Design method of cooling structure with bionic S-shaped spoiler ribs of different cross sections

Abstract

This invention discloses a design method for a bionic S-shaped spoiler rib cooling structure with different cross-sections. By comparing the effects of bionic S-shaped rib cooling structures with different cross-sections on the flow and heat transfer within the cooling channel within a turbine blade, the method measures the differences in heat transfer performance caused by variations in the cross-sectional shape of the blade cooling channel ribs due to harsh operating environments and engine lifespan, and selects the bionic S-shaped spoiler rib cross-section cooling structure with the best heat transfer performance. This method fully considers the wear of the cross-sectional shape of the blade cooling channel ribs due to engine lifespan, compares the effects of different cross-sectional shapes on channel heat transfer performance using bionic S-shaped rib cooling structures with different cross-sections, and proposes a bionic S-shaped rib cross-section design scheme with the best heat transfer performance.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbine blade cooling, and in particular to a design method for a cooling structure of bionic S-shaped spoiler ribs with different cross sections. Background Art

[0002] In the field of aviation gas turbines, where turbine inlet temperatures have reached as high as 2200K, efficient cooling design plays an increasingly important role. In high-pressure turbine blades, a typical hot-end component, ribbed channels not only provide cold air for external film cooling to isolate the high-temperature gas, but also enhance cooling through forced convection through the ribs. Research on the flow and heat transfer characteristics of ribbed channels is of great significance. The turbulent ribs are a key factor affecting ribbed channel performance and have long attracted keen attention from researchers.

[0003] As engines experience harsh operating conditions and increase their service life, the cross-sectional shape of the ribs in the turbine blade cooling channel begins to wear. These worn turbine blades may no longer meet turbine cooling requirements, leading to severe damage or even breakage, thus impacting engine performance stability and safety. Therefore, it is crucial to measure the impact of varying wear levels on the flow and heat transfer in the turbine cooling channel, compare the effects of different cross-sectional shapes on channel heat transfer performance, and identify the optimal bionic S-shaped rib cross-sectional shape for heat transfer. Summary of the Invention

[0004] The purpose of the present invention is to provide a design method for a cooling structure of bionic S-shaped spoiler ribs with different cross-sections, to compare the influence of the shape changes of the bionic S-shaped spoiler ribs caused by different degrees of wear on the flow and heat transfer of the turbine inner cooling channel, to compare the influence of different cross-sectional shapes on the heat transfer performance of the channel, and to provide a bionic S-shaped rib cross-section cooling structure with the best heat transfer.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A design method for a bionic S-shaped spoiler rib cooling structure with different cross-sections is characterized by comparing the effects of bionic S-shaped rib cooling structures with different cross-sections on the flow and heat transfer in the cooling channel inside a turbine blade, measuring the differences in heat transfer performance caused by changes in the cross-sectional shape of the ribs in the cooling channel inside the blade due to harsh operating environments and engine life, and selecting the bionic S-shaped spoiler rib cross-section cooling structure with the best heat transfer performance. The specific steps are as follows:

[0007] 1) Bionic S-shaped spoiler ribs of varying cross-sections are provided within a U-shaped cooling channel of a turbine blade, wherein the U-shaped cooling channel comprises a straight channel and a rotating channel connecting the straight channel. The bionic S-shaped spoiler ribs of varying cross-sections are provided within the straight channel of the U-shaped cooling channel and extend along the blade height on the inner wall surface of the turbine blade;

[0008] 2) The cross-sections of the bionic S-shaped spoiler ribs with different cross-sections include: rectangle, rectangle-semicircle, isosceles triangle, isosceles trapezoid, and ellipse. The bionic S-shaped spoiler ribs with different cross-sections are arranged on the upper and lower surfaces of the U-shaped cooling channel;

[0009] 3) The cold air flows into the inlet of the U-shaped cooling channel 2 and flows along the bionic S-shaped spoiler ribs 3 of different cross sections arranged inside the straight channel to the turning channel part. Semicircular guide vanes 4 are arranged in the turning channel part. The cold air passes through the straight channel and the turning channel to the outlet of the U-shaped cooling channel. Part of the cold air flows out from the air film holes on the leading edge of the blade and the slits 5 on the trailing edge.

[0010] 4) Establish a three-dimensional model of a ribbed channel with bionic S-shaped spoiler ribs of different cross-sections and perform simulation calculations to obtain the dimensionless Nusselt number, friction coefficient, and comprehensive heat transfer performance indicators;

[0011] 5) Taking into account the gain of the flow and heat transfer of the wave ribs, the bionic S-shaped spoiler ribs with a rectangular-semicircular cross-section are selected, which is more conducive to improving the comprehensive heat transfer performance of the turbine blade cooling channel.

