Intercooling regenerative water-enhanced turbofan engine and working method

Abstract

The invention belongs to the technical field of aviation turbine engines, and discloses an indirect-cooling regenerative water-enhanced turbofan engine which comprises a Brayton cycle and a supercritical water vapor Rankine cycle in a main flow path, and the two cycles are closely connected and are coupled by adding a steam turbine, a steam generator and a condenser. Meanwhile, liquid water can appear at an outlet of the steam turbine, the liquid water is jetted between the high-pressure gas compressor and the low-pressure gas compressor for indirect cooling, the intermediate temperature of the gas compressors is reduced, power consumption of the gas compressors is reduced, unit working medium thrust is improved, an indirect cooler is omitted, and practical application is facilitated; low-temperature steam at an outlet of the steam turbine can be jetted to an inlet of the low-pressure turbine for cooling, the cold air amount can be effectively reduced, and the unit working medium thrust can be effectively improved. The problems of high temperature difference and large loss of a steam generator are effectively solved, and compared with a conventional aero-engine, the total efficiency of the engine can be greatly improved, and the oil consumption rate and pollutant emission are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation turbine engines, and in particular relates to an indirect cooling and heat recovery water-enhanced turbofan engine and a working method thereof. Background Art

[0002] As the core power system of modern aircraft, the performance of aircraft engines is directly related to the flight efficiency, fuel consumption and environmental impact of aircraft. With the development of aviation technology, although traditional turbine engines can provide relatively stable thrust, their low fuel efficiency and emission problems are becoming increasingly prominent, and breakthroughs in new power technologies are urgently needed. In recent years, hybrid aircraft engines with steam cycle systems have begun to attract attention, but the overall layout of such engines is still in the exploratory stage. The water-enhanced turbofan engine proposed in the present invention adopts cycle technologies such as the Brayton cycle and the supercritical water vapor Rankine cycle, aiming to improve the overall thermal efficiency and reduce fuel consumption and emissions. The supercritical water vapor Rankine cycle system uses a steam turbine as a heat recovery and temperature control device, which can significantly improve the thermal efficiency and thrust of the engine while reducing harmful emissions.

[0003] Through the above analysis, the problems and defects of the prior art are as follows:

[0004] Although traditional turbine engines can provide relatively stable thrust, they have low fuel efficiency and increasingly prominent harmful emissions. Conventional intercooling cycles require large intercoolers, which is not conducive to practical applications. Steam generators produce high temperature differences due to phase change. The loss is high; conventional turbine cooling uses compressor bleed air, which has a high bleed air volume and low unit working fluid thrust. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides an indirect cooling and heat recovery water-enhanced turbofan engine.

[0006] The present invention is achieved in that an indirect cooling and heat recovery water-enhanced turbofan engine comprises:

[0007] The Brayton cycle in the main channel is closely linked to the supercritical water vapor Rankine cycle and is coupled through a steam turbine, a steam generator and a condenser. The main channel includes the following components: an air inlet, a fan, a booster compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and an inner tail nozzle, which are arranged and connected in sequence from front to back. The outer duct and the outer duct tail nozzle are connected in parallel with the inner components after the fan. In the supercritical water vapor Rankine cycle, the following components are included: a steam turbine, a steam generator, a condenser, a gas-liquid separator, a water pump motor and a water pump, which are connected in sequence to form a closed loop and a cycle.

