A polar deep ice hot water drilling annular active spoiler and self-triggering reamer

Abstract

This invention discloses an annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling, belonging to the field of polar ice hydrothermal drilling technology. The reamer includes an extension tube, a central shaft, and a reamer actuation assembly. The extension tube has asymmetrical scaling blocks arranged in an axial array on its outer side, constructing a periodic variable cross-section flow channel. This utilizes the Venturi effect and boundary layer separation principle to induce annular turbulence, enhancing heat exchange efficiency from a physical mechanism perspective. The central shaft has upper and lower chambers separated by sealing blocks. When the borehole freezes and narrows, the upward-lifting reamer guide shell, under vertical pressure from the borehole wall, overcomes the spring force, causing the reamer actuation assembly to move downwards, achieving an autonomous switching of the internal flow channel from a central straight path to lateral jetting, performing localized hydrothermal reaming at the narrowed area. After reaming, the reamer actuation assembly automatically resets under spring action. This invention has a simple structure, requires no control components to prevent drill bit jamming, and improves borehole diameter uniformity, making it suitable for deep polar ice drilling projects.

Description

Technical Field

[0001] This invention relates to the field of polar ice hydrothermal drilling technology, and more specifically, to an annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling. Background Technology

[0002] Hot water drilling in deep ice layers in polar regions such as Antarctica is an efficient method for obtaining information about the subglacial environment and conducting scientific observations. It utilizes ground-based boilers to produce hot water, which is then pumped to the hot water drilling tool via a high-pressure pump and a high-pressure hose. The drill bit at the bottom then sprays the hot water to melt the ice, enabling drilling. However, in deep-hole drilling at depths of several thousand meters, the surrounding ice temperature is extremely low (often below -30°C). The meltwater returning from the borehole refreezes during its long return journey, causing borehole diameter reduction. Severe reduction can lead to the hot water drilling tool getting stuck in the borehole during lifting, resulting in significant equipment damage and engineering accidents. Existing borehole reaming solutions rely heavily on the engineering experience of technicians for individual, separate reaming operations. These solutions suffer from cumbersome adjustments, insufficient heat exchange leading to uneven borehole diameter, and insufficient reliability and adaptability. Their reliability is limited in extreme environments, and they struggle to maintain borehole diameter during conventional hot water drilling. Currently, conventional solutions to the borehole diameter reduction problem during drilling mainly fall into two categories: First, based on engineering experience, the heat input is indirectly increased by artificially reducing the drill string lowering speed to achieve borehole enlargement; second, after detecting signs of diameter reduction, normal drilling is interrupted, and repeated "drill-lifting and reaming" operations are carried out. Both of these existing solutions have inherent drawbacks in practical application. Specifically, reducing the drill string lowering speed is an open-loop control method. Due to the lack of real-time downhole data support, quantitative control of the borehole enlargement amount cannot be achieved, resulting in inconsistent borehole diameter along the axial direction, easily forming irregular "skewer"-shaped wellbores. The drill-lifting and reaming method not only significantly extends the construction period and increases energy consumption, but the frequent reciprocating raising and lowering of the drill string also significantly increases the risk of friction damage between the hot water drilling high-pressure hose and the borehole wall. Furthermore, both methods face the problem of increased jet target distance during borehole enlargement, resulting in severe attenuation of the hot water energy reaching the borehole wall, failing to effectively break the cold water retention layer, leading to low borehole enlargement efficiency and difficulty in dealing with sudden diameter reduction. Summary of the Invention

[0003] The purpose of this invention is to address the problem in existing technologies where boreholes easily freeze and shrink in deep polar ice drilling, leading to drill bit entrapment, by providing an annular active turbulence and self-triggered reamer for deep polar ice hot water drilling.