[0012] Further, in step 4), the dimensionless Nusselt number is defined as follows:

[0013] Nu / Nu0=(hD / λ) / 0.023Re 0.8 Pr 0.4 (1)

[0014] Where h is the heat transfer coefficient, D is the characteristic length, λ is the thermal conductivity, Re is the inlet Reynolds number, and Pr is the Prandtl number;

[0015] The friction coefficient is used to measure the pressure loss caused by corrugated ribs with different cross sections and is defined as follows:

[0016] f=Δp / (0.5ρU 2 ), (2)

[0017] Where Δp is the pressure difference between the channel inlet and outlet, ρ represents the gas density, and U is the gas flow rate;

[0018] The indicators of comprehensive heat transfer performance are defined as follows:

[0019] TP=(Nu / Nu0) / (f / f0) 1 / 3 (3)

[0020] f0=0.507Re -0.3 (4)

[0021] Comprehensively considering the changes in the dimensionless Nusselt number and the friction coefficient, the bionic S-shaped spoiler rib with a rectangular-semicircular cross-section has the largest value in the comprehensive heat transfer performance of the bionic S-shaped spoiler rib, which is the optimal cross-sectional scheme. The bionic S-shaped spoiler rib with a rectangular-semicircular cross-section is selected.

[0022] Furthermore, the bionic S-shaped spoiler ribs with different cross sections include 10 wave rib units, and the wave rib units are composed of 4 circular arc ring segments.

[0023] Furthermore, the fillet radius r of the circular arc segment is 2 mm, and the rib height h of the bionic S-shaped spoiler ribs with different cross sections is e =2e, rib angle α=30°. The ratio of the rib length P to the rib thickness e of the bionic S-shaped spoiler rib units with different cross sections is 10.

[0024] Furthermore, the cross-sectional width of the bionic S-shaped spoiler ribs of different cross sections is all e, and the rib height h e =2e, the radius of the top circle of the rectangular-semicircular cross section is e / 2, the upper base of the trapezoidal cross section is e / 2, the upper base of the elliptical cross section is e, and the radius of the ellipse is 5mm.

[0025] Furthermore, a semicircular guide vane is provided in the U-shaped cooling channel, and the semicircular guide vane is arranged inside the rotating channel of the U-shaped cooling channel.

[0026] To address the issue of variations in turbine blade rib cross-sections caused by engine life and harsh environments, this paper proposes cooling structure designs with five bionic S-shaped spoiler rib cross-sections. The design also provides preliminary insights into the flow and heat transfer characteristics of these ribs with varying cross-sections. This innovative design measures the impact of rib shape variations within the turbine cooling channel on turbine cooling performance and provides a reference for optimal cooling design of bionic S-shaped spoiler ribs, which is crucial for ensuring the safe and reliable operation of aircraft gas turbines.

[0027] In terms of flow loss, the bionic S-shaped spoiler rib with a triangular cross section has the largest friction coefficient, followed by the isosceles trapezoidal cross section, and the rectangular, rectangular-semicircular, and elliptical cross sections have the smallest and similar sizes. In terms of heat transfer characteristics, the bionic S-shaped spoiler rib with an isosceles trapezoidal cross section has the best dimensionless Nusselt ratio, followed by the isosceles triangular cross section. In terms of overall performance, the bionic S-shaped spoiler rib with a rectangular-semicircular cross section has the best comprehensive heat transfer performance (TP) and is the best cross-section selection scheme among the research parameters of the present invention. The inclined rib side wall in the isosceles triangle and isosceles trapezoidal schemes effectively avoids flow separation within the rib height range, promotes the development of cold air near the wall along the span direction and flow direction, and improves the wall heat transfer performance (Nu / Nu0). At the same time, strong mixing also makes the flow loss larger. Therefore, although the isosceles trapezoidal and triangular cross sections have greater heat transfer advantages, they also bring greater flow losses, and therefore do not have higher comprehensive heat transfer performance.

