Turbofan engine and aircraft

Abstract

The present disclosure relates to the technical field of aero-engine, and particularly provides a turbofan engine and an aircraft, which comprises an air inlet channel, a center cone, a precooler, a core engine and a flow channel adjusting mechanism, the air inlet channel comprises an outer bypass duct and an inner bypass duct; the center cone is arranged at the front end of the turbofan engine; the precooler is arranged behind the center cone, the precooler is in a cylindrical shape, and the side wall can communicate the outer bypass duct and the inner bypass duct to pass through the airflow and cool the airflow; the core engine is arranged behind the precooler, and a plurality of mixing holes are arranged between the precooler and the core engine, the mixing holes can communicate the outer bypass duct and the inner bypass duct to pass through the airflow; and the flow channel adjusting mechanism is arranged in the outer bypass duct and can open and close the precooler and the mixing holes to control the flow direction of the airflow between the outer bypass duct and the inner bypass duct. The present disclosure combines the precooler with the flow channel adjusting mechanism, realizes targeted precooling of the inner bypass duct airflow, and avoids waste of the cold source of the outer bypass duct airflow and pressure loss.

Description

Technical Field

[0001] This disclosure relates to the field of aero-engine technology, and in particular to a turbofan engine and an aircraft. Background Technology

[0002] Compared to conventional turbojet engines, turbofan engines, by incorporating an external bypass fan, can provide higher propulsive efficiency and thrust at lower flight speeds. However, as flight speeds increase, the difference in airflow compression between the external and internal ducts widens, requiring the engine to possess variable cycle regulation capabilities to accommodate performance at different speeds. For example, the Pratt & Whitney J58 engine used in a certain foreign reconnaissance aircraft, by introducing a bypass combustion chamber (ramjet mode), allows the engine to operate stably at Mach 3.2. However, when the flight Mach number further increases to around 4, conventional turbofan engines face problems such as excessively high inlet temperatures and insufficient compressor surge margin, necessitating the use of pre-cooling technology to extend the engine's operating envelope.

[0003] However, traditional precooling technology has the following problems:

[0004] (1) Precoolers are usually located at the front of the engine, which means that all airflow entering the engine (including the bypass duct and the inner duct) must pass through the precooler, resulting in a waste of cooling resources. (The inner duct airflow needs to pass through the high boost ratio core engine, so it must be precooled, while the outer bypass duct airflow usually does not need to be precooled. If a precooler covering the entire intake section is installed before the engine inlet, most of the outer bypass duct airflow will also be unnecessarily cooled, resulting in a waste of cooling resources and additional flow resistance losses.)

[0005] (2) Although the precooler does not work at low speed (Ma<2), it still generates additional pressure loss, which affects engine efficiency.

[0006] (3) The integrated design of the precooler and the engine is not optimized enough and cannot adapt to the changes in airflow characteristics at different Mach numbers. Summary of the Invention

[0007] This disclosure is made in view of the above-mentioned problems. This disclosure provides a turbofan engine and an aircraft.

[0008] According to one aspect of this disclosure, a turbofan engine is provided, comprising:

[0009] An air intake, which includes an outer bypass duct and an inner bypass duct;

[0010] A central cone, wherein the central cone is disposed at the front end of the turbofan engine;

[0011] A precooler is disposed behind the central cone. The precooler is cylindrical and its sidewalls can connect the outer duct and the inner duct to allow airflow to pass through and cool the airflow.

[0012] The core unit is located behind the precooler and has multiple mixing holes between it and the precooler. The mixing holes can connect the outer bypass duct and the inner bypass duct to allow airflow.

[0013] A flow channel regulating mechanism is disposed in the outer bypass duct and is capable of opening and closing the precooler and the mixing hole to control the flow direction of the airflow between the outer bypass duct and the inner bypass duct.

[0014] Furthermore, according to one aspect of the turbofan engine of this disclosure, the core engine comprises, arranged sequentially from front to back:

[0015] The compressor, combustion chamber, high-pressure turbine, free turbine, and rear fan are provided. The rear fan is connected to the free turbine via a drive shaft. The airflow in the internal duct drives the free turbine to rotate, and the free turbine drives the rear fan to rotate.

[0016] Furthermore, according to one aspect of the turbofan engine of this disclosure, the core engine comprises, arranged sequentially from front to back:

[0017] The system includes a front fan, a compressor, a combustion chamber, a high-pressure turbine, and a free turbine. The front fan is connected to the free turbine via a drive shaft. Airflow in the internal duct drives the free turbine to rotate, and the free turbine drives the front fan to rotate.

[0018] Furthermore, according to one aspect of the turbofan engine disclosed herein, the flow channel adjustment mechanism includes:

[0019] The system comprises a first sliding sleeve, a second sliding sleeve, and an actuating mechanism. The first sliding sleeve is positioned in front of the second sliding sleeve. The actuating mechanism drives the first sliding sleeve and the second sliding sleeve to slide independently. The first sliding sleeve and the second sliding sleeve can slide to the outer periphery of the precooler or the outer periphery of the mixing hole, respectively.

