Corrugated heat shield with double-wall structure and aero-engine

Abstract

The present application provides a corrugated heat shield with a double-wall structure, comprising a corrugated air film orifice plate and an impact orifice plate, the corrugated air film orifice plate comprising a valley section and a peak section. The impact orifice plate is arranged radially outside the peak section, and an annular cavity between the impact orifice plate and the valley section and the outer wall of the afterburner is a cold air duct, and the impact orifice plate and the peak section form an impact cavity. The wall surface of the corrugated air film orifice plate is uniformly distributed with air film orifices in the circumferential direction, and the wall surface of the impact orifice plate is uniformly distributed with impact orifices in the circumferential direction. Cooling air forms an air film on the gas side of the heat shield, and on the other hand, enters the impact cavity through the impact orifices to perform impact heat exchange, and then flows out through the air film orifices to form a cooling air film, thereby forming efficient cooling on the peak section. The present application effectively improves the cooling efficiency while increasing the weight less, and the air film orifices can also make the pressure waves generated by the oscillating combustion enter the double-wall interior, thereby having a certain anti-vibration effect, improving the service life and reliability of the afterburner. The present application also provides an aircraft engine with a corrugated heat shield.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation gas turbine engines, and particularly relates to a corrugated heat shield with a double-wall structure and an aviation engine. BACKGROUND

[0002] Afterburner is an important component of modern military engines. Military aircraft often opens the afterburner to provide maximum thrust in a short time in the working state of take-off, climbing, acceleration, and pursuit. On the one hand, the temperature in the afterburner can reach above 2100K after ignition, far exceeding the temperature resistance limit of the cylinder material. On the other hand, the gas flow rate in the combustion chamber is high, and the pressure is low, which is prone to oscillatory combustion, affecting the service life. The heat shield is usually used to separate the high-temperature gas from the combustion chamber cylinder, which plays a certain role in inhibiting oscillatory combustion while isolating the high-temperature gas from the cylinder.

[0003] There are various forms of heat shields, among which the longitudinal corrugated heat shield with film holes is widely used due to its simple structure, good cooling performance, and effective suppression of longitudinal oscillation. In the 1990s, patent US5181379 proposed a corrugated plate with dense film holes, which makes the film jet more uniform and obtains a more uniform wall temperature distribution. Patent US5233828 proposes film holes with a directional angle based on the longitudinal corrugated heat shield. These film holes have a 20° angle in the flow direction and a 30-60° angle in the circumferential direction. The cooling efficiency of the corrugated plate fluctuates along the flow direction, and the cooling efficiency is lowest at the windward side of the main flow at the wave peak, which is prone to ablation and other damage. The new generation of aviation engines has higher afterburner temperature and less cooling gas, which poses new challenges to cooling design.

[0004] Double-wall impingement / film cooling technology is one of the advanced cooling methods for high-temperature components of modern engines. Before the gas film is formed by cooling gas, impingement heat exchange is performed first to achieve the effect of local heat exchange enhancement. The double-wall structure has structural strengthening effect and certain anti-vibration effect, which can improve the life and reliability of the afterburner. Patent CN112178691 A proposes a double-wall cooling structure with double-curved turbulence columns with film holes, which uses impingement heat exchange and convection heat exchange to enhance the cooling effect, but the heat shield increases the weight, which adversely affects the improvement of the engine thrust-to-weight ratio.

[0005] Double-wall cooling has evolved into various structures, including double-plate, plate-corrugated plate, corrugated plate-plate, etc. The plate-corrugated plate double-wall cooling structure improves the cooling effect of the corrugated plate, and the upstream cooling efficiency is significantly improved, but the weight of the heat shield is greatly increased. At the same time, due to the corrugation, the impingement distance is large at the wave peak section, and the impingement cooling has limited effect on the cooling efficiency of this place. SUMMARY

[0006] In order to avoid the shortcomings of the prior art, the present application provides a corrugated heat shield with a double-wall structure, which forms an air film on the gas side of the heat shield to reduce heat transfer to the heat shield, and further reduces the wall temperature at the corrugated peaks by adding impact plates at the peaks to further reduce the wall temperature through impact heat exchange. The impact plates are added only at the peaks, which effectively improves the cooling efficiency while adding less weight, and reduces the impact distance to improve the impact heat exchange effect. The air film holes can also allow pressure waves generated by oscillating combustion to enter the double-wall interior, and the reflected waves are attenuated, which has a certain anti-vibration effect and improves the service life and reliability of the afterburner.

