A wall slot structure for hydrofoil tip gap leakage flow control

Abstract

The application discloses a wall slot structure for regulating leakage flow in a hydrofoil tip gap, and the structure comprises a blade and a wall, wherein the wall is arranged opposite to the blade, a tip gap is formed between the tip of the blade and the wall, a plurality of slot bodies are arranged on the wall, the plurality of slot bodies are arranged in the projection area of the blade on the wall and are arranged in an array along the wall, wherein the slot bodies are arranged in extension along the flow direction to regulate the leakage flow in the tip gap, and the effective regulation of the leakage flow in the tip gap area is realized through simple and effective structure improvement.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, and more specifically to a wall groove structure for regulating leakage flow in the tip clearance of a hydrofoil. Background Technology

[0002] In aero-engines, compressors, turbines, and other machinery, a certain tip clearance is typically required between the rotor blade tip and the casing wall to prevent the blade from contacting the casing during operation due to thermal expansion, vibration, or assembly errors. However, when airflow passes through the blade passage, due to the pressure difference between the pressure and suction surfaces of the blade, some airflow leaks from the high-pressure side to the low-pressure side through the tip clearance, forming a tip leakage flow. This leakage flow interacts with the mainstream flow in the tip region, easily forming leakage vortex structures and causing significant flow losses and aerodynamic noise, adversely affecting the aerodynamic performance and stable operation of the turbine machinery.

[0003] To address flow problems in the blade tip clearance region, existing technologies typically employ active control methods to regulate the flow structure. For example, this involves introducing jet or suction devices near the casing or blade tip to compensate for the momentum of the local flow field. These methods usually rely on external energy input to actively intervene in the flow field, thereby controlling the leakage flow and its induced vortex structure. However, while these active control methods can suppress flow disturbances and improve flow response to some extent, they generally require additional energy supply and complex control systems. This not only increases the complexity of the system structure but may also lead to increased energy consumption, higher requirements for control system stability, and decreased system reliability, thus limiting their widespread application in practical equipment.

[0004] Therefore, how to effectively control the leakage flow in the blade tip clearance region through simple and effective structural improvements has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a wall slotted structure for regulating leakage flow in the tip clearance of hydrofoils, thereby solving the technical problem of how to effectively regulate leakage flow in the tip clearance region through simple and effective structural improvements in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention provides a wall groove structure for regulating leakage flow in the tip clearance of a hydrofoil, comprising: a blade; a wall surface, which is disposed opposite to the blade, with a tip clearance formed between the blade tip and the wall surface, and multiple grooves are formed on the wall surface, which are disposed in the projection area of ​​the blade on the wall surface and arranged in an array along the wall surface; wherein, the grooves extend along the flow direction to regulate the leakage flow in the tip clearance.

[0007] In some embodiments, the groove is an arc-shaped cross-section groove.

[0008] In some embodiments, the depth of the tank is H, the cross-sectional radius of the tank is R, and the following condition is met: 0.33≤H / R≤3.

[0009] In some embodiments, the blade tip clearance is δ, the cross-sectional radius of the groove is R, and the following condition is met: 0.05≤δ / R≤1.5.

[0010] In some embodiments, the axis of the tank is inclined relative to the flow direction.

[0011] In some embodiments, the angle between the axis of the tank and the flow direction is θ, and satisfies: 0°≤θ≤75°.

[0012] In some embodiments, multiple tanks are arranged in an array at equal intervals along the wall.

[0013] In some embodiments, the distance between adjacent tanks is S, the cross-sectional radius of the tank is R, and satisfies: 0.67≤S / R≤2.

[0014] In some embodiments, the arc-shaped cross-section groove is a semi-circular groove.

[0015] In some embodiments, the multiple tanks extend to the same length along the flow direction.