[0008] In the mainstream Brayton cycle described, the circulating working fluid mainly includes air and mixed gas. During the operation of the aircraft, air enters the fan of the turbofan engine through the air inlet. The fan rear flow passage is divided into an inner duct and an outer duct, among which, due to the higher bypass ratio brought by steam injection, the outer duct air flow accounts for most of the total intake flow. The outer duct air enters the outer duct tail nozzle and expands to generate thrust; the inner duct air is compressed in turn through the boost stage and the high-pressure compressor, and the boosted air enters the combustion chamber, mixes with the fuel and steam and burns to produce high-temperature and high-pressure gas. Subsequently, the gas enters the high-pressure turbine and the low-pressure turbine in turn to expand and do work, and the high-temperature gas will be cooled by the steam from the steam turbine outlet during this process. The high-pressure turbine provides power to the high-pressure compressor through the high-pressure shaft, and the low-pressure turbine provides power to the fan, the boost stage compressor and the water pump through the low-pressure shaft. The gas contains a large amount of water vapor, and the supercritical water vapor Rankine cycle is responsible for recovering the injected water. After the low-pressure turbine, the high-temperature gas still has a lot of energy, enters the hot end of the steam generator for heat recovery, and heats the high-pressure liquid water at the cold end to generate supercritical water vapor. The unrecovered water vapor in the gas at the hot end outlet of the steam generator needs to be further cooled by the hot end of the condenser, and the cold end of the condenser uses the ambient low-temperature air as the cooling source. The condensed mixture is separated by a gas-liquid separator, and the condensed water enters the water pump for pressurization. Since the pressure of the condensed water is low, the water pump pressurizes it to the critical pressure, and the water pump is driven by the low-pressure turbine. The remaining gas generates thrust through the internal tail nozzle; while the high-pressure condensed water enters the cold end of the steam generator and is heated to generate supercritical water vapor. The supercritical water vapor then enters the steam turbine to do work and cool down. The steam at the outlet of the steam turbine generates some liquid water, which is collected and sprayed between the compressor stages for intercooling, and the cooled steam is further sprayed into the turbine for cooling.

[0009] Furthermore, the supercritical water vapor Rankine cycle includes a steam turbine expansion process. The inlet of the steam turbine is connected to the cold end outlet of the steam generator, and the outlet is connected to the inlet of the combustion chamber. The water pump pressurizes the liquid water to above 23MPa to meet the supercritical state requirements. At the same time, the water pump has the performance to meet the working pressure range and the size is as small as possible. In addition, the steam turbine can effectively reduce the temperature of the supercritical water vapor during the expansion process. The hot end of the steam generator is connected to the hot end of the condenser, and the flow channel of the heat exchanger adopts a countercurrent arrangement to improve the heat exchange efficiency.

[0010] Furthermore, the high-pressure components, low-pressure components, combustion chamber and heat exchange components of the aviation turbine engine, the high-pressure components include a high-pressure turbine, a high-pressure compressor and a high-pressure shaft, the low-pressure components include a low-pressure turbine, a fan, a boost stage compressor and a low-pressure shaft, and the heat exchange components include an evaporator and a condenser.

[0011] Furthermore, the high-pressure condensed water first enters the evaporator, where it is heated to supercritical steam. The heated steam enters the steam turbine to expand and do work, and is then sprayed into the combustion chamber to participate in combustion, or used for turbine cooling. Finally, the steam is condensed and recovered as liquid water through the condenser, thereby realizing water circulation.

[0012] Furthermore, the condenser is arranged under the wing of the aircraft, and uses the aircraft skin for cooling, and recovers condensed water to improve circulation efficiency.

[0013] Furthermore, the heat exchanger is a single or a combination of multiple heat exchanger elements.

[0014] Furthermore, the evaporator in the heat exchange component is used to heat the condensed water into supercritical water vapor. After the steam is expanded by the steam turbine, it can be injected into the combustion chamber to mix with the gas to improve the combustion efficiency; or injected into the high-pressure turbine and the low-pressure turbine for cooling, thereby improving the thrust. The generated liquid water is injected into the inlet of the high-pressure compressor to cool the inlet air.

[0015] Furthermore, the control module monitors the gaseous water and liquid water content at the steam turbine outlet in real time through sensors, and controls the water injection device according to the optimal water injection amount, thereby optimizing the engine operating efficiency.

[0016] Furthermore, considering the needs of aviation operations, the water pump should minimize the volume and mass when compressing supercritical water. To this end, the heat exchanger components are made of high-temperature aviation alloy materials to achieve efficient heat exchange and lightweight

[0017] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0018] First, the steam cycle system uses steam injection technology to inject water vapor into the combustion chamber or turbine, thereby improving thermal efficiency and thrust in the key links of the engine. Liquid water is sprayed between the compressor stages, effectively reducing the power consumption of the compressor and increasing the aircraft's unit working fluid thrust. The coordinated work of the steam turbine, steam generator and condenser, with the help of heat exchange and water recovery technology, improves the efficiency of thermal energy conversion while reducing the overall energy consumption and emissions of the system. In addition, the integrated design of the water pump and heat exchanger makes the system more compact and efficient, achieving higher thrust and fuel efficiency without adding too much weight. By optimizing the steam injection amount, steam turbine power regulation and condensation return water design, the reasonable layout of the steam turbine and the cooling turbine effectively improves the overall performance of the engine and meets the aviation industry's demand for efficient and environmentally friendly power systems.

