A thin-walled welded layered gas delivery system for a tip jet rotor

Abstract

This invention belongs to the technical field of tip-jet hybrid propulsion systems, and particularly relates to a thin-walled welded stratified air delivery system for tip-jet rotors. It includes a centrally welded three-layered casing: from the inside out, a central inner tube surrounding the main drive shaft, an inner conduit, and an outer bypass duct. The three-layered casing forms the main body of the central weld and is connected to machined components. The central inner tube protects the main drive shaft from direct contact with the high-temperature combustion gas. The inner conduit carries the high-temperature combustion gas, while the outer bypass duct carries cool air. This stratified air delivery structure enables coordinated delivery of hot and cold air and heat exchange along the pipeline, providing effective thermal protection for the pipeline and stabilizing the combustion gas temperature within the optimal range. This reduces the heat resistance requirements of the hot gas pipeline and surrounding components, improving system thermal efficiency and operational safety.

Description

Technical Field

[0001] This invention belongs to the technical field of tip-jet hybrid propulsion systems, and particularly relates to a thin-walled welded stratified air delivery system for tip-jet rotors. Background Technology

[0002] Due to their vertical takeoff and landing (VTOL) and hovering capabilities, gyroplanes have low infrastructure requirements and immense potential for future urban transportation, making them a key player in the "low-altitude economy." Driven by this demand, and to balance the power-to-weight ratio and fuel economy of the propulsion system while meeting the requirements of high-speed cruise and VTOL, countries in Europe and America have begun research on tip-jet aircraft. Tip-jet propulsion technology is a drive technology applied to gyroplanes. It uses the reaction force generated by bleed air from inside the rotor being expelled through the tip nozzle to drive the rotor's rotation, thereby generating lift and thrust. Tip-jet aircraft provide lift to the rotor through the counter-torque formed by the high-pressure, high-speed airflow ejected from the tip. Its application value has attracted long-term research and exploration from relevant institutions and scholars both domestically and internationally. Although its development history spans nearly 80 years, the principle configuration of using a single propulsion system as an air source generator to power the rotor has always been unable to simultaneously meet the multi-performance requirements of aircraft.

[0003] In an engine-integrated propeller tip jet hybrid propulsion system, efficiently and reliably transmitting the high-temperature, high-pressure gas generated by the gas generator to the propeller tip is a challenging problem.

[0004] To address the gas delivery issue, Chinese invention patent application CN115258143A proposes a gas delivery path: a gas generator is the core of gas generation, internally mixing high-temperature exhaust gas from the engine, compressed air from the centrifugal supercharger, and booster fuel to generate high-temperature, high-pressure gas. The gas generator's outlet is then connected to the hollow main shaft of the blade tip jet rotor via a rotary joint, with the gas first entering the rotary joint. The driven part of the rotary joint is welded and fixed to the hollow main shaft, and the gas flows through the rotary joint into a gas passage inside the hollow main shaft. The rotor disk connecting the blades on the hollow main shaft has a flow guiding structure inside, and the gas is delivered along the passage to the nozzle at the blade tip for final injection. While this scheme effectively shortens the gas delivery distance, it does not consider the coordinated delivery of hot and cold gas and the design of heat exchange along the route. On the one hand, it lacks targeted thermal protection measures. High-temperature gas flows directly through the hot gas pipelines inside the main shaft and rotor, which not only places a great burden on material selection (which needs to take into account both high temperature resistance and strength) and weight reduction design, but also limits the ultimate performance of the entire power system. On the other hand, it is impossible to accurately control the gas temperature within the optimal operating range. If the temperature is too high, it will reduce thermal efficiency and pose safety hazards. If the temperature is too low, it will cause energy waste and lead to insufficient propulsion efficiency. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a thin-walled welded layered gas delivery system for a tip-jet rotor. Its layered gas delivery structure can achieve coordinated delivery of hot and cold gases and heat exchange along the pipeline, which not only provides effective thermal protection for the pipeline, but also stabilizes the gas temperature within the optimal range, thereby reducing the requirements for the heat resistance of the hot gas pipeline and surrounding components, and improving the system's thermal efficiency and operational safety.

[0006] The technical solution of the present invention is as follows: A thin-walled welded stratified air delivery system for a tip-jet rotor includes: a central inner tube, an inner inner duct, an outer duct, a gas inlet pipe, a cold air inlet pipe, a lower inner tube welded seat, and an upper inner tube welded seat; The central inner pipe, inner pipe, and outer pipe are welded together to form a three-layer casing. The gas inlet pipe is connected to the inner pipe, the outer pipe of the gas inlet pipe is connected to the outer pipe, the gas inlet pipe is nested inside the cold air inlet pipe, the central inner pipe is welded to the upper seat of the inner pipe, the inner pipe is welded to the upper seat of the inner pipe using full circumferential welding, and the outer pipe is welded to the lower seat of the inner pipe using full circumferential welding.

