Turbofan engine and aircraft

Abstract

The invention relates to the technical field of aero-engines, in particular to a turbofan engine and an aircraft, the turbofan engine comprises an air inlet channel, a center cone, a precooler, a core machine and a flow channel adjusting mechanism, and the air inlet channel comprises an outer duct and an inner duct; the central cone is arranged at the front end of the turbofan engine; the precooler is arranged behind the central cone and is cylindrical, and the side wall of the precooler can be communicated with the outer duct and the inner duct so that airflow can pass through the precooler and can be cooled; the core machine is arranged behind the precooler, a plurality of mixing holes are formed between the core machine and the precooler, and the mixing holes can communicate with the outer duct and the inner duct so that airflow can pass through the mixing holes; the flow channel adjusting mechanism is arranged on the outer duct and can open and close the precooler and the mixing hole so as to control the flow direction of airflow between the outer duct and the inner duct. Through combination of the precooler and the flow channel adjusting mechanism, targeted precooling of air flow in the inner duct is achieved, and meanwhile cold source waste and pressure loss of air flow in the outer duct are avoided.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of aero-engines, and in particular to a turbofan engine and an aircraft. BACKGROUND

[0002] Compared with a conventional turbojet engine, a turbofan engine can provide higher propulsive efficiency and thrust at lower flight speeds by introducing an outer bypass fan. However, when the flight speed increases, the difference in the compression degree of the airflow of the outer bypass and the inner bypass increases, and the engine needs to have variable cycle regulation capability to balance the performance at different speeds. For example, the Pratt & Whitney J58 engine used by a certain type of foreign reconnaissance aircraft introduces a bypass combustion chamber (ram mode) to enable the engine to work stably at a Mach number of 3.2. However, when the flight Mach number further increases to about 4, the conventional turbofan engine faces problems such as excessively high inlet air temperature and insufficient compressor surge margin, and needs to use pre-cooling technology to expand the working envelope of the engine.

[0003] However, the conventional pre-cooling technology has the following problems:

[0004] (1) The pre-cooler is usually arranged at the front end of the engine, causing all the airflow entering the engine (including the outer bypass and the inner bypass) to pass through the pre-cooler, resulting in waste of the cold source. (The inner bypass airflow needs to pass through the core engine with a high pressure ratio, and thus must be pre-cooled, while the outer bypass airflow usually does not need to be pre-cooled. If a pre-cooler covering the entire inlet cross section is arranged in front of the engine inlet, most of the outer bypass airflow will also be unnecessarily cooled, resulting in waste of the cold source and additional flow resistance loss.)

[0005] (2) The pre-cooler generates additional pressure loss at low speed stages (Ma < 2) although it does not work, affecting the efficiency of the engine.

[0006] (3) The integrated design of the pre-cooler and the engine is not optimized and cannot adapt to the change in the airflow characteristics at different Mach numbers. SUMMARY

[0007] The present disclosure is proposed in view of the above problems. The present disclosure provides a turbofan engine and an aircraft.

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

[0009] an inlet passage comprising an outer bypass and an inner bypass;

[0010] a center cone arranged at the front end of the turbofan engine;

[0011] A pre-cooler is arranged behind the center cone, the pre-cooler is cylindrical, and a side wall can communicate the outer duct and the inner duct to pass and cool the airflow;

[0012] A core engine is arranged behind the pre-cooler, and a plurality of mixing holes are arranged between the pre-cooler and the core engine, the mixing holes can communicate the outer duct and the inner duct to pass the airflow;

[0013] A flow channel adjusting mechanism is arranged in the outer duct, and can open and close the pre-cooler and the mixing holes to control the flow direction of the airflow between the outer duct and the inner duct.

[0014] In addition, according to an aspect of the turbofan engine of the present disclosure, the core engine comprises, arranged in sequence from front to back:

[0015] A compressor, a combustor, a high-pressure turbine, a free turbine, and a rear fan, the rear fan is connected to the free turbine through a transmission shaft, the airflow in the inner duct drives the free turbine to rotate, and the free turbine drives the rear fan to rotate.

[0016] In addition, according to an aspect of the turbofan engine of the present disclosure, the core engine comprises, arranged in sequence from front to back:

[0017] A front fan, a compressor, a combustor, a high-pressure turbine, and a free turbine, the front fan is connected to the free turbine through a transmission shaft, the airflow in the inner duct drives the free turbine to rotate, and the free turbine drives the front fan to rotate.

