Bionic micro-channel cooling device for disc laser crystal

Abstract

The invention discloses a novel micro-channel type cooling structure device for a disc laser. The novel micro-channel type cooling structure device comprises a sealing cover, a heat sink, a crystal, a supporting ring and a vortex-shaped channel. The sealing cover and the shell are made of copper-tungsten alloy vortex-shaped flow channels, the main body material of the vortex-shaped flow channels is diamond, and the vortex-shaped flow channels are realized through an etching process, and the vortex-shaped flow channels have the structural advantages that water inlets are formed in the periphery and water outlets are formed in the center, so that the influence on the crystal surface shape caused by overlarge stress generated on the back surface of a heat sink during collision of a traditional jet flow structure is avoided; the light beam quality is reduced; meanwhile, the four vortex flow channels are combined with local impact, so that the fluid generates strong secondary flow and boundary layer disturbance, the convective heat transfer coefficient is increased, a circular heat source of a light spot with the diameter of 17 mm is well adapted, and compared with a traditional micro-flow-channel structure, the temperature uniformity is greatly improved. The invention has the advantage that the problems of stress deformation and non-uniform heat dissipation existing in large-area sheet crystal heat exchange are solved through a unique bionic flow channel structure.

Description

Technical Field

[0001] This application relates to the field of disk laser crystal cooling devices, specifically to a novel microchannel disk laser crystal cooling structure device. Background Technology

[0002] Yb:YAG crystals, with their wide absorption bandwidth, long fluorescence lifetime, and high quantum efficiency, have become the mainstream gain medium for high-power disk lasers. While the revolutionary geometry of this laser significantly improves beam conversion efficiency, approximately 11% of the pump energy is converted into waste heat and deposited within the medium during operation. Existing cooling structures primarily cool one surface of the crystal, leading to a large temperature gradient and thermal stress within the crystal. On the one hand, excessive thermal stress can cause crystal cracking, limiting the increase in pump power density; on the other hand, an excessive temperature gradient can induce thermal lensing, resulting in resonant cavity instability and beam quality degradation. Therefore, efficient thermal management is a core issue in the development of high-power disk lasers.

[0003] Currently, water cooling remains the primary method for dissipating high heat flux densities at kilowatt levels and above. Among these methods, jet cooling is the most widely used, offering advantages such as simple structure and strong controllability. Various forms have been developed, including array jets, phase-change jets, and liquid metal jets. However, jet cooling and disk crystal heat transfer present an inherent contradiction: increasing the jet velocity is necessary to improve the heat transfer coefficient, but this simultaneously increases the axial stress on the back of the heat sink, making the hard and brittle Yb:YAG crystal prone to deformation, warping, breakage, or optical path distortion.

[0004] Microchannel cooling technology, due to its low pressure drop and excellent heat transfer efficiency, has been widely used for heat dissipation in electronic devices such as chips, and is also being explored for application in disk lasers. However, traditional microchannel structures still suffer from problems such as uneven heat transfer and difficulty in adapting to large-area circular heat sources. In recent years, biomimetic heat dissipation structures (such as fractal or hierarchical designs) have attracted attention. By simulating the efficient heat transfer mechanisms of organisms in nature, they are expected to achieve higher energy efficiency ratios and break through the 1000W / cm² heat dissipation capacity. However, existing solutions still need further optimization to simultaneously solve the challenges of stress control and uniformity. Summary of the Invention

[0005] Based on the research on the principles and characteristics of the aforementioned high-efficiency heat exchange structures, and addressing the problems of high thermal stress, high temperature gradient, and uneven heat exchange in the cooling of disk laser crystals, this application provides a biomimetic microchannel cooling device for disk laser crystals. This device draws inspiration from the hierarchical vortex arrangement of blood vessels in the ear of an African elephant—macroscopically, the main veins radially diffuse and then spirally coil to form multi-level vortex centers; microscopically, the capillary network is densely distributed along the vortex direction, with the densest center and sparser outwards, achieving large-area, low-axial-stress, slow-rotational flow and extending the heat exchange time—and through appropriate simplification, designs a vortex-shaped microchannel structure with water entering from the periphery and exiting from the center, effectively adapting to the high heat flux density and large-area heat dissipation requirements of disk laser crystals.

