Cascade voltage transformation type micro-channel heat dissipation structure and high-power laser cut-off diaphragm

Abstract

The invention discloses a stepped voltage transformation type micro-channel heat dissipation structure and a high-power laser cut-off diaphragm. The stepped voltage transformation type micro-channel heat dissipation structure comprises a flow channel (3), a gradually-broadened type micro-channel (4), a first stepped voltage transformation structure (5) and a second stepped voltage transformation structure (6). The first step variable-pressure structure (5) and the second step variable-pressure structure (6) comprise multi-stage oval cylinder arrays, the number of oval cylinders is increased step by step, the oval short axis length is decreased step by step, the fluid circulation sectional area is decreased step by step, and the flowing speed is increased step by step to form a jet flow effect to accelerate fluid. And finally, the fluid enters the gradually-broadened micro-channels (4) at a higher flow speed to realize flow heat exchange. According to the invention, a stepped variable-pressure structure with the number of elliptical cylinders gradually increased, the length of a short shaft gradually decreased and the total flow section gradually decreased is designed at the inlet section of the micro-channel, so that fluid can be rapidly pressurized and accelerated in a gradient manner, and the problem that the inlet pressure of the micro-channel is too large and concentrated is effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser devices, and more specifically, relates to a stepped variable pressure type microchannel heat dissipation structure and a high-power laser stop aperture having the same. Background Art

[0002] In high-power lasers, the aperture is an entity that restricts the light beam, and its function is to pass a light beam of a specific size and intercept unwanted stray light. When a laser beam of tens of kilowatts passes through the aperture hole, the laser power intercepted by the aperture is very considerable, and the extremely high power density distribution around the aperture hole will cause overheating, resulting in local air turbulence and affecting the beam quality. In the previous heat dissipation design of the aperture, using the method of fluid flowing through the macrochannel to absorb heat has an upper limit on the heat absorption capacity and cannot cope with the temperature rise problem caused by too high power density. Microchannel heat transfer is a new heat transfer structure that uses micron-sized channels for flow heat transfer. The channel size is usually between 10 microns and 1 mm, and the fluid flow state in the channel is extremely stable, and the heat transfer efficiency is very considerable. It has a series of advantages such as compact structure, high energy efficiency, lightness and convenience, long service life, and strong adaptability. It has been widely used in the fields of microelectronic devices, high-efficiency heat dissipation in aerospace, and heat transfer in automotive air conditioning systems.

[0003] Therefore, designing a microchannel heat dissipation flow path can effectively meet the requirements of efficient heat dissipation of the stop aperture. At present, the existing similar microchannel designs for the heat dissipation of high-power laser apertures do not solve the above problems of excessive pressure, flow redundancy, uneven flow path size, and kinetic energy loss. The patent "Embedded Adjustable High Heat Dissipation Performance Laser Stop Aperture" dissipates heat from the aperture by designing an additional aperture base and designing a transverse microchannel inside the base. On the one hand, the large-area microchannel causes huge frictional resistance along the way, and the problem of concentrated inlet pressure has not been solved; on the other hand, the patent does not consider the power density distribution of stray light within the basic conditions of heat design. In the actual heat transfer process, only a local part of the microchannel structure in the large-area microchannel plays a heat transfer role. The patent "Spiral Adjustable High-Power Laser Liquid-Cooled Stop Aperture" dissipates heat by setting microchannels in the inner cavity of the aperture blade, and a refrigerating liquid is introduced into the microchannel to cool down and control the deformation of the blade. However, this patent also does not consider the power distribution and flow distribution.