[0004] The objective of this invention is achieved through the following technical solution: an annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling, comprising an extension tube, scaling blocks, a central shaft, a reamer actuation assembly, and a reset mechanism; the extension tube has a hollow flow channel inside; the scaling blocks are arranged in pairs, with at least three pairs of scaling blocks arranged in an axial array and fixedly disposed on the outer wall of the extension tube, for forming a periodic variable cross-section structure in the annular flow channel; the upper end of the central shaft is connected to the extension tube, and the central shaft has an upper flow channel region and a lower flow channel region that are isolated from each other, and the tube wall of the central shaft has an upper inclined flow channel communicating with the upper flow channel region and a lower inclined flow channel communicating with the lower flow channel region; the reamer actuation assembly includes a reamer housing, a lateral nozzle mounted on the reamer housing, and a reamer guide shell fixed to the outer periphery of the reamer housing; the reamer actuation assembly is movably disposed in the annular flow channel... The reamer has an initial position (i.e., the normal lifting mode corresponding to the non-working state) and a trigger position (i.e., the self-triggered reaming mode corresponding to the working state). The reamer actuation component is configured to: when encountering a reduced-diameter ice layer, in response to a compressive force exceeding the preload applied by the borehole wall, move from the initial position to the trigger position; in the initial position, the reamer actuation component directs the hot water flowing to the hot water drill body and the bottom hot water drill nozzle; in the trigger position, the reamer actuation component switches the flow path, guiding the hot water originally flowing to the hot water drill body and the bottom hot water drill nozzle to the side nozzle; a reset mechanism is disposed between the central shaft and the reamer actuation component, used to apply the preload to the reamer actuation component, so that the reamer actuation component remains in the initial position under normal drilling conditions.

[0005] Furthermore, the outer contour of the reamer guide shell is configured such that it interferes with the borehole wall when the borehole diameter decreases, and directly receives the extrusion force from the reduced diameter borehole wall. This extrusion force forces the reamer action assembly to overcome the preload and move downward to the trigger position.

[0006] Furthermore, the scaling blocks are asymmetrical structures arranged in pairs, with the contraction angle of the upstream side of the scaling block being smaller than its expansion angle on the downstream side. The geometry of the scaling blocks is a structure obtained by merging two hollow frustums of different heights bottom to bottom and then cutting them longitudinally, so that the paired scaling blocks can hug each other and be tightly fastened to the outer wall of the extension pipe. In addition, in the scaling blocks, the axial length of the lower frustum is greater than the axial length of the upper frustum, so that when an annular flow channel is formed between the scaling blocks and the borehole wall, the length of the contraction section of the annular flow channel is greater than the length of the expansion section of the annular flow channel.

[0007] Furthermore, the contraction angle of the scaling block is 15° to 25°, the expansion angle is 30° to 45°, and the length ratio of the contraction segment to the expansion segment is 2:1 to 3:1.

[0008] Furthermore, a sealing block is fixedly installed inside the central shaft, and a fifth sealing ring and a sixth sealing ring are provided between the outer wall of the sealing block and the inner wall of the central shaft; the sealing block, the fifth sealing ring and the sixth sealing ring together divide the hollow flow channel inside the central shaft into an upper flow channel region and a lower flow channel region that are not connected to each other along the axial direction.

[0009] Furthermore, a fluid pressurization chamber and a fluid reversing chamber are formed between the expander housing and the outer wall of the central shaft; when the expander actuation assembly is in the initial position, the upper inclined flow channel is connected to the lower inclined flow channel through the fluid reversing chamber; when the expander actuation assembly is in the trigger position, the upper inclined flow channel is connected to the fluid pressurization chamber, and the fluid pressurization chamber is connected to the side nozzle.

[0010] Furthermore, the expander guide shell is a hollow rotary shell structure, which is sleeved on the outside of the expander outer shell and fixedly connected to the outer wall of the expander outer shell by at least three bolts evenly distributed along the circumference of the expander guide shell; the outer contour of the expander guide shell is a double frustum shape formed by two frustums of different heights combined bottom to bottom, and the bottom surfaces of the two frustums meet to form a rounded transition surface, and the overall outer contour surface is a smooth transition continuous surface; a variable diameter through hole is provided along the central axis of the expander guide shell, and the inner circumferential surface of the variable diameter through hole and the outer contour surface of the expander guide shell together form the hollow rotary shell structure; the outer contour surface of the expander guide shell is set as a flow guiding structure that can guide the hot water sprayed from the side nozzle to flow along the outer contour surface to the borehole wall.

[0011] Furthermore, the outer contour surface of the expander guide shell is composed of the side surface of a first frustum and the side surface of a second frustum. The heights of the first frustum and the second frustum are different, and their bottom diameters are equal. The variable diameter through hole includes at least two hole segments with different inner diameters, and each hole segment is transitioned by a conical surface or a stepped surface. The outer contour surface of the expander guide shell is arranged opposite to the injection outlet of the side nozzle, so that the hot water sprayed from the side nozzle flows towards the borehole wall along the tangential direction of the outer contour surface after being guided by the outer contour surface.

[0012] Furthermore, the reset mechanism includes a spring sleeved on the central shaft and a ring sleeve and a second retaining ring disposed at the lower part of the central shaft. The two ends of the spring abut against the ring sleeve and the expander guide shell, respectively, and always provide an upward preload force to the expander action assembly.