[0006] According to one aspect of this application, a biomimetic microchannel cooling device for a disk laser crystal is provided, comprising a disk crystal 1, a gasket 2, a cover 3, a heat sink 4, a sealing ring 5, a support ring 6, a housing 7, a water outlet channel 8, a vortex channel 9, and a water inlet channel 10.

[0007] The disc crystal 1 is fixed to the upper surface of the heat sink 4 by the gasket 2, and the cover 3 covers the disc crystal 1.

[0008] The heat sink 4 has a circular structure, and multiple vortex-shaped channels 9 are etched on its lower surface, spiraling from the periphery to the center.

[0009] The water inlet channel 10 is located around the heat sink 4 and is connected to the outer starting end of the vortex channel 9;

[0010] The water outlet channel 8 is located at the center of the heat sink 4 and is connected to the center end of the vortex channel 9.

[0011] The sealing ring 5 and the support ring 6 are disposed between the heat sink 4 and the outer shell 7 for sealing and fixing;

[0012] The coolant enters the vortex channel 9 from the outer water inlet channel 10, flows towards the center along the spiral path and carries away the heat, and is then discharged from the central water outlet channel 8.

[0013] The spiral structure of the vortex channel 9 is biomimetic to the vortex arrangement of blood vessels in the ear of an African elephant, forming a flow path that is sparse from the periphery to dense from the center, so as to prolong the heat exchange time of the coolant in the heat sink and achieve uniform heat exchange.

[0014] The vortex-shaped flow channel 9 includes four initial flow channels, extending into ten Archimedean spirals. Its trajectory conforms to the following equation in a Cartesian coordinate system with the center of the heat sink 4 as the origin:

[0015] The unit is mm, where t is a dimensionless parameter variable ranging from 0 to 1, corresponding to a complete spiral path that linearly increases from an initial radius of 0.3 mm to an end radius of 15.3 mm; the constant 15.7079632675 is approximately 5π, used to control the spiral angle to achieve ten turns;

[0016] The cross-section of the vortex channel 9 is rectangular, and its length-to-diameter ratio is 2 to 5, in order to optimize flow resistance and convective heat transfer performance and improve temperature uniformity.

[0017] The water inlet channel 10 has at least four water inlets evenly distributed around its circumference, and each water inlet adopts a transition structure in which a circular and rectangular flow channel are tangent.

[0018] The water outlet channel 8 is located at the center of the heat sink 4. It is a circular channel and is connected to a guide channel to prevent coolant backflow. The length of the guide channel is greater than the diameter of the water outlet channel to ensure stable flow direction and avoid coolant backflow.

[0019] The heat sink 4 has a diameter of 35 mm;

[0020] The heat sink 4 is made of diamond.

[0021] Four vortex-shaped channels 9, starting from the bottom and extending in ten circles, are directly etched on the lower surface of the heat sink 4, forming a biomimetic vortex path that is sparse from the periphery to dense from the center. Four water inlets are evenly arranged around the periphery, and a water outlet channel with a guide channel is set in the center. The coolant flows along the spiral path, inducing secondary flow and boundary layer disturbance, forming an optimized local jet impact effect in the central region, and achieving efficient and uniform heat exchange.

[0022] Compared with the prior art, this application has the following beneficial effects: (1) Significantly reduce axial stress: By replacing the traditional direct jet impact with a vortex flow channel, the warping, breakage or optical path deformation of the hard and brittle Yb:YAG crystal caused by high stress on the back of the heat sink is avoided; (2) Improve temperature uniformity: The flow path from sparse at the periphery to dense at the center is particularly suitable for circular spot heat sources (such as 17mm diameter), effectively reducing temperature gradient and thermal lensing effect; (3) Enhance heat transfer performance: The high surface area to volume ratio of the microchannel combined with secondary flow, boundary layer disturbance and local jet hot spot removal and other mechanisms work together to theoretically significantly improve the Nusselt number (Nu) compared with the reference value, which is suitable for high heat flux density conditions of >10–30MW / m²; (4) Simple structure and easy to manufacture: The overall thickness is about 4mm, the pressure drop is reasonable, and it can be realized by conventional micro-machining technology such as laser etching or CNC milling, which is convenient to integrate into the disk laser system. Attached Figure Description

[0023] Figure 1 This is a 45° cross-sectional view of the three-dimensional structure of a biomimetic microchannel cooling device for disk laser crystals.

[0024] Figure 2 This is a top view cross-sectional view of a biomimetic microchannel cooling device for disk laser crystals.