[0007] Preferably, the gas is transmitted to the inner duct through the gas inlet pipe, and the cold air is transmitted to the outer duct through the cold air inlet pipe, so that both achieve thermal protection and efficient heat exchange at the same time.

[0008] Preferably, the thin-walled welded stratified gas transmission system further includes a gearbox, and the inner tube welded lower seat is fixed to the gearbox upper cover.

[0009] Preferably, the inner tube welding seat matches the shape of the central inner tube to ensure the coaxiality of the central inner tube with the inner and outer culverts.

[0010] Preferably, a lower rotor swivel splitter is provided on the outer side of the central inner tube corresponding to the lower rotor disk, which divides the outer duct and inner duct into two sections and welds them to the outer duct and inner duct respectively, for distributing cold air evenly to the lower rotor and upper rotor.

[0011] Preferably, the internal pipeline adopts a method of segmented welding combined with intermediate openings to achieve gas diversion.

[0012] Preferably, the inner pipe is formed by welding an upper thin-walled cylinder, a middle hollow frustum, and a lower thin-walled cylinder in sequence, and the middle hollow frustum is provided with multiple air distribution holes.

[0013] Preferably, the lower rotor gyro distributor is externally equipped with a brush seal assembly, including a brush seal limiting ring, a brush seal fixing plate, a distributor brush ring, and a brush seal fixing plate.

[0014] Preferably, the thin-walled welded stratified gas transmission system further includes an upper rotor support, an upper bearing base plate, and an upper bearing seat. The upper rotor support is fastened to the outer duct pipe with screws, the upper bearing base plate is welded to the inner duct pipe, and the upper bearing seat is connected to the upper bearing base plate with screws.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The thin-walled welded layered air supply system for tip jet rotors proposed in this invention uses an inner duct and an outer duct to form two layers of air supply channels, which realizes thermal protection for hot-end components, reduces the negative impacts of overheating on metal parts such as creep and thermal fatigue, and ensures the coaxiality of the sleeve during long-term use.

[0016] 2. The thin-walled welded layered gas delivery system for tip-jet rotors proposed in this invention transmits fuel gas to the inner duct through a fuel gas inlet pipe and cold air to the outer duct through a cold air inlet pipe. The two airflows exchange heat efficiently during their flow in the ducts, achieving effective thermal protection for the ducts and surrounding components. It can also precisely control the fuel gas temperature within the optimal operating range of 400-500℃, further improving the performance ceiling of the tip-jet hybrid propulsion system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the thin-walled welded layered gas delivery system for a tip-jet rotor according to the present invention.

[0019] Figure 2 This is a cross-sectional schematic diagram of the thin-walled welded layered air delivery system for a tip-jet rotor according to the present invention.

[0020] Figure 3 This is a cross-sectional schematic diagram of the bearing fit at the gearbox.

[0021] Figure 4 This is an enlarged schematic diagram of the bottom of the inner tube weld.

[0022] Figure 5 This is a schematic diagram of the assembly of the thin-walled welded layered gas delivery system and the propeller disk system of the present invention.

[0023] The markings in the diagram are: 11-Upper rotor disk, 12-Lower rotor disk, 301-Upper bearing housing, 302-Upper bearing housing base plate, 303-Central inner tube, 304-Upper rotor support seat, 305-Inner duct, 3051-Upper section of inner duct, 3052-Lower section of inner duct, 306-Outer duct, 3061-Upper section of outer duct, 3062-Lower section of outer duct, 307-Lower rotor gyro splitter, 308-Cold air inlet pipe, 309-Gas inlet pipe, 310-Upper seat of inner tube welding, 311-Lower seat of inner tube welding, 401-Brush seal limiting ring, 402-First brush seal fixing plate, 403-Splitter brush ring, 404-Second brush seal fixing plate, 503-Main drive shaft, 510-Gearbox cover, 511-Second equal section bearing LRB055. Detailed Implementation

[0024] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0026] The thin-walled welded stratified air delivery system for a tip-mounted jet rotor proposed in this invention comprises three centrally welded sleeves: from the inside out, a central inner tube surrounding the main drive shaft, an inner duct, and an outer bypass duct. The three sleeves, forming the centrally welded main body, are connected to the machined components. The central inner tube is an elongated oval tube, protecting the main drive shaft from direct contact with the high-temperature exhaust gas. High-temperature exhaust gas flows directly through the inner duct, while cold air flows through the outer bypass duct. After passing through the lower rotor cyclone splitter, the equivalent cross-section is reduced to half of its original size. Therefore, both the outer bypass duct and the inner duct are divided into two sections by the cyclone splitter.