[0007] In one aspect of the application, a corrugated heat shield with a double-wall structure is provided, comprising:

[0008] A corrugated air film hole plate constitutes the inner wall of the cylinder of the afterburner, and the inner side is the gas duct of the afterburner. The corrugated air film hole plate has a cylindrical corrugated tube structure, and the cylindrical corrugated tube structure is connected by a plurality of wave structures at the head and tail in the axial direction. The wave structure includes a wave valley section recessed outward in the radial direction and a wave peak section protruding inward in the radial direction, and the wall surface of the corrugated air film hole plate is provided with air film holes in the circumferential direction; and

[0009] An impact hole plate is dispersedly arranged on the radial outer side of at least two wave peak sections of the corrugated air film hole plate. The annular cavity between the radial outer side of the impact hole plate and the wave valley section and the outer wall of the afterburner constitutes a cold gas duct. The impact cavity is formed between the radial inner side of the impact hole plate and the wave peak section, and the wall surface of the impact hole plate is provided with impact holes in the circumferential direction.

[0010] Preferably, the height H of the impact hole plate from the outermost side of the wave peak section is 0.5-1.2 times the corrugated amplitude A.

[0011] Preferably, the impact hole plates arranged on the radial outer sides of different wave peak sections have the same height H, or the impact hole plates arranged on the radial outer sides of different wave peak sections have different heights H according to the cooling requirements of different wave peak sections.

[0012] Preferably, the air film holes are evenly distributed on the wall surface of the corrugated air film hole plate in multiple groups in the axial direction. Multiple air film holes in each group are arranged on the same straight line in the circumferential direction to form an in-line distribution, or multiple air film holes in each group are arranged on two straight lines in the circumferential direction and are staggered in the axial direction to form a cross-line distribution.

[0013] Preferably, when the air film holes are in-line distributed, the impact holes are also in-line distributed, and when the air film holes are cross-line distributed, the impact holes are also cross-line distributed.

[0014] Preferably, the impact holes and the air film holes are staggered.

[0015] Preferably, the length L of the wave structure in the corrugated gas film orifice plate ranges from 50 to 90 mm, and the amplitude A ranges from 3 to 7 mm.

[0016] Preferably, the thickness δ1 of the corrugated gas film orifice plate ranges from 0.5 to 2.5 mm, and the thickness δ2 of the impact orifice plate ranges from 0.5 to 2.5 mm.

[0017] Preferably, the diameter D of the gas film orifice ranges from 0.4 to 3 mm, and the diameter D of the impact orifice ranges from 0.6 to 1.5 times the diameter D of the gas film orifice. f i f

[0018] In another aspect of the present application, an aero-engine is provided, which comprises the corrugated heat shield with a double-wall structure according to any one of the preceding embodiments.

[0019] The present application has the following advantages: the corrugated heat shield with a double-wall structure provided by the present application is cooled by a combination of gas film cooling and impact cooling; the corrugated plate is provided with gas film orifices, so that the cooling air forms a gas film on the inner wall of the heat shield, reducing the thermal load; the impact plate is added at the wave crest, and the divergent cooling and impact cooling are comprehensively applied, effectively improving the cooling effect of the main flow windward side of the corrugated heat shield and prolonging the service life of the heat shield. The impact plate is added only at the wave crest with higher thermal load, and the impact cooling effect is achieved with less weight increase, and the short impact distance is conducive to enhancing the impact cooling effect. Furthermore, the pressure wave generated by the oscillating combustion can enter the double-wall interior, and is attenuated after reflection, having a certain anti-vibration effect and improving the service life and reliability of the afterburner. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical scheme of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical scheme of the present application, but do not constitute a limitation on the technical scheme of the present application.

