A turbine having a shaft cooling function

Abstract

This invention relates to the field of turbines, specifically to a turbine with a shaft cooling function, comprising a shaft and a compressor impeller, a sleeve, and a turbine impeller arranged sequentially along the length of the shaft; the compressor impeller and the turbine impeller are assembled on the shaft and at both ends of the sleeve; it also includes a compressor rear housing, a first adjustment control, and a second adjustment control; the compressor rear housing surrounds the sleeve and forms an inflow channel between it and the back of the compressor impeller; the first adjustment control is detachably disposed in the inlet area of ​​the inflow channel; the second adjustment control is detachably disposed in the inflow channel and disposed within the first adjustment control; hollow protrusions are formed on the opposite side surfaces of the compressor impeller and the turbine impeller, and both ends of the sleeve are assembled to the two hollow protrusions; the compressor impeller, the turbine impeller, the sleeve, and the shaft enclose a cooling chamber; a second through hole is formed at both ends of the sleeve communicating with the cooling chamber; a communicating recess is formed on the wall of the hollow protrusion communicating with the cooling chamber and a second through hole.

Description

Technical Field

[0001] This invention relates to the field of turbine technology, and more specifically to a turbine with shaft cooling function. Background Technology

[0002] Currently, to address the sealing and cooling requirements between impellers in micro turbine units, the industry typically installs a fixed sealing structure at the compressor impeller back to control secondary flow leakage. Meanwhile, some technical solutions attempt to introduce the secondary flow leaking from the compressor impeller back into the turbine side, using this secondary flow to cool the high-temperature components on the turbine side, and achieving preliminary adjustment of the secondary flow rate by controlling the clearance size at the compressor impeller back.

[0003] However, the above technologies have certain shortcomings in practical applications:

[0004] On the one hand, the sealing structure at the back of the compressor impeller is often a fixed integral structure with the compressor impeller or compressor back shell. After the sealing structure is worn, maintenance and replacement are inconvenient. The replacement process requires changes to the impeller body structure. Moreover, it is difficult to flexibly adjust the clearance size at the back of the compressor impeller by flexibly replacing the sealing structure, thus making it difficult to control the secondary flow characteristics and the initial flow rate of the secondary flow.

[0005] On the other hand, the gap at the back of the compressor impeller is a fixed shape, and the gradual angle of the gap section cannot be adjusted. The above-mentioned technology fails to change the gap shape to adjust the static pressure of the secondary flow supply, making it difficult to achieve precise adjustment of the secondary flow rate and unable to adapt to the cooling and sealing requirements of the unit under different operating conditions.

[0006] In addition, existing commonly used turbines require additional air intake channels to introduce cold air from the compressor outlet or the outside to cool the high-temperature component, the shaft. This increases the structural complexity of the micro turbine unit, increases manufacturing costs and assembly difficulty, and does not meet the design requirements of miniaturization and lightweighting of micro turbine units.

[0007] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0008] The purpose of this invention is to provide a turbine with a shaft cooling function.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A turbine with shaft cooling function includes a shaft and a compressor impeller, a sleeve and a turbine impeller arranged sequentially along the length of the shaft; the compressor impeller and the turbine impeller are both mounted on the shaft; the two ends of the sleeve along the length of the shaft are respectively mounted on the compressor impeller and the turbine impeller;

[0011] The turbine also includes a compressor rear casing, a first control unit, and a second control unit;

[0012] The compressor rear housing surrounds the sleeve; an inflow channel is formed between the compressor rear housing and the back of the compressor impeller;

[0013] The first control unit is detachably installed in the inlet area of ​​the inflow channel and is used to regulate the secondary flow rate at the inlet area;

[0014] The second control unit is detachably disposed in the inflow channel and located inside the first control unit, for adjusting the expansion gradient of the flow cross-sectional area of ​​the inflow channel along the secondary flow direction;

[0015] Hollow protrusions are formed on the opposite side surface of the compressor impeller and the turbine impeller, and the sleeve is respectively fitted onto the two hollow protrusions at both ends of the shaft along the length direction.

[0016] The compressor impeller, the turbine impeller, the sleeve, and the rotating shaft together form a cooling chamber;

[0017] The sleeve has a second through hole at both ends of the shaft along the length direction, which communicates with the cooling chamber.

[0018] A communicating recess is formed on the wall of the hollow protrusion, which communicates with the cooling chamber and is connected to a second through hole.

[0019] The specific extent of the inlet area of ​​the inflow channel is not limited; please refer to the attached diagram. The inflow channel may include two sections: the first section extends axially along the axis of rotation, and the second section extends radially along the axis of rotation.

[0020] To illustrate this, we can take the example of a ring-shaped control panel where the first control panel surrounds the second control panel.

[0021] The sleeve can be designed in cylindrical, stepped cylindrical, or other shapes. The connection to the hollow protrusion described below can be achieved through transition fit with a key, interference fit with welding, or other methods, ensuring a secure connection. The sleeve can be made of high-temperature resistant alloys, carbon fiber composite materials, or other materials to ensure thermal conductivity and structural strength.

[0022] The inflow channel (which can be simply referred to as the flow channel; the outflow channel described below can be referred to here) can be designed as an expanding, contracting, or constant cross-section flow channel. The inner wall of the flow channel can be coated with a smooth coating to reduce flow resistance and flow loss.

[0023] For example, both the compressor impeller and the turbine impeller are locked to the rotating shaft by a shaft-end locking nut (or a pin connection, key connection, etc.). These structures of the compressor impeller can rotate at high speed around the axis of the rotating shaft to achieve gas compression and energy conversion. The compressor impeller is used to draw in air and pressurize, heat, and accelerate it, while the turbine impeller is used to convert the energy of the high-temperature, high-pressure gas into mechanical energy to drive the rotor system to rotate. The sleeve serves as an integrated component, facilitating the coordinated functions of cooling, sealing, and connection. The compressor impeller and turbine impeller are the basic structural components of the turbine rotor system; their specific working principles can be found in existing technologies.

[0024] The inflow channel is used to collect secondary flow leaking from the radial gap between the compressor impeller and the compressor rear casing (corresponding to the first section mentioned above), facilitating the control of the initial flow state of the secondary flow. Specifically, the first regulating control is detachably located in the inlet area of ​​the inflow channel. The first regulating control is easily replaceable without altering the impeller structure. By replacing the first regulating control with different shapes, the gap size in the inlet area can be flexibly adjusted, thereby controlling the gap flow characteristics and the initial flow rate of the secondary flow. Furthermore, the second regulating control is detachably located in the inflow channel, inside the first regulating control. The second regulating control is also easily replaceable, allowing for quick and simple changes to the spatial shape of the inflow channel. Specifically, by adjusting the expansion degree of the inflow channel (i.e., the gradient angle of the flow channel cross-section), the static pressure of the secondary flow supply is adjusted, thereby achieving precise regulation of the secondary flow rate within the inflow channel to adapt to the cooling and sealing requirements of the unit under different operating conditions. Adjusting the expansion degree of the inflow channel means adjusting the expansion gradient of the flow cross-sectional area of ​​the inflow channel along the secondary flow direction.

[0025] By combining the first and second adjustment controls, this application achieves the following effect:

[0026] Firstly, it changes the traditional fixed integrated structure, realizing the detachable and replaceable functions of the sealing structure, impeller structure and / or rear shell structure, so that maintenance can be completed without changing the impeller body structure when wear occurs, which significantly reduces the difficulty and cost of maintenance.

[0027] Secondly, it breaks through the limitation of fixed inflow channel shape in existing technology. By using the second adjustment control, the adjustable gap (referring to the inflow channel) cross-section design can be realized, and the gradual angle of the gap cross-section can be flexibly adjusted. This adjustment can effectively change the static pressure of the secondary flow supply, thereby achieving high-precision adjustment of the secondary flow rate to meet the differentiated needs of the unit for cooling airflow and sealing airflow under different operating conditions.

[0028] In summary, the improved ease of maintenance and enhanced flow control accuracy effectively address the bottlenecks hindering the development of micro turbine units, significantly improving the operational reliability and adaptability to complex and variable operating conditions.

[0029] Furthermore, the combined effect of the first regulating control and the secondary flow forms a double sealing barrier. On the one hand, the first regulating control can precisely control the size of the flowable area at the inlet region, reducing leakage. On the other hand, the secondary flow creates a certain static pressure in the flow channel, which can effectively block the intrusion of high-temperature combustion gas from the turbine side, while reducing the ineffective leakage of high-pressure gas from the compressor.