[0013] Furthermore, the upper part of the central shaft is provided with a first retaining ring, which is used to restrict the upward displacement of the hole expander action assembly, so that its upper end face abuts against the first retaining ring in the initial position.

[0014] Compared with the prior art, the present invention has the following advantages through the above design scheme:

[0015] First, self-triggering and automatic reset: the mechanical contact force between the borehole wall and the reamer guide shell directly drives the flow channel switching; due to the spring, after the borehole is expanded in the diameter reduction section, as the extrusion pressure disappears, the flow channel can automatically switch back to the normal flow path, effectively preventing excessive expansion and ensuring the consistency of the borehole diameter.

[0016] Second, the annular active turbulence-enhanced heat transfer design: A periodic variable cross-section flow channel composed of scaling blocks is set above the expander, and the length of the narrowing section of the fluid channel is longer than that of the enlarging section of the fluid channel (for example, the length ratio is controlled between 2:1 and 3:1). An asymmetric structure with slow contraction (contraction angle 15° to 25°) and rapid expansion (expansion angle 30° to 45°) is adopted. This specific structure, based on the Venturi effect and boundary layer fluid dynamics, can induce the fluid to produce a periodic "acceleration-deceleration" phenomenon and generate corresponding pressure pulsations. Specifically, when the hot water flows through the longer narrowing section of the channel, the flow area gradually decreases, forcing the fluid velocity to increase sharply and the static pressure to decrease. The high-speed fluid washes over the ice wall surface, effectively thinning the laminar sublayer that hinders heat transfer. Subsequently, when the fluid enters the shorter enlarging section of the channel, the flow area expands rapidly. According to classical fluid dynamics principles, this asymmetric rapid expansion structure will inevitably induce a strong adverse pressure gradient and boundary layer separation phenomenon, producing severe microscopic disturbances and vortex shedding. These spontaneously formed vortices draw the high-temperature mainstream from the center of the channel to the ice wall surface and replace the low-temperature meltwater near the wall, achieving periodic renewal of the boundary layer and breaking the cold water stagnant layer. Compared to a smooth channel with a constant cross-sectional area, this structure effectively improves the local convective heat transfer efficiency from a physical mechanism perspective, thereby efficiently enhancing the permeability maintenance effect of the water flow on the ice layer in this region.

[0017] Third, it has a simple and modular structure: the pure mechanical structure design does not require a sophisticated electronic sensing system and has extremely high reliability in the high pressure and low temperature environment of the polar regions; the modular design makes it easy to replace specific parts according to different ice layer parameters. Attached Figure Description

[0018] Figure 1 A schematic diagram of the annular active turbulence and self-triggered reamer structure for deep polar ice hydrothermal drilling provided by the present invention;

[0019] Figure 2 Axonometric schematic diagram of the annular active turbulence and self-triggered reamer structure for polar deep ice hydrothermal drilling provided by the present invention;

[0020] Figure 3 Front view of the annular active turbulence and self-triggered reamer structure for deep polar ice hydrothermal drilling provided by the present invention;

[0021] Figure 4 A front cross-sectional view of the annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling provided by the present invention;

[0022] Figure 5 A cross-sectional schematic diagram of the hole expander action component provided by the present invention when it is at the upper stop point of vertical displacement (normal lifting mode);

[0023] Figure 6 A cross-sectional schematic diagram of the hole expander action component provided by the present invention during the process of switching from the upper stop point of vertical displacement (normal lifting mode) to the lower stop point (diameter reduction self-triggered hole expansion mode);

[0024] Figure 7 This is a cross-sectional schematic diagram of the hole expander action component provided by the present invention when it is at the lower stop point of vertical displacement (diameter reduction self-triggered hole expansion mode).

[0025] The markings in the diagram are as follows: 1-First sealing ring; 2-Extension tube; 3-Scaling block; 4-Second sealing ring; 5-Central shaft; 6-First retaining ring; 7-Expander housing; 8-Side nozzle; 9-Expander guide shell; 10-Blocking block; 11-Third sealing ring; 12-Fourth sealing ring; 13-Fifth sealing ring; 14-Sixth sealing ring; 15-Seventh sealing ring; 16-Spring; 17-Ring sleeve; 18-Second retaining ring; 19-Pipe wrench groove; 20-Inlet of inclined flow channel; 21-Upper inclined flow channel; 22-Lower inclined flow channel; 23-Outlet of inclined flow channel; 24-Fluid pressurization chamber; 25-Nozzle inlet; 26-Fluid reversing chamber. Detailed Implementation

[0026] 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 noted that directional terms such as "upper" and "lower" used in this invention refer to the vertical direction when the hole expander is in use, and are only used to facilitate the description of the relative positional relationships between the components, and do not constitute a limitation on the scope of protection of the technical solution. The terms "first," "second," "third," "fourth," "fifth," and "sixth" are only used to distinguish different objects and do not represent a specific order of objects, nor do they have any limitation on the sequence of events.