[0021] Figure 1 FIG. 1 is a schematic view of the installation position of the corrugated heat shield with a double-wall structure in an afterburner according to the present application;

[0022] Figure 2 FIG. 2 is a schematic view of the annular structure of the corrugated heat shield with a double-wall structure according to the present application;

[0023] Figure 3 FIG. 3 is a schematic view of the overall structure of the gas film orifice fork row of the corrugated heat shield with a double-wall structure according to the present application;

[0024] Figure 4 ​​​This is a schematic diagram of the overall structure of a corrugated heat insulation screen with double-walled air film holes arranged in sequence according to the present invention;

[0025] Figure 5 This is a front view of a corrugated heat insulation screen with a double-wall structure according to the present invention;

[0026] Figure 6 This is a partial enlarged view of a corrugated heat insulation screen with a double-wall structure according to the present invention;

[0027] Figure 7 A cloud map showing the distribution of air film cooling efficiency of a traditional corrugated heat insulation screen;

[0028] Figure 8 This is a cloud map showing the air film cooling efficiency distribution of an embodiment of a corrugated heat insulation screen with a double-wall structure according to the present invention.

[0029] Figure 9 This is a flow line diagram of the spanwise average air film cooling efficiency of a corrugated heat insulation screen with a double-wall structure according to the present invention.

[0030] In the diagram: 1-Outer wall of the afterburner; 2-Corrugated film gas orifice plate; 21-Trough section; 22-Crest section; 3-Impact orifice plate; 4-Impact chamber; 5-Film gas orifice; 6-Impact hole; 7-Adjustable nozzle; λ-Corrugated length; A-Corrugated amplitude; δ1-Thickness of corrugated film gas orifice plate; δ2-Thickness of impact orifice plate; H-Height of impact orifice plate; B-Main flow gas; C-Cooling airflow; C1-Impact jet; C11-Wall jet; C12-Film gas jet; C13-Film gas jet; C2-Film gas jet. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are not intended to limit the invention or its application or use in any way. The invention can be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the invention thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0032] To facilitate the description of the structure of each component in the afterburner, this invention establishes a cylindrical coordinate system with the central axis of the aero-engine as the axis:

[0033] Taking the direction coinciding with the central axis of the afterburner as the axial direction, that is, Figure 1 The left-right direction, also known as the flow direction, is defined as the radial direction, which is the distance from the central axis on a plane perpendicular to the axial direction. Figure 1The direction of the up and down in the figure. The circumferential rotation direction around the central axis is circumferential, that is, Figure 1 The direction of the rotation of the center axis to the paper or out of the paper, also known as the development direction.

[0034] In combination Figures 1-2 The present application provides a corrugated heat shield with a double-wall structure, which is arranged inside the afterburner of an aero-engine and constitutes an inner wall. The inner side of the corrugated heat shield flows through the high-temperature main flow gas B, and the outer side constitutes a cooling gas flow channel with the outer wall 1 of the afterburner. During operation, the cooling gas flowing through the outer wall surface of the corrugated heat shield directly flows through the wall surface, and part of the heat is taken away through convective heat transfer, playing a role of convective cooling. Moreover, the pressure waves caused by oscillatory combustion enter the impingement cavity and the internal cooling gas duct through the gas film hole 5, and are reflected between the walls, and the energy gradually decreases; at the same time, it can cause gas column oscillation, so that the energy is converted into internal energy and dissipated, having a certain anti-vibration ability.