[0004] However, through the simulation of the heat dissipation process, it is found that there are the following problems in designing a microchannel structure in a larger-sized aperture: (1) The local pressure at the inlet section is too high ( Figure 4(in the red section). When the fluid enters the microchannel from the inlet, due to the extremely fine channel size of the microchannel, most of the fluid cannot flow into the microchannel in time, resulting in local flow redundancy and excessive pressure. This situation may cause local oscillations, and excessive pressure may burst the diaphragm wall and cause liquid leakage, thus affecting the normal operation of the laser; (2) Since the laser cooling liquid supply system is a multi-branch parallel connection, the excessive resistance at the inlet of the diaphragm branch will force the fluid to enter other branches, affecting the flow distribution of other branches and further affecting the normal working state; (3) In a diaphragm with a larger size, the flow resistance brought by the microchannel structure is huge, and the flow heat transfer capacity of the fluid in the latter section of the microchannel is attenuated, which is not conducive to ensuring its heat dissipation performance; (4) The stray light power density distribution shows a non-uniform gradient decrease, and the microchannel size should also be adjusted according to actual conditions. Summary of the Invention

[0005] In view of the above defects or improvement requirements of the prior art, the present invention provides a stepped variable pressure microchannel heat dissipation structure and a high-power laser cut-off diaphragm. The flow rate of the fluid is controlled by a flow valve before entering the flow channel. Considering the local pressure concentration problem at the inlet section, the fluid will pass through a stepped pressurization structure, which disperses the locally excessive pressure at the inlet section into a stepped pressurization distribution form, thereby avoiding the possibility of excessive local pressure at the microchannel inlet causing flow instability. And the fluid after pressurization can enter the microchannel at a faster flow rate to achieve the purpose of enhancing heat transfer. At the same time, according to the power density distribution of stray light around the diaphragm hole, the microchannel size is designed as a gradient increasing type outward along the diaphragm hole, which can relieve the flow resistance in the flow channel while meeting the heat dissipation requirements.

[0006] To achieve the above object, according to the first aspect of the present invention, a stepped variable pressure microchannel heat dissipation structure is provided, including a flow channel, a gradually expanding microchannel disposed in the flow channel, a first stepped variable pressure structure disposed at the inlet of the gradually expanding microchannel, and a second stepped variable pressure structure disposed at the outlet of the gradually expanding microchannel;

[0007] The first stepped variable pressure structure and the second stepped variable pressure structure include a multi-stage elliptical cylinder array. The number of elliptical cylinders increases step by step, the length of the short axis of the ellipse decreases step by step, and the fluid flow cross-sectional area decreases step by step. When the fluid flows through the elliptical cylinder, the local flow pressure increases due to the narrowing of the channel size, and the flow velocity increases to form a jet effect to accelerate the fluid. Each time the narrowest flow cross-sectional area clamped by the elliptical cylinders is passed, there is an increase in pressure and an enhancement of the jet. And with the gradual increase of the elliptical cylinders, the total flow cross-sectional area of each stage decreases in turn to form a greater increase in pressure and flow velocity. Finally, the fluid enters the gradually expanding microchannel at a higher flow velocity to achieve flow heat transfer.

[0008] Further, a spoiler array is provided between the outlets of the first stepped voltage transformation structure and the second stepped voltage transformation structure and the inlet of the gradually expanding microchannel to balance the influence of the flow rates at different positions.

[0009] Further, the first stepped voltage transformation structure and the second stepped voltage transformation structure adopt a streamlined elliptical cylinder structure form.

[0010] Further, the first stepped voltage transformation structure and the second stepped voltage transformation structure adopt one of the structural forms of a triangular cylinder, a polygonal cylinder or a cylinder.

[0011] Further, the number of stages of the first stepped voltage transformation structure, the second stepped voltage transformation structure, the spoiler array and the gradually expanding microchannel is designed according to the specific power distribution and the flow channel pressure distribution.

[0012] Further, the gradually expanding microchannel adopts a gradually expanding size design to match the heat dissipation requirements of different power distributions.

[0013] Further, a stepped boost / drop structure is locally applied to the gradually expanding microchannel;

[0014] Further, series-parallel connections are made between different gradually expanding microchannels to make the fluid collide and mix.

[0015] Further, along the direction of increasing the outer radius of the aperture, the design sizes of the gradually expanding microchannel increase in sequence.