[0019] The invention solves the problem: The invention overcomes the shortcomings of conventional steam jet aircraft engine layout and solves the problem of extra weight caused by water in water-enhanced engines and energy loss during cooling. By introducing steam turbines and steam-cooled turbines, and combining the Brayton cycle with the supercritical water vapor Rankine cycle, the invention significantly improves thermal efficiency and thrust output, while effectively reducing energy consumption and emissions.

[0020] Compared with traditional regenerative aircraft engines, the engine condenser design proposed in this invention is located in the wing and fuselage, and uses high-speed and low-temperature air in the high-altitude environment to cool the internal engine exhaust, which is much lower than the engine internal cooling design temperature, thereby significantly reducing the condenser's requirements for heat exchange performance. Through the coupled design of the steam generator, condenser and water pump, the system not only achieves efficient heat exchange and water recovery, but also optimizes the overall performance and effectively reduces the system weight.

[0021] By optimizing the design of the water pump and heat exchanger, the efficient operation of the engine under different working conditions is ensured. By improving various aspects of the steam cycle system, the present invention provides a more environmentally friendly and efficient aviation engine solution, meeting the future aviation industry's higher requirements for power system performance and environmental friendliness.

[0022] (1) By placing the condenser outside the wing and fuselage surface, especially by utilizing the high-speed flow and low temperature of the air on the wing surface, the engine's requirements for the condenser's heat exchange performance are effectively reduced, while avoiding the pressure loss caused by designing the condenser in the external duct.

[0023] (2) By combining the Brayton cycle and the supercritical steam Rankine cycle, the heat recovery and conversion efficiency of the engine is optimized, significantly improving the overall thermal efficiency. At the same time, the synergy between the steam cycle system and the gas turbine enhances the thrust output performance of the engine, further improving the overall performance of the power system.

[0024] (3) Liquid water intercooling is sprayed to the high-pressure compressor inlet, which reduces the power consumption of the compressor and effectively increases the unit working fluid thrust; steam cooling reduces the heat load and work done by the turbine, increases the inherent thrust, and reduces the demand for cooling air.

[0025] (4) The compact design of the water pump and heat exchanger optimizes the engine structure, improving the energy efficiency and reliability of the system without increasing excessive weight.

[0026] (5) Compared with the conventional steam jet aircraft engine layout, the circulation components of the present invention are relatively independent, the supercritical water steam circulation system and the core engine system are easy to repair, and the use and maintenance costs are low.

[0027] Second, the expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0028] The invention optimizes energy recovery and utilization, combines the Brayton cycle and the supercritical steam Rankine cycle, and greatly improves the fuel utilization rate of the engine, with a fuel saving rate of up to 15.06%. This technology can be widely used in commercial passenger aircraft, military transport aircraft and future high-efficiency aviation platforms, creating new market growth points for aviation manufacturing companies.

[0029] The technical solution of the present invention overcomes the technical prejudice: in the traditional view, the steam cycle system is considered unsuitable for aircraft engines due to the increased weight and complexity. The present invention realizes efficient energy recovery and weight control of the system through the supercritical steam Rankine cycle and the efficient and lightweight heat exchange design, effectively overcoming the technical prejudice that the steam system is unsuitable for aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a simplified diagram of the cycle mode of the indirect cooling and heat recovery water-enhanced turbofan engine (steam is injected into the combustion chamber) provided by an embodiment of the present invention;

[0031] Figure 2 It is a simplified diagram of the cycle mode of the indirect cooling and heat recovery water-enhanced turbofan engine (steam injection to the turbine) provided by an embodiment of the present invention;

[0032] Figure 3 This is an example cycle diagram of an indirect cooling and heat recovery water-enhanced turbofan engine provided by an embodiment of the present invention;

[0033] Figure 4 It is a simplified diagram of the arrangement of the condenser of the indirect cooling and heat recovery water-enhanced turbofan engine provided by an embodiment of the present invention;

[0034] Figure 5 2 is a schematic diagram showing the analysis results of the total efficiency of the indirect cooling and regenerative water-enhanced turbofan engine according to an embodiment of the present invention as a function of the amount of water injection;