[0027] Compared to the traditional tip-jet hybrid propulsion system, this invention includes the following improvements: First, the gas delivery system of this invention does not have a dedicated load-bearing structure. The internal stress during system operation is borne by three layers of piping: the central inner pipe, the inner duct, and the outer duct. Therefore, the materials and manufacturing processes of these three layers of piping have very high requirements. Second, in this invention, the combustion gas and cold air exchange heat during transmission, improving the overall thermal efficiency of the hybrid propulsion system. The two airflows are mixed at the rotor tip before being ejected, increasing the flow rate of the tip-jet propulsion.

[0028] Because the three-layer casing—central inner tube, inner duct, and outer duct—is centrally welded, and the walls of all three layers are relatively thin (1mm for the central inner tube, 1mm for the inner duct, and 2.69mm for the outer duct), manufacturing this gas transmission system is quite difficult. This invention rationally plans the welding sequence of the machined parts and the inner and outer ducts: welding begins at the central weld's bleed-out starting point, followed by welding the machined parts that serve as bearing positioning surfaces, and finally welding the outer duct. During the welding process, it is crucial to ensure that the three-layer casing shaft does not experience assembly conflicts, thus placing extremely high demands on the 20 welding points. The total length of the central weld can reach 1.6m, making it the longest welded component in the jet rotor subsystem. Within this 1.6m length, the design requires the coaxiality of the key machined parts in the central weld to be controlled within 0.8mm, significantly less than the Class 1 precision requirement of 5mm. Therefore, during the pipe rolling and component welding process at the center weld, processing errors must be controlled in each step, with each step inspected to ensure that the machined dimensions of the parts meet the overall dimensional requirements of the center weld. The processing precision and difficulty far exceed those of ordinary industrial products. Within the inner pipe, because the cyclone splitter distributes the gas flow into the two rotors, the inner pipe needs to have a uniform diameter change while ensuring a seal. A process of stamping with a diameter-changing die is used to form the diameter-changing pipe section in one step, reducing the number of welds and improving the overall strength of the center weld.

[0029] Example 1 like Figure 1 , Figure 2As shown, a thin-walled welded layered air delivery system for a tip-mounted jet rotor includes three main components: a central inner duct 303, an inner duct 305, and an outer bypass duct 306. All three ducts are made of specialized sheet metal materials that meet both high-temperature resistance and rigidity requirements, and are formed using a rolling process. This satisfies the core requirement of lightweighting in aerospace propulsion systems (thin-walled design optimizes power-to-weight ratio) while also bearing the internal stresses generated during system operation, preventing deformation or failure due to incompatible materials. After the gas turbine generates high-temperature, high-pressure gas, the gas is precisely transmitted to the inner pipe 305 through the gas inlet pipe 309. At the same time, the outer pipe 306 simultaneously delivers cold air. The two work together to achieve the core functions of thermal protection and efficient heat exchange: the high-temperature gas transfers heat to the inner wall of the inner pipe 305 through heat conduction and convection (the inner pipe is a thin-walled cylinder with a thickness of 1mm, balancing heat transfer efficiency and structural strength). The heat is then transferred to the outer wall inside the inner pipe through heat conduction and is quickly carried away by the cold air between the inner and outer pipes through heat conduction and convection. This achieves effective thermal protection for the pipes and surrounding components, and precisely controls the gas temperature within the optimal operating range of 400-500℃ through heat exchange along the pipe. This prevents the gas temperature from being too high, which would reduce thermal efficiency or cause safety hazards, and also prevents the temperature from being too low, which would cause energy waste. Finally, the two airflows mix at the rotor tip and are ejected, which not only improves thermal efficiency but also increases the jet flow at the rotor tip, enhancing the propulsion effect.

[0030] The thin-walled welded stratified gas transmission system of this invention has numerous components and requires extremely high assembly precision. Its assembly and connection structure design revolves around "ensuring coaxiality, sealing performance, and structural stability." The bottommost part is the inner tube welded lower seat 311, which is fastened to the gearbox cover 510 below by 18 M5×10_GB_T5781 hexagonal head bolts. This connection method not only ensures the installation stability of the entire gas transmission system in the normal direction, but also provides a unified assembly benchmark, laying the foundation for the precise assembly of all subsequent components and avoiding the cumulative coaxiality error caused by benchmark offset.