[0018] In addition, according to an aspect of the turbofan engine of the present disclosure, the flow channel adjusting mechanism comprises:

[0019] A first sliding sleeve, a second sliding sleeve, and an actuating mechanism, the first sliding sleeve is arranged in front of the second sliding sleeve, the actuating mechanism drives the first sliding sleeve and the second sliding sleeve to slide independently, and the first sliding sleeve and the second sliding sleeve can slide to the outer periphery of the pre-cooler or the outer periphery of the mixing hole, respectively.

[0020] In addition, according to an aspect of the turbofan engine of the present disclosure, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve slides to the outer periphery of the pre-cooler to close the pre-cooler, the second sliding sleeve slides to the outer periphery of the core engine to open the mixing hole, and the airflow enters the outer duct and the inner 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 center cone, the second sliding sleeve slides to the outer periphery of the mixing hole to open the precooler and close the mixing hole, and the airflow enters the outer duct and enters the inner duct after cooling.

[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, 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 duct.

[0023] In addition, according to the turbofan engine of one aspect of the present disclosure, when the flight Mach number of the aircraft is Ma<2, the first sliding sleeve slides to the outer periphery of the center cone, the second sliding sleeve slides to the outer periphery of the precooler to close the precooler, and the mixing hole is opened, and the airflow enters the outer duct and the inner 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 center cone, the second sliding sleeve slides to the outer periphery of the mixing hole to open the precooler and close the mixing hole, and the airflow enters the outer duct and enters the inner duct after cooling.

[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, 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 duct.

[0026] In addition, according to the turbofan engine of one aspect of the present disclosure, the side wall of the precooler is a tube fin heat exchanger or a micro-channel plate heat exchanger, and a cooling medium flows inside to cool the airflow passing through.

[0027] In addition, according to the turbofan engine of one aspect of the present disclosure, further comprising:

[0028] Afterburner, the afterburner is arranged at the rear of the core engine.

[0029] In addition, according to the turbofan engine of one aspect of the present disclosure, further comprising:

[0030] Nozzle, the nozzle is arranged at the tail end of the turbofan engine and can adjust the throat area.

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

[0032] According to the turbofan engine and the aircraft of the embodiments of the present disclosure, through the innovative combination of radial partition pre-cooling, fan layout and multi-modal variable cycle control, the performance of the turbofan engine in the high-speed field is significantly improved, so that the engine successfully breaks through the speed limit of the traditional turbofan while maintaining the low-speed high-efficiency advantage of the turbofan, and provides a new power solution for future high-speed aircraft.

[0033] It is to be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further explanation of the subject technology claimed. BRIEF DESCRIPTION OF DRAWINGS

[0034] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[0035] Figure 1 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is opened and the pre-cooler is closed;

[0036] Figure 2 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is closed and the pre-cooler is opened;

[0037] Figure 3 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is closed and the pre-cooler is opened;

[0038] Figure 4 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is opened and the pre-cooler is closed;

[0039] Figure 5 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is closed and the pre-cooler is opened;

[0040] Figure 6 For the structural schematic diagram of the turbofan engine according to the embodiments of the present disclosure, the mixing hole is closed and the pre-cooler is opened.

[0041] BRIEF DESCRIPTION OF DRAWINGS

[0042] Air inlet 1, center cone 2, pre-cooler 3, core engine 4, compressor 41, combustion chamber 42, high-pressure turbine 43, free turbine 5, rear fan 6, afterburner 7, nozzle 8, flow channel adjusting mechanism 9, first sliding sleeve 91, second sliding sleeve 92, actuating mechanism 93, mixing hole 10, outer bypass 11, inner bypass 12, front fan 13, split shoulder 14, first casing 15, second casing 16. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present disclosure more obvious, the example embodiments according to the present disclosure will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all embodiments of the present disclosure, and it should be understood that the present disclosure is not limited by the example embodiments described here.

[0044] The present embodiment provides a turbofan engine and an aircraft, which realizes targeted pre-cooling of the inner bypass airflow by combining the pre-cooler with the flow channel adjusting mechanism, while avoiding the waste of cold source and pressure loss of the outer bypass airflow.

[0045] The implementation of the embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0046] As shown in Figure 1 , Figure 2 , Figure 3 The present embodiment provides a turbofan engine, which comprises: an air inlet 1, a center cone 2, a pre-cooler 3, a core engine 4 and a flow channel adjusting mechanism 9.