[0027] like Figures 1 to 7As shown, this invention proposes an annular active flow disturbance and self-triggered reamer for deep polar ice hydrothermal drilling, comprising an extension tube 2, a scaling block 3, a central shaft 5, a reamer actuation assembly, and a reset mechanism. The extension tube 2 is threadedly connected to the lower part of the high-pressure hose of the hydrothermal drill. The outer wall of the extension tube 2 is axially arrayed with scaling blocks 3 for disturbing the upward flow of water. The central shaft 5 is internally separated into upper and lower flow channels by a sealing block 10, a fifth sealing ring 13, and a sixth sealing ring 14. The reamer actuation assembly is sleeved on the outside of the central shaft 5. When encountering a narrow-diameter ice layer, the pressure of the borehole wall triggers the reamer actuation assembly to move downwards, achieving a flow channel switch. This guides the hot water originally flowing to the hydrothermal drill body and the bottom hydrothermal drill nozzle to the side nozzle 8 to perform localized reaming operations. The extension tube 2 is a tubular component with multiple outer diameters. It serves two purposes: firstly, it provides a mounting base for the scaling blocks 3 and vertically limits their movement; secondly, it has a pipe wrench groove 19 machined on its outer surface to facilitate the disassembly and maintenance of the drill bit. When the drill bit is in operation, the extension tube 2 is threadedly connected to the externally threaded connector at the lower end of the high-pressure hot water drilling hose (used to supply hot water to the drill bit) via its internal thread at its upper end. A first sealing ring 1 is installed between the extension tube 2 and the high-pressure hot water drilling hose to achieve a seal. The scaling blocks 3 are arranged in pairs along the axial center of the outer wall of the extension tube 2 and are fixed with bolts. Each scaling block 3 is formed by merging two hollow frustums bottom-to-bottom and then longitudinally cutting them along the axial direction. The lower part of the extension tube 2 is threaded to the central shaft 5 and sealed via a second sealing ring 4. A sealing block 10 is fixedly installed inside the central shaft 5. A fifth sealing ring 13 and a sixth sealing ring 14 are provided between the outer wall of the sealing block 10 and the inner wall of the central shaft 5. The sealing block 10, the fifth sealing ring 13, and the sixth sealing ring 14 together divide the hollow flow channel inside the central shaft 5 axially into an upper flow channel region and a lower flow channel region that are not connected to each other. The outer wall of the central shaft 5 is fitted with a first retaining ring 6, a reamer housing 7, a ring sleeve 17, and a second retaining ring 18 from top to bottom, and the first retaining ring 6 and the second retaining ring 18 are respectively locked onto the central shaft 5 by bolts. The lower end of the central shaft 5 is connected to the hot water drilling tool body through an external thread. The reamer actuation assembly includes a reamer housing 7, a side nozzle 8, and a reamer guide shell 9. Three sealing rings disposed on the inner wall of the expander housing 7 form a dynamic sealing fit with the outer wall of the central shaft 5, together constituting the fluid pressurization chamber 24 and the fluid reversing chamber 26. The three sealing rings are the third sealing ring 11, the fourth sealing ring 12, and the seventh sealing ring 15. The reset mechanism includes a spring 16, which is pre-compressed between the expander guide shell 9 and the ring sleeve 17, and presses the expander actuating assembly against the first retaining ring 6 in the initial state.

[0028] Specifically, both the first sealing ring 1 and the second sealing ring 4 are used to achieve static sealing. The first sealing ring 1 is installed in the annular groove at the upper end of the extension tube 2, and when compressed, it is used to prevent leakage at the connection between the hot water drill high-pressure hose and the extension tube 2. The second sealing ring 4 is installed in the annular groove at the upper end of the central shaft 5, and is used to prevent leakage at the threaded connection between the extension tube 2 and the central shaft 5.

[0029] Specifically, the extension pipe 2 is a tubular component with a hollow channel, used to connect the upper hot water drill high-pressure hose to the lower central shaft 5. An installation section is provided in the middle region of the extension pipe 2, the outer diameter of which is smaller than the outer diameter of other regions of the extension pipe 2, and the scaling block 3 is fixedly assembled on this installation section. Furthermore, the outer surface of the extension pipe 2 is also machined with a pipe wrench groove 19 to facilitate the use of pipe wrenches for disassembling and assembling the drill bit on the construction site.