[0035] Further referring to Figures 3-6 The corrugated heat shield of the present application is composed of a corrugated gas film hole plate 2 and an impingement hole plate 3; the corrugated gas film hole plate 2 is a cylindrical corrugated tube structure, including a wave trough section 21 recessed outward in the radial direction and a wave crest section 22 protruding inward in the radial direction. The corrugated gas film hole plate 2 constitutes the inner wall of the cylinder of the afterburner, and the inner side is the gas duct of the afterburner. The annular cavity between the impingement hole plate 3 and the wave trough section 21 and the outer wall 1 of the afterburner is the cooling gas duct. The impingement hole plate 3 is dispersedly arranged on the radial outer side of at least two wave crest sections 22 of the corrugated gas film hole plate 2. The annular cavity between the radial outer side of the impingement hole plate 3 and the wave trough section 21 and the outer wall 1 of the afterburner constitutes the cooling gas duct, and the radial inner side of the impingement hole plate 3 and the wave crest section 22 form the impingement cavity 4. Since the impingement hole plate 3 is dispersedly arranged on the radial outer side of at least two wave crest sections 22 of the corrugated gas film hole plate 2, it can more effectively perform impingement cooling on the wave crest section 22 with higher thermal load with less weight increase.

[0036] The wall surface of the corrugated gas film hole plate 2 is uniformly distributed with gas film holes 5, and the wall surface of the impingement hole plate 3 is uniformly distributed with impingement holes 6. Part of the cooling air forms a gas film on the gas side of the heat shield through the gas film holes 5, reducing the heat transfer to the heat shield; another part enters the impingement cavity through the impingement holes 6 for impingement heat exchange, further reducing the wall temperature at the corrugated wave crest, and then flows out from the gas film holes.

[0037] Specifically referring to Figure 6The cooling air flow C passes through the heat shield in two streams, namely the impingement jet C1 and the film jet C2. The impingement jet C1 enters the impingement cavity through the impingement hole 6 to form an impingement cooling on the inner wall of the crest section 22, to form a wall jet C11 to take away part of the heat, and the impingement jet C1 flows out of the film hole 5 to form an effective film covering on the outer wall of the crest section 22 to form a cold air heat insulation layer. The other film jet C2 flows out of the film hole 5 to effectively protect the outer wall of the trough section 21.

[0038] As shown in Figure 5 , it is a front view of the corrugated heat shield with a double-wall structure, in which the height H and the corrugated amplitude A are marked. In some preferred embodiments, the height H of the impingement hole plate 3 from the outermost side of the crest section 22 is 0.5-1.2 times the corrugated amplitude A, so as to better ensure the cooling efficiency of the crest section, especially the windward side of the main flow. If H is too small, the impingement plate is too close to the film plate, and the coverage area of the impingement heat exchange for improving the cooling efficiency is too small. If H is too large, the impingement distance is too large, and the impingement heat exchange effect is poor.

[0039] It should be further pointed out that, although Figure 5 the standard sinusoidal wave is taken as an example to show the front view of the corrugated heat shield, and the height H and the corrugated amplitude A are shown in the figure, those skilled in the art should understand that the corrugated heat shield of the present application can also adopt other wave structures, such as a modified sinusoidal wave, and the above-mentioned parameters will be defined by the specific structure of the corrugated heat shield in a similar manner.

[0040] In some preferred embodiments, considering that the temperature fluctuation in the length range of the corrugated heat shield along the flow direction is limited, the impingement hole plates 3 arranged on the radial outer side of different crest sections 22 have the same height H, so as to reduce the processing difficulty and improve the processing precision. Of course, for the more severe working conditions of the aero-engine and the more severe temperature fluctuation in the length range of the corrugated heat shield along the flow direction, the impingement hole plates 3 arranged on the radial outer side of different crest sections 22 can also have different heights H according to the cooling requirements of different crest sections 22, so as to make the corrugated heat shield have a longer service life.

[0041] Referring to Figures 3-4 , the film holes 5 are evenly distributed on the wall surface of the corrugated film hole plate 2 in multiple groups along the axial direction, and multiple film holes 5 in each group are arranged on the same straight line along the circumferential direction to form a row distribution as shown in Figure 4 . Of course, multiple film holes 5 in each group are arranged on two straight lines along the circumferential direction and staggered in the axial direction to form a row distribution as shown in Figure 3The forked distribution of the plurality of air film holes 5 is better than the straight distribution, and the mixing between the air flows is easier, and the cold air coverage area is wider. In addition, the plurality of air film holes 5 in each group are preferably arranged in different straight lines and are equally spaced in the circumferential direction, so that the air film coverage of the outer surface of the corrugated air film hole plate 2 is more uniform.