[0035] Figure 6 2 is a schematic diagram showing the analysis results of the thermal efficiency of the indirect cooling and heat recovery water-enhanced turbofan engine according to the embodiment of the present invention as a function of the water injection amount;

[0036] Figure 7 It is a schematic structural diagram of a steam generator of an indirect cooling and regenerative water-enhanced turbofan engine provided by an embodiment of the present invention;

[0037] Figure 8 It is a schematic diagram of the condenser structure of an indirect cooling and heat recovery water-enhanced turbofan engine provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] like Figure 1 As shown, an indirect cooling regenerative water-enhanced turbofan engine provided by an embodiment of the present invention comprises:

[0040] The Brayton cycle and supercritical steam Rankine cycle in the main flow are tightly coupled and connected to each other through steam turbine, steam generator and condenser. The main flow includes the air inlet, fan, booster compressor, high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine and internal tail nozzle. These components are arranged and connected from front to back in sequence, and the external duct and external duct tail nozzle are connected in parallel with the internal components behind the fan. The supercritical steam Rankine cycle consists of a steam turbine, steam generator, condenser, gas-liquid separator and water pump. The above components are connected in sequence to form a closed cycle.

[0041] In the mainstream Brayton cycle described, the circulating working fluid mainly includes air and mixed gas. During the operation of the aircraft, air enters the fan of the turbofan engine through the air inlet. The fan rear flow passage is divided into an inner duct and an outer duct, among which, due to the higher bypass ratio brought by steam injection, the outer duct air flow accounts for most of the total intake flow. The outer duct air enters the outer duct tail nozzle and expands to generate thrust; the inner duct air is compressed in turn through the boost stage and the high-pressure compressor, and the boosted air enters the combustion chamber, mixes with the fuel and steam and burns to produce high-temperature and high-pressure gas. Subsequently, the gas enters the high-pressure turbine and the low-pressure turbine in turn to expand and do work, and the high-temperature gas will be cooled by the steam from the steam turbine outlet during this process. The high-pressure turbine provides power to the high-pressure compressor through the high-pressure shaft, and the low-pressure turbine provides power to the fan, the boost stage compressor and the water pump through the low-pressure shaft. The gas contains a large amount of water vapor, and the supercritical water vapor Rankine cycle is responsible for recovering the injected water. After the low-pressure turbine, the high-temperature gas still has a lot of energy, enters the hot end of the steam generator for heat recovery, and heats the high-pressure liquid water at the cold end to generate supercritical water vapor. The unrecovered water vapor in the gas at the hot end outlet of the steam generator needs to be further cooled by the hot end of the condenser, and the cold end of the condenser uses the ambient low-temperature air as the cooling source. The condensed mixture is separated by a gas-liquid separator, and the condensed water enters the water pump for pressurization. Since the pressure of the condensed water is low, the water pump pressurizes it to the critical pressure, and the water pump is driven by the low-pressure turbine. The remaining gas generates thrust through the internal tail nozzle; while the high-pressure condensed water enters the cold end of the steam generator and is heated to generate supercritical water vapor. The supercritical water vapor then enters the steam turbine to do work and cool down. The steam at the outlet of the steam turbine generates some liquid water, which is collected and sprayed between the compressor stages for intercooling, and the cooled steam is further sprayed into the turbine for cooling.

[0042] The supercritical water vapor Rankine cycle provided by the embodiment of the present invention is provided with a steam turbine expansion; the steam turbine inlet is connected to the cold end outlet of the steam generator, and the steam turbine outlet is connected to the combustion chamber inlet; the water pump pressurizes the liquid water to above 23MPa to meet the supercritical state requirements, and the water pump has the performance to meet the working pressure range and the size is as small as possible. The steam turbine can reduce the temperature of the supercritical water vapor; the hot end of the steam generator is connected to the hot end of the condenser, and the heat exchanger flow channel is arranged in a countercurrent type.

[0043] The embodiments of the present invention provide a high-pressure component, a low-pressure component, a combustion chamber and a heat exchange component of an aviation turbine engine, wherein the high-pressure component includes a high-pressure turbine, a high-pressure compressor and a high-pressure shaft, the low-pressure component includes a low-pressure turbine, a fan, a boost stage compressor and a low-pressure shaft, and the heat exchange component includes an evaporator and a condenser.