[0030] Furthermore, hollow protrusions are formed on the opposite surfaces of the compressor impeller and turbine impeller. The sleeve is fitted (with an interference fit) onto the two hollow protrusions at both ends along the length of the shaft to achieve a secure connection, ensuring connection stability during high-speed rotation of the shaft and preventing relative slippage between the basic components of the rotor system. The hollow protrusions can be integrally formed with the compressor impeller or turbine impeller and can be considered as hollow bosses.

[0031] In addition, the compressor impeller (or the back of the compressor impeller), the turbine impeller (or the back of the turbine impeller), the sleeve, and the shaft together form a cooling chamber; the sleeve has a second through hole connected to the cooling chamber at both ends of the shaft along its length; the wall of the hollow protrusion has a connecting recess connected to the cooling chamber, and the connecting recess is connected to a second through hole (that is, the second through hole is connected to the cooling chamber through the connecting recess).

[0032] The secondary flow flows along the inflow channel. A portion of the secondary flow sequentially passes through the second perforation near the compressor impeller (hereinafter referred to as the inflow hole), then through the connecting recess near the compressor impeller, and enters the cooling chamber (also known as the axial cooling chamber). It then sequentially flows through the connecting recess near the turbine impeller, then through the second perforation near the turbine impeller (hereinafter referred to as the outflow hole), and exits the cooling chamber. Specifically, the sleeve can have circumferentially distributed inflow holes and outflow holes. The shape (circular, elliptical, oblong, etc.) and number of these holes are designed according to cooling requirements. Their arrangement can be circumferentially distributed, spiral, etc., without specific limitations. The inflow hole connects to the adjacent connecting recess (which can be a groove) to form the input channel of the axial cooling chamber, used to introduce a portion of the secondary flow into the axial cooling chamber. The outflow hole connects to the adjacent connecting recess to form the output channel of the axial cooling chamber, used to discharge the secondary flow that has completed its cooling process, achieving the recycling of the secondary flow.

[0033] In summary, this application does not require additional air intake channels (or additional air sources) to cool the high-temperature component, the shaft, thus avoiding an increase in the structural complexity of the micro turbine unit, reducing manufacturing costs and assembly difficulty, and meeting the design requirements of miniaturization and lightweighting of micro turbine units.

[0034] It should be noted that the shaft cooling chamber is a closed structure. The secondary flow entering this chamber can be used to cool the inner wall of the shaft and sleeve, thereby indirectly cooling the inner wall of the air bearing. This reduces the thermal load on the inner wall of the air bearing, promotes coordinated cooling of the inner and outer walls, facilitates precise matching of cooling air volume between the outer wall and the shaft, and addresses the need for precise control of cooling uniformity between the inner and outer walls of the bearing. This solves the problems of uneven cooling and overheating failure in air bearings. The airflow finally flows into the outlet channel. The shaft cooling chamber can be designed as annular, spiral, or multi-chambered structures. By changing the chamber structure, the residence time of the secondary flow within the chamber can be extended, improving the cooling effect. Baffles and guide plates can be added to the shaft cooling chamber to enhance fluid turbulence and further improve cooling uniformity.

[0035] In a further technical solution, the first adjustment control includes a first sealing ring and a sealing boss disposed opposite to each other in the length direction of the rotating shaft;

[0036] The first sealing ring is detachably installed in the first groove on the rear housing of the compressor, and the opening of the first groove faces the back of the compressor impeller;

[0037] The sealing boss is integrally formed with the back of the compressor impeller.

[0038] The first sealing ring can be easily replaced without changing the impeller structure (such as the compressor impeller). By flexibly replacing the first sealing ring with different shapes, the gap size at the inlet area of ​​the inflow channel can be flexibly adjusted, thereby controlling the gap flow characteristics and the initial flow rate of the secondary flow according to the requirements.

[0039] The combined action of the first sealing ring, the sealing boss, and the secondary flow forms a double sealing barrier. On one hand, the first sealing ring and the sealing boss can precisely control the size of the flowable area at the inlet, reducing leakage. On the other hand, the secondary flow creates a certain static pressure within the flow channel, effectively blocking the intrusion of high-temperature combustion gases from the turbine side, while also reducing ineffective leakage of high-pressure gas from the compressor. Compared to existing labyrinth seal structures, leakage losses are significantly reduced, and sealing reliability is significantly improved. Furthermore, the wear of the first sealing ring is controllable, allowing for easy replacement after wear, avoiding the high maintenance costs caused by impeller wear. Regarding blocking the intrusion of high-temperature combustion gases from the turbine side, it should be added that the area blocking this intrusion is not limited to the back of the compressor impeller. In fact, by maintaining a controllable flow rate of secondary flow throughout the entire secondary flow domain and then exiting from the radial gap on the turbine side, high-temperature combustion gases from the turbine side are prevented from flowing into the secondary flow domain from the radial gap.

[0040] A further technical solution involves using a graphene sealing ring as the first sealing ring. Graphene possesses excellent energy absorption, vibration damping, thermal conductivity, and wear resistance. Its carbon atoms are arranged in a single-layer two-dimensional honeycomb lattice, resulting in higher mechanical strength than steel and better thermal conductivity than copper. When the rotor system experiences faults or rapid changes in operating conditions, leading to significant vibrations, the graphene sealing ring can absorb vibration energy and mitigate the impact through its own deformation, thus protecting the rotor system and preventing seal failure and impeller structure damage. In contrast, existing technologies often employ rigid structures for gap sealing. When the rotor system experiences faults or rapid changes in operating conditions, resulting in significant vibrations, rigid seals are prone to friction and wear against the impeller, leading to impeller damage, seal failure, and impacting the operational stability of the rotor system.

[0041] The material of the first sealing ring can be replaced with graphene-doped ceramics, graphite packing-reinforced composite materials, or other materials that are easily worn, absorb energy and dampen vibrations, and have excellent thermal conductivity. Among them, graphite packing-reinforced composite materials have good self-lubricating and compression resilience properties, which can further improve the sealing and vibration damping effects. The shape of the first sealing ring can be designed as an annular or stepped annular shape, and the thickness and inner diameter can be flexibly designed according to the gap adjustment requirements. The connection method between the first sealing ring and the first groove can be a snap-fit ​​connection, a bolt connection, etc., to achieve easy replacement and gap adjustment functions.

[0042] The material of the sealing boss is not limited, as long as it achieves the corresponding purpose.

[0043] In a further technical solution, the first sealing ring has a first mating surface facing the sealing boss, and the sealing boss has a second mating surface facing the first sealing ring. Both the first mating surface and the second mating surface are curved surfaces. For example, if the cross-sections of both are semi-circular, the flow rate of the secondary flow can be further controlled by extending the secondary flow path (compared to when both mating surfaces are straight), resulting in better control of the secondary flow.

[0044] A further technical solution involves the second adjustment control unit comprising a second sealing ring, which is detachably mounted in a second groove on the compressor rear housing. The opening of the second groove faces the back of the compressor impeller. With this configuration, the flowable area of ​​the inflow channel can be quickly and easily adjusted by simply replacing the second sealing ring. For example, by adjusting the expansion degree (i.e., the gradient angle of the flow channel cross-section) at the side of the inlet area of ​​the inflow channel, the static pressure of the secondary flow can be changed, thereby precisely adjusting the secondary flow rate to meet the cooling and sealing requirements of the unit under different operating conditions.

[0045] It is understandable that the first groove surrounds the second groove.

[0046] The second sealing ring (the fourth adjustment control described below can be referenced here) can be designed as an arc-shaped structure, a stepped structure, or an inclined structure with different degrees of expansion, without the need for complete replacement. It can also be a bolt-adjustable structure, where the flow channel expansion is changed by adjusting the bolts, thus achieving continuous adjustment of the secondary flow rate and flow state. The material of the second sealing ring can be a high-temperature resistant alloy, engineering plastic, etc., to meet the requirements of flow channel shape adjustment and high-temperature resistance.

[0047] In a further technical solution, the turbine also includes an air bearing that surrounds the sleeve, and a portion of the compressor rear housing surrounds the air bearing;

[0048] A third groove is provided on the rear housing of the compressor, and the air bearing abuts against the bottom wall and side wall of the third groove;

[0049] The bottom wall of the third groove is provided with a first through hole and a fourth groove connected to the first through hole, and the sleeve passes through the first through hole;

[0050] A fifth groove, which communicates with the fourth groove, is provided on the side wall of the third groove.