[0042] Further, when the air film holes 5 are in a straight distribution, the impact holes 6 are also in a straight distribution, and when the air film holes 5 are in a forked distribution, the impact holes 6 are also in a forked distribution. In addition, the impact holes 6 are staggered with the air film holes 5, so that the impact air flow of the impact holes 6 does not directly face the air film holes 5 and flows out of the air film holes 5, but absorbs heat in the impact cavity 4 and then flows out of the air film holes 5, improving the cooling efficiency.

[0043] Continuing to refer to Figure 5 , the length L of the wave structure in the corrugated air film hole plate 2 is in the range of 50-90mm, and the amplitude A is in the range of 3-7mm. If the amplitude A is too large and exceeds 7mm, the cold air flow through the wave peak and wave valley positions in the cooling channel will be greatly different, the temperature difference between the peaks and valleys of the heat shield will be large, and the wave peak will easily touch the flame, causing the wall temperature to rise and even ablation. If the amplitude A is too small and less than 3mm, the processing difficulty will be increased, and the impact hole plate 3 will be too close to the corrugated air film hole plate 2, and the air film superposition effect will be weakened.

[0044] The thickness δ1 of the corrugated air film hole plate 2 is in the range of 0.5-2.5mm, and similarly, the thickness δ2 of the impact hole plate 3 is in the range of 0.5-2.5mm. If the thickness of the corrugated air film hole plate 2 or the impact hole plate 3 is too small, the structural strength of the heat shield will be reduced, and if the thickness is too large, the weight will be increased, which is not conducive to improving the thrust-to-weight ratio.

[0045] In order to ensure the cooling effect, the opening area of the air film hole needs to be accurately controlled, and the air film hole area should be less than 10% of the surface area of the heat shield. If the hole diameter is too large, the hole spacing will be large (the opening will be sparse), which will affect the cooling effect. Based on this, the diameter D f of the air film hole 5 of the present application is 0.4-3mm. If the hole diameter of the air film hole is too small, it is not conducive to processing, and it may be blocked, and if the hole diameter is too large, the blowing ratio will be reduced under the same cold air volume, which is not conducive to the outflow of cold air. Correspondingly, the diameter D i of the impact hole 6 is 0.6-1.5 times the diameter D f of the air film hole 5, which can ensure that enough impact air flow enters the impact cavity to meet the needs of cooling and subsequent air film holes 5, and can also consider the processability.

[0046] The following introduces the embodiment of the present application in combination with the calculation results of numerical simulation. The embodiment is a corrugated heat shield with double-wall structure. The thickness of the corrugated air film hole plate is 1mm, and the thickness of the impact hole plate is 0.6mm. The corrugation is a standard sine wave, the length L is 60mm, and the corrugation amplitude A is 5mm. The air film holes are arranged in a forked row. The air film hole diameter D f is 0.8mm, the hole spacing and hole row spacing are 5mm, and the impact hole diameter D i is the same as D f . The air film holes and the impact holes are both vertically opened. The impact plate height H is 0.8A. On this basis, numerical simulation is carried out on the traditional uniform opening corrugated heat shield, the boundary conditions are shown in Table 1, and the operating pressure is 474800Pa.