[0020] Furthermore, according to one aspect of the turbofan engine disclosed herein, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve slides to the outer periphery of the precooler to close the precooler, and the second sliding sleeve slides to the outer periphery of the core engine to open the mixing orifice, allowing airflow to enter the outer bypass duct and the inner bypass duct;

[0021] When the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve slides to the outer periphery of the mixing hole to open the precooler and close the mixing hole. The second sliding sleeve slides to the outer periphery of the core machine, and the airflow enters the outer bypass duct, cools, and then enters the inner bypass duct.

[0022] When the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve slides to the outer periphery of the precooler to close the precooler, and the second sliding sleeve slides to the outer periphery of the mixing hole to close the mixing hole, and the airflow only enters the outer bypass duct.

[0023] Furthermore, according to one aspect of the turbofan engine disclosed herein, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve slides to the outer periphery of the central cone, the second sliding sleeve slides to the outer periphery of the precooler to close the precooler, and the mixing orifice is opened, allowing airflow to enter the outer bypass duct and the inner bypass duct;

[0024] When the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve slides to the outer periphery of the central cone, the second sliding sleeve slides to the outer periphery of the mixing hole to open the precooler and close the mixing hole, the airflow enters the outer bypass duct, and after cooling, enters the inner bypass duct;

[0025] When the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve slides to the outer periphery of the precooler to close the precooler, and the second sliding sleeve slides to the outer periphery of the mixing hole to close the mixing hole, and the airflow only enters the outer bypass duct.

[0026] Furthermore, according to one aspect of the present disclosure, the sidewall of the precooler is a tube-fin heat exchanger or a microchannel plate heat exchanger, with a cooling medium flowing inside to cool the passing airflow.

[0027] Furthermore, the turbofan engine according to one aspect of this disclosure also includes:

[0028] An afterburner is located at the rear of the core machine.

[0029] Furthermore, the turbofan engine according to one aspect of this disclosure also includes:

[0030] The tail nozzle is located at the tail end of the turbofan engine and can adjust the throat area.

[0031] According to another aspect of this disclosure, an aircraft is provided, comprising: a turbofan engine according to any one of the above-described technical solutions.

[0032] The turbofan engine and aircraft according to the embodiments of this disclosure significantly improve the performance of the turbofan engine in the high-speed field through the innovative combination of radial partition precooling, fan layout and multi-modal variable cycle control. This enables the engine to maintain the advantages of low-speed high efficiency of turbofan engines while successfully breaking through the speed limit of traditional turbofans, providing a brand-new power solution for future high-speed aircraft.

[0033] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0034] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0035] Figure 1 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole is open and the precooler is closed;

[0036] Figure 2 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole is closed and the precooler is open;

[0037] Figure 3 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole and the precooler are closed;

[0038] Figure 4 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole is open and the precooler is closed;

[0039] Figure 5 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole is closed and the precooler is open;

[0040] Figure 6 This is a schematic diagram of a turbofan engine according to an embodiment of the present disclosure, in which the mixing hole and the precooler are closed.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Inlet duct, 2. Central cone, 3. Precooler, 4. Core engine, 41. Compressor, 42. Combustion chamber, 43. High-pressure turbine, 5. Free turbine, 6. Rear fan, 7. Afterburner, 8. Tail nozzle, 9. Flow channel adjustment mechanism, 91. First sliding sleeve, 92. Second sliding sleeve, 93. Actuation mechanism, 10. Mixing hole, 11. Outer bypass duct, 12. Inner bypass duct, 13. Front fan, 14. Flow splitting shoulder, 15. First housing, 16. Second housing. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this disclosure more apparent, exemplary embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure. It should be understood that this disclosure is not limited to the exemplary embodiments described herein.

[0044] This disclosure provides a turbofan engine and an aircraft that achieves targeted precooling of the inner bypass airflow by combining a precooler with a flow channel adjustment mechanism, while avoiding waste of cold source and pressure loss of the outer bypass airflow.

[0045] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0046] like Figure 1 , Figure 2 , Figure 3 As shown, this disclosure provides a turbofan engine, including: an air intake 1, a central cone 2, a precooler 3, a core engine 4, and a flow channel adjustment mechanism 9;

[0047] The intake duct 1 includes an outer bypass duct 11 and an inner duct 12. The outer bypass duct 11 is located between the outer circumference of the first casing 15 and the central cone 2, the outer circumference of the precooler 3, and the outer circumference of the core engine 4. The inner duct 12 is located in the inner ring of the precooler 3 and the inner ring of the casing where the mixing holes 10 are provided. The ratio of the airflow of the outer bypass duct 11 to the airflow of the inner duct 12 is called the bypass ratio, which is an important design parameter of the turbofan engine. It has a great influence on the engine's fuel consumption rate and thrust-to-weight ratio.