[0047] The air inlet 1 comprises an outer bypass 11 and an inner bypass 12, the outer bypass 11 is located between the outer circumference of the center cone 2, the outer circumference of the pre-cooler 3 and the outer circumference of the core engine 4, and the inner bypass 12 is located in the inner ring of the pre-cooler 3 and the inner ring of the casing in which the mixing hole 10 is arranged; the ratio of the air flow of the outer bypass 11 to the inner bypass 12 is the bypass ratio, which is an important design parameter of the turbofan engine, and has a great influence on the specific fuel consumption and the thrust-to-weight ratio of the engine;

[0048] The center cone 2 is arranged at the front end of the turbofan engine, also known as the fairing cone, and is mainly used for flow regulation of the airflow entering the air inlet 1;

[0049] The pre-cooler 3 is cylindrical, and the pre-cooler 3 is arranged behind the center cone 2, the side wall of the pre-cooler 3 can communicate the outer bypass 11 and the inner bypass 12 to pass the airflow and cool the airflow, the airflow passing through is from the outer bypass 11 to the inner bypass 12, as shown by the hollow arrow in Figure 2 The pre-cooler 3 radially partitions the air inlet 1 to separate the outer bypass 11 and the inner bypass 12;

[0050] The core engine 4 is the main power device of the engine, and is arranged behind the precooler 3 and has a plurality of mixing holes 10 arranged between the precooler 3 and the core engine 4. The mixing holes 10 can communicate the outer duct 11 and the inner duct 12 to guide the airflow from the outer duct 11 to the inner duct 12 through the airflow, so as to introduce the airflow in the outer duct 11 into the inner duct 12 at low speed, and the arrow in Figure 1 indicates the airflow direction. A cylindrical casing can be arranged between the second casing 16 of the core engine 4 and the precooler 3, and the mixing holes 10 are arranged on the sidewall of the casing;

[0051] The flow channel adjusting mechanism 9 is arranged in the outer duct 11 and can be sleeved on the outer periphery of the precooler 3 and the mixing holes 10 to open and close the precooler 3 and the mixing holes 10 to control the flow direction of the airflow between the outer duct 11 and the inner duct 12. Because the precooler 3 and the mixing holes 10 both have the function of communicating the outer duct 11 and the inner duct 12, the flow channel adjusting mechanism 9 selectively opens the precooler 3 or the mixing holes 10, and does not open the precooler 3 and the mixing holes 10 at the same time.

[0052] The turbofan engine in the 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, breaks through the speed limit of the traditional turbofan while maintaining the low-speed high-efficiency advantage of the turbofan, and provides a new power solution for future high-speed aircraft.

[0053] In some possible implementations, as shown in Figure 1 , Figure 2 , Figure 3 The core engine 4 includes, in sequence from front to back:

[0054] The compressor 41, the combustor 42, the high-pressure turbine 43, the free turbine 5 and the rear fan 6, the rear fan 6 is connected to the free turbine 5 through a transmission 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, the combustor 42 and the high-pressure turbine 43 are coaxially connected to form a gas generator. When the core engine 4 is in normal operation, the compressed air of the compressor 41 is mixed with fuel in the combustor 42 and combusted, the high-temperature gas drives the high-pressure turbine 43 to work and drives the compressor 41 to rotate. After the gas leaves the high-pressure turbine 43, it continues to expand to drive the free turbine 5, and the free turbine 5 drives the rear fan 6 to rotate through the transmission shaft to accelerate the air passing through the fan.

[0056] The rear fan 6 is arranged in the outer duct 11 at the rear end of the core engine 4, and the size and shape of the blade are designed to provide large-flow air acceleration at a low pressure ratio to generate an outer duct thrust.

[0057] The airflow in the inner channel 12 generates a part of the thrust, the fan blades of the front fan 13 are located in the outer channel 11, the front fan 13 can play a role of a low-pressure compressor, and the rotation of the front fan 13 can drive the airflow in the outer channel 11 to generate another part of the thrust. The proportion of the two parts of the thrust in the entire engine is related to the bypass ratio.

[0058] In some possible embodiments, as shown in Figure 4 , Figure 5 , Figure 6 illustrated, the core engine 4 includes, in sequence from front to back:

[0059] The front fan 13, the compressor 41, the combustor 42, the high-pressure turbine 43 and the free turbine 5 are coaxially connected to form a gas generator. When the core engine 4 is normally working, the compressor 41 compresses air, and the compressed air is mixed with fuel in the combustor 42 and combusted, the high-temperature gas drives the high-pressure turbine 43 to work, and drives the compressor 41 to rotate. After the gas leaves the high-pressure turbine 43, the gas continues to expand to drive the free turbine 5, and the free turbine 5 drives the front fan 13 to rotate through a transmission shaft, and accelerates the air passing through the fan.