[0051] The secondary flow in the inflow channel can sequentially enter the first perforation, the fourth groove, and the fifth groove to cool the outer peripheral surface of the air bearing;

[0052] The secondary flow in the inflow channel can enter the gap between the air bearing and the sleeve (hereinafter referred to as the first gap) to form an air film within the gap.

[0053] The air bearing can be installed by embedding, bolt fixing, etc., as long as it does not affect the formation of the outer wall cooling channel and the air gap chamber (i.e., the first gap).

[0054] The secondary flow in the inflow channel can enter the first perforation through the gap between the sleeve and the wall of the first perforation. A small portion of this secondary flow directly enters the first gap between the air bearing and the sleeve. Specifically, the outer wall of the sleeve and the inner wall of the air bearing together form the air gap chamber during air bearing operation. This air gap chamber is connected to the inflow channel. This air gap chamber can introduce a very small portion of the secondary flow for the generation of the air film during air bearing operation, thus eliminating the need for an additional air source and simplifying the unit structure. At the same time, the temperature of the secondary flow is moderate, which can prevent the air film from failing due to excessively high or low temperatures, ensuring the stable operation of the air bearing (the air bearing relies on the air film for non-contact support; the faster the rotational speed, the stronger the air film rigidity and the more stable the load-bearing capacity). The airflow after the air film fails eventually flows into the outflow channel described below, specifically referring to the method of secondary flow into the first gap, which will not be elaborated here.

[0055] The secondary flow in the inflow channel can enter the first perforation through the gap between the sleeve and the wall of the first perforation. A portion of this secondary flow sequentially enters the fourth and fifth grooves before contacting the outer circumferential surface of the air bearing. Specifically, the fourth and fifth grooves constitute a bearing cooling groove. This bearing cooling groove, together with the outer wall of the air bearing, forms an outer wall cooling channel. This outer wall cooling channel can introduce secondary flow to cool the outer wall of the air bearing, thereby blocking the transfer of high temperature from the turbine side to the outer wall of the air bearing. Finally, this airflow flows into the outflow channel described below (the outflow method is the same as the inflow method of the bearing cooling groove; that is, grooves and perforations can be correspondingly opened on the turbine back shell described below). The bearing cooling grooves can be arranged in different numbers and with different cross-sectional shapes (rectangular, trapezoidal, arc-shaped, etc.). The arrangement of the bearing cooling grooves can be circumferentially distributed, axially arranged, etc., as long as an effective cooling channel is formed between them and the outer wall of the air bearing to achieve cooling of the bearing outer wall.

[0056] In summary, the turbine in this application integrates sealing, cooling, and bearing air supply functions into one unit, eliminating the commonly used shaft end sealing assembly, bleed air channel, and air bearing air source. This simplifies the overall structure of the unit, reduces the number of parts, lowers manufacturing costs and assembly difficulty, and meets the design requirements of "miniaturization and lightweighting" for micro turbine units. Furthermore, the adjustment structures are primarily easy to replace, allowing component replacement and parameter adjustments without disassembling the entire turbine, significantly reducing maintenance costs and workload, and improving maintenance convenience.

[0057] Regarding the aforementioned induced draft channel and air source for the air bearing, the following supplementary information is provided: In existing commonly used turbines, an additional induced draft channel is required to introduce cool air from the compressor outlet or the outside to cool high-temperature components such as the air bearing, shaft, and turbine impeller back. At the same time, an additional air source is required to provide a working air film for the air bearing. This solution not only increases the structural complexity of the unit, but the additional induced draft also causes a loss of effective output power of the compressor, reducing the overall power generation efficiency of the unit.

[0058] In a further technical solution, a third adjustment control (not shown in the figure) is installed in the fourth tank, which is used to adjust the size of the area in the fourth tank that can be used for secondary flow.

[0059] The function of the third adjustment control can be referenced from that of the second adjustment control.

[0060] The third adjustment control unit may include flow channel blockers. By installing different numbers and sizes of flow channel blockers, the flow area of ​​at least a portion of the aforementioned outer wall cooling channel can be flexibly adjusted, thereby regulating the cooling flow rate of the air bearing's outer wall. This facilitates precise matching of the cooling air volume between the air bearing's outer wall and the shaft, promoting the achievement of the requirement for precise control of the cooling uniformity of the bearing's inner and outer walls. The flow channel blockers can employ structures with different thicknesses, numbers of through holes, and through hole sizes. They can also utilize a sliding, adjustable block structure, changing the flow area of ​​the fourth groove by sliding the blockers to achieve continuous control of the cooling flow rate. The blockers can be made of high-temperature resistant rubber, metal alloys, etc., possessing good sealing and high-temperature resistance properties.

[0061] It should be emphasized that achieving a precise ratio of cooling air volume between the outer wall and the shaft of the air bearing requires data calculation. This data calculation is not an innovative point of this application; rather, it is an existing, mature, and feasible practice.

[0062] In a further technical solution, there are multiple fourth and fifth grooves, and the number of both is the same. This can ensure cooling of multiple areas of the outer wall of the air bearing and achieve a better cooling effect.

[0063] The fourth and fifth grooves are evenly distributed around the central axis of the air bearing, which ensures uniform cooling of multiple areas on the outer wall of the air bearing. This further facilitates the precise allocation of cooling air between the outer wall and the shaft, and further promotes the achievement of the requirement for precise control of the cooling uniformity of the inner and outer walls of the air bearing.

[0064] In a further technical solution, the turbine also includes a turbine back casing and a fourth control unit. An outflow channel is formed between the turbine back casing and the back of the turbine impeller. This outflow channel is used to collect the secondary flow entering the inflow channel.

[0065] The fourth adjustment control is installed inside the outflow channel and is used to adjust the shape of the area inside the outflow channel that allows for secondary flow.

[0066] The formation of the outflow channel is similar to that of the inflow channel described above. The secondary flow entering the inflow channel can be collected and discharged through the outflow channel. As mentioned above, the output channel of the axial cooling chamber is connected to the outflow channel, and the secondary flow that has completed the cooling process is discharged to the outflow channel, realizing the recycling of the secondary flow.

[0067] The outflow channel is used to collect all the secondary flow that has completed the cooling process (or, in other words, the secondary flow that enters through the inflow channel, including the secondary flow that exits due to film failure) and to regulate the outflow state of the secondary flow. For example, the fourth regulating control device includes a secondary flow outflow state adjustment ring, which can be referenced to the second sealing ring mentioned above. The shape of the outflow channel (such as the cross-sectional size of the flow channel and the outlet angle) can be changed by easily replacing the secondary flow outflow state adjustment ring, thereby adjusting the velocity and direction of the secondary flow when it exits, reducing the degree of mutual interference between the secondary flow and the mainstream when it flows into the turbine impeller, reducing flow losses, and ultimately improving the energy conversion efficiency on the turbine side. A flow guiding structure can be added inside the outflow channel to guide the secondary flow to precisely mix with the mainstream, further improving energy utilization efficiency.

[0068] Ultimately, all the secondary flows that have completed cooling, sealing, and air supply to the air bearings converge in the outlet channel. Within this channel, these secondary flows cool the turbine impeller back and turbine rear casing, two high-temperature components. This further utilizes the secondary flows to reduce the temperature of the high-temperature components within the turbine unit, extending their service life. In summary, this application utilizes secondary flows to comprehensively cool high-temperature components such as the shaft, turbine impeller back, and turbine rear casing, effectively blocking the transmission of high-temperature loads on the turbine side, reducing the operating temperature of each component, preventing component failure due to high-temperature aging and deformation, and extending the service life of core components such as the impeller, bearings, and shaft (generally by more than 30%).

[0069] It should be noted that in existing technologies, secondary flow is generally simply introduced to the turbine side without precise flow organization and utilization. This not only fails to achieve the sealing effect of the secondary flow but also increases the flow loss of the turbine's main flow due to the disordered flow state of the secondary flow. This application, through the setting of the fourth control control (referring to the above control structure, the specific construction is not limited), allows the secondary flow to pass through the radial gap between the turbine impeller and the turbine back shell at a preset speed and direction (achieving less secondary flow loss). Then, it mixes with the high-temperature, high-pressure main flow gas at the turbine nozzle. The mixed gas flows into the turbine impeller together, driving the turbine impeller to rotate and do work, realizing the cascade utilization of the secondary flow, minimizing energy waste, and improving the overall power generation efficiency of the unit.