[0048] The central cone 2 is located at the front end of the turbofan engine and is also called the rectifier cone. It is mainly used to rectify the airflow entering the intake duct 1.

[0049] The precooler 3 is cylindrical and located behind the central cone 2. The sidewall of the precooler 3 connects the outer bypass duct 11 and the inner bypass duct 12 to allow airflow to pass through and cool it. The airflow flows from the outer bypass duct 11 to the inner bypass duct 12. Figure 2 As shown by the hollow arrow in the image, the precooler 3 radially divides the intake duct 1, separating the outer bypass duct 11 and the inner bypass duct 12.

[0050] The core engine 4 is the main power-generating device of the engine. It is located behind the precooler 3, and multiple mixing holes 10 are provided between it and the precooler 3. These mixing holes 10 connect the outer bypass duct 11 and the inner bypass duct 12 to allow airflow. The airflow flows from the outer bypass duct 11 to the inner bypass duct 12, and is used to introduce airflow from the outer bypass duct 11 into the inner bypass duct 12 at low speeds. Figure 1 The arrows in the diagram indicate the direction of airflow. A cylindrical casing can be installed between the second housing 16 of the core unit 4 and the precooler 3, with mixing holes 10 located on the side wall of the casing.

[0051] The flow channel regulating mechanism 9 is located on the outer bypass duct 11, specifically fitted around the periphery of the precooler 3 and the mixing hole 10. It can open and close the precooler 3 and the mixing hole 10 to control the airflow direction between the outer bypass duct 11 and the inner bypass duct 12. Because both the precooler 3 and the mixing hole 10 connect the outer bypass duct 11 and the inner bypass duct 12, the flow channel regulating mechanism 9 will selectively open either the precooler 3 or the mixing hole 10, and will not open both simultaneously.

[0052] The turbofan engine in this embodiment significantly improves the performance of the turbofan engine in the high-speed field through the innovative combination of radial partition precooling, fan layout and multi-modal variable cycle control. While maintaining the advantages of low-speed high efficiency of turbofan engines, the engine successfully breaks through the speed limit of traditional turbofans, providing a brand-new power solution for future high-speed aircraft.

[0053] In some possible implementations, such as Figure 1 , Figure 2 , Figure 3 As shown, core machine 4 includes the following components arranged from front to back:

[0054] The compressor 41, combustion chamber 42, high-pressure turbine 43, free turbine 5 and rear fan 6 are connected to the free turbine 5 via a drive shaft. The airflow in the inner duct 12 drives the free turbine 5 to rotate, and the free turbine 5 drives the rear fan 6 to rotate.

[0055] The compressor 41, combustion chamber 42, and high-pressure turbine 43 are coaxially connected to form a gas generator. During normal operation of the core engine 4, the compressor 41 compresses air, which then mixes and burns with fuel in the combustion chamber 42. The high-temperature gas drives the high-pressure turbine 43 to perform work, rotating the compressor 41. After leaving the high-pressure turbine 43, the gas continues to expand, driving the free turbine 5. The free turbine 5, through a drive shaft, drives the rear fan 6 to rotate, accelerating the air passing through the fan.

[0056] The rear fan 6 is located in the outer bypass duct 11 at the rear of the core machine 4. Its blade size and blade profile are designed to provide a large flow of air acceleration at a low pressure ratio to generate bypass thrust.

[0057] The airflow in the inner bypass duct 12 generates a portion of the thrust. The blades of the rear fan 6 are located in the outer bypass duct 11. The rear fan 6 can act as a low-pressure compressor. The rotation of the rear fan 6 can drive the airflow in the outer bypass duct 11 to generate another portion of the thrust. The proportion of the two portions of thrust in the entire engine is related to the bypass ratio.

[0058] In some possible implementations, such as Figure 4 , Figure 5 , Figure 6 As shown, core machine 4 includes the following components arranged from front to back:

[0059] The system includes a front fan 13, a compressor 41, a combustion chamber 42, a high-pressure turbine 43, and a free turbine 5. The front fan 13 is connected to the free turbine 5 via a drive shaft. The airflow in the inner duct 12 drives the free turbine 5 to rotate, and the free turbine 5 drives the front fan 13 to rotate.

[0060] The compressor 41, combustion chamber 42, and high-pressure turbine 43 are coaxially connected to form a gas generator. During normal operation of the core engine 4, the compressor 41 compresses air, which then mixes and burns with fuel in the combustion chamber 42. The high-temperature gas drives the high-pressure turbine 43 to perform work, rotating the compressor 41. After leaving the high-pressure turbine 43, the gas continues to expand, driving the free turbine 5. The free turbine 5, through a drive shaft, drives the front fan 13 to rotate, accelerating the air passing through the fan.

[0061] The front fan 13 is located in the front bypass duct 11 of the core machine 4. Its blade size and blade profile are designed to provide a large flow of air acceleration at a low pressure ratio to generate bypass thrust.