[0044] The condensed water provided in the embodiment of the present invention first enters the evaporator to be heated into high-temperature steam, and the steam then enters the steam turbine to expand and do work and is then sprayed into the combustion chamber to participate in combustion or for turbine cooling, and is finally condensed and recovered into liquid water through the condenser to realize water circulation.

[0045] The condenser provided in the embodiment of the present invention is arranged under the wing of an aircraft, uses the aircraft skin for cooling, and recycles condensed water to improve circulation efficiency.

[0046] The heat exchanger provided in the embodiment of the present invention is a single or a combination of multiple heat exchanger elements.

[0047] The evaporator in the heat exchange component provided in the embodiment of the present invention is used to heat condensed water into supercritical water vapor. After entering the steam turbine for expansion, the steam is injected into the combustion chamber to mix with the fuel gas to improve the combustion efficiency or injected into the high and low pressure turbines for cooling to increase the thrust.

[0048] The control module provided in the embodiment of the present invention monitors the gaseous water and liquid water content at the steam turbine outlet in real time through sensors, and controls the water injection device according to the optimal water injection amount to optimize the engine operating efficiency.

[0049] In the embodiment of the present invention, taking aviation operation into consideration, the water pump compresses supercritical water to meet the requirements of minimizing volume and mass, and the heat exchanger components are made of high-temperature aviation alloys to meet the requirements of efficient heat exchange and lightweight.

[0050] Example: Application of indirect cooling and heat recovery water-enhanced turbofan engine in commercial passenger aircraft

[0051] In a commercial passenger aircraft, the indirect cooling and regenerative water-enhanced turbofan engine of the present invention is used. The system installs a condenser under the aircraft skin, effectively reduces the exhaust temperature by utilizing the air cooling effect during high-speed flight, and at the same time recovers the condensed water and heats it into high-temperature steam through an efficient heat exchange device. The heated steam is sprayed into the combustion chamber and mixed with the gas for combustion, thereby improving the combustion efficiency and thrust output, or the steam is sprayed into the turbine for cooling at the same time.

[0052] This system not only significantly improves the engine's operating efficiency, but also effectively reduces emissions, providing a more environmentally friendly and efficient power solution for commercial aviation.

[0053] like Figure 1 As shown, the intercooled regenerative water-enhanced turbofan engine in this embodiment is a dual-shaft gas turbine, including a combustion chamber, a high-pressure compressor, a low-pressure compressor, a high-pressure turbine, a low-pressure turbine, a steam turbine and a regenerator. The main flow channel includes components such as an air inlet, a fan, a booster compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and an internal tail nozzle. These components are arranged and connected from front to back in sequence, and the outer duct and the outer duct tail nozzle are connected in parallel with the internal components behind the fan. The supercritical water vapor Rankine cycle includes a steam turbine, a steam generator, a condenser, a gas-liquid separator and a water pump. The above components are connected in sequence and form a loop to form a cycle. Figure 1 The steam turbine cooling arrangement is shown. Supercritical steam is expanded by the steam turbine and cooled to 470K before being injected into the combustion chamber. Liquid water generated at the steam turbine outlet is injected into the high-pressure compressor inlet for mixing cooling, thereby effectively improving the power-to-weight ratio. Figure 2 It shows that supercritical water vapor is expanded and cooled to 470K through a steam turbine and then sprayed into the low-pressure turbine. The liquid water produced at the steam turbine outlet is also sprayed into the high-pressure compressor inlet to help cool the compressor inlet, reduce compressor power consumption and increase thrust.

[0054] The engine cruising state is selected as the reference state. The bypass ratio of this large bypass intercooling and reheating water enhanced turbofan engine is 32.9. Hydrogen is used as fuel. The combustion of hydrogen can produce enough water to participate in the water cycle. The fan internal and external pressure ratio is 1.5, the pressure ratio of the booster compressor is 2.33, the pressure ratio of the high-pressure compressor is 12, the total pressure ratio is 41.9, the inlet air flow is 196kg / s, and the combustion chamber outlet temperature is 1730K. The original cycle high-pressure compressor inlet temperature is 363.9K, and the outlet temperature is 767.7K. After adding intercooling and reheating water enhancement, the high-pressure compressor outlet temperature is reduced to 603.5K, a decrease of 164.1K, and the compressor power consumption is reduced by 20.5%. When the water injection amount is optimal at a water-steam ratio of 23.2%, the engine total efficiency is 45.2% and the thermal efficiency is 58%. The power-to-weight ratio is 3.46 kN / kg, which is 73% higher than the 2 kN / kg of the original engine. It can be inferred that the total weight of the engine remains basically unchanged after adding the supercritical steam cycle components.