[0060] The compressor 41, the combustor 42 and the high-pressure turbine 43 are coaxially connected to form a gas generator. When the core engine 4 is normally working, the compressor 41 compresses air, and the compressed air is mixed with fuel in the combustor 42 and combusted, the high-temperature gas drives the high-pressure turbine 43 to work, and drives the compressor 41 to rotate. After the gas leaves the high-pressure turbine 43, the gas continues to expand to drive the free turbine 5, and the free turbine 5 drives the front fan 13 to rotate through a transmission shaft, and accelerates the air passing through the fan.

[0061] The front fan 13 is arranged in the outer channel 11 at the front end of the core engine 4, and the size and the shape of the blades of the front fan 13 are designed to provide large-flow air acceleration at a low pressure ratio to generate outer channel thrust.

[0062] The airflow in the inner channel 12 generates a part of the thrust, the fan blades of the front fan 13 are located in the outer channel 11, the front fan 13 can play a role of a low-pressure compressor, and the rotation of the front fan 13 can drive the airflow in the outer channel 11 to generate another part of the thrust. The proportion of the two parts of the thrust in the entire engine is related to the bypass ratio.

[0063] The fan blades of the front fan 13 are provided with a flow separation shoulder 14, the front end of the flow separation shoulder 14 can be connected to the casing provided with the mixing hole 10, and the rear end of the flow separation shoulder 14 can be connected to the second shell 16 of the core engine 4. The gap with a proper distance at the connection positions does not affect the rotation of the front fan 13, and the flow separation shoulder 14 can play a role of separating the outer channel 11 and the inner channel 12.

[0064] In some possible embodiments, as shown in Figure 1 , Figure 2 , Figure 3 illustrated, the flow channel adjusting mechanism 9 includes:

[0065] The first sliding sleeve 91, the second sliding sleeve 92 and the actuating mechanism 93, the first sliding sleeve 91 is arranged 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 be able 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 outer periphery of the center cone 2, the precooler 3, the casing provided with the mixing hole 10 and the second shell 16 can be provided with sliding rails corresponding to the first sliding sleeve 91 and the second sliding sleeve 92, and the first sliding sleeve 91 and the second sliding sleeve 92 can slide along the sliding rails. The actuating mechanism 93 can adopt electric drive, pneumatic drive or hydraulic drive mode to realize automatic control.

[0067] For the core engine 4 using the rear fan 6 or the front fan 13, the sliding modes of the first sliding sleeve 91 and the second sliding sleeve 92 are different, which are described as follows.

[0068] In some possible embodiments, for the core engine 4 using the rear fan 6, as shown in Figure 1 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, the second sliding sleeve 92 slides to the outer periphery of the core engine 4 to open the mixing hole 10, the airflow enters the outer duct 11 and the inner duct 12, and the airflow entering the inner duct 12 through the mixing hole 10 is not cooled;

[0069] As shown in Figure 2 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, and the second sliding sleeve 92 slides to the outer periphery of the core engine 4, the airflow enters the outer duct 11 and enters the inner duct 12 after cooling;

[0070] As shown in Figure 3 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 duct 11.

[0071] In some possible embodiments, for the core engine 4 using the front fan 13, as shown in Figure 4 When the flight Mach number of the aircraft is Ma<2, the first sliding sleeve 91 slides to the outer periphery of the center cone 2, the second sliding sleeve 92 slides to the outer periphery of the precooler 3 to close the precooler 3 and open the mixing hole 10, the airflow enters the outer duct 11 and the inner duct 12, and the airflow entering the inner duct 12 through the mixing hole 10 is not cooled;

[0072] As shown in Figure 5 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 center cone 2, the second sliding sleeve 92 slides to the outer periphery of the mixing hole 10 to open the precooler 3, and the mixing hole 10 is closed, the airflow enters the outer duct 11, and after cooling, enters the inner duct 12;

[0073] As shown in Figure 6 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, 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 duct 11.

[0074] In some possible embodiments, as shown in Figure 1 , Figure 4 The side wall of the precooler 3 is a tube-fin heat exchanger or a micro-channel plate heat exchanger, and a cooling medium flows inside to cool the airflow passing through.

[0075] Tube-fin structure: composed of multiple cooling tubes uniformly distributed in the circumferential direction and fins connected outside the tubes, low-temperature cooling medium (such as liquid metal or supercritical fluid) flows in the cooling tubes, and air flows radially from the outside to the inside in the fin gap, transferring heat to the cooling medium and being cooled.