[0070] This application allows for flexible replacement of various control structures (such as the fourth control component) to adapt to micro turbine rotor systems of different sizes and power without requiring significant modifications to the core structure. It is applicable to various high-speed rotating and variable-condition micro turbine generator sets, such as portable micro turbine generators, aviation-aided micro turbines, and small distributed energy turbine units, with broad application prospects.

[0071] It is understandable that a turbine may include conventional structures such as compressor end caps, diffuser blades, turbine end caps, and turbine nozzles. These conventional structures work together with the aforementioned structures to ensure the normal operation of the unit.

[0072] For example, when the turbine is operating, air is drawn in through the compressor inlet. After being pressurized, heated, and accelerated by the high-speed rotation of the compressor impeller, most of the airflow flows into the downstream diffuser blades. Inside the diffuser, the gas's velocity energy is further converted into pressure energy, providing the conditions for subsequent turbine work. Simultaneously, a small portion of the high-pressure gas passes through the radial gap between the compressor impeller and the compressor housing (which is an inflow channel), forming a secondary flow and facilitating its collection and regulation. Regarding the control of secondary flow, the above content is summarized and illustrated with examples as follows: During unit operation, the flow ratio of the two cooling airflows (air bearing outer wall cooling and shaft cooling) can be precisely adjusted according to different operating conditions by adjusting the first sealing ring (changing to a different specification), the second sealing ring (changing to a different expansion degree), the flow channel block (adjusting the flow area), and the inlet and outlet holes on the sleeve (changing sleeves with different hole types and numbers). This achieves uniform cooling of the inner and outer walls of the air bearing and comprehensive cooling of the shaft, effectively preventing the high-temperature load on the turbine side from being transmitted to the air bearing and compressor side through the shaft, avoiding air bearing failure due to overheating, and preventing compressor efficiency reduction due to temperature rise, ensuring stable operation of the unit under different operating conditions.

[0073] Furthermore, during turbine operation, its internal structure allows for precise flow organization, transforming the originally harmful wheel-back leakage flow into a secondary flow that serves both sealing and cooling functions. This strategy eliminates reliance on expensive high-performance shaft end seals, dedicated cold gas ejector channels, and air bearing supply systems, effectively reducing the risk of high-temperature combustion gas intrusion and lowering the additional energy consumption of traditional auxiliary systems. Simultaneously, by utilizing the friction-induced temperature rise characteristics of the secondary flow, a highly efficient cascade cooling system is constructed: ensuring sufficient cooling temperature differences for all heated components while significantly increasing the temperature of the secondary flow entering the turbine side. This not only drastically reduces mixing losses between the secondary and mainstream flows but also achieves efficient cascade utilization of the energy from the wheel-back secondary flow, thereby significantly improving the overall thermal efficiency of the unit.

[0074] Meanwhile, during turbine operation, the presence of the aforementioned multiple control structures allows for precise adjustment of secondary flow rate, flow state, and cooling flow ratio according to different loads and speeds of the unit. This enables precise and controllable bearing cooling, bearing operation air supply, shaft cooling, and high-temperature component cooling on the turbine side under various operating conditions. This effectively avoids cooling loss due to excessive airflow and high-temperature failure due to insufficient airflow, adapting to the variable operating requirements of micro-turbine units. Furthermore, the first sealing ring, made of easily wear-prone materials such as graphene, possesses excellent energy absorption and shock absorption performance, effectively buffering rotor vibration and impact, preventing impeller wear, protecting the rotor system, reducing the unit's failure rate, and improving operational stability and service life.

[0075] It should be noted that current industry research mainly focuses on secondary flow control and sealing cooling optimization for large turbines. However, the structural dimensions and operating conditions of large turbines differ fundamentally from those of micro turbines, and their technical solutions cannot be directly applied to micro turbine generator sets. The aforementioned solutions are particularly suitable for micro turbine generator sets operating at high speeds and under varying conditions.

[0076] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0077] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0078] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0079] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0080] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0081] The working principle and advantages of this invention are as follows:

[0082] In this application, the inflow channel is used to collect secondary flow leaking from the radial gap between the compressor impeller and the compressor rear casing, facilitating the control of the initial flow state of the secondary flow. Specifically, the first regulating control is detachably installed in the inlet area of ​​the inflow channel. The first regulating control can be easily replaced without changing the impeller structure. By replacing the first regulating control with different shapes, the gap size in the inlet area can be flexibly adjusted, thereby controlling the gap flow characteristics and the initial flow rate of the secondary flow. In addition, the second regulating control is detachably installed in the inflow channel and located inside the first regulating control. The second regulating control can also be easily replaced, enabling quick and easy changes to the spatial shape of the inflow channel. Specifically, by adjusting the expansion of the inflow channel, the static pressure of the secondary flow supply is adjusted, thereby achieving precise adjustment of the secondary flow rate within the inflow channel to adapt to the cooling and sealing requirements of the unit under different operating conditions.

[0083] By combining the first and second adjustment controls, this application achieves the following effect:

[0084] Firstly, it changes the traditional fixed integrated structure, realizing the detachable and replaceable functions of the sealing structure, impeller structure and / or rear shell structure, so that maintenance can be completed without changing the impeller body structure when wear occurs, which significantly reduces the difficulty and cost of maintenance.

[0085] Secondly, it breaks through the limitation of fixed inflow channel shape in existing technology. The inflow channel cross-section design can be adjusted through the second adjustment control, and the angle of the gap cross-section can be flexibly adjusted. This adjustment can effectively change the static pressure of the secondary flow supply, thereby achieving high-precision adjustment of the secondary flow rate to meet the differentiated requirements of the unit for cooling airflow and sealing airflow under different operating conditions.

[0086] In summary, the improved ease of maintenance and enhanced flow control accuracy effectively address the bottlenecks hindering the development of micro turbine units, significantly improving the operational reliability and adaptability to complex and variable operating conditions.

[0087] Furthermore, the combined effect of the first regulating control and the secondary flow forms a double sealing barrier. On the one hand, the first regulating control can precisely control the size of the flowable area at the inlet region, reducing leakage. On the other hand, the secondary flow creates a certain static pressure in the flow channel, which can effectively block the intrusion of high-temperature combustion gas from the turbine side, while reducing the ineffective leakage of high-pressure gas from the compressor.

[0088] In addition, hollow protrusions are formed on the opposite side surfaces of the compressor impeller and turbine impeller. The two ends of the sleeve in the length direction of the rotating shaft are respectively fitted onto the two hollow protrusions to achieve a tight connection, ensure the connection stability when the rotating shaft rotates at high speed, and avoid relative sliding between the basic components of the rotor system.

[0089] Furthermore, the compressor impeller, turbine impeller, sleeve, and shaft together form a cooling chamber. The sleeve has second through-holes connecting to the cooling chamber at both ends along the length of the shaft. A connecting recess connecting to the cooling chamber is formed on the wall of the hollow protrusion, and this connecting recess communicates with a second through-hole. Secondary flow flows along the inflow channel. A portion of the secondary flow sequentially flows through the second through-hole near the compressor impeller (hereinafter referred to as the inflow hole), then through the connecting recess near the compressor impeller, and finally out of the cooling chamber. The inflow hole communicates with the adjacent connecting recess, forming the input channel of the axial cooling chamber to introduce a portion of the secondary flow. The outflow hole communicates with the adjacent connecting recess, forming the output channel of the axial cooling chamber to discharge the secondary flow that has completed its cooling process, thus achieving the recycling of the secondary flow.

[0090] In summary, this application does not require additional air intake channels (or additional air sources) to cool the high-temperature component, the shaft, thus avoiding an increase in the structural complexity of the micro turbine unit, reducing manufacturing costs and assembly difficulty, and meeting the design requirements of miniaturization and lightweighting of micro turbine units. Attached Figure Description

[0091] Figure 1 This is a cross-sectional view of a turbine according to an embodiment of the present invention;

[0092] Figure 2 for Figure 1 A partial schematic diagram;

[0093] Figure 3 This is a schematic diagram of the compressor impeller in an embodiment of the present invention;

[0094] Figure 4 This is a schematic diagram of the turbine impeller structure according to an embodiment of the present invention;

[0095] Figure 5 This is a schematic diagram of the compressor rear housing according to an embodiment of the present invention;

[0096] Figure 6 This is a schematic diagram of the sleeve structure according to an embodiment of the present invention.