[0055] The high-pressure components include the high-pressure compressor, high-pressure turbine and high-pressure shaft; the low-pressure components include the low-pressure compressor, low-pressure turbine, exhaust compressor, water pump and low-pressure shaft; the heat exchanger components include the evaporator and condenser. Specifically, the high-pressure turbine drives the high-pressure compressor through the high-pressure shaft, and at the same time, the high-pressure shaft outputs power outward; the low-pressure turbine drives the fan, booster compressor and water pump through the low-pressure shaft.

[0056] The working principle of the low-pressure part is relatively complex. The low-pressure turbine receives the gas from the high-pressure turbine and drives the low-pressure compressor and exhaust compressor through the low-pressure shaft. The low-pressure compressor further compresses the air and sends it into the combustion chamber. At the same time, the low-pressure turbine also provides power to the water pump through the low-pressure shaft motor, driving the water pump to send the condensed water in the condenser to the evaporator for heating to generate high-temperature steam. The output power of the steam turbine is connected to the low-pressure shaft to drive the system together.

[0057] The evaporator plays a key role in the entire system. The condenser recovers the steam generated after combustion and cools it into liquid water, which is then sent to the evaporator to be heated into high-temperature steam. The evaporator is connected to the high-temperature part of the engine through a heat exchanger, and uses the heat generated by combustion to heat the water into high-temperature steam. The steam is then sprayed into the combustion chamber and mixed with the gas to further improve the combustion efficiency and effectively reduce the exhaust gas temperature. The combination of the steam cycle system and the gas turbine not only improves the energy utilization efficiency, but also recovers the waste heat through the recuperator, thereby reducing the overall energy consumption. Supercritical water vapor works in the steam turbine to cool down. The liquid water generated at the outlet of the steam turbine will be collected and sprayed into the compressor stage for intercooling, and the cooled steam will also be sprayed into the turbine for cooling. The steam generator is made of GH4133 material, with an inner diameter of 1.3 meters and an outer diameter of 2.7 meters, which enhances the heat exchange efficiency. The surface of the heat exchanger is covered with an enhanced heat exchange coating, and the heat exchange efficiency reaches 90%.

[0058] according to Figure 3 For example, the amount of water sprayed by an indirect-cooled regenerative water-enhanced turbofan engine (expressed as the water-air ratio WAR, WaterAirRatio) varies in the range of 0 to 47.7%. The low-pressure turbine outlet pressure is set to 23.2 kPa (i.e., ambient pressure), and the supercritical water is compressed to 25 MPa, and the water vapor temperature in the steam generator is raised to above 650 K. Under this condition, the changes in the total efficiency and fuel economy of the continuous steam injection aviation turbine engine at different water-air ratios (WAR) are calculated. Experimental data show that compared with conventional geared turbofan engines, the performance of the engine at different water-vapor ratios is significantly improved. The total efficiency of a conventional geared turbofan engine is 36.8%. By optimizing the water-vapor ratio WAR and introducing supercritical water vapor injection, the total efficiency and fuel economy of the engine have been significantly improved, respectively. For specific changes, see. Figure 3 .

[0059] Air enters the system through the inlet 1 and is compressed step by step through the booster stage 22 and the high-pressure compressor 25. The booster stage achieves preliminary pressurization of the air through an axially mounted fan, while the high-pressure compressor further increases the pressure of the air to ensure that the high-pressure air required for combustion in the combustion chamber 31 is provided. This process realizes a continuous air flow connection through the internal channel 24.

[0060] The high-pressure air enters the combustion chamber 31, is fully mixed with the injected fuel and burns, and produces high-temperature and high-pressure gas. The combustion chamber is connected to the high-pressure turbine 41, and the high-pressure gas drives the high-pressure turbine to rotate, completing energy conversion and releasing part of the shaft work, and is connected to the compressor 25 through the high-pressure shaft 3 to realize the power cycle.