[0062] The airflow in the inner bypass duct 12 generates a portion of the thrust. The blades of the front fan 13 are located in the outer bypass duct 11. The front fan 13 can act as a low-pressure compressor. The rotation of the front fan 13 can drive the airflow in the outer bypass duct 11 to generate another portion of the thrust. The proportion of the two portions of thrust in the entire engine is related to the bypass ratio.

[0063] The front fan 13 has a splitting shoulder 14 on its blades. The front end of the splitting shoulder 14 can connect to the casing with the mixing hole 10, and the rear end can connect to the second housing 16 of the core machine 4. The connection position has a gap of appropriate distance so as not to affect the rotation of the front fan 13. The splitting shoulder 14 can serve to separate the outer bypass duct 11 and the inner bypass duct 12.

[0064] In some possible implementations, such as Figure 1 , Figure 2 , Figure 3 As shown, the flow channel adjustment mechanism 9 includes:

[0065] The first sliding sleeve 91, the second sliding sleeve 92, and the actuating mechanism 93 are provided. The first sliding sleeve 91 is located in front of the second sliding sleeve 92. The actuating mechanism 93 drives the first sliding sleeve 91 and the second sliding sleeve 92 to slide independently. The first sliding sleeve 91 and the second sliding sleeve 92 can slide to the outer periphery of the precooler 3 or the outer periphery of the mixing hole 10, respectively.

[0066] The central cone 2, the precooler 3, the casing with the mixing hole 10, and the outer circumference of the second housing 16 can be provided with slide rails corresponding to the first sliding sleeve 91 and the second sliding sleeve 92, allowing the first sliding sleeve 91 and the second sliding sleeve 92 to slide along the slide rails. The actuation mechanism 93 can be driven by electricity, pneumatics, or hydraulics to achieve automated control.

[0067] For the core machine 4 that uses a rear fan 6 or a front fan 13, the sliding methods of the first sliding sleeve 91 and the second sliding sleeve 92 are different, as described below.

[0068] In some possible implementations, for the core machine 4 employing a rear-mounted fan 6, such as Figure 1 As shown, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve 91 slides to the outer periphery of the precooler 3 to close the precooler 3, and the second sliding sleeve 92 slides to the outer periphery of the core machine 4 to open the mixing hole 10. The airflow enters the outer bypass duct 11 and the inner bypass duct 12. The airflow enters the inner bypass duct 12 through the mixing hole 10 without being cooled.

[0069] like Figure 2 As shown, when the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve 91 slides to the outer periphery of the mixing hole 10 to open the precooler 3 and close the mixing hole 10. The second sliding sleeve 92 slides to the outer periphery of the core machine 4, and the airflow enters the outer bypass duct 11, and after cooling, enters the inner bypass duct 12.

[0070] like Figure 3 As shown, when the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve 91 slides to the outer periphery of the precooler 3 to close the precooler 3, and the second sliding sleeve 92 slides to the outer periphery of the mixing hole 10 to close the mixing hole 10, and the airflow only enters the outer bypass duct 11.

[0071] In some possible implementations, for the core machine 4 employing a front-mounted fan 13, such as Figure 4 As shown, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve 91 slides to the outer periphery of the central cone 2, the second sliding sleeve 92 slides to the outer periphery of the precooler 3 to close the precooler 3, and the mixing hole 10 is opened, the airflow enters the outer bypass duct 11 and the inner bypass duct 12, and the airflow enters the inner bypass duct 12 through the mixing hole 10 without being cooled.

[0072] like Figure 5 As shown, when the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve 91 slides to the outer periphery of the central cone 2, the second sliding sleeve 92 slides to the outer periphery of the mixing hole 10 to open the precooler 3 and close the mixing hole 10, the airflow enters the outer bypass duct 11, and after cooling, enters the inner bypass duct 12.

[0073] like Figure 6 As shown, when the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve 91 slides to the outer periphery of the precooler 3 to close the precooler 3, and the second sliding sleeve 92 slides to the outer periphery of the mixing hole 10 to close the mixing hole 10, and the airflow only enters the outer bypass duct 11.

[0074] In some possible implementations, such as Figure 1 , Figure 4 As shown, the sidewall of the precooler 3 is a tube-fin heat exchanger or a microchannel plate heat exchanger, with a cooling medium flowing inside to cool the passing airflow.

[0075] Tube-fin structure: It consists of multiple cooling tubes evenly distributed around the circumference and fins connected to the outside of the tubes. Low-temperature cooling medium (such as liquid metal or supercritical fluid) flows inside the cooling tubes. Air flows radially from the outside to the inside in the gaps between the fins, transferring heat to the cooling medium and being cooled.