[0028] The beneficial effects of the present invention are as follows:

[0029] Cooling air flows into the U-shaped cooling channel's inlet, following bionic S-shaped spoiler ribs of varying cross-sections. Semicircular guide vanes are placed in the return channel, and the cooling air then flows through the straight and return channels to the U-shaped cooling channel's outlet. Some of the cooling air exits through the film holes on the leading edge and the slits on the trailing edge. By placing bionic S-shaped spoiler ribs of varying cross-sections on the upper and lower surfaces of the U-shaped cooling channel within the blade, the heat transfer effect is enhanced, improving the channel's heat transfer performance and strengthening the turbine blade's tolerance to high-temperature environments, thereby ensuring safe and reliable operation of the aircraft gas turbine. A comparative analysis of the heat transfer performance, flow losses, and overall heat transfer performance of five bionic S-shaped spoiler rib cross-sections revealed that the rectangular-semicircular cross-section exhibited the best overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic cross-sectional view of a cooling channel in a turbine blade according to an embodiment of the present invention;

[0031] Figure 2 Schematic cross-sectional view of a bionic S-shaped spoiler rib cooling structure with different cross-sections in an embodiment of the present invention;

[0032] Figure 3 Schematic diagrams of five cross-sectional structural dimensions of bionic S-shaped spoiler rib cooling structures with different cross sections in an embodiment of the present invention;

[0033] Figure 4 1. A top view of a bionic S-shaped spoiler rib with different cross sections in an embodiment of the present invention;

[0034] Figure 5 1 is a comparison diagram of the dimensionless Nusselt numbers of bionic S-shaped spoiler ribs with different cross sections in an embodiment of the present invention;

[0035] Figure 6 1 is a comparison diagram of the friction coefficients of bionic S-shaped spoiler ribs with different cross sections in an embodiment of the present invention;

[0036] Figure 7 This is a comparison chart of the comprehensive heat exchange performance of bionic S-shaped spoiler ribs with different cross sections in an embodiment of the present invention;

[0037] Attached: 1-turbine blades, 2-U-shaped cooling channels, 3-bionic S-shaped spoiler ribs with different cross-sections, 4-guide vanes, 5-slits, 6-spoiler columns. DETAILED DESCRIPTION

[0038] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0039] Example 1

[0040] A design method for bionic S-shaped spoiler rib cooling structures with different cross-sections is proposed. By comparing the effects of bionic S-shaped rib cooling structures with different cross-sections on the flow and heat transfer in the cooling channel inside the turbine blade, the differences in heat transfer performance caused by changes in the cross-sectional shape of the ribs in the cooling channel inside the blade due to harsh working environment and engine life are measured, and the bionic S-shaped spoiler rib cross-section cooling structure with the best heat transfer performance is selected.

[0041] Bionic S-shaped spoiler rib cooling structures with different cross-sections are applied to the straight channel part of the U-shaped cooling channel inside the blade.

[0042] like Figure 1 As shown, bionic S-shaped spoiler ribs 3 of varying cross-sections are positioned within the straight channel of the U-shaped cooling channel 2 on the upper and lower surfaces of the U-shaped cooling channel 2, extending along the inner wall of the turbine blade 1 along the blade's height. Cooling air flows into the U-shaped cooling channel 2 from its inlet, along the bionic S-shaped spoiler ribs 3 of varying cross-sections within the straight channel, and into the reversing channel, where semicircular guide vanes 4 are positioned. The cooling air then flows through the straight and reversing channels to the U-shaped cooling channel outlet, with some exiting through the film holes and slits 5 on the trailing edge of the blade. Figure 1 In the figure, 6 is a spoiler column.

[0043] like Figure 2 and Figure 3 As shown, the cross-sections of the bionic S-shaped spoiler ribs 3 with different cross-sections have five shapes: rectangle, rectangle-semicircle, triangle, isosceles trapezoid, and ellipse. The rib height h of the bionic S-shaped spoiler ribs 3 with different cross-sections e=2e. Three-dimensional models of ribbed channels with bionic S-shaped spoiler ribs of different cross sections were established and simulation calculations were performed.

[0044] like Figure 4 As shown, the bionic S-shaped spoiler ribs 3 with different cross sections include 10 continuously arranged wave rib units P, the ratio of the wave rib unit rib length P to the rib thickness e is 10, the circular ring fillet radius r is 2 mm, and the rib angle α=30°.

