Air film and internal turbulence combined cooling device and application thereof

Abstract

This invention discloses a cooling device and its application using a film cooling system with internal turbulence, belonging to the field of aero-engines. It includes a cold-side plate, a hot-side plate, and hollow turbulence columns. The cold-side plate is located on one side of the cold air passage, and the hot-side plate is located on the other side of the high-temperature gas passage. Several hollow turbulence columns are arranged between the cold-side and hot-side plates, connecting the cold air passage and the high-temperature gas passage through hollow holes in the columns, forming an intermediate channel containing the hollow turbulence columns between the two plates. This invention utilizes the low flow resistance and easy outflow characteristics of the hollow holes to prevent backflow of gas. Simultaneously, it leverages the advantages of low internal turbulence resistance and good external film adhesion of the inclined hollow turbulence columns. This structure is suitable for areas requiring high cooling efficiency but prone to backflow of gas, such as high-temperature nozzle walls. Numerical verification shows that this structure achieves better cooling performance and lower flow resistance than existing impact + film cooling double-wall structures.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engines, and particularly relates to a cooling device with film cooling and internal disturbance and application. BACKGROUND

[0002] Military fighters often obtain extra thrust through afterburner when taking off in a short distance or maneuvering quickly, in addition to the maximum throttle opening of the engine. Because of the limited space of the afterburner, the burning gas acts on the convergent section nozzle wall in the form of oblique impact, which easily causes gas backflow and leads to serious consequences. Research shows that the gas temperature of the tail nozzle at this time will be as high as 2000K or more. In addition, the pressure gradient from the engine nozzle inlet to the outlet is relatively large, which easily causes strong suction of the expansion section gas and aggravates the occurrence of the convergent section backflow.

[0003] The impingement double-wall film cooling technology is one of the advanced cooling methods for modern engine high-temperature components. Before the formation of the gas film, the impingement heat exchange coefficient can be fully utilized to achieve the effect of local heat exchange enhancement. The existing literature compares the cooling performance of the new impingement / divergence cooling layer plate heat shield, demonstrates its feasibility for application in the afterburner, and performs comparative analysis of the same working conditions with the corrugated plate heat shield and the single-layer flat plate heat shield. The results show that the impingement / divergence cooling layer plate heat shield has good cooling effect. The double-wall structure has structural strengthening effect, and the outflow of the gas film hole has a certain anti-vibration effect, which can improve the life and reliability of the afterburner. However, the double-wall cooling structure in the existing technology can achieve good heat exchange effect, but the internal flow resistance of the double-wall is large, and it is greatly affected by the change of the primary and secondary flow total pressure ratio. It is not easy to flow out in the case of small pressure ratio, and it is not suitable for application in the convergent section of the engine nozzle.

[0004] At present, the methods for reducing the internal flow resistance of the double-wall are being studied at home and abroad, such as adding pits to the target surface and changing the shape of the disturbance column. However, due to the large turning and vortex of the fluid in the impingement-film case, the flow loss is large, and the improvement effect is not significant.

[0005] The advanced aero-engine afterburner is relatively short, and the combustion flame obliquely impacts on the convergent section of the nozzle. Due to the scouring action of the gas, on the one hand, the convergent section heat shield has a large thermal load, and the gas is easily backflowed from the convergent section gas film hole into the cold gas channel due to the influence of the expansion section opening suction, so that the heat shield loses the heat insulation ability. The traditional porous structure flat plate has low cooling effect and is difficult to form effective protection for the convergent section wall surface, while the impingement+film double-wall structure has large internal flow resistance and is not easy to flow out in the case of small pressure ratio. In addition, due to the low-pressure suction of the expansion section gas, most of the cooling gas is sucked into the expansion section with milder working conditions, which to some extent causes the waste of cooling gas and aggravates the occurrence of the convergent section gas backflow. SUMMARY

[0006] TECHNICAL PROBLEMS TO BE SOLVED

[0007] In order to avoid the deficiencies of the prior art, the application provides a cooling device with gas film and internal disturbance, which forms an intermediate channel with disturbance columns between two layers of plates, and the hollow disturbance columns are arranged staggeredly, which utilizes the characteristics of small flow resistance and easy outflow of the hollow holes, so that the backflow of the combustion gas can be avoided, and the advantages of small internal disturbance flow resistance and good external gas film adhesion of the inclined hollow disturbance column are utilized. The structure is suitable for the area where high cooling efficiency is required but the backflow of the combustion gas is easy to occur, such as the high-temperature nozzle wall. Through numerical verification, the cooling device has better cooling effect and smaller flow resistance than the existing impact + gas film double-layer wall structure.