[0030] Specifically, the scaling block 3 is a key component for enhancing heat transfer. These scaling blocks 3 are installed in pairs and fixed to the extension pipe 2 with bolts. The geometry of the scaling block 3 is a longitudinally segmented structure consisting of two hollow frustums of different heights joined together, facilitating their tight clamping and installation on the extension pipe 2. In this structure, the axial length of the lower frustum is greater than that of the upper frustum, resulting in a longer contraction section than expansion section in the flow channel formed between the scaling block 3 and the borehole wall. The scaling block 3 has an asymmetrical frustum-shaped outer contour, which causes a periodic change in the fluid flow cross-section between the returning hot water and the borehole wall, characterized by a gradual decrease in cross-section over a longer distance followed by a gradual increase in cross-section over a shorter distance. This structural change induces a sudden change in water flow velocity and generates vortices, thereby stripping away the cold water layer adhering to the borehole wall surface and enhancing heat exchange efficiency.

[0031] Specifically, the central shaft 5 is the internal main support structure of the reamer. A movable reamer actuating assembly is fitted around the outside of the central shaft 5, and a hollow flow channel is provided inside the central shaft 5 for hot water circulation. A pipe wrench groove 19 is machined on the outer surface of the central shaft 5 to facilitate the assembly and disassembly of the drilling tool using pipe wrenches on the construction site.

[0032] Specifically, the sealing block 10 is installed inside the central shaft 5 and achieves compression sealing through the fifth sealing ring 13 and the sixth sealing ring 14. The sealing block 10, the fifth sealing ring 13, and the sixth sealing ring 14 work together to divide the hollow flow channel inside the central shaft 5 into two unconnected parts, forcing the hot water flowing in from above to change direction and enter the inclined flow channel system opened on the pipe wall of the central shaft 5.

[0033] Specifically, both the first retaining ring 6 and the second retaining ring 18 are used to achieve axial limiting function. The first retaining ring 6 is installed in the groove opened in the upper part of the central shaft 5 to limit the maximum upward displacement of the hole expander actuating assembly, that is, to limit its vertical displacement upper stop point; the second retaining ring 18 is installed in the groove opened in the lower part of the central shaft 5 to limit the downward displacement of the ring sleeve 17 and to provide a force support point for the spring 16 located above the ring sleeve 17.

[0034] Specifically, the expander housing 7 is sleeved on the outside of the central shaft 5, and it serves to support the expander guide shell 9 and the side nozzle 8. The inner wall of the expander housing 7 is fitted with a third sealing ring 11, a fourth sealing ring 12, and a seventh sealing ring 15. These sealing rings fit snugly against the outer wall of the central shaft 5, thus separating the fluid pressurization chamber 24 and the fluid reversing chamber 26 between the expander housing 7 and the central shaft 5. When the expander housing 7 slides up and down relative to the central shaft 5, the relative positions of the sealing rings change accordingly, thereby switching the water flow path.

[0035] Specifically, the lateral nozzle 8 is installed on the expander housing 7 via a threaded connection. When the expansion operation is triggered, the high-pressure hot water formed in the fluid pressurization chamber 24 enters the lateral nozzle 8 through the nozzle inlet 25 and is sprayed outward at high speed to melt the ice layer that has narrowed in diameter.

[0036] Specifically, the expander guide shell 9 is sleeved on the outer periphery of the expander outer shell 7 and fixedly connected to the outer wall of the expander outer shell 7 by at least three bolts evenly distributed along the circumference of the expander guide shell 9. The expander guide shell 9 has a hollow rotary shell structure, and its shape is formed by combining two truncated cones of different heights with their bottom surfaces facing each other, forming a large-diameter double truncated cone outline. Specifically, the outer contour surface of the expander guide shell 9 includes the side surface of the first truncated cone and the side surface of the second truncated cone. The first truncated cone and the second truncated cone have different heights, and their bottom diameters are equal. The bottom surfaces of the two truncated cones meet each other, and the meeting point forms a rounded transition, resulting in a smooth transition shape for the overall outer contour surface. A coaxial variable-diameter through hole is provided along the central axis of the expander guide shell 9, thereby forming a hollow rotary shell structure enclosed by two layers of rotary surfaces. The variable-diameter through hole includes at least two hole segments with different inner diameters, and adjacent hole segments are connected by a conical surface or a stepped surface. The outer contour surface of the reamer guide shell 9 is positioned opposite to the injection outlet of the side nozzle 8, allowing the hot water ejected from the side nozzle 8 to flow tangentially along the outer contour surface towards the borehole wall after being guided by it. The reamer guide shell 9 has two main functions: First, when the drill bit encounters a reduced borehole diameter, the outer contour of the reamer guide shell 9 is pressed against the reduced borehole wall, transmitting the pressure to the reamer housing 7, which pushes the entire reamer actuation assembly downwards, thereby triggering the reaming action; Second, the outer contour surface of the reamer guide shell 9 can guide the hot water ejected from the side nozzle 8 to flow along the surface of the reamer guide shell 9 towards the borehole wall, thereby improving the utilization rate of hot water.