[0045] like Figure 5 、 6 As shown in Figure 7, compared with other cross sections, the dimensionless Nusselt number of the isosceles trapezoidal bionic S-shaped spoiler rib is the largest, indicating that the heat transfer performance of the isosceles trapezoidal bionic S-shaped spoiler rib is the best, and the dimensionless Nusselt number (Nu / Nu0) of the rectangular cross section scheme is increased by 0.24831, an increase of 20.52%. Figure 5 As shown in Figure 2. While isosceles trapezoids and isosceles triangles improve heat transfer, their friction coefficient (f) is significantly larger, as shown in Figure 2. Figure 6 As shown. Comprehensively considering the changes in the dimensionless Nusselt number (Nu / Nu0) and the friction coefficient (f), the bionic S-shaped spoiler rib with a rectangular-semicircular cross-section has the largest value of 2.9127 in the comprehensive heat transfer performance of the bionic S-shaped spoiler rib, which is the best cross-section scheme. Figure 7 As shown. This shows that although the bionic S-shaped spoiler ribs with isosceles triangle and isosceles trapezoidal cross sections have better heat transfer capabilities, the flow losses caused at the same time are greater. Taking into account the gains of wave rib flow heat transfer, the bionic S-shaped spoiler ribs with rectangular-semicircular cross sections should be selected for corresponding turbine blade cooling design in practical engineering applications, which is more conducive to the improvement of the comprehensive heat transfer performance of the turbine blade cooling channel. In order to comprehensively compare the flow heat transfer performance of bionic S-shaped spoiler ribs with several different cross sections, the present invention defines the dimensionless Nusselt number (Nu / Nu0), friction coefficient (f), and comprehensive heat transfer performance index (TP), and provides a data table of the dimensionless Nusselt number, friction coefficient and comprehensive heat transfer performance of the bionic S-shaped spoiler ribs under 5 cross sections when the Reynolds number is 25000. See Table 1

[0046] Table 1

[0047] cross section <![CDATA[Nu / Nu0]]> f TP rectangle 1.20993 1.95047 2.78571 Rectangle-Semicircle 1.23251 1.85584 2.9127 Isosceles triangle 1.39052 4.33784 2.46825 Isosceles trapezoid 1.45824 3.46849 2.79365 oval 1.2754 2.06752 2.86508

[0048] The dimensionless Nusselt number is defined as follows:

[0049] v / Nu0=(hD / λ) / 0.023Re 0.8 PR 0.4 (1)

[0050] Where h is the heat transfer coefficient, D is the characteristic length, λ is the thermal conductivity, Re is the inlet Reynolds number, and Pr is the Prandtl number.

[0051] The friction coefficient is used to measure the pressure loss caused by corrugated ribs with different cross sections and is defined as follows:

[0052] f=Δp / (0.5ρU 2 ), (2)

[0053] Where Δp is the pressure difference between the channel inlet and outlet, ρ represents the gas density, and U is the gas flow rate.

[0054] The indicators of comprehensive heat transfer performance are defined as follows:

[0055] TP=(Nu / Nu0) / (f / f0) 1 / 3 (3)

[0056] The present invention's bionic S-shaped spoiler rib cooling structure with varying cross-sections enhances heat exchange and improves the channel's heat transfer performance by arranging these ribs on the upper and lower surfaces of the blade's internal U-shaped cooling channel. Cooling air flows into the U-shaped cooling channel's inlet, following the bionic S-shaped spoiler ribs of varying cross-sections. Semicircular guide vanes are positioned in the revolving channel, and the air then flows through the straight and revolving channels to the U-shaped cooling channel's outlet. Some of the air then flows out through the film holes on the blade's leading edge and the slits on the trailing edge.