[0008] The technical scheme of the application is: a cooling device with gas film and internal disturbance, characterized by comprising a cold-side plate, a hot-side plate and a hollow disturbance column, the cold-side plate is located on one side of a cold gas channel, and the hot-side plate is located on one side of a high-temperature combustion gas channel.

[0009] A plurality of hollow disturbance columns are arranged between the cold-side plate and the hot-side plate, the cold gas channel and the high-temperature combustion gas channel are communicated through the hollow holes of the hollow disturbance columns, and an intermediate channel containing the hollow disturbance columns is formed between the two layers of plates.

[0010] The further technical scheme of the application is that the hollow disturbance columns are arranged staggeredly and have an inclination angle of 20-90° with the direction of the gas flow in the intermediate channel.

[0011] The further technical scheme of the application is that the hollow hole diameter D of the hollow disturbance column is between 0.5-5 mm. i

[0012] The further technical scheme of the application is that the spanwise hole spacing P and the streamwise hole spacing S of the hollow hole are 3-10 times the hollow hole diameter D i .

[0013] The further technical scheme of the application is that the hollow holes are distributed in a positive diamond shape in the streamwise direction.

[0014] The further technical scheme of the application is that the average height H of the channel formed by the hot-side plate and the cold-side plate is 1-10 times the hollow hole diameter D i .

[0015] The further technical scheme of the application is that the radial cross-sectional shape of the hollow disturbance column is circular, elliptical, water-drop-shaped or hyperbolic.

[0016] The further technical scheme of the application is that the cross section of the hollow hole of the hollow disturbance column is consistent with the radial cross-sectional shape of the hollow disturbance column.​

[0017] An engine nozzle characterized in that: the cooling device of the film cooling plus internal disturbance is installed on the inside of the outer wall of the convergent section of the engine nozzle and is connected to the single-layer corrugated plate of the afterburner through a transition corrugation;

[0018] The cold side plate and the outer wall of the convergent section of the nozzle form an outer channel, and the hot side plate forms the inner wall surface of the nozzle; the cold side plate and the outer wall of the convergent section of the nozzle are closed at the end, so that all the cold gas of the outer channel flows out through the hollow holes of the hollow disturbance column, forming a cooling gas film on the hot side plate; and the total pressure outflow is used to reduce the incidence of backflow of the gas.

[0019] Advantages

[0020] The cooling device of the film cooling plus internal disturbance with a hollow column provided by the application makes full use of the advantages of small flow resistance of the inclined disturbance column to enhance convective cooling and the advantages of the inclined hollow hole to easily form a gas film, so that high-efficiency cooling is achieved. The specific implementation principle is as follows: Figure 2 As shown in FIG. 1, a part of the cooling gas B flows out D on the hot side plate gas side through the hollow hole 3, forming a gas film layer, and reducing the heat transfer of the main flow gas A to the hot side plate; another part of the cooling gas C flows at high speed through the disturbance column row 4 under the suction of the gas in the nozzle expansion section, and carries away the heat of the hot side plate 2 and the hollow column; the staggered arrangement of the disturbance column ensures that the disturbance is more sufficient, and at the same time, the outflow of the hollow hole forms a uniform coverage on the surface of the hot side plate; the disturbance column 4 has an inclination of 20-90° with the intermediate passage gas flow C, which on the one hand makes the flow cross section elliptical, reduces the internal flow resistance, and on the other hand makes the cooling gas flow D have a small angle with the main flow A, ensures the adhesion of the cooling gas to the wall surface, and thus achieves higher cooling effect and reduces the mixing loss of the nozzle. Figure 5 As shown in FIG. 2, the cold side plate is connected to the outer wall of the convergent section of the nozzle at the end to form a closed cavity, and the total pressure outflow can reduce the risk of backflow of the gas as much as possible; the combination of internal disturbance cooling and external gas film cooling improves the cooling effect while avoiding the disadvantage of too large flow resistance of the traditional double-wall impact + gas film structure. Figure 6 As shown in FIG. 3, the column surface shapes of the elliptical shape 12, the hyperbolic shape 13 and the water drop shape 14 not only make the gas film adhere better to the surface of the gas and enhance the heat exchange effect, but also reduce the flow resistance of the internal column row.