[0076] Micro-channel structure: composed of multiple layers of parallel micro-channel plates stacked in a ring shape, cooling medium flows in the micro channels inside the micro-channel plates in the circumferential direction, and air flows radially in the narrow gap between adjacent micro-channel plates for heat exchange. The micro-channel structure utilizes advanced technologies such as additive manufacturing to achieve very high heat exchange efficiency and compact volume. The cooling medium circuit of the precooler 3 is connected to a cold source system (not shown in the figure), which can use low-temperature fuel (liquid hydrogen, etc.) carried by the aircraft or an independent refrigeration cycle to provide continuous cold supply.

[0077] In some possible embodiments, as shown in Figure 1 , Figure 4 The turbofan engine further comprises: a afterburner 7, which is arranged at the rear of the core engine 4.

[0078] The afterburner 7 is provided with fuel nozzles and igniters, which can inject fuel and ignite when needed, so that the mixed gas flow is further combusted and heated, and is discharged at high speed from the tail nozzle 8 to generate additional thrust.

[0079] The afterburner 7 can inject additional fuel and ignite combustion when needed (such as high-speed sprint or climb), to greatly increase the exhaust velocity and thus provide additional thrust in a short time. The presence of the afterburner 7 allows the core engine 4 to reduce power or even be in windmill mode (idling without power), but still generate main thrust through the afterburner 7.

[0080] In some possible embodiments, as shown in FIG. 1, the turbofan engine further comprises a tail nozzle 8 disposed at the tail end of the turbofan engine, capable of adjusting the throat area. Figure 1 、 Figure 4 The tail nozzle 8 is a variable-area nozzle, which can adjust the throat area according to the engine operating condition, expand or shrink, so as to optimize the thrust and efficiency.

[0081] The tail nozzle 8 is a variable-area nozzle, which can adjust the throat area according to the engine operating condition, expand or shrink, so as to optimize the thrust and efficiency.

[0082] The turbofan engine of the present disclosure can work in multiple modes including low-speed mode, medium-speed mode and high-speed mode at different flight Mach numbers through the above structural design. The working state and airflow path of each component of the engine are different in each mode to achieve high efficiency in a wide Mach number range. Taking the turbofan engine with the rear fan 6 as an example:

[0083] a. Low-speed mode (Ma < 2). When the flight Mach number is low, the total temperature of the inlet air is relatively low, and the engine does not need to start the precooler. At this time, the first sliding sleeve 91 of the flow passage adjusting mechanism is in a position closing the inner ring passage (the side wall of the precooler 3), the inner ring passage (the side wall of the precooler 3) of the engine inlet is closed, and all air flows from the outer ring passage into the engine. Part of the air entering the outer ring directly enters the inner channel 12 through the mixing hole 10 (at this time, the core engine 4 works normally, and the compressor 41 sucks part of the outer ring air), and the other part bypasses the core engine 4 as an outer channel airflow directly to the rear fan 6. After compression, combustion and expansion work in the core engine 4, the gas drives the high-pressure turbine 43 and continues to flow backward, and 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, mixes with the exhaust gas of the core engine 4 at the fan outlet (or mixes through the respective pipelines before the afterburner 7), and then enters the afterburner 7 together. In the low-speed stage, the afterburner 7 is usually not working (or only opened for a short time when additional thrust is needed), and the mixed gas flow is expanded and discharged through the tail nozzle 8 to generate thrust. During the entire low-speed mode, the precooler 3 does not participate in the work, avoiding unnecessary pressure loss, and the engine runs in the conventional turbofan mode, with high propulsive efficiency.