[0097] In the attached diagrams above:

[0098] 1. Shaft; 2. Compressor impeller;

[0099] 3. Sleeve; 31. Second perforation;

[0100] 4. Turbine impeller;

[0101] 5. Compressor rear casing; 51. First tank; 52. Second tank; 53. Third tank; 54. First perforation; 55. Fourth tank; 56. Fifth tank;

[0102] 6. First control panel;

[0103] 61. First sealing ring; 611. First mating surface;

[0104] 62. Sealing boss; 621. Second mating surface;

[0105] 7. Second adjustment control; 71. Second sealing ring;

[0106] 8. Inflow channel; 81. Entrance area;

[0107] 9. Air bearings;

[0108] 10. Hollow convex part; 101. Connected concave part;

[0109] 20. Cooling chamber; 30. Turbine rear shell; 40. Fourth control valve; 50. Outflow channel;

[0110] 60. Compressor end cap; 70. Diffuser blade; 80. Turbine end cap; 90. Turbine nozzle. Detailed Implementation

[0111] The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the embodiments of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0112] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0113] See Figures 1-6 A turbine with shaft cooling function includes a shaft 1 and a compressor impeller 2, a sleeve 3 and a turbine impeller 4 arranged sequentially along the length of the shaft 1; the compressor impeller 2 and the turbine impeller 4 are both mounted on the shaft 1; the two ends of the sleeve 3 along the length of the shaft 1 are respectively mounted on the compressor impeller 2 and the turbine impeller 4;

[0114] The turbine also includes a compressor rear casing 5, a first control panel 6, and a second control panel 7;

[0115] The compressor rear housing 5 surrounds the sleeve 3; an inflow channel 8 is formed between the compressor rear housing 5 and the back of the compressor impeller 2;

[0116] The first control unit 6 is detachably disposed in the inlet region 81 of the inflow channel 8 and is used to regulate the secondary flow rate at the inlet region 81;

[0117] The second adjustment control 7 is detachably disposed in the inflow channel 8 and located inside the first adjustment control 6, for adjusting the expansion gradient of the flow cross-sectional area of ​​the inflow channel 8 along the secondary flow direction.

[0118] The specific range of the inlet region 81 of the inflow channel 8 is not limited, and can be referred to the attached figure. The inflow channel 8 may include two sections: the cross-section of the first section extends axially along the rotating shaft 1, and the cross-section of the second section extends radially along the rotating shaft 1.

[0119] Taking the example where both the first tuning control 6 and the second tuning control 7 are circular, with the first tuning control 6 surrounding the second tuning control 7.

[0120] The sleeve 3 can be designed in the shape of a cylinder, a stepped cylinder, etc., and the connection with the hollow protrusion 10 described below can be achieved by means of transition fit with key connection, interference fit with welding, etc., to ensure a firm connection. The sleeve 3 can be made of materials such as high-temperature resistant alloys and carbon fiber composite materials to ensure thermal conductivity and structural strength.

[0121] The inflow channel 8 (which can be simply referred to as the flow channel; the outflow channel 50 described below can be referred to here) can be designed as a gradually expanding, gradually contracting, or constant cross-section flow channel. The inner wall of the flow channel can be provided with a smooth coating to reduce flow resistance and reduce flow loss.

[0122] For example, both the compressor impeller 2 and the turbine impeller 4 are locked and fixed to the rotating shaft 1 by shaft end locking nuts (or by pin connection, key connection, etc.). These structures of the compressor impeller 2 can rotate at high speed around the axis of the rotating shaft 1 to realize gas compression and energy conversion. Among them, the compressor impeller 2 is used to draw in air and pressurize, heat, and accelerate it, while the turbine impeller 4 is used to convert the energy of high-temperature and high-pressure gas into mechanical energy to drive the rotor system to rotate. The sleeve 3 serves as an integrated component, promoting the coordinated functions of cooling, sealing, and connection. The compressor impeller 2 and the turbine impeller 4 are the basic structural components of the turbine rotor system, and the specific working principle can be referred to the prior art. The turbine rotor system includes the compressor impeller 2, the turbine impeller 4, the rotating shaft 1, and the bearings described below.

[0123] The inflow channel 8 is used to collect secondary flow leaking from the radial gap between the compressor impeller 2 and the compressor rear casing 5 (corresponding to the first section mentioned above), facilitating the control of the initial flow state of the secondary flow. Specifically, the first regulating control 6 is detachably installed in the inlet region 81 of the inflow channel 8. The first regulating control 6 can be easily replaced without changing the impeller structure. By replacing the first regulating control 6 with different shapes, the gap size of the inlet region 81 can be flexibly adjusted, thereby controlling the gap flow characteristics (i.e., the pressure, velocity, and other flow characteristics of the fluid in the gap) and the initial flow rate of the secondary flow. In addition, the second regulating control 7 is detachably installed in the inflow channel 8 and located inside the first regulating control 6. The second regulating control 7 can also be easily replaced, allowing for quick and easy changes to the spatial shape of the inflow channel 8. Specifically, by adjusting the expansion degree of the inflow channel 8 (i.e., the gradual angle of the flow channel cross-section), the static pressure of the secondary flow supply can be adjusted, thereby achieving precise adjustment of the secondary flow rate within the inflow channel 8 to adapt to the cooling and sealing requirements of the unit under different operating conditions. Adjusting the expansion degree of inflow channel 8 means adjusting the expansion gradient of the flow cross-sectional area of ​​inflow channel 8 along the direction of secondary flow.

[0124] By cooperating with the first adjustment control 6 and the second adjustment control 7, this application achieves the following effect:

[0125] Firstly, it changes the traditional fixed integrated structure, realizing the detachable and replaceable functions of the sealing structure, impeller structure and / or rear shell structure, so that maintenance can be completed without changing the impeller body structure when wear occurs, which significantly reduces the difficulty and cost of maintenance.

[0126] Secondly, it breaks through the limitation of the fixed shape of the inflow channel 8 in the existing technology. The adjustable gap (referring to the inflow channel 8) cross-section design is realized through the second adjustment control 7, which realizes the flexible adjustment of the gradual angle of the gap cross-section. This adjustment can effectively change the static pressure of the secondary flow supply, thereby realizing high-precision adjustment of the secondary flow rate to meet the differentiated needs of the unit for cooling airflow and sealing airflow under different operating conditions.

[0127] In summary, the improved ease of maintenance and enhanced flow control accuracy effectively address the bottlenecks hindering the development of micro turbine units, significantly improving the operational reliability and adaptability to complex and variable operating conditions.

[0128] Furthermore, the synergistic effect of the first regulating control 6 and the secondary flow forms a double sealing barrier. On the one hand, the first regulating control 6 can precisely control the size of the flowable area at the inlet region 81, reducing leakage. On the other hand, the secondary flow forms a certain static pressure in the flow channel, which can effectively block the intrusion of high-temperature combustion gas on the turbine side, while reducing the ineffective leakage of high-pressure gas from the compressor.

[0129] It should be noted that the first adjustment control 6 is detachably disposed in the inlet area 81 of the inflow channel 8. It can be that the first adjustment control 6 is detachably disposed as a whole, or that a part of the first adjustment control 6 is detachably disposed (this application will describe it accordingly).

[0130] In one embodiment of this application, the first adjustment control 6 includes a first sealing ring 61 (also known as an adjustment ring) and a sealing boss 62 disposed opposite to each other in the length direction of the rotating shaft 1.

[0131] The first sealing ring 61 is detachably installed in the first groove 51 on the compressor rear housing 5, and the opening of the first groove 51 faces the back of the compressor impeller 2.

[0132] The sealing boss 62 is integrally formed with the back of the compressor impeller 2.

[0133] The first sealing ring 61 can be easily replaced without changing the impeller structure (such as the compressor impeller 2). By flexibly replacing the first sealing ring 61 with different shapes, the gap size at the inlet area 81 of the inflow channel 8 can be flexibly adjusted, thereby controlling the gap flow characteristics and the initial flow rate of the secondary flow according to the requirements.

[0134] The combined action of the first sealing ring 61, the sealing boss 62, and the secondary flow forms a double sealing barrier. On one hand, the first sealing ring 61 and the sealing boss 62 can precisely control the size of the flowable area at the inlet region 81, reducing leakage. On the other hand, the secondary flow forms a certain static pressure in the flow channel, which can effectively block the intrusion of high-temperature gas from the turbine side, while reducing the ineffective leakage of high-pressure gas from the compressor. Compared with the existing labyrinth seal structure, leakage loss is greatly reduced, and sealing reliability is significantly improved. In addition, the wear of the first sealing ring 61 is controllable, and it can be easily replaced after wear, avoiding the high maintenance costs caused by impeller wear. Regarding the blocking of high-temperature gas intrusion from the turbine side, it is worth noting that the area blocking the intrusion of high-temperature gas from the turbine side is not limited to the back of the compressor impeller 2. In fact, it is achieved by maintaining a controllable flow rate of secondary flow throughout the entire secondary flow domain and then flowing out from the radial gap on the turbine side, preventing high-temperature gas from the turbine side from flowing into the secondary flow domain from the radial gap on the turbine side.