[0031] Above the inner tube welding lower seat 311 are an outer duct pipe 306 and an inner tube welding upper seat 310. The structure of the inner tube welding upper seat 310 is specially adapted to the welding requirements of the central inner tube 303. Through precise dimensional matching, it provides a stable welding carrier for the central inner tube, while effectively transmitting and dispersing the internal stress during system operation, ensuring the coaxiality of the central inner tube with the inner and outer duct pipes. The inner tube welding upper seat 310 and the inner tube welding lower seat 311 are connected by welding. The weld is continuous and dense, ensuring the integrity of the structure. The outer duct pipe 306 serves as a cold air transport channel. It adopts a full-circumference welding process with the inner tube welding lower seat 311. The weld is free of defects such as porosity and slag inclusions, ensuring no leakage during cold air transport and guaranteeing heat exchange efficiency.

[0032] The inner pipe 305, as the core channel for high-temperature gas transmission, is welded to the inner pipe's upper seat 310 using full-circumferential welding. Strict welding process control ensures reliable gas sealing and prevents safety risks caused by high-temperature gas leakage. The cold air inlet pipe 308 and the gas inlet pipe 309 serve as the inlet components for cold air and high-temperature gas, respectively, and are welded to the outer duct pipe 306 and the inner pipe 305. Before welding, laser cutting is used to process cuts on the pipes, ensuring dimensional accuracy and edge smoothness, and a perfect fit with the outer wall of the inlet pipe. Welding proceeds from the inside out, first welding the gas inlet pipe 309 to the inner pipe 305 (prioritizing high-temperature gas sealing), then welding the cold air inlet pipe 308 to the outer duct pipe 306 (secondarily ensuring cold air sealing), providing double protection to prevent cross-flow of hot and cold air.

[0033] like Figure 4 As shown, the central inner tube 303 is welded to the inner tube welding seat 310. Specifically, the central inner tube is a thin-walled cylinder with an outer diameter of 52mm and a thickness of 1mm. Inside the central inner tube is the main drive shaft with an outer diameter of 47mm. High-temperature gas flows between the inner pipe and the central inner tube. Its structural design is fully adapted to the installation requirements of the main drive shaft, and can completely isolate the main drive shaft from the high-temperature gas throughout the entire working cycle of the system, avoiding deformation, creep or performance degradation of the shaft due to high temperature. At the same time, it maintains coaxiality with the other two layers of pipes through precise welding.

[0034] Figure 5A schematic diagram of the assembly of the thin-walled welded stratified gas delivery system and the propeller disk system of the present invention is shown. The propeller disk system includes an upper propeller disk 11 and a lower propeller disk 12. The thin-walled welded stratified gas delivery system of this invention needs to simultaneously meet the gas supply requirements of both the upper and lower rotors. For the outer duct 306 and the inner duct 305, a dedicated flow-dividing structure is designed at the lower rotor disk: For the outer duct 306, a lower rotor gyratory flow divider 307 is installed at the lower rotor disk 12. This lower rotor gyratory flow divider 307 is optimized for fluid dynamics, enabling it to evenly distribute cold air to the lower and upper rotors. This satisfies the immediate gas supply requirements of the lower rotor while ensuring that the cold air delivered to the upper rotor meets design standards in terms of pressure, temperature, density, and other parameters, avoiding uneven flow distribution that could affect heat exchange and blade tip thrust. For the inner duct 305, a segmented welding design combined with a central opening is used to achieve gas flow diversion. The segmented structure can adapt to pressure changes after airflow distribution, and the precise position of the central opening ensures stable gas flow to both rotors, reducing pressure loss caused by airflow disturbance. Specifically, the inner pipe 305 is welded together in three sections: upper, middle, and lower. The lower section is a thin-walled cylinder with an outer diameter of 138 mm, and the upper section is a thin-walled cylinder with an outer diameter of 100 mm. The upper and lower sections are welded together in the middle by a hollow frustum similar in shape to a converging nozzle. Ten rounded rectangular gas distribution holes are provided in the connecting section of the hollow frustum in the middle. The gas flows from bottom to top. When it flows through the middle section, without the aid of external force, part of it flows down to the lower rotor, and part of it continues to flow up into the thin-walled cylinder with an outer diameter of 100 mm, where it continues to be transported by the upper rotor.

[0035] On the outside of the lower rotor cyclone splitter 307, a brush seal assembly (including a brush seal limiting ring 401, a first brush seal fixing plate 402, a splitter brush ring 403, and a second brush seal fixing plate 404) is installed. This brush seal assembly adopts a flexible sealing design, which can adapt to the rotation conditions of the cyclone splitter, effectively blocking the leakage of cold air and high-temperature gas at the welded joint, while reducing the frictional wear between the seal and the rotating parts, extending the service life, and ensuring the sealing performance and reliability of the system during long-term operation. The body of the lower rotor cyclone splitter 307 is welded together from the upper and lower sections. It is connected to the outer duct pipe 306 and the inner duct pipe 305 by welding. The welds are strictly inspected to ensure that there is no gas leakage during the splitting process.