[0076] Microchannel structure: Consists of multiple parallel microchannel plates stacked in a ring. The cooling medium flows circumferentially within the microchannel channels inside the plates, while air flows radially through narrow gaps between adjacent microchannel plates for heat exchange. The microchannel structure utilizes advanced processes such as additive manufacturing to achieve very high heat exchange efficiency and a compact size. The cooling medium loop of the precooler 3 is connected to a cold source system (not shown in the figure), which can provide a continuous cooling supply, for example, using cryogenic fuel (liquid hydrogen, etc.) carried by the aircraft or an independent refrigeration cycle.

[0077] In some possible implementations, such as Figure 1 , Figure 4 As shown, the turbofan engine also includes an afterburner 7, which is located behind the core engine 4.

[0078] The afterburner 7 is equipped with a fuel nozzle and an igniter, which can inject fuel and ignite it when needed, so that the mixture can be further burned and heated, and then discharged at high speed from the tail nozzle 8 to generate additional thrust.

[0079] The afterburner 7 can inject and ignite additional fuel when needed (such as during high-speed sprints or climbs) to significantly increase exhaust velocity, thereby providing additional thrust for a short period of time. The presence of the afterburner 7 allows the core engine 4 to generate primary thrust even when its power is reduced or in windmill mode (idling without power) through combustion in the afterburner 7.

[0080] In some possible implementations, such as Figure 1 , Figure 4 As shown, the turbofan engine also includes a tail nozzle 8, which is located at the tail end of the turbofan engine and can adjust the throat area.

[0081] The tail nozzle 8 is an adjustable area nozzle, which can adjust the throat area according to the engine operating conditions to expand or shrink it in order to optimize thrust and efficiency.

[0082] The turbofan engine disclosed herein, through the aforementioned structural design, can operate in multiple modes at different flight Mach numbers, including low-speed, medium-speed, and high-speed modes. The operating states and airflow paths of the engine components differ in each mode, achieving efficient operation over a wide Mach number range. Taking a turbofan engine with a rear-mounted fan 6 as an example:

[0083] a. Low-speed mode (Ma<2). At lower flight Mach numbers, the total intake air temperature is relatively low, and the engine does not require the precooler to be activated. At this time, the first sliding sleeve 91 of the flow channel adjustment mechanism is in the closed inner ring channel (side wall of precooler 3) position, the inner ring channel of the engine intake (side wall of precooler 3) is closed, and all airflow enters the engine from the outer ring channel. Part of the air entering the outer ring enters the inner ring channel 12 directly through the mixing hole 10 (at this time, the core engine 4 is working normally, and the compressor 41 draws in part of the outer ring air), and the other part flows directly to the rear fan 6 as the bypass airflow, bypassing the core engine 4. After compression, combustion, and expansion in the core engine 4, the gas drives the high-pressure turbine 43 and continues to flow backward, then drives the free turbine 5 to rotate the rear fan 6. The part of the outer ring airflow that does not enter the core engine 4 directly enters the rear fan 6 and is accelerated, mixing with the gas discharged from the core engine 4 at the fan outlet (or mixing through their respective pipes before the afterburner 7), and then entering the afterburner 7 together. During the low-speed phase, the afterburner 7 is typically inactive (or only briefly activated when additional thrust is required), and the mixed airflow expands and exits through the exhaust nozzle 8 to generate thrust. Throughout the low-speed mode, the precooler 3 does not engage, avoiding unnecessary pressure loss, and the engine operates in conventional turbofan mode, achieving high propulsion efficiency.

[0084] b. Medium-speed mode (2≤Ma<3.5). As the flight speed increases to Mach 2 or higher, the total intake air temperature gradually rises. To protect the core engine 4 and expand the operating envelope, the engine begins to activate the precooler 3. When the Mach number reaches approximately 2, the control system issues a command, and the actuator 93 pushes the first sliding sleeve 91 to move axially, gradually opening the inner ring passage of the intake (the side wall of the precooler 3), while simultaneously closing the mixing orifice 10 at the rear end of the precooler 3. At this time, the engine intake air is divided into two streams: an outer ring airflow and an inner ring airflow. The outer ring airflow no longer enters the inner duct 12 through the mixing orifice 10, but directly enters the rear fan 6 as the bypass airflow, and flows to the afterburner 7 after being accelerated by the fan; the inner ring airflow enters the annular precooler 3 through the opened inner ring passage (the side wall of the precooler 3), is cooled by the cooling medium to a predetermined temperature (e.g., reduced to near ambient temperature or even lower, depending on design requirements) before entering the compressor 41 of the core engine 4. Pre-cooled air significantly reduces the inlet temperature of compressor 21, allowing it to operate at higher converted speeds without stalling. This enables the engine to maintain a larger airflow and pressure ratio at higher Mach numbers. The pre-cooled air is compressed and combusted within the core engine 4. The resulting high-temperature combustion gases drive the high-pressure turbine 43, which in turn drives the free turbine 5, which in turn drives the rear-mounted fan 6. The exhaust gases from the core engine 4 merge with the bypass airflow accelerated by the fan in the afterburner 7. At medium speeds, the afterburner 7 can be selectively activated as needed: in the Mach 2-3 range, if higher thrust is required, a small amount of afterburner can be activated to supplement thrust; during cruise, afterburner remains off to save fuel. With the precooler activated, the core engine 4 can continue to operate stably at high speeds around Mach 3, while the bypass airflow, not being pre-cooled, avoids wasted cooling and additional flow losses. Through the effective operation of the precooler 3, the engine can maintain stable thrust output around Mach 3, unlike traditional turbofan engines which experience a sharp performance drop due to intake overheating.