[0016] Further, the gradually expanding microchannel is subjected to multi-segment processing, and a plurality of stepped voltage transformation structures are arranged in adjacent segment microchannels to re-pressurize and accelerate the fluid to enhance its fluidity.

[0017] Further, it further includes a channel entrance and exit provided at the end of the flow channel.

[0018] Further, it further includes a flow valve provided at the end of the flow channel;

[0019] The flow valve is used for flow feedback and adjustment of the aperture branch to timely control the flow rate through the aperture branch.

[0020] According to the second aspect of the present invention, a high-power laser cutoff aperture is provided, which includes an aperture plate and the stepped voltage transformation type microchannel heat dissipation structure provided on the aperture plate.

[0021] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0022] 1. In the structure of the present invention, the flow rate of the fluid is controlled by a flow rate valve before entering the flow channel. Considering the local pressure concentration problem in the inlet section, the fluid passes through a stepped pressure boosting structure, which disperses the locally over-concentrated pressure in the inlet section into a stepped pressure boosting distribution form, thereby avoiding the possibility of flow instability caused by excessive local pressure at the microchannel inlet. Moreover, the fluid after pressure boosting can enter the microchannel at a faster flow rate, achieving the purpose of enhancing heat transfer. At the same time, according to the power density distribution of stray light around the aperture, the size of the microchannel is designed to increase gradually in a gradient manner outward along the aperture, which can relieve the flow resistance in the flow channel while meeting the heat dissipation requirements.

[0023] 2. In the structure of the present invention, by designing multiple passive stepped pressure transformation structures in the microchannel, the purpose of boosting the flow rate is achieved. On the one hand, the stepped pressure transformation structure can re-accelerate the fluid flow and ensure the heat transfer performance. On the other hand, the simple passive pressure transformation design avoids the sharp increase in processing cost and time caused by the complexity of the flow channel structure.

[0024] 3. In the structure of the present invention, a stepped pressure transformation structure is designed in the inlet section of the microchannel, where the number of elliptical cylinders increases gradually, the minor axis length decreases gradually, and the total flow cross-section decreases gradually. This can rapidly boost the pressure in a gradient manner to accelerate the fluid and effectively solve the problem of excessive and concentrated pressure at the microchannel inlet.

[0025] 4. In the structure of the present invention, the power distribution on the aperture decreases in a gradient manner from the hole edge to the surrounding. The size of the microchannel is designed to increase gradually outward along the hole edge, which can effectively meet the heat dissipation requirements and greatly relieve the flow resistance at the same time.

[0026] 5. In the structure of the present invention, row cylinders are arranged at the end of the stepped pressure boosting structure, which can further disturb the high-speed fluid to enhance its heat transfer performance and provide guarantee for the heat transfer of the fluid entering the microchannel.

[0027] 6. In the structure of the present invention, a multi-segment microchannel design is applied in the heat dissipation flow channel of a larger-sized aperture. A stepped pressure boosting / dropping structure is arranged between adjacent microchannels, which can effectively boost the fluid flow rate and ensure the flow characteristics and heat transfer performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the aperture model in the embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the microchannel stepped pressure boosting structure model in the embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of a two-segment microchannel and two stepped structures in the embodiment of the present invention;

[0031] Figure 4 It is the original microchannel pressure distribution in the embodiment of the present invention;

[0032] Figure 5 This is the pressure distribution in the channel after adding a gradient supercharging structure to the embodiment of the present invention.

[0033] Figure 6 This is the temperature comparison result between the macro-channel and the micro-channel in the embodiment of the present invention. Among them, 6(a) is the simulation result of the macro-channel, and 6(b) is the simulation result of the micro-channel.