[0016] Compared with existing technologies, the wall slotted structure for controlling leakage flow in the tip clearance of hydrofoils provided by this invention achieves passive control of leakage flow in the tip clearance region by setting an array of slots extending along the airflow direction in the wall region corresponding to the blade. This structure allows some of the leakage flow to enter the interior of the slots, forming local backflow or turbulent flow within the slots, thereby changing the flow structure near the tip clearance and weakening the development of leakage vortices, thus improving the flow state in the tip region. Compared with existing technologies, this application does not require the introduction of additional energy input or complex control systems; effective control of tip clearance leakage flow can be achieved simply by modifying the wall structure. It is not only simple in structure and reliable in implementation, but also helps to reduce system complexity and maintenance costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the blade tip clearance provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a tank provided in an embodiment of the present invention; Figure 3 This is a cross-sectional schematic diagram of a tank provided in an embodiment of the present invention; Figure 4This is a top view of a tank provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 10. Blade; 20. Wall. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] To address the technical problem of how to effectively control the leakage flow in the tip clearance region through simple and effective structural improvements in the prior art, this invention provides a wall slotted structure for controlling the leakage flow in the tip clearance region of a hydrofoil, which can effectively control the leakage flow in the tip clearance region, thereby improving the flow characteristics in the tip region.

[0021] It should be noted that the wall slotting structure for regulating leakage flow in the tip clearance of hydrofoil described in this invention is applicable to, but not limited to, fluid machinery. For ease of explanation, this invention only uses the application of the wall slotting structure for tip clearance leakage flow in fluid machinery as an example. The principle of applying the wall slotting structure for tip clearance leakage flow in other types of equipment is essentially the same as that applied in fluid machinery, and will not be elaborated here.

[0022] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the blade tip clearance provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a tank structure provided in an embodiment of the present invention. The structure mainly includes blades 10 and a wall surface 20 disposed opposite to the blades 10. By making simple improvements to the structure of the wall surface 20, the leakage flow in the blade tip gap region can be effectively controlled, thereby improving the flow state near the blade tip region.

[0023] In fluid machinery, blades 10 are typically mounted on a rotor and rotate with it. To prevent the blades 10 from contacting the casing due to thermal expansion, vibration, or assembly errors during high-speed rotation, a certain distance is usually maintained between the blade tip and the inner wall of the casing; this distance forms the blade tip clearance. When airflow passes through the blade 10 channel, due to the pressure difference between the pressure surface and suction surface of the blade 10, some airflow leaks from the high-pressure side to the low-pressure side through this clearance, thus forming a leakage flow in the blade tip region and further generating a leakage vortex structure.

[0024] To regulate the leakage flow, multiple grooves are formed on the wall surface 20. These grooves are arranged within the area of ​​the blade tip of the blade 10 covering the wall surface 20, which can be understood as the area of ​​the wall surface 20 swept by the blade tip during rotation. Multiple groove structures are set within this area and arranged in an array along the direction of the wall surface 20. For example, in the area of ​​the wall surface 20 above the blade 10 channel, multiple grooves can be arranged sequentially along the airflow direction, maintaining a certain spatial spacing between the grooves to form a regular array structure.

[0025] Each groove extends along the airflow direction, forming a slender recess. In other words, the extension direction of the groove is roughly consistent with the mainstream airflow direction in the blade's 10 passage. With this structural arrangement, when the leakage flow in the blade tip clearance passes through the grooved area, some of the airflow will enter the interior of the groove, forming a local backflow or turbulent flow structure within the groove, thereby changing the flow state near the blade tip clearance and weakening the development of leakage vortices.

[0026] In this embodiment, this application provides an array of grooves extending along the airflow direction in the wall 20 region corresponding to the blade 10. This allows the leakage flow in the blade tip clearance to partially enter the grooves as it passes through the grooved area, forming local backflow or turbulent flow within the grooves. This alters the flow structure near the blade tip clearance and weakens the development of leakage vortices. Unlike existing active control methods that rely on external energy input, actuators, or feedback control systems for flow regulation, this application uses an array of grooves on the wall 20 to passively regulate the leakage flow in the blade tip clearance by intervening in the flow solely through the structure itself. This requires no additional energy input or complex control systems to adjust the leakage flow in the blade tip clearance region. While reducing structural complexity and system energy consumption, it improves structural reliability and engineering applicability, thus achieving the goal of effectively regulating the leakage flow in the blade tip clearance region through simple and effective structural improvements.