[0036] In the upper rotor section, the upper rotor support 304 and the outer duct 306 are fastened together by 18 M310_GB_T70.1 socket head cap screws. The screws are evenly distributed around the circumference to ensure balanced force distribution and prevent deformation of the outer duct due to excessive local stress. This also facilitates subsequent disassembly and maintenance. The upper bearing seat base plate 302 and the inner duct 305 are welded together to further enhance the structural stability of the inner duct and provide an installation foundation for the upper bearing seat 301. The upper bearing seat 301 and the upper bearing seat base plate 302 are connected by 9 M46_GB_T70.1 socket head cap screws. This connection method balances stability and assembly precision, providing accurate support for the rotation of the upper rotor.

[0037] After the thin-walled welded stratified air delivery system of this invention is assembled with the rotor and transmission system, it is necessary to ensure the assembly accuracy of the seals and rotating parts at the mating points to avoid the cumulative effect of errors on system performance. The following is a description of the key bearing mating structure: like Figure 3 As shown, at the gearbox at the bottom of the gas transmission system, the gearbox cover 510 and the main drive shaft 503 are connected by an interference fit of the second equal section bearing LRB055 511. This bearing has the characteristics of high load-bearing capacity and high rotational accuracy, and can adapt to the high-speed rotation of the main drive shaft. At the same time, the interference fit ensures that there is no relative displacement between the bearing and the shaft and housing, thus ensuring transmission accuracy and stability.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thin-walled welded layered gas delivery system for a tip jet rotorcraft, characterized by, Includes: central inner pipe, inner duct, outer duct, gas inlet pipe, cold air inlet pipe, lower inner pipe welding seat and upper inner pipe welding seat; The central inner pipe, inner pipe, and outer pipe are welded together to form a three-layer casing. The gas inlet pipe is connected to the inner pipe, the outer pipe of the gas inlet pipe is connected to the outer pipe, the gas inlet pipe is nested inside the cold air inlet pipe, the central inner pipe is welded to the upper seat of the inner pipe, the inner pipe is welded to the upper seat of the inner pipe using full circumferential welding, and the outer pipe is welded to the lower seat of the inner pipe using full circumferential welding.

2. The thin-walled welded stratified gas delivery system according to claim 1, characterized in that, Gas is transported to the inner duct through gas inlet pipe, and cold air is transported to the outer duct through cold air inlet pipe, achieving both thermal protection and efficient heat exchange simultaneously.

3. The thin-walled welded layered gas transmission system of claim 1, wherein, The thin-walled welded stratified gas transmission system also includes a gearbox, and the inner tube welded lower seat is fixed to the gearbox cover.

4. The thin-walled welded layered gas transmission system of claim 1, wherein, The inner tube welding seat matches the shape of the central inner tube, ensuring the coaxiality of the central inner tube with the inner and outer culverts.

5. The thin-walled welded stratified gas delivery system according to claim 1, characterized in that, The lower rotor gyratory splitter is located on the outer side of the central inner tube, corresponding to the lower rotor disk. It divides the outer duct and inner duct into two sections and welds them to the outer duct and inner duct respectively, so as to evenly distribute the cold air to the lower rotor and the upper rotor.

6. The thin-walled welded layered gas transmission system of claim 1, wherein, The internal pipeline uses a combination of segmented welding and intermediate openings to achieve gas diversion.

7. The thin-walled welded layered gas transmission system of claim 6, wherein, The inner pipe is formed by welding an upper thin-walled cylinder, a middle hollow truncated cone, and a lower thin-walled cylinder in sequence. The middle hollow truncated cone is provided with multiple air distribution holes.

8. The thin-walled welded layered gas transmission system of claim 1, wherein, The lower rotor gyro distributor is externally equipped with a brush seal assembly, including a brush seal limiting ring, a brush seal fixing plate, a distributor brush ring, and a brush seal fixing plate.

9. The thin-walled welded layered gas transmission system of claim 1, wherein, The thin-walled welded stratified gas transmission system also includes an upper rotor support, an upper bearing base plate, and an upper bearing housing. The upper rotor support is fastened to the outer duct pipe with screws, the upper bearing base plate is welded to the inner duct pipe, and the upper bearing housing is connected to the upper bearing base plate with screws.

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