[0021] After numerical verification, as shown in FIG. 4 and FIG. 5, Figure 7 and Figure 8The figures show a comparative cloud map and a line graph comparing the overall cooling efficiency of an embodiment of the present invention with that of a traditional impact + air film double-wall model with an opening at the same location. Under the same air film cooling air volume, the overall cooling efficiency of the present invention increases from 0.636 to 0.818, improving the overall cooling efficiency to 1.29 times that of the traditional structure. The total pressure loss coefficient of the cold air decreases from 1.03 for the traditional impact + air film double-wall model to 0.62, a decrease to 60.2%.

[0022] In summary, the advantages of this invention are: (1) less cooling air consumption and high cooling efficiency; (2) small angle between the cold air and the mainstream, and low mixing loss; (3) low internal flow resistance and cold air total pressure outflow, which can avoid gas backflow. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a cooling device with air film and internal turbulence according to the present invention;

[0024] Figure 2 This is a flow diagram of a cooling device with air film and internal turbulence according to the present invention;

[0025] Figure 3 This is a schematic diagram showing the characteristic dimensions of a cooling device with air film and internal turbulence according to the present invention;

[0026] Figure 4 This is a schematic diagram of the hole arrangement of a cooling device with air film and internal turbulence according to the present invention;

[0027] Figure 5 This is a schematic diagram illustrating the application scenario of the present invention in the convergent section of an engine nozzle;

[0028] Figure 6 This is a schematic diagram of the structural form of the hollow turbulence column in this invention;

[0029] Figure 7 This is a cloud map comparing the overall cooling efficiency of an embodiment of the present invention with that of a single-layer multi-oblique-hole plate model;

[0030] Figure 8 This is a line graph comparing the spanwise average comprehensive cooling efficiency of an embodiment of the present invention with that of a single-layer multi-sloping-hole flat plate model;

[0031] Explanation of reference numerals in the attached diagrams: 1. Cold-side plate; 2. Hot-side plate; 3. Hollow hole; 4. Hollow turbulence column; 5. External wall of the afterburner; 6. Single-layer corrugated plate of the afterburner; 7. Main combustion gas duct; 8. External wall of the nozzle convergent section; 9. External wall of the nozzle diverging section; 10. Impact-film double-wall cooling structure of the nozzle diverging section; 11. Circular hollow turbulence column; 12. Elliptical hollow turbulence column; 13. Teardrop-shaped hollow turbulence column; 14. Hyperbolic hollow turbulence column; A. Mainstream combustion gas; B. External duct cooling airflow; C. Cooling airflow between the double-layer plates; D. Outflow from the hollow hole; Di , Inner diameter of the hollow turbulence column; D o 1. Outer diameter of the hollow column; H. Average height of the channel between the plates; P. Spacing of the hollow column rows; S. Spacing of the hollow column rows; θ. Angle between the hollow column and the airflow in the middle channel. Detailed Implementation

[0032] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] This implementation case is a specific example of a cooling device with a hollow column, film cooling, and internal turbulence applied to an engine nozzle.

[0035] The high-temperature, low-pressure gas discharged from the turbine enters the main gas duct 7 after diffusion, mixes with the fuel injected by the fuel nozzle, and then reignites to form high-temperature gas. This gas has an oblique impact on the converging section of the nozzle. The temperature of the mainstream high-temperature gas A can reach as high as 2200K, far exceeding the melting point of the material. Therefore, the nozzle wall needs to be cooled.

[0036] See Figure 1 , Figure 2 , Figure 3 , Figure 4 This embodiment describes a cooling device with a hollow column, a film cooling system with internal turbulence, comprising a cold-side plate 1, a hot-side plate 2, and a hollow turbulence column 4 connecting the two plates. The cold-side plate contains staggered hollow holes 3. The cold-side plate 1 and the outer wall surface 8 of the nozzle convergence section form a cold air channel, creating an intermediate channel between the two plates. The hot-side plate 2 forms the inner wall surface of the combustion gas in the high-temperature component.

[0037] Figure 2 and Figure 5The diagram illustrates the operation of a film cooling device with hollow columns and internal turbulence in the nozzle convergent section. This device is connected to a single-layer corrugated plate in the afterburner via a transition corrugation. Part of the cooling air from the afterburner's outer duct enters the outer duct formed by the cold-side plate and the outer wall of the nozzle convergent section, becoming the cooling airflow B. The end of the outer duct in the convergent section is closed, causing all the cooling air to pass through the hollow columns to form an outflow D, creating a cooling film on the hot-side plate 2. Another part of the cooling air from the afterburner's outer duct passes through the intermediate channel, where it is cooled by the turbulence of the hollow column array at a certain angle to the flow direction and the suction effect of the expansion section.