[0034] In all the drawings, the same reference numerals represent the same technical features. Specifically: 1 - diaphragm plate, 2 - channel inlet and outlet, 3 - flow channel, 4 - gradually expanding micro-channel, 5 - first stepped pressure-changing structure, 6 - second stepped pressure-changing structure, 7 - flow valve. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] Embodiment 1

[0037] As Figure 4 shown is the pressure distribution of the original micro-channel. Through simulation analysis, it is found that at the inlet of the flow channel in Figure 4 , the pressure at the front end of the micro-channel is large and concentrated. To solve the above problems, as Figures 1 - 3As shown in the figure, an embodiment of the present invention provides a stepped variable pressure microchannel heat dissipation structure, which includes a flow channel 3, a gradually expanding microchannel 4 provided in the flow channel 3, a first stepped variable pressure structure 5 provided at the entrance of the gradually expanding microchannel 4, and a second stepped variable pressure structure 6 provided at the exit of the gradually expanding microchannel 4; the first stepped variable pressure structure 5 and the second stepped variable pressure structure 6 include a multi-stage elliptical cylinder array, the number of elliptical cylinders increases step by step, the length of the short axis of the ellipse decreases step by step, the cross-sectional area of fluid flow decreases step by step, and when the fluid flows through the elliptical cylinder, the local flow pressure increases due to the narrowing of the channel size, and the flow velocity increases to form a jet effect to accelerate the fluid. Each time the narrowest flow area clamped by the elliptical cylinders is passed, there is an increase in pressure and an enhancement of the jet. And with the gradual increase of the elliptical cylinders, the total flow area of each stage decreases in turn to form a greater increase in pressure and flow velocity. Finally, the fluid enters the gradually expanding microchannel 4 at a higher flow velocity to achieve flow heat transfer, realizing the splitting of the overly concentrated pressure in the inlet section into a pressure distribution form with a gradient increase, thereby solving the problems of flow redundancy, excessive local pressure and concentration in the inlet section. In the structure of the present invention, the flow rate of the fluid is controlled by a flow valve before entering the flow channel. Considering the local pressure concentration problem in the inlet section, the fluid will pass through a stepped pressurization structure, dispersing the overly concentrated pressure in the inlet section into a stepped pressurization distribution form, thereby avoiding the possibility of flow instability caused by excessive local pressure at the microchannel inlet. And the fluid after pressurization can enter the microchannel at a faster flow velocity, achieving the purpose of enhancing heat transfer. At the same time, according to the power density distribution of stray light around the aperture, the microchannel size is designed to increase in a gradient manner outward along the aperture, which can relieve the flow resistance in the flow channel while meeting the heat dissipation requirements.

[0038] Further, when the fluid flows into the microchannel, the flow rate of the aperture branch is macroscopically regulated by a flow valve. After passing through the stepped pressurization structure, the fluid is quickly pressurized and accelerated into the microchannel, avoiding the problems of flow redundancy, pressure surge and concentration at the microchannel inlet. Since the power distribution of stray light decreases in a gradient manner from the hole edge outward, the microchannel size is designed to expand in a stepped manner in the direction outward along the aperture radius, relieving the flow resistance while meeting the heat dissipation requirements. When the aperture size is large, by designing a multi-stage microchannel and setting a multi-stage pressurization and acceleration structure between adjacent microchannels, the flow characteristics of the fluid in the flow channel can always be observable, and at the same time, the heat transfer performance of the entire microchannel heat dissipation system is also guaranteed.

[0039] To achieve the purpose of supercharging and accelerating, an elliptical cylinder with a streamlined shape is adopted as the structure for stepped supercharging, rather than other forms such as heat exchange fins and concave-convex structures. The aim is to minimize the kinetic energy loss or even backflow caused by the impact of the fluid on the local structure while considering supercharging and accelerating. At the end of the gradient supercharging structure, the fluid passes through cylindrical turbulators before entering the microchannel. The turbulator is located at the front end of the microchannel entrance. Its function is to turbulize and mix the fluid entering the microchannel again and distribute the flow velocity. Specifically, the first stepped pressure-changing structure 5 and the second stepped pressure-changing structure 6 adopt the structure form of an elliptical cylinder with a streamlined shape. Or adopt one of the structure forms of a triangular cylinder, a polygonal cylinder or a cylinder structure with a gradually expanding outer shape. The fluid flows through the flow valve into the heat dissipation channel. After passing through the stepped pressure-changing structure, the pressure rises rapidly, and the fluid accelerates, and can enter the microchannel with greater kinetic energy, improving the heat exchange performance. When the aperture size is large, the microchannel can be designed in sections and a multi-stage boosting / depressurizing structure can be set therein, which can effectively boost the flow velocity and ensure its considerable heat dissipation performance.