[0135] In one embodiment of this application, the first sealing ring 61 is configured as a graphene sealing ring. Graphene possesses excellent energy absorption, vibration damping, thermal conductivity, and wear resistance. Its carbon atoms are arranged in a single-layer two-dimensional honeycomb lattice, exhibiting higher mechanical strength than steel and better thermal conductivity than copper. When the rotor system experiences faults or rapid changes in operating conditions, resulting in significant vibrations, the graphene sealing ring can absorb vibration energy and mitigate vibration impacts through its own deformation, thus protecting the rotor system and preventing seal failure and impeller structure damage. In contrast, existing gap sealing components often employ rigid structures. When the rotor system experiences faults or rapid changes in operating conditions, resulting in significant vibrations, rigid seals are prone to friction and wear with the impeller, leading to impeller damage, seal failure, and affecting the operational stability of the rotor system.

[0136] The material of the first sealing ring 61 can be replaced with graphene-doped ceramics, graphite packing-reinforced composite materials, or other materials that are easy to wear, absorb energy and dampen vibrations, and have excellent thermal conductivity. Among them, graphite packing-reinforced composite materials have good self-lubricating and compression resilience properties, which can further improve the sealing and vibration damping effects. The shape of the first sealing ring 61 can be designed as an annular or stepped annular shape, and the thickness and inner diameter can be flexibly designed according to the gap adjustment requirements. The connection method between the first sealing ring 61 and the first groove 51 can be a snap-fit ​​connection, a bolt connection, etc., to achieve easy replacement and gap adjustment functions.

[0137] The material of the sealing boss 62 is not limited, as long as it achieves the corresponding purpose.

[0138] In one embodiment of this application, the first sealing ring 61 has a first mating surface 611 facing the sealing boss 62, and the sealing boss 62 has a second mating surface 621 facing the first sealing ring 61. Both the first mating surface 611 and the second mating surface 621 are curved surfaces. For example, if the cross-section of both is semi-circular, the flow rate of the secondary flow can be further controlled by extending the secondary flow path (compared to when both mating surfaces are straight), resulting in better control of the secondary flow.

[0139] In one embodiment of this application, the second adjustment control 7 includes a second sealing ring 71, which is detachably installed in a second groove 52 on the compressor rear housing 5. The opening of the second groove 52 faces the back of the compressor impeller 2. With this configuration, the flowable area of ​​the inflow channel 8 can be quickly and easily adjusted by simply replacing the second sealing ring 71. For example, by adjusting the expansion degree (i.e., the gradient angle of the flow channel cross-section) on the side of the inlet area 81 of the inflow channel 8, the secondary flow static pressure can be changed, thereby precisely adjusting the secondary flow rate to meet the cooling and sealing requirements of the unit under different operating conditions.

[0140] It is understandable that the first groove 51 surrounds the second groove 52.

[0141] The second sealing ring 71 (the fourth adjustment control 40 described below can be referred to here) can be designed as an arc-shaped structure, a stepped structure, or an inclined structure with different degrees of expansion, without the need for complete replacement. It can also adopt a bolt-adjustable structure, where the expansion degree of the flow channel is changed by adjusting the bolts, thereby achieving continuous adjustment of the secondary flow rate and flow state. The material of the second sealing ring 71 can be a high-temperature resistant alloy, engineering plastic, etc., to meet the requirements of flow channel shape adjustment and high-temperature resistance.

[0142] In one embodiment of this application, the turbine further includes an air bearing 9, which surrounds the sleeve 3, and a portion of the compressor rear housing 5 surrounds the air bearing 9;

[0143] A third groove 53 is provided on the rear housing 5 of the compressor, and the air bearing 9 abuts against the bottom wall and side wall of the third groove 53.

[0144] The bottom wall of the third groove 53 is provided with a first through hole 54 and a fourth groove 55 connected to the first through hole 54, and the sleeve 3 passes through the first through hole 54.

[0145] A fifth groove 56, which is connected to the fourth groove 55, is provided on the side wall of the third groove 53.

[0146] The secondary flow in the inflow channel 8 can sequentially enter the first perforation 54, the fourth groove 55 and the fifth groove 56 to cool the outer peripheral surface of the air bearing 9;

[0147] The secondary flow in the inflow channel 8 can enter the gap between the air bearing 9 and the sleeve 3 (hereinafter referred to as the first gap) to form an air film in the gap.

[0148] The air bearing 9 can be installed by embedding, bolt fixing, etc., as long as it does not affect the formation of the outer wall cooling channel and the air gap chamber (i.e., the first gap).

[0149] The secondary flow in the inflow channel 8 can enter the first perforation 54 through the gap between the sleeve 3 and the wall of the first perforation 54. A small portion of this secondary flow directly enters the first gap between the air bearing 9 and the sleeve 3. Specifically, the outer wall of the sleeve 3 and the inner wall of the air bearing 9 together form the air gap chamber during the operation of the air bearing 9. This air gap chamber is connected to the inflow channel 8. A very small portion of the secondary flow can be introduced into this air gap chamber for the generation of the air film during the operation of the air bearing 9, thus eliminating the need for an additional air source and simplifying the unit structure. At the same time, the temperature of the secondary flow is moderate, which can prevent the air film from failing due to excessively high or low temperatures, ensuring the stable operation of the air bearing 9 (the air bearing 9 relies on the air film for non-contact support; the faster the rotation speed, the stronger the air film rigidity and the more stable the load-bearing capacity). The airflow after the air film fails eventually flows into the outflow channel 50 described below. The specific method of secondary flow entering the first gap is similar and will not be elaborated here.

[0150] The secondary flow in the inflow channel 8 can enter the first perforation 54 through the gap between the sleeve 3 and the wall of the first perforation 54. A portion of this secondary flow sequentially enters the fourth groove 55 and the fifth groove 56 before contacting the outer circumferential surface of the air bearing 9. Specifically, the fourth groove 55 and the fifth groove 56 constitute a bearing cooling groove. This bearing cooling groove, together with the outer wall of the air bearing 9, forms an outer wall cooling channel. This outer wall cooling channel can introduce secondary flow to cool the outer wall of the air bearing 9, thereby blocking the transfer of high temperature from the turbine side to the outer wall of the air bearing 9. Finally, this airflow flows into the outflow channel 50 (the outflow method is the same as the inflow method of the bearing cooling groove; that is, grooves and perforations can be correspondingly opened on the turbine rear shell 30). The bearing cooling grooves can be arranged in different numbers and with different cross-sectional shapes (rectangular, trapezoidal, arc-shaped, etc.). The arrangement of the bearing cooling grooves can be circumferentially distributed, axially arranged, etc., as long as an effective cooling channel is formed between them and the outer wall of the air bearing 9 to achieve cooling of the bearing outer wall.

[0151] In summary, the turbine in this application integrates sealing, cooling, and bearing air supply functions into one unit, eliminating the commonly used shaft end sealing assembly, air intake channel, and air bearing 9 air source. This simplifies the overall structure of the unit, reduces the number of parts, lowers manufacturing costs and assembly difficulty, and meets the design requirements of "miniaturization and lightweighting" for micro turbine units. Furthermore, the adjustment structures are primarily easy to replace, allowing component replacement and parameter adjustments without disassembling the entire turbine, significantly reducing maintenance costs and workload, and improving maintenance convenience.

[0152] Regarding the aforementioned induced draft channel and air source for air bearing 9, the following supplement is provided: In existing commonly used turbines, an additional induced draft channel is required to introduce cool air from the compressor outlet or the outside to cool high-temperature components such as air bearing 9, shaft 1, and turbine impeller 4. At the same time, an additional air source is required to provide a working air film for air bearing 9. This scheme not only increases the structural complexity of the unit, but the additional induced draft also causes a loss of effective output power of the compressor, reducing the overall power generation efficiency of the unit.

[0153] In one embodiment of this application, a third adjustment control (not shown in the figure) is installed in the fourth tank 55, and the third adjustment control is used to adjust the size of the area in the fourth tank 55 that can be used for secondary flow.

[0154] The function of the third adjustment control can be referenced from that of the second adjustment control 7.