[0085] c. High-speed mode (3.5≤Ma<4). When the flight speed further increases to Mach 3.5 or higher, even after pre-cooling, the operating environment of core engine 4 remains extremely harsh (extremely high total intake air temperature, high compression work, and high turbine heat load). In order to obtain sufficient thrust when approaching Mach 4, the engine gradually transitions to high-speed ramjet mode. When the Mach number reaches around 3.5, the engine control system begins to implement a medium-speed to high-speed mode transition strategy: First, the fuel supply to core engine 4 is gradually reduced, causing the output power of core engine 4 to decrease, and the speed of high-pressure turbine 43 and compressor 41 to decrease; at the same time, the angle of the guide vanes in front of the rear fan 6 is adjusted to match the reduced airflow and prevent the fan and compressor 41 from surging or stalling. As the power of core engine 4 continues to decrease, core engine 4 eventually stops injecting fuel and enters a "windmill" state (i.e., the core engine rotor passively rotates under the impact of high-speed airflow, but does not produce effective power output). At this point, the first sliding sleeve 91 of the inner ring passage of the air intake (the side wall of the precooler 3) closes again under the action of the control system, cutting off the airflow in the inner ring, and the precooler 3 also stops the circulation of the cooling medium (the cold source supply is shut off). Thus, in the high-speed phase, almost all the intake air enters the engine through the outer ring passage, bypassing the precooler 3 and the core engine 4. The air entering the outer ring passes directly through the rear fan 6, but since the core engine 4 has stopped working, the free turbine 5 and the fan lose their power source, and the fan blades rotate freely in the high-speed airflow like a windmill (with very little airflow resistance). After passing through the fan, the air directly enters the afterburner 7, which is operating at full power. A large amount of fuel is injected and mixed with the air for combustion, producing high-temperature, high-pressure gas, which is discharged at high speed through the tailpipe 8, generating the main thrust. In high-speed mode, the engine is essentially equivalent to a ramjet engine, utilizing the ram compression effect of the high-speed intake air to generate thrust through combustion in the afterburner, while the core engine and fan only serve as part of the airflow passage and do not actively provide mechanical work. This mode transition enables the engine to continue operating at high speeds of around Mach 4, breaking through the speed limitations of traditional turbofan engines.

[0086] It is important to emphasize that the transitions between the aforementioned modes are continuously adjustable. For example, during the transition from medium speed to high speed, the reduction in core engine power 4 and the increase in afterburner thrust 7 are gradual to ensure smooth and continuous thrust output without significant interruptions or sudden drops. Similarly, during the transition from low speed to medium speed, the precooler 3 is engaged gradually. By precisely controlling the opening of the sliding sleeve and mixing orifice 10, the airflow in the inner ring gradually increases while the airflow entering the inner duct 12 in the outer ring gradually decreases, thus avoiding abrupt changes in compressor 41 intake conditions caused by flow path switching. The engine control system (e.g., FADEC) adjusts the precooler cold source flow rate, sliding sleeve position, mixing orifice opening, fan guide vane angle, and afterburner fuel supply in real time based on parameters such as flight Mach number, altitude, and throttle commands to optimize engine performance and ensure safety margins.

[0087] The turbofan engine disclosed herein has the following significant innovations in structure and working principle:

[0088] (1) Radial Partition Precooling Structure: To address the different airflow requirements of the inner and outer bypass ducts of a turbofan engine, a radial partition annular precooler arrangement in the inlet is proposed for the first time. By designing the precooler as a cylindrical annular shape that only covers the inner duct inlet area, cooling is achieved only for the core engine inlet, while the outer bypass airflow does not pass through the precooler. In contrast, existing solutions such as the ATREX engine and JAXA's PCTJ precooled turbojet engine typically use precoolers covering the entire inlet cross-section to cool the entire incoming flow, without considering separate precooling for the inner duct to avoid wasting the cold source for the outer bypass. The radial partition precooling structure disclosed in this paper effectively improves the cold source utilization rate and reduces unnecessary cooling power consumption and flow losses, making it a pioneering achievement internationally.

[0089] (2) Rear-mounted fan layout: This disclosure places the fan behind the core engine and drives it with an independent free turbine. This configuration differs from traditional front-mounted fan turbofan engines. The rear-mounted fan configuration for high-speed turbofan engines, combined with pre-cooling technology, is unprecedented in the prior art. The introduction of the rear-mounted fan avoids the problem of front-mounted fans being susceptible to shock waves during high-speed flight. At the same time, the free turbine recovers energy from the combustion gases to drive the fan, improving the engine's overall thrust and efficiency. In addition, the rear-mounted fan layout simplifies the overall engine structure: the fan and core engine are decoupled through the free turbine, and their designs are relatively independent, reducing complex transmission mechanisms and making the engine have fewer components, lighter weight, and simpler manufacturing.