[0027] In some embodiments of this application, the groove formed on the wall 20 can adopt an arc-shaped cross-section structure. That is, when viewed in a cross-section perpendicular to the extension direction of the groove, the bottom contour of the groove is an arc curve, rather than a straight line or a broken line structure. Compared with traditional rectangular grooves, trapezoidal grooves, and other cross-sectional shapes with obvious sharp angles, the bottom and sidewalls of the arc-shaped cross-section groove transition through a continuous curve, thereby forming a smoother overall groove structure. This structural form allows the airflow to have a smoother flow path when entering or leaving the groove, reducing flow separation or local energy loss caused by geometric abrupt changes.

[0028] In terms of specific structural implementation, the arc-shaped cross-section can be represented as a circular arc profile. For example, the bottom profile is composed of a circular arc, gradually transitioning to the wall surface 20 on both sides, thus forming a smooth curved surface structure. In some embodiments, the arc-shaped cross-section can adopt an approximately semi-circular structure, that is, forming a semi-circular groove on the cross-section. Through this structural design, a space of a certain volume can be formed inside the groove. When the leakage flow in the blade tip gap passes through the slotted area, part of the airflow can enter the interior of the groove along the arc-shaped profile, forming a local backflow area or turbulent flow structure inside the groove.

[0029] Furthermore, the arc-shaped cross-section groove can be appropriately adjusted according to specific application requirements. For example, the arc profile can be slightly stretched or compressed to form arc structures with different curvatures, adapting to application requirements under different sizes or flow conditions. By adjusting the geometry of the arc profile, the flow path and recirculation structure of the airflow after entering the groove can be altered to some extent, thereby affecting the flow state in the blade tip clearance region to varying degrees.

[0030] In this embodiment, by setting the groove to an arc-shaped cross-section structure, a relatively smooth flow transition can be maintained during the airflow entering and leaving the groove, while ensuring a relatively simple structure and ease of manufacturing. This also creates a stable disturbance or backflow region within the groove, thereby altering the flow structure near the blade tip clearance and weakening the development of leakage vortices. Thus, the control effect of the grooved wall structure 20 on the leakage flow at the blade tip clearance can be further enhanced.

[0031] In one embodiment, the groove depth is H, the cross-sectional radius is R, and the condition 0.33 ≤ H / R ≤ 3 is met. Here, the groove depth H represents the depth dimension of the groove extending from the surface of the wall 20 into the interior of the wall 20, and the cross-sectional radius R represents the curvature dimension of the arc-shaped cross-section groove. When the groove cross-section has a semi-circular structure, R can be understood as the radius dimension of the semi-circular contour.

[0032] When the H / R value is too small, for example, significantly less than 0.33, the tank is shallow overall, and the flow space that can be accommodated inside the tank is small. The leakage flow in the blade tip clearance enters the tank body with less airflow when passing through the slotted area, making it difficult to form an effective backflow or disturbance structure inside the tank. This has a limited effect on regulating the flow state near the blade tip clearance and makes it difficult to effectively control the leakage flow.

[0033] Conversely, when the H / R value is too large, such as significantly greater than 3, the tank depth is relatively large. Although the airflow can enter the tank more easily, the excessively deep tank may lead to a strong and unstable flow structure inside the tank. This may not only increase local flow losses, but also have an adverse effect on the structural strength and fabrication feasibility of the wall surface, thereby reducing the overall engineering applicability of the structure.

[0034] In this embodiment, by controlling H / R within the range of 0.33 ≤ H / R ≤ 3, a good balance can be achieved between the tank structure size and the flow control effect. On the one hand, the tank has sufficient internal space to allow some of the leakage flow to enter the tank and form a stable backflow or turbulent flow structure; on the other hand, it avoids the structural complexity and unstable flow problems caused by an excessively deep tank, thereby improving the control effect on the leakage flow at the blade tip clearance while ensuring structural simplicity and feasibility.