[0084] b. Medium speed mode (2 < Ma < 3.5). As the flight speed increases to Mach number 2 or above, the total temperature of the inlet air gradually increases. In order to protect the core engine 4 and expand the working envelope, the engine begins to use the precooler 3. When the Mach number reaches about 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 (the side wall of the precooler 3) of the inlet, while synchronously closing the mixing hole 10 at the rear end of the precooler 3. At this time, the engine inlet air is divided into two streams: the outer ring air flow and the inner ring air flow. The outer ring air flow no longer passes through the mixing hole 10 into the inner channel 12, but directly enters the rear fan 6 as an outer channel air flow, and after being accelerated by the fan, flows to the afterburner 7; the inner ring air flow enters the annular precooler 3 through the opened inner ring passage (the side wall of the precooler 3), and is cooled to a predetermined temperature (for example, reduced to near ambient temperature or even lower, depending on the design requirements) by the cooling medium before entering the compressor 41 of the core engine 4. The pre-cooled air significantly reduces the temperature at the inlet of the compressor 41, and the compressor 21 can work at a higher converted speed without stalling, thereby allowing the engine to maintain a larger air flow and pressure ratio at a higher Mach number. The pre-cooled air is compressed and burned in the core engine 4, and the high-temperature gas generated drives the high-pressure turbine 43, and then drives the free turbine 5 to drive the rear fan 6. The exhaust gas from the core engine 4 is combined with the outer channel air flow accelerated by the fan in the afterburner 7. In the medium speed stage, the afterburner 7 can be selectively opened as needed: in the Mach number range of 2-3, if higher thrust is needed, the afterburner can be opened slightly to supplement the thrust; if in the cruising state, the afterburner is kept closed to save fuel. Through the use of the precooler, the core engine 4 can continue to work stably at a high speed of Mach number 3, and the outer channel air flow avoids wasting the cold source and additional flow loss. Through the effective work of the precooler 3, the engine can maintain stable thrust output at Mach number 3, without the performance of the traditional turbofan engine being sharply reduced due to the overheating of the inlet air.

[0085] c. High-speed mode (3.5 < Ma < 4). When the flight speed is further increased to Mach number above 3.5, the working environment of the core engine 4 is still very harsh (the total temperature of the inlet air is extremely high, and the compression work and turbine heat load are very large) even after pre-cooling. In order to obtain sufficient thrust at Mach number close to 4, the engine gradually transitions to a high-speed ram mode. When the Mach number reaches about 3.5, the engine control system begins to implement a mode conversion strategy from medium speed to high speed: first, the fuel supply of the core engine 4 is gradually reduced, so that the output power of the core engine 4 is reduced, and the rotation speed of the high-pressure turbine 43 and the compressor 41 is reduced; At the same time, the guide vane angle in front of the rear fan 6 is adjusted to match the reduced air flow to prevent the fan and the compressor 41 from surging or stalling. As the power of the core engine 4 continues to decrease, the core engine 4 eventually stops fuel injection and enters the "windmill" state (i.e., the core engine rotor is passively rotated by high-speed airflow impact, but does not produce effective power output). At this time, the first sliding sleeve 91 in the inner ring passage of the inlet (the side wall of the pre-cooler 3) is re-closed under the action of the control system, the inner ring airflow is cut off, and the pre-cooler 3 also stops the circulation flow of the cooling medium (the cold source supply is closed). In this way, during the high-speed stage, almost all of the inlet air enters the engine from the outer ring passage and no longer passes through the pre-cooler 3 and the core engine 4. The air entering the outer ring directly passes through the rear fan 6, but since the core engine 4 has stopped working, the free turbine 5 and the fan lose the power source, and the fan blades freely rotate in the windmill state (very small resistance to airflow). After the air flows through the fan, it directly enters the afterburner 7, at this time the afterburner 7 is in full-power working state, a large amount of fuel is injected and mixed with air to burn, high-temperature and high-pressure gas is generated, and the gas is discharged at high speed through the tail nozzle 8 to generate the main thrust. In the high-speed mode, the engine is essentially equivalent to a ramjet engine, which uses the ram compression effect of high-speed inlet air to burn in the afterburner to generate thrust, and the core engine and the fan only serve as part of the airflow passage and do not actively provide mechanical work. This mode conversion enables the engine to continue to operate at high speed around Mach number 4, breaking through the speed limit of traditional turbofan engines.

[0086] It is emphasized that the transition between the above-mentioned modes is continuous and adjustable. For example, when transitioning from medium speed to high speed, the decrease of core engine 4 power and the increase of afterburner 7 thrust are gradual to ensure smooth and continuous thrust output without obvious thrust interruption or drop. Similarly, when transitioning from low speed to medium speed, the gradual engagement of precooler 3 is achieved by precisely controlling the opening of sliding sleeve and mixing hole 10 to gradually increase the inner circle airflow and decrease the outer circle airflow entering inner duct 12, thereby avoiding the sudden change of compressor 41 inlet conditions caused by flow path switching. The engine control system (e.g. FADEC) will adjust the precooler cold source flow, sliding sleeve position, mixing hole opening, fan guide vane angle, and afterburner fuel supply in real time according to parameters such as flight Mach number, altitude, and throttle command, to optimize engine performance and ensure safety margin.