[0090] (3) Multimodal Variable Cycle Control: The engine disclosed herein can automatically switch operating modes according to the flight Mach number, achieving a smooth transition between low-speed high-efficiency turbofan mode, medium-speed pre-cooled turbofan mode, and high-speed ramjet mode. This process is achieved through the coordinated control of the inlet sliding sleeve, mixing orifice, core engine, and afterburner, which is a novel variable cycle control strategy. Unlike traditional variable cycle engines that only change the bypass ratio (such as the third bypass of the F-120 engine), this disclosure introduces pre-cooling and ramjet combustion in a higher speed range, expanding the concept of variable cycle. The engine can maintain high performance in all modes: at low speeds, it operates in conventional turbofan mode with low fuel consumption; at high speeds, pre-cooling and afterburner combustion are activated, significantly increasing thrust, thus providing good operating capability in a wide range of Mach numbers from 0 to 4.

[0091] In some possible implementations, embodiments of this disclosure also provide an aircraft, including: a turbofan engine according to any one of the above embodiments. The aircraft is typically an airplane, and may be a passenger plane, transport plane, fighter jet, or similar type.

[0092] The turbofan engine and aircraft according to embodiments of the present disclosure have been described above with reference to the accompanying drawings, and have the following advantages:

[0093] (1) Extending the upper limit of flight Mach number: By utilizing the combined effect of the fan and the precooler, this disclosure can increase the upper limit of flight Mach number of the turbofan engine from the traditional approximately 2.5 to about 4. The precooler effectively reduces the core engine intake temperature, avoiding compressor stall and overheating at high speeds, allowing the engine to operate stably in the Mach number range of 3 to 4; at the same time, the combination of the rear fan and the afterburner provides thrust gain similar to that of a ramjet engine at high speeds, ensuring the thrust level required for high-speed flight. This means that aircraft using the engine disclosed in this disclosure are expected to achieve continuous flight from transonic to hypersonic speeds, and have great application potential in military high-speed interception, strategic reconnaissance, and civilian hypersonic transport.

[0094] (2) Reduced precooling energy consumption and losses: Through the flow channel adjustment mechanism, this disclosure achieves complete bypass of the precooler in the low-speed stage, allowing the core engine airflow to bypass the precooler when cooling is not required, thereby avoiding the additional pressure loss and cold source consumption caused by the precooler. In traditional schemes, the precooler is often always connected in series in the intake duct, which generates certain flow resistance and cooling power consumption even at low speeds, reducing engine efficiency. In this disclosure, the precooler is isolated from the airflow at low speeds, and the engine operates in conventional turbofan mode without the additional resistance of the precooler, ensuring the economy of low-speed cruising. The precooler is only activated when needed at high speeds, truly achieving on-demand cooling and improving system efficiency.

[0095] (3) Improved cold source utilization efficiency: Since the precooler only cools the airflow in the inner duct, this disclosure avoids unnecessary cooling of the airflow in the outer bypass duct, which does not require cooling, thereby significantly improving the utilization rate of the cold source. The energy of the cold source (e.g., cryogenic fuel or cooling medium) is concentrated on reducing the core engine inlet temperature, maximizing its effectiveness. This not only reduces the amount of cold source carried or the power required to generate cooling, but also reduces the size and weight requirements of the precooler. In contrast, if all the inlet air is cooled, the precooler needs to handle a larger airflow, and its size and cooling load will increase exponentially. This disclosure, through radial partitioned cooling, significantly reduces the cooling demand and precooler size while achieving the same core engine inlet temperature control effect, which is of great significance for improving the engine thrust-to-weight ratio and range.

[0096] (4) Simple structure and high thrust-to-weight ratio: Through radial partitioning, the integrated design of the precooler and the engine is more compact, reducing the additional space requirements. The rear-mounted fan layout makes the engine structure simpler. The rear-mounted fan is connected to the core engine through a free turbine, eliminating the long shaft connecting the fan and the low-pressure turbine in traditional turbofan engines, reducing the number of transmission components and support points.

[0097] (5) Strong multimodal adaptability: Through the coordinated adjustment of the axial sliding sleeve and mixing orifice, the airflow optimization distribution at different Mach numbers is achieved, improving the engine's adaptability and reliability. The engine disclosed herein can adapt to various flight conditions, from takeoff, subsonic cruise, transonic acceleration to hypersonic sprint, through flexible mode switching. At low speeds, it operates in turbofan mode, which has low fuel consumption and high propulsion efficiency; at high speeds, it switches to pre-cooled turbofan or ramjet mode to obtain the required high thrust output. This wide speed range adaptability means that aircraft using this engine do not need to rely on rocket boosters or multiple engine combinations like traditional high-speed aircraft. A single engine can complete the entire mission profile, simplifying aircraft design and reducing system complexity.