[0038] In this implementation case, the average height H of the channel between the two plates is 2.5mm, and the inner diameter D of the hollow turbulence column is... i The outer diameter D of the hollow turbulence column is 1mm. o The spacing between the hollow turbulence columns is 1.5mm, the directional spacing P is 3mm, the directional spacing S is 1.5mm, and the angle θ between the hollow turbulence columns and the airflow in the middle channel is 30°.

[0039] Because the cold-side plate and outer wall form a straight cold air channel that is sealed at the end, and the hollow holes have lower flow resistance compared to the double-walled impingement film structure, the risk of backflow of combustion gas can be reduced. Part of the cooling gas from the afterburner passes through the hollow holes under the constraint of the sealed cavity and forms a film layer on the hot-side plate, thus significantly reducing the heat transfer from the combustion gas to the hot-side plate. Another part of the cooling gas passes through the hollow column array in the middle channel, where the strong suction of the nozzle expansion section enhances convective heat transfer, carrying away heat from the hot-side plate and further reducing its temperature, thus providing good protection for the entire nozzle expansion section wall. Numerical calculations were performed to compare this implementation case with a traditional impingement + film double-wall model with the same opening ratio and opening position. Specific calculation settings are shown in Table 1, and the cooling effect comparison between the implementation case and the traditional impingement + film double-wall model is shown in Table 1. Figure 7 and Figure 8 Under the same cooling air consumption, this implementation case improves the overall cooling efficiency to 1.29 times that of the traditional impact + film double-wall structure, and reduces the total pressure loss coefficient of the cooling air by 60.2%.

[0040] Table 1. Implementation Cases and Numerical Calculation Methods for the Impact + Air Film Double-wall Model

[0041]

[0042] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An engine nozzle employing a cooling device with film cooling and internal turbulence, characterized in that: The cooling device includes a film cooling system with internal turbulence, which is installed on the inner side of the outer wall of the converging section of the engine nozzle and connected to the single-layer corrugated plate of the afterburner chamber via a transition corrugation. The air-film cooling device with internal turbulence includes a cold-side plate, a hot-side plate, and hollow turbulence columns. The cold-side plate is located on one side of the cold air passage, and the hot-side plate is located on the other side of the high-temperature gas passage. Several hollow turbulence columns are arranged between the cold-side plate and the hot-side plate. The cold air passage and the high-temperature gas passage are connected through the hollow holes of the hollow turbulence columns, and an intermediate channel containing hollow turbulence columns is formed between the two plates. The cold-side plate and the outer wall of the nozzle convergent section form an outer bypass duct, and the hot-side plate forms the inner wall of the nozzle; the cold-side plate and the outer wall of the nozzle convergent section are closed at the end, so that all the cold air in the outer bypass duct flows out through the hollow holes of the hollow turbulence column and forms a cooling gas film on the hot-side plate; and the total pressure outflow reduces the rate of gas backflow. The hollow turbulence columns are arranged in an alternating manner, forming an angle of 20-90° with the airflow direction of the central channel; The radial cross-sectional shape of the hollow baffle column is circular, elliptical, teardrop-shaped, or hyperbolic; the cross-sectional shape of the hollow hole of the hollow baffle column is consistent with the radial cross-sectional shape of the hollow baffle column. Part of the cooling air from the afterburner duct enters the bypass duct formed by the cold-side plate and the outer wall of the nozzle convergent section, becoming a cooling airflow. The end of the bypass duct of the convergent section is closed, causing all the cooling air to flow out through the hollow column and form a cooling air film on the hot-side plate. Another part of the cooling air from the afterburner duct passes through the intermediate channel and is cooled on the hot-side plate by the turbulence of the hollow column array at a certain angle to the flow direction and the suction of the expansion section.

2. The engine nozzle employing a cooling device with film cooling and internal turbulence as described in claim 1, characterized in that: The hollow pore diameter D of the hollow turbulence column i Between 0.5 and 5 mm.

3. The engine nozzle employing a cooling device with film cooling and internal turbulence as described in claim 2, characterized in that: The spanwise hole spacing P and the flow-wise hole spacing S of the hollow holes are 3-10 times the hollow hole diameter D. i .

4. The engine nozzle employing a cooling device with film cooling and internal turbulence as described in claim 3, characterized in that: The hollow holes are distributed in a rhomboid shape in the flow direction.

5. The engine nozzle employing a cooling device with film cooling and internal turbulence as described in claim 4, characterized in that: The average height H of the channel formed by the hot-side plate and the cold-side plate is 1-10 times the diameter D of the hollow hole. i Inside.

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