[0040] The power density of stray light near the aperture decreases in a gradient distribution trend. Therefore, at different radius positions, the requirements for the heat dissipation capacity of the microchannel are not the same. If all microchannels adopt the same size, there will be a problem that the additional heat dissipation performance cannot be exerted and the resistance will be further increased. Therefore, along the direction of increasing outer radius from the aperture, the design size of the microchannel should increase in sequence, while ensuring the heat exchange performance, reducing the resistance during the flow process. Specifically, the first stepped pressure-changing structure 5, the second stepped pressure-changing structure 6, the turbulator array and the gradually expanding microchannel 4 are designed in terms of the number of stages according to the specific power distribution and the flow channel pressure distribution. The gradually expanding microchannel 4 adopts a gradually expanding size design to match the heat dissipation requirements of different power distributions, and a stepped boosting / depressurizing structure is applied locally, or series-parallel connection is carried out between different gradually expanding microchannels 4 to make the fluid impact and mix, and similar effects can also be obtained. In addition, the gradually expanding microchannel 4 is segmented, and a plurality of stepped pressure-changing structures are arranged in adjacent segments of the microchannel to re-supercharge and accelerate the fluid to strengthen its fluidity.

[0041] In addition, a turbulator array is provided between the outlets of the first stepped pressure-changing structure 5 and the second stepped pressure-changing structure 6 and the inlet of the gradually expanding microchannel 4 to balance the influence of the flow rate at different positions. In addition, in the microchannel structure, there is usually a huge flow resistance. Therefore, it is necessary to segment the microchannel and arrange a plurality of stepped pressure-changing structures in adjacent segments of the microchannel to re-supercharge and accelerate the fluid to strengthen its fluidity, and continue to carry out flow heat exchange in the microchannel when entering the next stage again.

[0042] Furthermore, the structure further includes a channel inlet / outlet 2 provided at the end of the flow channel 3 and a flow valve 7 provided at the end of the flow channel 3; the flow valve 7 is used for flow feedback and regulation of the diaphragm branch to timely control the flow rate through the diaphragm branch and avoid a sudden increase in the local pressure of the microchannel due to excessive inlet flow rate, which belongs to the macroscopic flow regulation means of the inlet section.

[0043] To verify the heat dissipation performance of the structure designed by the present invention, through simulation analysis, the results are as Figure 5 and Figure 6 shown. After stepwise pressurization treatment, the pressure at the inlet of the microchannel increases in a gradient manner, and no obvious pressure concentration distribution appears. The pressure distribution within the entire microchannel becomes more uniform compared to the non-tapering microchannel. Through the analysis of the data shown in the figure, it can be clearly seen that the microchannel structure of this design has significant advantages in terms of pressure distribution and heat dissipation performance optimization. Specifically, the maximum static pressure value at the inlet of the microchannel is approximately 2.49×10 4 Pa, and the minimum value is close to -6.84×10 2 Pa, and the overall pressure increases in a gradient along the microchannel. This result indicates that through stepwise pressurization treatment, the microchannel can effectively avoid the common local pressure concentration problem in traditional designs, ensure the uniformity of the internal pressure distribution, and thus enhance the flow stability. This uniform pressure distribution characteristic significantly reduces the risk of structural stress concentration and equipment performance degradation caused by pressure fluctuations. Combining with the power distribution characteristic of the diaphragm, it is found that the power density is mainly concentrated near the hole edge and shows a gradient decrease trend with the increase of distance. To adapt to this characteristic, the microchannel is designed to gradually increase in size outward along the hole edge. This tapering design can not only effectively conduct and dissipate the heat in the high power density area but also significantly relieve the resistance in fluid flow. Compared with the traditional non-tapering microchannel, the tapering microchannel design optimizes the kinetic energy loss of the internal fluid and effectively improves the overall thermal management performance of the system. Figure 5 The static pressure distribution gradient shown in

