The ratio of the impact hole (1) diameter to the rib width K is 1.8, the ratio of the impact hole flow direction spacing L1 to the rib width K is 16, and the ratio of the impact hole span direction spacing L2 to the rib width K is 8.

7. A turbine blade internal impingement-rib combined cooling structure according to claim 1 or 2, characterized in that: The plurality of ribs (2) are divided into a plurality of groups, the plurality of groups of ribs (2) are arranged on the impact target plate (101) at intervals along the airflow direction, each group of ribs (2) comprises a plurality of ribs (2), and the plurality of ribs (2) in each group of ribs (2) are arranged at intervals along the airflow direction.

8. The turbine blade internal impingement-rib combined cooling structure according to claim 7, characterized in that: The spacing between any two adjacent groups of ribs (2) is equal and is L3, and the ratio of L3 to the rib width K is 16; the spacing between each group of ribs (2) is equal and is L4, and the ratio of L4 to the rib width K is 6.8; the ratio of the rib height W1 to the rib width K is 1, the rib angle α is 120°, the inner and outer sides of the rib are two arcs respectively, the rib edge is tangent to the two arcs on the rib respectively, the two arcs on the rib are each part of a concentric circle, the ratio of the radius R2 of the large arc on the rib to the rib width K is 2, the ratio of the radius R1 of the small arc on the rib to the rib width K is 1, and the ratio of the rib side length L5 to the rib width K is 2.2.

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