[0047] Table 1 Numerical simulation boundary conditions of the embodiment

[0048]

[0049]

[0050] Figure 7 、 Figure 8 respectively show the air film cooling efficiency distribution cloud diagram of the traditional corrugated heat shield and the embodiment of the corrugated heat shield with double-wall structure of the present application, Figure 9 is the spanwise average cooling efficiency (the cooling efficiency is defined by , wherein T ∞ is the main stream gas temperature, T c is the cooling air flow temperature, and T W is the heat shield wall temperature) along the streamwise line. In the same cold gas outflow condition (the blowing ratio BR = 0.5, the blowing ratio BR is defined by the formula , wherein m represents the mass flow, A represents the cross-sectional area, ρ represents the density, and u represents the velocity; the subscript c represents the cooling air flow, and ∞ represents the main stream gas). In combination with the calculation results of numerical simulation, it can be known that the cold gas of the embodiment of the present application forms a better cooling effect, especially the spanwise average air film cooling efficiency on the windward side of the main stream is obviously improved. In the cycle, the average air film cooling efficiency is improved by 4.16%.

[0051] The above merely describes the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A corrugated heat shield having a double-walled structure, characterized by, The application relates to a corrugated air film hole plate (2) which constitutes the inner wall of a cylinder of a thrust chamber, the inner side of the corrugated air film hole plate (2) being a gas duct of the thrust chamber, the corrugated air film hole plate (2) being in a cylindrical corrugated tube structure, the cylindrical corrugated tube structure being connected by a plurality of wave structures at the head and tail in the axial direction, the wave structure comprising a wave trough section (21) which is concave outward in the radial direction and a wave crest section (22) which is convex inward in the radial direction, and the wall surface of the corrugated air film hole plate (2) being provided with air film holes (5) in the circumferential direction; and an impact hole plate (3) which is arranged in the radial direction outside at least two wave crest sections (22) of the corrugated air film hole plate (2), the impact hole plate (3) constituting a cold gas duct with the wave trough section (21) and the outer wall (1) of the thrust chamber between the radial outer side of the impact hole plate (3) and the annular cavity, the impact hole plate (3) forming an impact cavity (4) between the radial inner side of the impact hole plate (3) and the wave crest section (22), and the wall surface of the impact hole plate (3) being provided with impact holes (6) in the circumferential direction. The height H of the impact hole plate (3) from the outermost side of the wave crest section (22) is 0.5-1.2 times the corrugated amplitude A. The impact hole plates (3) arranged outside different wave crest sections (22) have the same height H, or the impact hole plates (3) arranged outside different wave crest sections (22) have different heights H according to the cooling requirements of different wave crest sections (22). The air film holes (5) are arranged in multiple groups on the wall surface of the corrugated air film hole plate (2) in the axial direction, multiple air film holes (5) in each group are arranged on the same straight line in the circumferential direction and are in a straight-line distribution, or multiple air film holes (5) in each group are arranged on two straight lines in the circumferential direction and are in a cross-line distribution.

2. The corrugated heat shield having a double-walled structure according to claim 1, characterized by: When the air film holes (5) are in a straight-line distribution, the impact holes (6) are also in a straight-line distribution, and when the air film holes (5) are in a cross-line distribution, the impact holes (6) are also in a cross-line distribution.

3. The corrugated heat shield having a double-walled structure according to claim 1, characterized by: The impact holes (6) and the air film holes (5) are arranged alternately.

4. The corrugated heat shield having a double-walled structure according to claim 3, characterized by: The length L of the wave structure in the corrugated air film hole plate (2) is 50-90 mm, and the amplitude A is 3-7 mm.

5. The corrugated heat shield having a double-walled structure according to claim 4, characterized by: The thickness of the corrugated air film hole plate (2) is 0.5-2.5 mm, and the thickness of the impact hole plate (3) is 0.5-2.5 mm.

6. The corrugated insulation panel having a double wall structure according to claim 1, wherein: The aero-engine comprises the corrugated heat shield with a double-layer wall structure as claimed in any one of claims 1-8.

7. The corrugated insulation panel having a double wall structure according to claim 1, wherein: ​ 8. The corrugated insulation panel having a double wall structure according to claim 1, wherein: The gas film hole (5) diameter D f is 0.4-3 mm, the impact hole (6) diameter D i is 0.6-1.5 times the gas film hole (5) diameter D f .

9. An aeroengine characterised in that, ​

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