[0035] In one embodiment, the tip clearance is δ, and the cross-sectional radius of the groove is R, satisfying 0.05 ≤ δ / R ≤ 1.5. Here, the tip clearance δ represents the distance between the tip of the blade 10 and the wall surface 20, while the cross-sectional radius R represents the curvature dimension of the arc-shaped cross-sectional groove. In the case of using a semi-circular cross-sectional groove, R can be understood as the radius dimension of the semi-circular profile.

[0036] When the value of δ / R is too small, for example, significantly less than 0.05, it indicates that the blade tip clearance is too small relative to the channel size. In this case, the leakage flow in the blade tip clearance is small, and the airflow cannot effectively enter the channel, thus weakening the channel's control over the leakage flow and making the influence of the slotted structure on the flow state in the blade tip region relatively limited.

[0037] Conversely, when δ / R is too large, for example, significantly greater than 1.5, it indicates that the blade tip clearance is too large relative to the channel size. In this case, the leakage flow has strong momentum and a large flow rate when passing through the blade tip clearance. The airflow is more likely to directly cross the slotted area without entering the channel, thereby reducing the channel's interference with the leakage flow and making it difficult for the slotted structure to form an effective flow regulation effect.

[0038] In this embodiment, by controlling δ / R within the range of 0.05 ≤ δ / R ≤ 1.5, a more reasonable matching relationship can be achieved between the blade tip clearance dimension and the channel structure dimensions. Within this range, some of the leakage flow in the blade tip clearance can enter the channel and form disturbances or backflow structures within the channel, thereby changing the flow state near the blade tip clearance and weakening the development of leakage vortices, further enhancing the control effect of the slotted wall structure 20 on the leakage flow in the blade tip clearance.

[0039] Please see Figure 3 , Figure 3This is a cross-sectional schematic diagram of a channel provided in an embodiment of the present invention. In one embodiment, the axis of the channel is inclined relative to the flow direction. The axis of the channel can be understood as the centerline along the length of the channel, while the flow direction corresponds to the mainstream direction of airflow in the blade 10 channel, for example, the direction in which airflow flows from the inlet side to the outlet side of the blade 10 channel. When viewed from the wall 20, the channel is not completely parallel to the airflow direction, but is arranged at a certain angle relative to the airflow direction.

[0040] The channel can be arranged at a certain angle relative to the mainstream direction, so that the extension direction of the channel forms an angle with the airflow direction. With this structural arrangement, when the leakage flow in the blade tip clearance passes through the slotted area, the airflow entering the channel not only flows along the channel direction, but also generates lateral deflection or disturbance inside the channel, thereby changing the development path of the leakage flow in the blade tip region.

[0041] When the axis of the tank is tilted relative to the flow direction, the leaking flow is more likely to form asymmetrical backflow structures or local vortex structures inside the tank, thereby enhancing the tank's interference with the leaking flow. Compared to a tank arranged entirely along the flow direction, an tilted tank can alter the flow trajectory of the leaking flow to some extent, causing the leaking flow to undergo more significant deflection and diffusion when passing through the slotted area, thus weakening the development of leakage vortices.

[0042] In this embodiment, by tilting the channel axis relative to the flow direction, the channel's ability to control the tip clearance leakage flow can be enhanced without increasing structural complexity. This makes the influence of the slotted structure on the flow state in the tip region more significant, thereby further improving the control effect on the tip clearance leakage flow.

[0043] Furthermore, in some embodiments of this application, the angle between the axis of the channel and the flow direction is θ, and satisfies 0°≤θ≤75°. Here, the angle θ represents the angle between the extension direction of the channel and the mainstream direction of the airflow in the blade 10 channel. For example, when the axis of the channel is completely aligned with the airflow direction, the angle θ is 0°, while when the axis of the channel is tilted relative to the airflow direction, a corresponding angle θ is formed.

[0044] When the included angle θ is too small, for example, close to 0°, the tank is basically arranged along the flow direction. At this time, the flow path of the leakage flow after entering the tank is relatively consistent with the mainstream direction. The lateral deflection and disturbance generated by the airflow inside the tank are relatively weak, so the adjustment effect on the flow structure in the blade tip gap region is limited, and it is difficult to have a significant impact on the development of the leakage flow.