[0037] Specifically, the spring 16, the sleeve 17, and the second retaining ring 18 together constitute a reset mechanism. The sleeve 17 is fitted onto the lower part of the central shaft 5 and its downward displacement is limited by the second retaining ring 18. The spring 16 is pre-compressed and positioned between the sleeve 17 and the internal step of the reamer guide shell 9. When the reamer is not in operation, the pre-tension force of the spring 16 pushes the reamer actuating component upwards to the position of the first retaining ring 6. When the reamer encounters a reduced borehole diameter, the reamer actuating component is compressed and overcomes the elastic force of the spring 16, moving towards the sleeve 17 to activate the hot water reaming function. After reaming the borehole wall, the pressure of the borehole wall on the reamer guide shell 9 decreases, and the spring 16, relying on its elastic restoring force, pushes the reamer actuating component back to the vertical displacement upper stop position (i.e., the reamer remains in the normal lifting mode in a non-operating state).

[0038] Specifically, the upper circumferential part of the central shaft 5 has an upper positioning groove, and the first retaining ring 6 is embedded in the upper positioning groove and locked in place by bolts, thereby forming an upper limit structure that restricts the upward axial movement of the hole expander actuation assembly. The lower circumferential part of the central shaft 5 has a lower positioning groove, the ring sleeve 17 is sleeved on the outer circumference of the central shaft 5, and the second retaining ring 18 is installed in the lower positioning groove and locked in place by bolts. The lower part of the ring sleeve 17 has a limiting groove for accommodating the second retaining ring 18, and the second retaining ring 18 prevents the ring sleeve 17 from displacing downward relative to the central shaft 5. The lower part of the ring 17 extends radially outward with a raised step. The spring 16 is in a pre-compressed state, with its two ends abutting between the raised step of the ring 17 and the variable diameter step of the inner hole of the expander guide shell 9. Under the action of the pre-tightening force of the spring 16, the expander actuating assembly, including the expander housing 7 and the expander guide shell 9, is always subjected to an upward thrust, so that its upper end face is kept in close contact with the lower end face of the first retaining ring 6, thereby maintaining it in the initial position, that is, the upper stop point of the vertical displacement of the expander actuating assembly.

[0039] Specifically, the inclined flow channel system includes an inclined flow channel inlet 20, an upper inclined flow channel 21, a lower inclined flow channel 22, and an inclined flow channel outlet 23. Hot water enters the upper inclined flow channel 21 through the inclined flow channel inlet 20. When the reamer is in normal lifting mode, the water flows into the lower inclined flow channel 22 through the transition effect of the fluid reversing chamber 26, and flows to the hot water drill body through the inclined flow channel outlet 23. When the reamer actuation component moves down due to the compression effect of the borehole diameter reduction and triggers the reaming function, the fourth sealing ring 12 moves down and crosses the corresponding flow channel opening, thereby cutting off the above-mentioned conventional flow path, allowing the high-pressure water in the upper inclined flow channel 21 to directly enter the fluid pressurization chamber 24. After being pressurized in the fluid pressurization chamber 24, it flows to the lateral nozzle 8 and sprays a high-temperature and high-pressure hot water jet outward to achieve the reaming function. It should be noted that, in the technical solution of the present invention, the upward-sloping flow channel 21 is constructed to extend upward at an angle from the horizontal reference plane where its fluid inlet is located; the downward-sloping flow channel 22 is constructed to extend downward at an angle from the same horizontal reference plane. Vertically, the upward-sloping flow channel 21 and the downward-sloping flow channel 22 are located above and below the blocking block 10, respectively.