[0025] Figure 3 This is a 90° cross-sectional view of the three-dimensional structure of a biomimetic microchannel cooling device for disk laser crystals.

[0026] The components include: 1. Disc crystal, 2. Gasket, 3. Cover, 4. Heat sink, 5. Sealing ring, 6. Support ring, 7. Outer shell, 8. Water outlet channel, 9. Vortex flow channel, and 10. Water inlet channel. Detailed Implementation

[0027] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0028] Example 1

[0029] Figure 1 This is a 45° cross-sectional view of the three-dimensional structure of a biomimetic microchannel cooling device for disk laser crystals, showing the overall assembly relationship and fixing method of the device.

[0030] Figure 2 This is a top view cross-sectional view of a biomimetic microchannel cooling device for disk laser crystals, showing the structure of the vortex channel on the lower surface of the heat sink and the flow layout of water inlet at the periphery and water outlet at the center.

[0031] Figure 3 This is a 90° cross-sectional view of the three-dimensional structure of a biomimetic microchannel cooling device for disk laser crystals, and... Figure 1 The difference lies in the cutting position, which is through the outer inlet. Figure 3 The leftmost and rightmost sides show the water inlet channels, but the fixing devices are not shown.

[0032] refer to Figure 1 , Figure 2 and Figure 3 As shown, this application provides a biomimetic microchannel cooling device for disk laser crystals, including a disk crystal 1, a gasket 2, a cover 3, a heat sink 4, a sealing ring 5, a support ring 6, a housing 7, a water outlet channel 8, a vortex channel 9, and a water inlet channel 10.

[0033] The heat sink 4 is made of circular diamond material with a diameter of 35mm. As the core component of the cooling device, its upper surface is in close contact with the disk crystal 1 to efficiently conduct and dissipate the waste heat generated by the disk crystal 1. The lower surface of the heat sink 4 is directly machined with four initial vortex channels 9 by laser etching or CNC milling. These vortex channels 9 adopt a biomimetic design, drawing inspiration from the hierarchical vortex arrangement of blood vessels in an African elephant's ear, extending into a ten-turn Archimedean spiral structure. The trajectory of the vortex channels 9 in a Cartesian coordinate system (unit: mm) with the center of the heat sink 4 as the origin conforms to the following equation:

[0034]

[0035] Where t is a dimensionless parameter variable, ranging from 0 to 1, corresponding to a complete spiral path that linearly increases from an initial radius of 0.3 mm to an end radius of 15.3 mm; the constant 15.7079632675 is approximately 5π, used to control the spiral angle to achieve ten turns; the cross-section of the vortex channel 9 is rectangular, with a length-to-diameter ratio of 2-5 for its height to width, in order to optimize flow resistance and convective heat transfer performance and improve temperature uniformity.

[0036] The water inlet channel 10 is located on the periphery of the heat sink 4, with at least four inlets evenly distributed circumferentially. Each inlet adopts a transition structure where a circular and rectangular flow channel are tangent, and is directly connected to the starting end of the vortex flow channel 9 to facilitate uniform injection of coolant. The water outlet channel 8 is located at the center of the heat sink 4, is a circular channel, and is connected to a guide channel to prevent coolant backflow. The length of the guide channel is greater than the diameter of the water outlet channel to ensure stable flow direction and prevent coolant backflow.

[0037] The disc crystal 1 is fixed to the upper surface of the heat sink 4 by a gasket 2. The gasket 2 is used to buffer and evenly distribute pressure, preventing the crystal from being directly deformed by force. A cover 3 covers the disc crystal 1 and, together with the heat sink 4, forms a protective cavity. The cover 3 is made of copper-tungsten alloy or diamond material to enhance heat conduction and corrosion resistance. A housing 7 surrounds the entire device, providing external support and isolation. The housing 7 can also be made of copper-tungsten alloy or diamond material. A sealing ring 5 and a support ring 6 are disposed between the heat sink 4 and the housing 7 to seal and fix the entire structure.

[0038] The assembly process of the cooling device is as follows: First, the disc crystal 1 is placed on the upper surface of the heat sink 4 through the gasket 2 and covered and fixed with the cover 3; then, the heat sink 4 is placed into the outer shell 7, and the support ring 6 and the sealing ring 5 are used for positioning and sealing to ensure that all components fit tightly without gaps.