[0155] The third adjustment control can include flow channel blockers. By installing different numbers and sizes of flow channel blockers, the flow area of ​​at least a portion of the aforementioned outer wall cooling channel can be flexibly adjusted, thereby regulating the cooling flow rate of the outer wall of the air bearing 9. This facilitates precise matching of the cooling air volume between the outer wall of the air bearing 9 and the shaft, promoting the achievement of the requirement for precise control of the cooling uniformity of the inner and outer walls of the bearing. The flow channel blockers can adopt structures with different thicknesses, numbers of through holes, and through hole sizes. Alternatively, a sliding adjustable blocker structure can be used, changing the flow area of ​​the fourth groove 55 by sliding the blocker to achieve continuous control of the cooling flow rate. The blocker material can be high-temperature resistant rubber, metal alloys, etc., possessing good sealing performance and high-temperature resistance.

[0156] It should be emphasized that achieving a precise ratio of cooling air volume between the outer wall of the air bearing 9 and the shaft requires data calculation. This data calculation is not an innovative point of this application, but rather a mature and feasible existing practice.

[0157] In one embodiment of this application, there are multiple fourth grooves 55 and multiple fifth grooves 56, and the number of both is the same. This can ensure that multiple areas of the outer wall of the air bearing 9 are cooled, and achieve a better cooling effect.

[0158] The fourth groove 55 and the fifth groove 56 are evenly distributed around the central axis of the air bearing 9. This ensures the uniformity of cooling in multiple areas of the outer wall of the air bearing 9, further facilitating the precise ratio of cooling air volume between the outer wall and the shaft of the air bearing 9, and further promoting the need to precisely control the cooling uniformity of the inner and outer walls of the air bearing 9.

[0159] In one embodiment of this application, hollow protrusions 10 are formed on the opposite surfaces of the compressor impeller 2 and the turbine impeller 4. The sleeve 3 is respectively fitted (with an interference fit) onto the two hollow protrusions 10 at both ends of the shaft 1 along its length, achieving a tight connection and ensuring the connection stability when the shaft 1 rotates at high speed, thus preventing relative sliding between the basic components of the rotor system. The hollow protrusions 10 can be integrally formed with the compressor impeller 2 or the turbine impeller 4, and can be regarded as hollow bosses.

[0160] In one embodiment of this application, the compressor impeller 2 (or the back of the compressor impeller 2), the turbine impeller 4 (or the back of the turbine impeller 4), the sleeve 3, and the rotating shaft 1 together form a cooling chamber 20.

[0161] The sleeve 3 has a second through hole 31 at both ends of the shaft 1 along the length direction, which communicates with the cooling chamber 20;

[0162] The hollow protrusion 10 has a communicating recess 101 that communicates with the cooling chamber 20 on its wall, and the communicating recess 101 communicates with a second through hole 31.

[0163] The second perforation 31 is connected to the cooling chamber 20 through the connecting recess 101.

[0164] The secondary flow flows along the inflow channel 8. A portion of the secondary flow sequentially passes through the second perforation 31 near the compressor impeller 2 (hereinafter referred to as the inflow hole) and the connecting recess 101 near the compressor impeller 2, entering the cooling chamber 20 (also known as the axial cooling chamber 20). Then, it sequentially flows through the connecting recess 101 near the turbine impeller 4 and the second perforation 31 near the turbine impeller 4 (hereinafter referred to as the outflow hole), exiting the cooling chamber 20. Specifically, the sleeve 3 can have circumferentially distributed inflow holes and outflow holes. The hole shape (circular, elliptical, waist-shaped, etc.) and quantity are designed according to cooling requirements. The arrangement of the holes can be circumferentially distributed, spirally arranged, etc., without specific limitations. The inflow hole communicates with the adjacent connecting recess 101 (which can be a groove) to form the input channel of the axial cooling chamber 20, used to introduce a portion of the secondary flow into the axial cooling chamber 20. The outflow hole is connected to the adjacent connecting recess 101 to form the output channel of the axial cooling chamber 20, which is used to discharge the secondary flow that has completed the cooling effect and realize the recycling of the secondary flow.

[0165] In summary, this application does not require additional air intake channels to cool the high-temperature component 1 of the rotating shaft, thus avoiding an increase in the structural complexity of the micro turbine unit, reducing manufacturing costs and assembly difficulty, and meeting the design requirements of miniaturization and lightweighting of micro turbine units.

[0166] The axial cooling chamber 20 is a closed structure. The secondary flow entering this chamber can be used to cool the inner walls of the shaft 1 and sleeve 3, thereby indirectly cooling the inner wall of the air bearing 9. This reduces the thermal load on the inner wall of the air bearing 9, achieving coordinated cooling of the inner and outer walls of the air bearing 9. This facilitates precise matching of the cooling air volume between the outer wall of the air bearing 9 and the axial cooling, promoting the need for precise control of the cooling uniformity of the inner and outer walls of the bearing, and solving the problems of uneven cooling and overheating failure of the air bearing 9. The airflow finally flows into the outflow channel 50. The axial cooling chamber 20 can be designed as annular, spiral, or multi-chambered structures. By changing the chamber structure, the residence time of the secondary flow in the chamber can be extended, improving the cooling effect. Turbulence vanes, guide plates, and other structures can be added to the axial cooling chamber 20 to enhance fluid turbulence and further improve cooling uniformity.

[0167] In one embodiment of this application, the turbine further includes a turbine back shell 30 and a fourth control control 40. An outflow channel 50 is formed between the turbine back shell 30 and the back of the turbine impeller 4. The outflow channel 50 is used to collect the secondary flow entering the inflow channel 8.

[0168] The fourth adjustment control 40 is installed inside the outflow channel 50 and is used to adjust the shape of the area inside the outflow channel 50 that allows for secondary flow.

[0169] The formation of the outflow channel 50 is similar to that of the inflow channel 8 described above. The secondary flow entering the inflow channel 8 can be collected and discharged through the outflow channel 50. As described above, the output channel of the axial cooling chamber 20 is connected to the outflow channel 50, and the secondary flow that has completed the cooling effect is discharged to the outflow channel 50, realizing the recycling of the secondary flow.

[0170] The outflow channel 50 is used to collect all the secondary flow that has completed the cooling process (or the secondary flow that flows in through the inflow channel 8, including the secondary flow that flows out due to film failure) and to regulate the outflow state of the secondary flow. For example, the fourth regulating control 40 includes a secondary flow outflow state adjustment ring, which can refer to the second sealing ring 71 described above. The shape of the outflow channel 50 (such as the cross-sectional size of the flow channel and the outlet angle) can be changed by easily replacing the secondary flow outflow state adjustment ring, thereby adjusting the speed and direction of the secondary flow out, reducing the degree of mutual interference between the secondary flow and the mainstream when flowing into the turbine impeller 4, reducing flow losses, and ultimately improving the energy conversion efficiency on the turbine side. A flow guiding structure can be added inside the outflow channel 50 to guide the secondary flow and the mainstream to mix precisely, further improving energy utilization efficiency.

[0171] Ultimately, all the secondary flows that have completed cooling, sealing, and air supply to the air bearing 9 converge in the outlet channel 50. Within this channel, these secondary flows cool the turbine impeller 4 back and the turbine rear casing 30, two high-temperature components. This further utilizes the secondary flows to reduce the temperature of the high-temperature components within the turbine unit, extending their service life. In summary, this application comprehensively cools high-temperature components such as the shaft 1, turbine impeller 4 back, and turbine rear casing 30 through secondary flows, effectively blocking the transmission of high-temperature loads on the turbine side, reducing the operating temperature of each component, preventing component failure due to high-temperature aging and deformation, and extending the service life of core components such as the impeller, bearings, and shaft 1 (generally by more than 30%).

[0172] It should be noted that in existing technologies, secondary flow is generally simply introduced to the turbine side without precise flow organization and utilization. This not only fails to achieve the sealing effect of the secondary flow but also increases the flow loss of the turbine's main flow due to the disordered flow state of the secondary flow. This application, through the setting of the fourth control control 40 (referring to the above control structure, the specific construction is not limited), allows the secondary flow to pass through the radial gap between the turbine impeller 4 and the turbine back shell 30 at a preset speed and direction (achieving less secondary flow loss). Then, it mixes with the high-temperature and high-pressure main flow gas at the turbine nozzle 90. The mixed gas flows into the turbine impeller 4 together, driving the turbine impeller 4 to rotate and do work, realizing the cascade utilization of the secondary flow, minimizing energy waste, and improving the overall power generation efficiency of the unit.