[0040] The working principle of the annular active turbulence-inducing and self-triggered reamer for deep polar ice hydrothermal drilling provided by this invention is as follows:

[0041] 1. Regular Enhancement Mode (Non-Work Status):

[0042] like Figure 4 and Figure 5As shown, when the borehole diameter is normal and sufficient for the drill bit and reamer to pass through, the reamer's actuating component is at the vertical displacement upper stop position. At this time, the hot water flows sequentially through the extension pipe 2, the upper flow channel area of ​​the central shaft 5, the inclined flow channel inlet 20, the upper inclined flow channel 21, the fluid reversing chamber 26, the lower inclined flow channel 22, the inclined flow channel outlet 23, the flow channel area of ​​the central shaft 5, and the hot water drill bit body, finally exiting from the bottom hot water drill nozzle. The hot water ejected from the bottom hot water drill nozzle mixes with the melt water in the hole and flows upwards along the annular flow channel, passing through the area where the array scaling block 3 is located. To actively enhance the heat transfer effect, the scaling block 3 adopts an asymmetric streamlined structure design. Its water-facing contraction angle is set to 15° to 25°, making the flow channel narrowing section longer; its back-facing expansion angle is set to 30° to 45°, making the flow channel enlarging section shorter, and the length ratio of the flow channel narrowing section to the flow channel enlarging section is 2:1 to 3:1. When the fluid enters the narrowing section of the flow channel, the Venturi effect increases the flow velocity, causing strong scouring and thinning of the laminar sublayer of the ice wall. When the fluid enters the rapidly expanding section, the steep expansion angle generates a significant adverse pressure gradient, actively inducing boundary layer separation and vortex shedding. Based on the periodic pulsating heat transfer mechanism triggered by the above geometric parameters, the problem of low heat transfer efficiency in traditional smooth, uniform cross-section flow channels is fundamentally improved. This effectively enhances the ability of the returned hot water to melt and maintain the borehole wall, thereby preventing engineering accidents.

[0043] 2. Diameter reduction self-triggered hole expansion mode (working state):

[0044] like Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, when encountering a narrow-diameter ice layer during the lifting process, i.e., when the borehole diameter is smaller than the outer diameter of the expander guide shell 9, the borehole wall exerts a downward squeezing force on the expander guide shell 9. Under the squeezing force, the expander actuation assembly overcomes the thrust of the spring 16 and moves downward to the lower stop position of the vertical displacement. At this time, the fourth sealing ring 12 moves synchronously with the expander actuation assembly, crosses the preset flow channel opening, cuts off the communication path between the upper inclined flow channel 21 and the fluid reversing chamber 26, and switches to the communication state between the upper inclined flow channel 21 and the fluid pressurization chamber 24. The hot water flow direction becomes: sequentially flowing through the upper inclined flow channel 21, the fluid pressurization chamber 24, and the nozzle inlet 25, and finally being ejected by the lateral nozzles 8 arranged in a circumferential array. High-pressure hot water is ejected laterally and efficiently melts the narrow-diameter ice layer section under the guidance of the expander guide shell 9. As the ice wall gradually melts, the squeezing force decreases, and the spring 16 pushes the expander actuation assembly to reset upward. Once the orifice returns to its normal size, the water flow channel automatically switches back to the normal lifting mode under the action of spring force.

Claims

1. An annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling, characterized in that, The device includes an extension tube (2), a scaling block (3), a central shaft (5), an expander actuation assembly, and a reset mechanism; the extension tube (2) has a hollow flow channel inside; the scaling blocks (3) are arranged in pairs, with at least three pairs of scaling blocks (3) arranged in an axial array and fixedly disposed on the outer wall of the extension tube (2) to form a periodic variable cross-section structure in the annular flow channel; the upper end of the central shaft (5) is connected to the extension tube (2), and the central shaft (5) has an upper flow channel region and a lower flow channel region that are isolated from each other. The tube wall of the central shaft (5) has an upper inclined flow channel (21) that communicates with the upper flow channel region and a lower inclined flow channel (22) that communicates with the lower flow channel region; the expander actuation assembly includes an expander housing (7), a side nozzle (8) installed on the expander housing (7), and an expander guide shell fixed to the outer periphery of the expander housing (7). 9) The reamer actuation assembly is movably disposed outside the central shaft (5) and has an initial position and a trigger position; wherein, the reamer actuation assembly is configured to: when encountering a narrow-diameter ice layer, in response to the extrusion force exceeding the preload applied to it by the borehole wall, move from the initial position to the trigger position; in the initial position, the reamer actuation assembly conducts the hot water flowing to the hot water drill body and the bottom hot water drill nozzle; in the trigger position, the reamer actuation assembly switches the flow channel, guiding the hot water originally flowing to the hot water drill body and the bottom hot water drill nozzle to the side nozzle (8); the reset mechanism is disposed between the central shaft (5) and the reamer actuation assembly, for applying the preload to the reamer actuation assembly, so that the reamer actuation assembly remains in the initial position under normal drilling conditions.

2. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that, The outer contour of the reamer guide shell (9) is configured such that when the borehole diameter is reduced, it interferes with the borehole wall and directly receives the extrusion force from the reduced borehole wall. This extrusion force forces the reamer action assembly to move downward to the trigger position against the preload force.

3. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that, The scaling blocks (3) are asymmetrical structures arranged in pairs. The contraction angle of the front side of the scaling blocks (3) is smaller than the expansion angle of the back side. The geometry of the scaling blocks (3) is a structure obtained by merging two hollow frustums of different heights bottom to bottom and then cutting them longitudinally, so that the paired scaling blocks (3) can hug each other and be tightly fastened to the outer wall of the extension pipe (2). In addition, in the scaling blocks (3), the axial length of the lower frustum is greater than the axial length of the upper frustum, so that when an annular flow channel is formed between the scaling blocks (3) and the borehole wall, the contraction section length of the annular flow channel is greater than the expansion section length of the annular flow channel.

4. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 3, characterized in that, The contraction angle of the scaling block (3) is 15° to 25°, the expansion angle is 30° to 45°, and the length ratio of the contraction segment to the expansion segment is 2:1 to 3:

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5. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that, A sealing block (10) is fixedly installed inside the central shaft (5). A fifth sealing ring (13) and a sixth sealing ring (14) are provided between the outer wall of the sealing block (10) and the inner wall of the central shaft (5). The sealing block (10), the fifth sealing ring (13) and the sixth sealing ring (14) together divide the hollow flow channel inside the central shaft (5) into an upper flow channel region and a lower flow channel region that are not connected to each other along the axial direction.

6. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that, The expansion housing (7) and the outer wall of the central shaft (5) form a fluid pressurization chamber (24) and a fluid reversing chamber (26); when the expansion actuation assembly is in the initial position, the upper inclined flow channel (21) is connected to the lower inclined flow channel (22) through the fluid reversing chamber (26); when the expansion actuation assembly is in the trigger position, the upper inclined flow channel (21) is connected to the fluid pressurization chamber (24), and the fluid pressurization chamber (24) is connected to the side nozzle (8).

7. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that, The expander guide shell (9) is a hollow rotary shell structure, which is sleeved on the outside of the expander shell (7) and fixedly connected to the outer wall of the expander shell (7) by at least three bolts evenly distributed around the circumference of the expander guide shell (9); the outer contour of the expander guide shell (9) is a double frustum shape formed by two frustums of different heights combined bottom to bottom, and the bottom surfaces of the two frustums are connected to form a rounded transition surface, and the overall outer contour surface is a smooth transition continuous surface; a variable diameter through hole is provided along the central axis of the expander guide shell (9), and the inner circumferential surface of the variable diameter through hole and the outer contour surface of the expander guide shell (9) together form the hollow rotary shell structure; the outer contour surface of the expander guide shell (9) is set as a guide structure that can guide the hot water sprayed from the side nozzle (8) to flow along the outer contour surface to the borehole wall.

8. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 7, characterized in that, The outer contour surface of the expander guide shell (9) is composed of the side surface of the first frustum and the side surface of the second frustum. The heights of the first frustum and the second frustum are different, and the bottom diameters of the two are equal. The variable diameter through hole includes at least two hole segments with different inner diameters, and each hole segment is transitioned by a conical surface or a stepped surface. The outer contour surface of the expander guide shell (9) is arranged opposite to the injection outlet of the side nozzle (8), so that the hot water sprayed by the side nozzle (8) flows towards the borehole wall along the tangential direction of the outer contour surface after being guided by the outer contour surface.

9. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that: The reset mechanism includes a spring (16) sleeved on the central shaft (5) and a ring sleeve (17) and a second retaining ring (18) located at the lower part of the central shaft (5). The two ends of the spring (16) abut against the ring sleeve (17) and the expander guide shell (9) respectively, and always provide an upward preload force for the expander action assembly.

10. The annular active turbulence and self-triggered reamer for deep polar ice hydrothermal drilling according to claim 1, characterized in that: The upper part of the central shaft (5) is provided with a first retaining ring (6) to restrict the upward displacement of the hole expander action assembly, so that its upper end face abuts against the first retaining ring (6) in the initial position.

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