[0061] The high-pressure gas further flows from the high-pressure turbine 41 to the low-pressure turbine 45. The low-pressure turbine is mechanically connected to components such as the water pump and the steam turbine through the low-pressure shaft 5. The rotation output of the low-pressure turbine provides shaft work for the water pump and the steam turbine. In addition, the low-pressure turbine is connected to the steam generator 61 through the steam recovery system 63 to realize the waste heat utilization of the exhaust gas.

[0062] The steam generator 61 in the system uses the heat of exhaust gas to convert liquid water into high-temperature steam. The steam drives the shaft power output through the steam turbine 62. At the same time, the steam is separated into gaseous and liquid parts after being processed by the gas-liquid separator 63. The gaseous steam is recycled and the liquid water is re-injected into the water tank 64 through the water pump, forming a complete steam cycle.

[0063] The exhaust gas after combustion enters the cooler 73 through the exhaust pipe 71, and the exhaust gas temperature is reduced by the cooler before being discharged into the atmosphere. The cooler is connected to the main exhaust system through the external cooling pipe 72, and its installation position ensures the smooth flow of exhaust gas and heat dissipation efficiency.

[0064] The system ensures stable and efficient energy and fluid transfer between modules through precise connection and position design. The water pump motor and steam generator use independent control systems to ensure efficient operation of water circulation and heat recovery. At the same time, the coordinated work of the gas-liquid separator and the cooling system, through reliable connection and installation, ensures that the exhaust gas meets the standards and improves the overall efficiency and safety of the system.

[0065] Figure 4 Shows the placement of the condensers on the aircraft wing and fuselage.

[0066] Figure 5 and Figure 6 It is shown that the overall efficiency and thermal efficiency increase with the increase of water-steam ratio, reaching a maximum value at WAR=23.2% (overall efficiency 45.2% and thermal efficiency 58%, respectively).

[0067] Figure 8 The specific form of the aviation steam generator is shown, which is mainly composed of front and rear water-cooled walls and tube bundles. The high-temperature gas directly contacts the tube bundle, so that the working fluid is reheated in the water-cooled wall to generate water vapor. In terms of material selection, the key components of the steam generator can be made of high-temperature aviation alloy materials, including but not limited to nickel-based alloys, cobalt-based alloys, etc. The specific material selection can be determined according to actual working conditions and needs.

[0068] In summary, the present invention proposes an indirect cooling and regenerative water-enhanced turbofan engine. The engine significantly improves the energy recovery efficiency and combustion efficiency by introducing supercritical water vapor Rankine cycle, steam injection technology and high-efficiency heat exchange technology. The condenser is installed under the wing, and uses high-speed flight air to cool and recover the heat of the exhaust gas. The steam generator heats the condensed water into supercritical steam, and improves the combustion efficiency and thrust output through steam injection. At the same time, the indirect cooling design effectively reduces the power consumption of the compressor and improves the power-to-weight ratio. The present invention uses hydrogen fuel as a power source, which further improves the environmental performance of the system and reduces emissions. Experimental results show that the engine has significant advantages in thrust-to-weight ratio, fuel efficiency and overall efficiency, especially in energy saving and emission reduction, and has broad application prospects.

[0069] Example 1: High-efficiency cycle control and dual-operating conditions application

[0070] This embodiment provides a specific operating method based on an indirect cooling and heat recovery water-enhanced turbofan engine, which is suitable for both high load and stable cruising conditions.

[0071] 1) Structural layout and component operation

[0072] In the main flow path, air enters the fan through the air inlet duct and flows to the inner duct and the outer duct.

[0073] The compressed air enters the booster compressor and the high-pressure compressor. The compressed high-pressure air is mixed with supercritical water vapor and fuel and burns in the combustion chamber.

[0074] The high-temperature and high-pressure combustion gas expands and performs work through the high-pressure turbine and the low-pressure turbine. The high-pressure shaft drives the high-pressure compressor, and the low-pressure shaft drives the fan and the boost stage compressor.

[0075] 2) Steam cycle and heat recovery process

[0076] The high-temperature combustion gas discharged from the turbine enters the hot end of the steam generator, heats the high-pressure condensate and generates supercritical steam.