[0045] Conversely, when the included angle θ is too large, for example, significantly greater than 75°, the angle between the extension direction of the tank and the airflow direction is large. When the airflow passes through the slotted area, it is not easy to smoothly enter the interior of the tank. Instead, it is more likely to directly sweep across the slot opening along the wall 20, thereby reducing the possibility of forming an effective backflow or disturbance structure inside the tank, which weakens the control effect of the slotted structure on the leakage flow.

[0046] In this embodiment, by controlling the included angle θ within the range of 0°≤θ≤75°, a more reasonable geometric relationship can be formed between the extension direction of the channel and the airflow direction. On the one hand, the channel can provide an appropriate guiding path for the airflow entering the channel, allowing some of the leakage flow to enter the channel interior; on the other hand, the inclined setting can also cause a certain degree of deflection and disturbance of the airflow inside the channel, thereby changing the flow structure near the blade tip clearance region and weakening the development of leakage vortices, further improving the control effect of the grooved structure on the blade tip clearance leakage flow.

[0047] Please see Figure 4 , Figure 4 This is a top view of a groove provided in an embodiment of the present invention. In one embodiment, adjacent grooves maintain a substantially consistent spacing, so that multiple grooves form a regularly arranged structure on the wall surface 20. For example, in the area of ​​the wall surface 20 above the blade 10 channel, multiple grooves can be sequentially arranged along the airflow direction, and the distance between adjacent grooves can be kept consistent, thereby forming a groove array structure arranged along the flow direction. Alternatively, multiple grooves can be sequentially arranged in a certain direction in the area of ​​the wall surface 20 corresponding to the blade 10 channel, so that the grooves present a regular and uniform spatial distribution.

[0048] If the distribution of the channels is irregular, such as with large variations in spacing, it may result in densely packed channels in some areas and sparsely packed channels in others, leading to uneven spatial distribution of flow control effects. By using an array arrangement with equal spacing, the channels can form a more uniform structural distribution on the wall 20, ensuring that the leakage flow is continuously disturbed as it passes through the slotted areas, thereby facilitating a stable change in the flow structure of the blade tip clearance region.

[0049] In this embodiment, by arranging multiple slots at equal intervals on the wall 20, the slotted area can form a continuously distributed control structure in space. When the leakage flow in the blade tip clearance passes through this area, the leakage flow can interact with multiple slots in sequence, causing the airflow to continuously generate disturbances or backflow structures as it enters different slots, thereby gradually changing the flow state near the blade tip clearance.

[0050] Furthermore, in one embodiment, the spacing between adjacent grooves is S, and the cross-sectional radius of the groove is R, satisfying 0.67 ≤ S / R ≤ 2. The spacing S can be the center distance or edge distance between two adjacent grooves along the wall surface 20, while the cross-sectional radius R represents the curvature dimension of the arc-shaped cross-section groove. When the groove cross-section is a semi-circular structure, R is the radius dimension of the semi-circular profile.

[0051] When the S / R value is too small, for example, significantly less than 0.67, the spacing between adjacent tanks is too small, and multiple tanks are too densely distributed on the wall 20. In this case, the airflow enters the next tank before it has returned to a stable flow state after entering one tank, which can easily lead to mutual interference between the flow structures of adjacent tanks, thereby reducing the control effect of a single tank on the leakage flow.

[0052] Conversely, when the S / R value is too large, such as significantly greater than 2, the spacing between adjacent slots is large, and the slots are sparsely distributed on the wall 20. In this case, the leakage flow in the blade tip clearance may only interact with a few slots when passing through the slotted area, and most of the airflow will directly pass through the unslotted area, thus weakening the overall control capability of the slotted structure over the leakage flow.

[0053] In this embodiment, by controlling the flow ratio (S / R) within the range of 0.67 ≤ S / R ≤ 2, a reasonable balance can be achieved between the channel distribution density and the flow control effect. On the one hand, maintaining an appropriate spacing between the channels allows the airflow to interact with multiple channels sequentially as it passes through the slotted area; on the other hand, it avoids excessive channel density that could lead to mutual interference of the flow structures. Thus, while ensuring a reasonable structural arrangement, the slotted structure on the wall surface 20 forms a continuous and stable flow control region in space, thereby further enhancing the control effect on the leakage flow at the blade tip clearance.