[0039] Working principle: Coolant (such as deionized water) enters the vortex channel 9 from the outer inlet channel 10, flowing slowly and rotating towards the center along a spiral path. This flow path induces secondary flow and periodic boundary layer disturbances, prolonging the contact time between the coolant and the heat sink 4, achieving uniform heat exchange and efficiently removing waste heat generated by the disc crystal 1 (suitable for high heat flux density >10–30 MW / m²). In the central region, the flow forms a local jet impact effect, further removing hot spot heat. Subsequently, the coolant is discharged from the central outlet channel 8, guided by a flow channel to avoid backflow. This design avoids the axial high stress problem of traditional jet cooling, reduces the risk of warping or breakage of Yb:YAG crystals, while improving temperature uniformity and reducing thermal stress and thermal lensing effects.

[0040] In this embodiment, the biomimetic vortex structure of the vortex channel 9 ensures a significant improvement in heat transfer coefficient and keeps the pressure drop within a reasonable range, making it suitable for thermal management of high-power disk lasers. Manufactured using conventional micromachining techniques, it is cost-effective and easy to integrate.

[0041] Example 2

[0042] This embodiment is basically the same as Embodiment 1, except that: diamond material is preferentially used for the cap 3 and the outer shell 7 to further improve the overall thermal conductivity; at the same time, the number of turns of the vortex channel 9 can be adjusted to 8-12 turns according to the actual application to adapt to heat sources with different diameters of laser spots (such as a 17mm diameter circular laser spot heat source), ensuring that the flow path matches the heat source distribution. The working principle remains unchanged, and this adjustment can fine-tune the parameters according to the laser power density to optimize the heat transfer performance.

[0043] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications or substitutions made by those skilled in the art within the scope of the technology disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A biomimetic microchannel cooling device for disk laser crystals, characterized in that, It includes a disc crystal (1), a gasket (2), a cover (3), a heat sink (4), a sealing ring (5), a support ring (6), a housing (7), a water outlet channel (8), a vortex flow channel (9), and a water inlet channel (10). The disc crystal (1) is fixed to the upper surface of the heat sink (4) by a gasket (2), and a cover (3) covers the disc crystal (1); The heat sink (4) has a circular structure, and multiple vortex-shaped channels (9) are etched on the lower surface, spiraling from the periphery to the center. The water inlet channel (10) is located around the heat sink (4) and is connected to the outer starting end of the vortex channel (9); The water outlet channel (8) is located at the center of the heat sink (4) and is connected to the center end of the vortex channel (9); The sealing ring (5) and the support ring (6) are disposed between the heat sink (4) and the outer shell (7) for sealing and fixing; The coolant enters the vortex channel (9) from the outer water inlet channel (10), flows towards the center along the spiral path and carries away the heat, and is then discharged from the center water outlet channel (8); The spiral structure of the vortex channel (9) is biomimetic to the vortex arrangement of blood vessels in the ear of an African elephant, forming a flow path that is sparse from the periphery to dense from the center, so as to prolong the heat exchange time of the coolant in the heat sink and achieve uniform heat exchange.

2. The biomimetic microchannel cooling device for disk laser crystals according to claim 1, characterized in that, The vortex flow channel (9) includes four initial flow channels, which extend into ten Archimedean spirals. Their trajectories in the Cartesian coordinate system with the center of the heat sink (4) as the origin conform to the following equation: where t is a dimensionless parameter variable ranging from 0 to 1 corresponding to a linear increase in the starting radius of 0.3 mm to the end radius of 15.3 mm for a complete helical path; the constant 15.7079632675 is approximately 5π to control the helix angle to achieve ten turns of coiling; The cross-section of the vortex channel (9) is rectangular, and the length-to-diameter ratio of its height to width is 2 to 5, in order to optimize flow resistance and convective heat transfer performance and improve temperature uniformity.

3. The biomimetic microchannel cooling device for disk laser crystals according to claim 2, characterized in that, The water inlet channel (10) has at least four water inlets evenly distributed around its circumference, and each water inlet adopts a transition structure in which a circular and rectangular flow channel are tangent. The water outlet channel (8) is located at the center of the heat sink (4). It is a circular channel and is connected to a guide channel to prevent coolant backflow. The length of the guide channel is greater than the diameter of the water outlet channel to ensure stable flow direction and prevent coolant backflow.

4. The biomimetic microchannel cooling device for disk laser crystals according to claim 1, characterized in that, The heat sink (4) has a diameter of 35 mm; The heat sink (4) is made of diamond.

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