[0057] In the present invention, in terms of flow loss, the triangular cross-section bionic S-shaped spoiler rib has the largest friction coefficient, followed by the isosceles trapezoidal cross-section, and the rectangular, rectangular-semicircular, and elliptical cross-sections are the smallest and similar in size. In terms of heat transfer characteristics, the isosceles trapezoidal cross-section bionic S-shaped spoiler rib has the best dimensionless Nusselt ratio, followed by the isosceles triangular cross-section. In terms of overall performance, the rectangular-semicircular cross-section bionic S-shaped spoiler rib has the best comprehensive heat transfer performance (TP), which is the best cross-section selection scheme among the research parameters of the present invention. The inclined rib side wall in the isosceles triangle and isosceles trapezoid schemes effectively avoids flow separation within the rib height range, promotes the development of cold air near the wall along the span direction and flow direction, and improves the wall heat transfer performance (Nu / Nu0). At the same time, strong mixing also makes the flow loss larger. Therefore, although the isosceles trapezoidal and triangular cross-sections have greater heat transfer advantages, they also bring greater flow losses, and therefore do not have higher comprehensive heat transfer performance. Taking into account the gain of heat transfer through the wave ribs, a bionic S-shaped spoiler rib with a rectangular-semicircular cross section should be selected in practical engineering applications for turbine blade cooling design, which is more conducive to improving the comprehensive heat transfer performance of the turbine blade cooling channel.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A design method for a cooling structure of bionic S-shaped spoiler ribs with different cross-sections, characterized in that: By comparing the effects of bionic S-shaped rib cooling structures with different cross-sections on the flow and heat transfer in the cooling channels within turbine blades, the differences in heat transfer performance caused by changes in the cross-sectional shape of the ribs in the cooling channels within the blades due to harsh operating environments and engine life are measured, and the bionic S-shaped spoiler rib cross-sectional cooling structure with the best heat transfer performance is selected. The specific steps are as follows: 1) Bionic S-shaped spoiler ribs (3) with different cross sections are provided in a U-shaped cooling channel (2) of a turbine blade (1), wherein the U-shaped cooling channel (2) includes a straight channel and a rotary channel for connecting the straight channels, and the bionic S-shaped spoiler ribs (3) with different cross sections are provided inside the straight channel of the U-shaped cooling channel and extend along the blade height direction on the inner wall surface of the turbine blade (1); 2) The cross-sections of the bionic S-shaped spoiler ribs (3) with different cross sections include: rectangle, rectangle-semicircle, isosceles triangle, isosceles trapezoid, and ellipse, and the bionic S-shaped spoiler ribs (3) with different cross sections are arranged on the upper and lower surfaces of the U-shaped cooling channel; 3) The cold air flows in from the inlet of the U-shaped cooling channel (2), flows along the bionic S-shaped spoiler ribs (3) of different cross sections arranged inside the straight channel to the revolving channel part, and a semicircular guide vane (4) is arranged in the revolving channel part. The cold air passes through the straight channel and the revolving channel to the outlet of the U-shaped cooling channel, and part of the cold air flows out from the air film holes on the leading edge of the blade and the slits (5) on the trailing edge; 4) Establish a three-dimensional model of a ribbed channel with bionic S-shaped spoiler ribs of different cross-sections and perform simulation calculations to obtain the dimensionless Nusselt number, friction coefficient, and comprehensive heat transfer performance indicators; 5) Taking into account the flow and heat transfer gains of the wave ribs, a bionic S-shaped spoiler rib with a rectangular-semicircular cross section is selected, which is beneficial to improving the comprehensive heat transfer performance of the turbine blade cooling channel; In step 4), the dimensionless Nusselt number is defined as follows: (1)； Where, h is the heat transfer coefficient, D is the characteristic length, is the thermal conductivity, Re is the inlet Reynolds number, Pr is the Prandtl number; The friction coefficient is used to measure the pressure loss caused by corrugated ribs with different cross sections and is defined as follows: (2)； Where, is the pressure difference between the channel inlet and outlet, ρ represents the gas density, U is the gas flow rate; The indicators of comprehensive heat transfer performance are defined as follows: (3)； (4)； In step 5), considering the changes in the dimensionless Nusselt number and the friction coefficient, the bionic S-shaped spoiler rib with a rectangular-semicircular cross-section has the largest value in the comprehensive heat transfer performance of the bionic S-shaped spoiler rib, which is the optimal cross-sectional scheme. The bionic S-shaped spoiler rib with a rectangular-semicircular cross-section is selected.

2. The design method of the cooling structure of bionic S-shaped spoiler ribs with different cross sections according to claim 1 is characterized in that: In step 1), the bionic S-shaped spoiler ribs (3) of different cross sections include 10 wave rib units, and the wave rib units are composed of 4 circular arc ring segments.

3. The design method of the cooling structure of bionic S-shaped spoiler ribs with different cross sections according to claim 2, characterized in that: The fillet radius of the circular arc segment r The rib height of the bionic S-shaped spoiler ribs with different cross sections is 2mm. h e = 2e， rib angle α = 30°; rib length of bionic S-shaped spoiler rib units with different cross sections P Thick ribs e The ratio is 10.

4. The design method of the cooling structure of bionic S-shaped spoiler ribs with different cross sections according to claim 3 is characterized in that: The cross-sectional width of the bionic S-shaped spoiler ribs with different cross-sections is e , rib height value h e = 2e , the radius of the top circle of the rectangular-semicircular cross section is e / 2, the upper base of the trapezoidal cross section is e / 2, the upper base of the elliptical cross section is e , the ellipse radius is 5mm.

5. The design method of the cooling structure of bionic S-shaped spoiler ribs with different cross sections according to claim 1, characterized in that: In step 1), a semicircular guide vane (4) is provided in the U-shaped cooling channel (2), and the semicircular guide vane (4) is arranged inside the rotary channel of the U-shaped cooling channel.

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