[0054] In one embodiment, when viewed in a cross section perpendicular to the extension direction of the groove, the bottom profile of the groove has a semi-circular curved structure, that is, the cross section of the groove is composed of a circular arc, the two ends of which are connected to the wall 20, thereby forming a structure similar to a semi-circular groove.

[0055] Compared to rectangular or trapezoidal channels with sharp angles, the bottom profile of a semi-circular channel is continuous and smooth. When airflow passes through the slotted area, it can enter the channel along the semi-circular curved surface, thus forming a relatively smooth flow transition. This can reduce local separation or abrupt flow changes when airflow enters the channel to a certain extent, allowing the airflow to form a more stable turbulent flow or recirculation structure inside the channel.

[0056] When the leakage flow in the blade tip clearance passes through the semi-circular groove region, some of the airflow can enter the groove along the semi-circular curved surface, forming a local recirculation zone inside the groove, thereby altering the flow structure near the blade tip clearance. In this way, the development process of the leakage flow can be disturbed, weakening the leakage vortex structure formed by the leakage flow.

[0057] In this embodiment, by designing the arc-shaped cross-section groove as a semi-circular structure, the airflow can maintain a relatively smooth flow path when entering and leaving the groove, while ensuring that the groove structure is simple and easy to process. Stable flow disturbances are also formed inside the groove, thereby further improving the control effect of the grooved structure on the tip clearance leakage flow.

[0058] In one embodiment, when multiple channels are arranged on the wall 20, the extension range of each channel in that direction is consistent, so that all channels have the same geometric length, that is, the distance between the beginning and end of each channel is the same, thus forming a channel structure with a uniform length. If the lengths of different channels differ greatly, it may cause some channels to generate strong disturbances to the airflow, while other channels may have a weaker impact on the airflow, resulting in an uneven spatial distribution of the flow control effect.

[0059] In this embodiment, by setting the extension length of multiple slots to be the same, each slot can have a uniform structural scale in space, thereby creating a more uniform flow control effect when the airflow passes through the slotted area. When the leakage flow in the blade tip gap passes through this area, the flow process of the airflow in different slots is basically the same, so that the airflow entering the interior of each slot can form similar backflow or disturbance structures, thereby producing a continuous and stable interference effect on the leakage flow as a whole.

[0060] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A wall slotted structure for regulating leakage flow in the tip clearance of a hydrofoil, characterized in that, include: blade; A wall surface is disposed opposite to the blade, and a blade tip gap is formed between the blade tip and the wall surface. Multiple grooves are formed on the wall surface, and the multiple grooves are disposed in the projection area of ​​the blade on the wall surface and arranged in an array along the wall surface. The groove extends along the flow direction to regulate the leakage flow in the blade tip gap.

2. The wall slotting structure according to claim 1, characterized in that, The groove is an arc-shaped cross-section groove.

3. The wall slotting structure according to claim 2, characterized in that, The depth of the trough is H, the cross-sectional radius of the trough is R, and the following condition is met: 0.33≤H / R≤3.

4. The wall slotting structure according to claim 2, characterized in that, The blade tip clearance is δ, and the cross-sectional radius of the groove is R, satisfying: 0.05≤δ / R≤1.

5.

5. The wall slotting structure according to claim 1, characterized in that, The axis of the tank is inclined relative to the flow direction.

6. The wall slotting structure according to claim 5, characterized in that, The angle between the axis of the tank and the flow direction is θ, and satisfies: 0°≤θ≤75°.

7. The wall slotting structure according to claim 2, characterized in that, The multiple grooves are arranged in an array at equal intervals along the wall.

8. The wall slotting structure according to claim 7, characterized in that, The distance between adjacent tanks is S, and the cross-sectional radius of the tank is R, satisfying: 0.67≤S / R≤2.

9. The wall slotting structure according to claim 2, characterized in that, The arc-shaped cross-section groove is a semi-circular groove.

10. The wall slotting structure according to claim 1, characterized in that, The multiple tanks extend to the same length along the flow direction.

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