[0087] The turbofan engine of the present disclosure has the following significant innovations in structure and working principle:

[0088] (1) Radial partitioned precooler structure: A radial partitioned annular precooler arrangement in the intake duct is proposed for the first time to meet the different needs of turbofan engine inner and outer duct airflow. By designing the precooler as a cylindrical annulus and covering only the inner duct intake area, the cooling of the core engine intake is realized, while the outer duct airflow does not pass through the precooler. In contrast, in existing schemes such as the ATREX engine and the PCTJ precooled turbojet engine of JAXA, the precooler usually covers the entire intake cross section and cools all the incoming flow, without considering the design of separate precooling for the inner duct to avoid waste of the outer duct cold source. The radial partitioned precooler structure of the present disclosure effectively improves the utilization rate of the cold source, reduces unnecessary cooling power consumption and flow loss, and is a pioneering design internationally.

[0089] (2) Rear fan layout: The fan of the present disclosure is arranged behind the core engine and driven by an independent free turbine, which is different from the traditional front fan turbofan engine. The rear fan is used for high-speed turbofan engine configuration and combined with the precooling technology, which has no precedent in the prior art. The introduction of the rear fan avoids the problem that the front fan is easily affected by the shock wave at high speed, and at the same time, the free turbine recovers energy from the gas to drive the fan, improving the total thrust and efficiency of the engine. In addition, the rear fan layout simplifies the overall structure of the engine: the fan and the core engine are decoupled by the free turbine, and the designs are relatively independent, reducing the complex transmission mechanism, making the engine have fewer components, lighter weight, and easier manufacturing.

[0090] (3) Multi-mode variable cycle control: The engine of the present disclosure can automatically switch the working mode according to the flight Mach number, realizing the smooth transition of the low-speed high-efficiency turbofan mode, the medium-speed pre-cooling turbofan mode and the high-speed ramjet mode. This process is realized through the coordinated control of the inlet sliding sleeve, the mixing hole and the core engine and the afterburner, and belongs to a novel variable cycle control strategy. Unlike the traditional variable cycle engine which only changes the bypass ratio (such as the third bypass of the F-120 engine), the present disclosure introduces pre-cooling and ramjet combustion in the higher speed domain, expanding the concept of variable cycle. The engine can maintain high performance in each mode: at low speed, it runs in the conventional turbofan mode, with low fuel consumption; at high speed, pre-cooling and afterburning ramjet are enabled, and the thrust is greatly improved, so that the engine has good working ability in a wide range of Mach numbers from 0 to 4.

[0091] In some possible implementations, the present disclosure also provides an aircraft, comprising: the turbofan engine according to any one of the above embodiments. The aircraft is usually an airplane, which can be a passenger plane, a transport plane or a fighter plane, etc.

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

[0093] (1) Extending the upper limit of flight Mach number: By utilizing the combined action of the fan and the pre-cooler, the present disclosure can increase the upper limit of flight Mach number of the turbofan engine from about 2.5 of the traditional one to about 4. The pre-cooler effectively reduces the core engine inlet temperature, avoiding the stall and overheating of the compressor at high speed, so that the engine can still work stably in the range of Mach number 3-4; 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 speed, ensuring the required thrust level for high-speed flight. This means that the aircraft using the engine of the present disclosure is expected to realize continuous flight from subsonic to hypersonic speed, and has great application potential in the fields of military high-speed interception, strategic reconnaissance and civil hypersonic transportation, etc.

[0094] (2) Reducing pre-cooling energy consumption and loss: Through the flow channel adjusting mechanism, the present disclosure realizes the complete bypass of the pre-cooler at low speed, so that the core engine airflow does not pass through the pre-cooler when cooling is not needed, thereby avoiding the additional pressure loss and cooling source consumption caused by the pre-cooler. In the traditional scheme, the pre-cooler is always connected in series in the inlet, which will produce certain flow resistance and cooling power consumption even at low speed, reducing the engine efficiency. In the present disclosure, the pre-cooler is isolated from the airflow at low speed, and the engine runs in the conventional turbofan mode without the additional resistance of the pre-cooler, ensuring the economy of low-speed cruising. The pre-cooler is only enabled when high speed is needed, truly realizing on-demand cooling and improving the system efficiency.

[0095] (3) Improve the efficiency of the cold source: Since the precooler only cools the inner bypass airflow, the present disclosure avoids unnecessary cooling of the outer bypass airflow that does not need to be cooled, thereby significantly improving the utilization rate of the cold source. The energy of the cold source (such as low-temperature fuel or cooling medium) is concentrated to reduce the core engine inlet temperature, so that it can be used to the maximum. This not only reduces the amount of cold source carried or the power required to generate cold, but also reduces the size and weight requirements of the precooler. In contrast, if the entire inlet air is cooled, the precooler needs to handle a larger air flow, and the size and cooling load will be doubled. The present disclosure significantly reduces the cooling capacity requirement and the precooler scale through radial partition cooling, while achieving the same core engine inlet temperature control effect, which is of great significance to improving the engine thrust-to-weight ratio and range.