[0044] Example 2

[0045] As Figure 1 shown, an embodiment of the present invention provides a stepped variable pressure microchannel heat dissipation structure, which includes a diaphragm plate 1, a channel inlet and outlet 2, a flow channel 3, a gradually expanding microchannel 4, a first stepped variable pressure structure 5 at the microchannel inlet, a second stepped variable pressure structure 6 at the microchannel outlet, and a flow valve 7. Among them, the microchannel size range is designed according to the heat dissipation requirements. The width of the microchannel in the inlet section is 200 μm, which gradually expands to 800 μm along the radial direction outward, and the expansion ratio is 4:1, which can effectively match the hydrodynamic and heat dissipation performance. Oval cylinders are arranged in the inlet section. By controlling the decreasing of the minor axis length of the cylinders (decreasing from 8 mm to 3 mm) and the increasing of the number of cylinders (increasing from 1 to 5), the initial stepped pressurization of the fluid is achieved. The first stepped variable pressure structure 5 effectively alleviates the problem of pressure concentration at the microchannel inlet. Through the gradually increasing oval cylinders, the pressure distribution gradually decreases from 2.49×10 4 Pa to about 1.8×10 4 Pa, the average value at the inlet. This avoids the impact of the outlet fluid on other components of the heat dissipation system. In addition, a series-parallel flow channel design is adopted in the microchannel, so that the fluid undergoes multiple impacts and mixing during the flow process, improving the heat transfer efficiency. The length of the series flow channel is 2 mm, the width of the parallel section is controlled at 100 μm, and the total length of the flow channel is about 8 mm, optimizing the balance between the heat dissipation efficiency and the structural compactness. It is found through analysis that the heat dissipation efficiency of the entire structure is increased by 50%-60%, which is particularly suitable for the thermal management requirements of high-power lasers. The structure of the present invention designs a stepped variable pressure structure with gradually increasing number of oval cylinders, gradually decreasing minor axis length, and gradually decreasing total flow cross-section in the microchannel inlet section, which can quickly increase the pressure gradient to accelerate the fluid and effectively solve the problem of excessive and concentrated pressure at the microchannel inlet.

[0046] Example 3

[0047] In another embodiment of the present invention, a high-power laser stop aperture is provided, which includes a diaphragm plate 1 and a stepped-transformer microchannel heat dissipation structure provided on the diaphragm plate 1. The stepped boost / buck structure provided in the microchannel is one of the key innovations of the present invention. This structure boosts the fluid flow rate to an ideal range by arranging multiple boost structures between adjacent microchannels while maintaining stable fluid flow. Specifically, the stepped boost / buck structure adopts a tapered geometric design, with its inlet width decreasing step by step (e.g., decreasing from 8 mm to 2 mm), and the outlet section gradually expanding. Through the combination of this tapering and expansion, the kinetic energy of the fluid is effectively increased when passing through each section of the boost / buck structure, thus avoiding the common problems of flow rate reduction and flow stagnation in traditional microchannels. In addition, the stepped boost / buck structure further optimizes the heat transfer performance through a distributed flow disturbance design. Elliptical cylinder or polygonal cylinder flow disturbance modules are arranged in the gaps between adjacent microchannels at the front and rear ends, and their spacing and shape are finely adjusted according to the power distribution characteristics of the aperture. For example, in the high heat flux area, the cylinder spacing is reduced to 1 mm to enhance local fluid mixing and heat exchange; while in the low heat flux area, the cylinder spacing can be increased to 5 mm to reduce flow resistance and improve the overall heat dissipation efficiency. Such a layout design enables the aperture to maintain good heat dissipation performance under different thermal load conditions.