[0098] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0099] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0100] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0101] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0102] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0103] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0104] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A turbofan engine, characterized in that, include: Air intake (1), the air intake (1) includes an outer bypass duct (11) and an inner bypass duct (12); A central cone (2) is disposed at the front end of the turbofan engine; The precooler (3) is located behind the central cone (2). The precooler (3) is cylindrical and its sidewalls can connect the outer duct (11) and the inner duct (12) to allow airflow to pass through and cool the airflow. The core machine (4) is located behind the precooler (3) and has multiple mixing holes (10) between it and the precooler (3). The mixing holes (10) can connect the outer bypass duct (11) and the inner bypass duct (12) to allow airflow. The flow channel regulating mechanism (9) is disposed in the outer bypass duct (11) and can open and close the precooler (3) and the mixing hole (10) to control the flow direction of the airflow between the outer bypass duct (11) and the inner bypass duct (12); The flow channel adjustment mechanism (9) includes: The system comprises a first sliding sleeve (91), a second sliding sleeve (92), and an actuating mechanism (93). The first sliding sleeve (91) is located in front of the second sliding sleeve (92). The actuating mechanism (93) drives the first sliding sleeve (91) and the second sliding sleeve (92) to slide independently. The first sliding sleeve (91) and the second sliding sleeve (92) can slide to the outer periphery of the precooler (3) or the outer periphery of the mixing hole (10), respectively. When the flight Mach number of the aircraft is Ma<2, the first sliding sleeve (91) slides to the outer periphery of the precooler (3) to close the precooler (3), and the second sliding sleeve (92) slides to the outer periphery of the core machine (4) to open the mixing hole (10), and the airflow enters the outer bypass duct (11) and the inner bypass duct (12). When the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve (91) slides to the outer periphery of the mixing hole (10) to open the precooler (3) and close the mixing hole (10), the second sliding sleeve (92) slides to the outer periphery of the core machine (4), the airflow enters the outer bypass duct (11), and after cooling, enters the inner bypass duct (12). When the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve (91) slides to the outer periphery of the precooler (3) to close the precooler (3), and the second sliding sleeve (92) slides to the outer periphery of the mixing hole (10) to close the mixing hole (10), and the airflow only enters the outer bypass duct (11).

2. The turbofan engine according to claim 1, characterized in that, The core machine (4) comprises, from front to back, the following components: The compressor (41), combustion chamber (42), high-pressure turbine (43), free turbine (5) and rear fan (6) are connected to the free turbine (5) via a drive shaft. The airflow in the inner duct (12) drives the free turbine (5) to rotate, and the free turbine (5) drives the rear fan (6) to rotate.

3. The turbofan engine according to claim 1, characterized in that, The core machine (4) comprises, from front to back, the following components: The unit comprises a front fan (13), a compressor (41), a combustion chamber (42), a high-pressure turbine (43), and a free turbine (5). The front fan (13) is connected to the free turbine (5) via a drive shaft. The airflow in the inner duct (12) drives the free turbine (5) to rotate, and the free turbine (5) drives the front fan (13) to rotate.

4. The turbofan engine according to claim 1, characterized in that, When the flight Mach number of the aircraft is Ma<2, the first sliding sleeve (91) slides to the outer periphery of the central cone (2), the second sliding sleeve (92) slides to the outer periphery of the precooler (3) to close the precooler (3), and the mixing hole (10) is opened, and the airflow enters the outer bypass duct (11) and the inner bypass duct (12). When the flight Mach number of the aircraft is 2≤Ma<3.5, the first sliding sleeve (91) slides to the outer periphery of the central cone (2), the second sliding sleeve (92) slides to the outer periphery of the mixing hole (10) to open the precooler (3) and close the mixing hole (10), the airflow enters the outer bypass (11), and after cooling, enters the inner bypass (12). When the flight Mach number of the aircraft is 3.5≤Ma<4, the first sliding sleeve (91) slides to the outer periphery of the precooler (3) to close the precooler (3), and the second sliding sleeve (92) slides to the outer periphery of the mixing hole (10) to close the mixing hole (10), and the airflow only enters the outer bypass duct (11).

5. The turbofan engine according to claim 1, characterized in that, The sidewall of the precooler (3) is a tube-fin heat exchanger or a microchannel plate heat exchanger, with a cooling medium flowing inside to cool the passing airflow.

6. The turbofan engine according to claim 1, characterized in that, Also includes: Afterburner (7) is located behind the core machine (4).

7. The turbofan engine according to claim 1, characterized in that, Also includes: Tail nozzle (8), which is located at the tail end of the turbofan engine, can adjust the throat area.

8. An aircraft, characterized in that, include: The turbofan engine according to any one of claims 1-7.

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