[0173] This application allows for flexible replacement of various control structures (such as the fourth control component 40) to adapt to micro turbine rotor systems of different sizes and power without requiring significant modifications to the core structure. It is applicable to various high-speed rotating and variable-condition micro turbine generator sets, such as portable micro turbine generators, aviation-aided micro turbines, and small distributed energy turbine units, with broad application prospects.

[0174] It is understood that the turbine may include conventional structures such as compressor end cap 60, diffuser blades 70, turbine end cap 80, and turbine nozzle 90. These conventional structures cooperate with the structures in any of the above embodiments to ensure the normal operation of the unit.

[0175] For example, when the turbine is operating, air is drawn in through the compressor inlet. After being pressurized, heated, and accelerated by the high-speed rotation of the compressor impeller 2, most of the airflow flows into the downstream diffuser blades 70. Inside the diffuser, the velocity energy of the gas is further converted into pressure energy, providing conditions for subsequent turbine work. At the same time, a small portion of the high-pressure gas passes through the radial gap between the compressor impeller 2 and the compressor rear casing 5 (belonging to the inflow channel 8), forming a secondary flow, which facilitates the collection and regulation of the secondary flow. Regarding the control of secondary flow, the above content is summarized and illustrated with examples as follows: During unit operation, the flow ratio of the two cooling airflows (cooling the outer wall of the air bearing 9 and cooling the shaft) can be precisely adjusted according to different operating conditions by adjusting the first sealing ring 61 (replacing with different specifications), the second sealing ring 71 (replacing with different expansion degrees), the flow channel block (adjusting the flow area), and the inlet and outlet holes opened on the sleeve 3 (replacing with sleeves 3 with different hole types and numbers). This achieves uniform cooling of the inner and outer walls of the air bearing 9 and comprehensive cooling of the shaft 1, effectively preventing the high-temperature load on the turbine side from being transmitted to the air bearing 9 and the compressor side through the shaft 1, avoiding failure of the air bearing 9 due to overheating, and preventing the compressor from experiencing efficiency reduction due to temperature rise, thus ensuring stable operation of the unit under different operating conditions.

[0176] Furthermore, during turbine operation, its internal structure enables precise flow organization, transforming the originally harmful wheel-back leakage flow into a secondary flow that serves both sealing and cooling functions. This strategy eliminates reliance on expensive high-performance shaft end seals, dedicated cold gas ejector channels, and air bearing supply systems, effectively reducing the risk of high-temperature combustion gas intrusion and lowering the additional energy consumption of traditional auxiliary systems. Simultaneously, by utilizing the friction-induced temperature rise characteristics of the secondary flow, a highly efficient cascade cooling system is constructed: ensuring sufficient cooling temperature differences for all heated components while significantly increasing the temperature of the secondary flow entering the turbine side. This not only drastically reduces mixing losses between the secondary and main flow but also achieves efficient cascade utilization of the energy from the wheel-back secondary flow, thereby significantly improving the overall thermal efficiency of the unit.

[0177] Meanwhile, during turbine operation, the presence of the aforementioned multiple control structures allows for precise adjustment of secondary flow rate, flow state, and cooling flow ratio according to different loads and speeds of the unit. This enables precise and controllable bearing cooling, bearing operation air supply, shaft 1 cooling, and turbine-side high-temperature component cooling under various operating conditions. This effectively avoids cooling loss due to excessive cooling air flow and high-temperature failure due to insufficient cooling air flow, adapting to the variable operating conditions of micro-turbine units. Furthermore, the first sealing ring 61, made of easily wear-prone materials such as graphene, possesses excellent energy absorption and shock absorption performance. This effectively buffers rotor vibration and impact, prevents impeller wear, protects the rotor system, reduces the unit's failure rate, and improves operational stability and service life.

[0178] It should be noted that current industry research mainly focuses on secondary flow control and sealing cooling optimization for large turbines. However, the structural dimensions and operating conditions of large turbines differ fundamentally from those of micro turbines, and their technical solutions cannot be directly applied to micro turbine generator sets. The solution described in this application, however, is particularly suitable for micro turbine generator sets operating at high speeds and under varying conditions.

[0179] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A turbine with shaft cooling function, characterized in that: It includes a rotating shaft (1) and a compressor impeller (2), a sleeve (3) and a turbine impeller (4) arranged sequentially along the length of the rotating shaft (1); the compressor impeller (2) and the turbine impeller (4) are both mounted on the rotating shaft (1); the sleeve (3) is mounted on the compressor impeller (2) and the turbine impeller (4) at both ends along the length of the rotating shaft (1). The turbine also includes a compressor back casing (5), a first control unit (6) and a second control unit (7); The compressor rear housing (5) surrounds the sleeve (3); an inflow channel (8) is formed between the compressor rear housing (5) and the back of the compressor impeller (2); The first control unit (6) is detachably disposed in the inlet area (81) of the inflow channel (8) and is used to regulate the secondary flow rate at the inlet area (81); The second adjustment control (7) is detachably disposed in the inflow channel (8) and disposed inside the first adjustment control (6) to adjust the expansion gradient of the flow cross-sectional area of ​​the inflow channel (8) along the secondary flow direction; Hollow protrusions (10) are formed on the side surface of the compressor impeller (2) opposite to the turbine impeller (4). The sleeve (3) is respectively fitted onto the two hollow protrusions (10) at both ends of the shaft (1) along its length. The compressor impeller (2), the turbine impeller (4), the sleeve (3) and the rotating shaft (1) together form a cooling chamber (20). The sleeve (3) has a second perforation (31) at both ends of the shaft (1) along the length direction, which communicates with the cooling chamber (20). The hollow protrusion (10) has a communicating recess (101) that communicates with the cooling chamber (20) on its wall, and the communicating recess (101) communicates with a second perforation (31).

2. A turbine with shaft cooling function according to claim 1, characterized in that: The first adjustment control (6) includes a first sealing ring (61) and a sealing boss (62) disposed opposite to each other in the length direction of the rotating shaft (1). The first sealing ring (61) is detachably installed in the first groove (51) on the compressor rear housing (5), and the opening of the first groove (51) faces the back of the compressor impeller (2). The sealing boss (62) is integrally formed with the back of the compressor impeller (2).

3. A turbine with shaft cooling function according to claim 2, characterized in that: The first sealing ring (61) is a graphene sealing ring.

4. A turbine with shaft cooling function according to claim 2, characterized in that: The first sealing ring (61) has a first mating surface (611) facing the sealing boss (62), and the sealing boss (62) has a second mating surface (621) facing the first sealing ring (61). Both the first mating surface (611) and the second mating surface (621) are curved surfaces.

5. A turbine with shaft cooling function according to claim 1, characterized in that: The second control unit (7) includes a second sealing ring (71), which is detachably installed in a second groove (52) on the compressor rear housing (5), with the opening of the second groove (52) facing the back of the compressor impeller (2).

6. A turbine with shaft cooling function according to claim 1, characterized in that: The turbine also includes an air bearing (9) surrounding the sleeve (3), and a portion of the compressor rear housing (5) surrounding the air bearing (9). A third groove (53) is provided on the rear housing (5) of the compressor, and the air bearing (9) abuts against the bottom wall and side wall of the third groove (53); The bottom wall of the third groove (53) is provided with a first through hole (54) and a fourth groove (55) connected to the first through hole (54), and the sleeve (3) passes through the first through hole (54). A fifth groove (56) connected to the fourth groove (55) is provided on the side wall of the third groove (53). The secondary flow in the inflow channel (8) can sequentially enter the first perforation (54), the fourth groove (55) and the fifth groove (56) to cool the outer peripheral surface of the air bearing (9); The secondary flow in the inflow channel (8) can enter the gap between the air bearing (9) and the sleeve (3) to form an air film in the gap.

7. A turbine with shaft cooling function according to claim 6, characterized in that: A third adjustment control is installed inside the fourth tank (55), which is used to adjust the size of the area inside the fourth tank (55) where secondary flow can occur.

8. A turbine with shaft cooling function according to claim 6, characterized in that: There are multiple fourth grooves (55) and multiple fifth grooves (56), and the number of both is the same.

9. A turbine with shaft cooling function according to claim 1, characterized in that: The turbine also includes a turbine back shell (30) and a fourth control control (40), and an outflow channel (50) is formed between the turbine back shell (30) and the back of the turbine impeller (4), which is used to collect the secondary flow entering the inflow channel (8); The fourth adjustment control (40) is installed in the outflow channel (50) and is used to adjust the shape of the area in the outflow channel (50) that can be used for secondary flow.

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