[0048] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A step-by-step transformer microchannel heat dissipation structure, characterized in that: It comprises a flow channel (3), a gradually widening microchannel (4) arranged in the flow channel (3), a first step-by-step pressure-changing structure (5) arranged at the inlet of the gradually widening microchannel (4), and a second step-by-step pressure-changing structure (6) arranged at the outlet of the gradually widening microchannel (4); The first step-by-step pressure-changing structure (5) and the second step-by-step pressure-changing structure (6) comprise a multi-stage elliptical cylinder array, wherein the number of elliptical cylinders increases step by step, the length of the elliptical minor axis decreases step by step, and the cross-sectional area of ​​the fluid flow decreases step by step. When the fluid flows through the elliptical cylinder, the local flow pressure increases due to the narrowing of the channel size, forcing the flow velocity to increase to form a jet effect to accelerate the fluid. Each time the fluid passes through the narrowest flow area sandwiched by the elliptical cylinder, the pressure increases and the jet is enhanced. Moreover, as the number of elliptical cylinders increases step by step, the total flow area of ​​each stage decreases in turn to form a greater pressure increase and flow velocity increase. Finally, the fluid enters the gradually widened microchannel (4) at a higher flow velocity to achieve flow heat exchange at high power.

2. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 1, characterized in that: A flow disturbance array is provided between the outlets of the first step pressure changing structure (5) and the second step pressure changing structure (6) and the inlet of the gradually widened microchannel (4) to promote full mixing of the fluid and balance the influence of flow at different positions.

3. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 2, characterized in that: The first step voltage transformation structure (5) and the second step voltage transformation structure (6) are in the form of streamlined elliptical cylinder structures.

4. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 2, characterized in that: The first step voltage transformation structure (5) and the second step voltage transformation structure (6) are in the form of a triangular column, a polygonal column or a column structure with a gradually widened shape.

5. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 4, characterized in that: The first step pressure transformation structure (5), the second step pressure transformation structure (6), the spoiler array and the gradually widened microchannel (4) are designed in stages according to specific power distribution and flow channel pressure distribution.

6. A step-by-step voltage-changing microchannel heat dissipation structure according to any one of claims 1 to 5, characterized in that: The gradually widened microchannel (4) adopts a gradually widened size design to match the heat dissipation requirements of different power distributions.

7. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 6, characterized in that: The gradually widened microchannel (4) locally applies a stepped pressure increase / depressurization structure.

8. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 6, characterized in that: Different gradually widened microchannels (4) are connected in series or in parallel to allow the fluid to collide and become agitated.

9. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 8, characterized in that: Along the direction of increasing radius toward the outside of the aperture, the channel design dimensions of the gradually widened microchannel (4) increase successively.

10. The step-by-step voltage-changing microchannel heat dissipation structure according to claim 9, characterized in that: The gradually widened microchannel (4) is processed into multiple sections, and a plurality of stepped pressure-changing structures are arranged in adjacent sections of the microchannel to re-pressurize and accelerate the fluid to enhance its fluidity.

11. A step-by-step voltage-changing microchannel heat dissipation structure according to any one of claims 1 to 5, characterized in that: It also includes a channel inlet and outlet (2) arranged on the front or side of the flow channel (3).

12. A step-variable microchannel heat dissipation structure according to any one of claims 1 to 5, characterized in that: It also includes a flow valve (7) arranged at the end of the flow channel (3); The flow valve (7) is used for feedback and regulation of the flow of the aperture branch, so as to timely control the flow through the aperture branch.

13. A high power laser cut-off aperture, characterized in that: It comprises an aperture plate (1), and a stepped voltage-changing microchannel heat dissipation structure as claimed in any one of claims 1 to 12, which is arranged on the aperture plate (1).

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