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

[0097] (5) Strong adaptability to multiple modes: Through the coordinated adjustment of the axial sliding sleeve and the mixing hole, the airflow is optimally distributed under different Mach numbers, improving the adaptability and reliability of the engine. The engine of the present disclosure can adapt to various flight conditions from take-off, subsonic cruise, transonic acceleration to hypersonic sprint through flexible mode conversion. At low speed, it runs in turbofan mode, with low fuel consumption and high propulsion efficiency; at high speed, it switches to precooled turbofan or ramjet mode to obtain the required large thrust output. This wide speed range adaptability enables the aircraft using the engine to complete the entire mission profile with a single engine, simplifying the aircraft design and reducing system complexity.

[0098] The basic principles of the present disclosure are described above in combination with specific embodiments, but it should be noted that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and not limitations, and these advantages, advantages, effects, etc. cannot be considered as the must-have of each embodiment of the present disclosure. In addition, the above specific details of the disclosure are only for the purpose of example and understanding, and are not limited to the above specific details. The above specific details do not limit the present disclosure to the above specific details.

[0099] The block diagrams of devices, apparatuses, equipment, systems referred to in the present disclosure are merely illustrative examples and are not intended to require or imply that the connection, arrangement, configuration must be as shown in the block diagrams. These devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner as will be appreciated by those skilled in the art. Words such as "include," "contain," "have," etc. are open-ended words that are to be interpreted to mean "including but not limited to," and are to be interpreted not to exclude other items. The words "or" and "and" as used herein are to be interpreted as the word "and / or," and are to be interpreted not to exclude other items. The word "such as" as used herein is to be interpreted as the phrase "such as but not limited to," and is to be interpreted not to exclude other items.

[0100] Also, as used herein, the term "or" as used in the context of "at least one of A, B, or C" means A or B or C or any combination thereof. Further, the term "example" is used to mean "serving as an example, instance, or illustration," and is not to be construed as preferred or advantageous over other examples. The term "include" is used to mean "comprise or consist of, whether or not associated with the term "including."

[0101] It is also important to note that the systems and methods of the present disclosure can be embodied in a variety of forms including, but not limited to, a data processor, a computer program product, a computer, one or more tangible computer readable storage devices, one or more computer-implemented methods, information, or a bit of information. Additionally, the systems and methods of the present disclosure can be embodied as one or more computers or computer-implements methods that can be used in a networked environment.

[0102] Various changes, modifications and improvements in the herein described technologies can be made within the teachings of the technology, particularly in light of the above teachings. It is therefore intended that the here disclosed technology not be limited to the particular composition, method, and / or process disclosed. Rather, the scope of the technology includes all techniques that can be practiced and which fall within the principles described herein. Additionally, the scope of the claims of the present disclosure is not limited to the specific aspects described herein. Rather, the scope of the claims includes any process, machine, manufacture, composition of matter, means, methods and steps similar to the ones described herein those currently or newly developed which accomplish substantially the same results as the claims. Accordingly, the appended claims are intended to cover all such modifications and changes as fall within the true scope of the disclosure.

[0103] The above description of the disclosed aspects is intended to be illustrative and not restrictive. Many modifications and variations of the aspects described herein will be apparent to those skilled in the art from this disclosure, and it is intended that the disclosure encompass all such modifications and variations. Therefore, it is contemplated that the application will be practiced in sub-combinations of these methods, systems, and articles of manufacture.

[0104] The foregoing description has been presented for the purposes of illustration and description. Furthermore, the description is not intended to limit the embodiments of the disclosure to the forms disclosed herein. Although the various example aspects and embodiments have been described herein with regard to particular aspects and embodiments, those skilled in the art will recognize that certain modifications, changes, substitutions, additions and sub-combinations can be made without departing from the spirit of the disclosure.

Claims

1. A turbofan engine, characterized in that, include: An air intake (1) is provided, which 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; A 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).

2. The turbofan engine according to claim 1, characterized in that, The core machine (4) comprises, arranged from front to back, the following: 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, 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.

5. The turbofan engine according to claim 4, 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 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).

6. The turbofan engine according to claim 4, 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 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).

7. 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.

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

9. 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, is capable of adjusting the throat area.

10. An aircraft, characterized in that, include: The turbofan engine according to any one of claims 1-9.

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