[0077] The generated supercritical water vapor enters the steam turbine to expand and do work. Part of the steam is injected into the combustion chamber to participate in combustion, and part is used for cooling the high and low pressure turbines.

[0078] The steam at the outlet of the steam turbine is mixed with liquid water, cooled at the hot end of the condenser, and the liquid water is separated by a gas-liquid separator. The liquid water is pressurized by a water pump and returned to the cold end of the steam generator to achieve a closed cycle.

[0079] 3) Water spray cooling and thrust increase control under special working conditions

[0080] During high-load takeoff conditions, the amount of steam injected into the combustion chamber is increased to improve combustion efficiency and thrust output.

[0081] In stable cruising conditions, steam is mainly used for cooling high and low pressure turbines to ensure system operation stability and fuel economy.

[0082] The steam at the steam turbine outlet is cooled to a suitable temperature and then recycled, effectively improving the cycle efficiency.

[0083] Example 2: Double interference assembly and high-precision processing technology

[0084] The present embodiment provides a double interference assembly method for an indirect cooling and regenerative water-enhanced turbofan engine to solve the problems of precision error and thermal stress of heterogeneous materials during assembly of components.

[0085] 1) Assembly steps

[0086] First interference fit: heated fit

[0087] The transfer positioning block 2 (made of aluminum alloy) is heated to a predetermined temperature, expanded, and then assembled onto the rotor shaft 3 (made of structural steel), achieving a stable interference fit through the principle of thermal expansion and contraction.

[0088] Secondary hole processing

[0089] Due to the influence of assembly error, the installation hole of the limit pin 1 is difficult to be completely aligned, so it is necessary to use a high-precision CNC machining center to perform secondary hole making after the first assembly is completed. Specific operation:

[0090] The prefabricated holes are processed by group drilling, leaving an allowance of 0.10.2mm;

[0091] The single-side allowance after rough boring is 0.020.05mm;

[0092] Precision boring is performed to achieve a hole diameter deviation of less than 0.01 mm and a surface roughness of less than Ra0.8.

[0093] 2) Second interference fit assembly: Liquid nitrogen cooling assembly

[0094] The limiting pin 1 is cooled to the temperature of liquid nitrogen, and then inserted into the assembly hole after shrinking, so as to avoid the influence of the overall heating on the stability of the first assembly structure.

[0095] During the normal temperature recovery process, the limit pin, the transfer positioning block 2 and the rotor shaft 3 form a cross double interference structure, which enhances the stability and centrifugal force resistance under high-speed rotation conditions.

[0096] 3) Assembly quality control and inspection

[0097] The sensor is used to monitor the installation accuracy of the limit pin to ensure that the circular runout is less than 0.02mm.

[0098] The go / no-go gauge detects the accuracy of the assembly holes to ensure the high reliability and long life of the overall assembly structure.

[0099] Embodiment 1 focuses on the engine workflow and dual-mode operation efficiency, and achieves thrust increase and efficient cooling through steam injection and heat recovery processes.

[0100] Example 2 focuses on the double interference assembly process, and solves the assembly accuracy and structural stability problems of dissimilar materials through a combination of heating and liquid nitrogen cooling assembly.

[0101] Depend on Figure 5 and Figure 6 It can be seen that the total efficiency of the indirect cooling and regenerative water-enhanced turbofan engine is about 7.2% higher than that of the traditional engine. The introduction of water vapor in the combustion chamber improves the temperature distribution of the combustion process and increases the combustion efficiency by 3% to 5%. The peak combustion temperature is reduced by about 100-200K, reducing the generation of harmful gases such as nitrogen oxides (NOx) and improving environmental performance.

[0102] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. An indirect cooling and regenerative water-enhanced turbofan engine, characterized in that: The engine includes a Brayton cycle and a supercritical water vapor Rankine cycle in the main flow path, the two cycles being coupled to each other; The main flow path includes: air inlet, fan, booster compressor, high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine and internal tail nozzle; The outer duct and the inner duct are arranged in parallel, and the outer duct is connected to the outer duct tail nozzle; The supercritical steam Rankine cycle includes: a steam turbine, a steam generator, a condenser, a gas-liquid separator and a water pump, and the above components are sequentially connected through flow channels to form a closed loop; The steam at the outlet of the steam turbine is connected to the combustion chamber through a flow channel, participates in combustion or is injected into the turbine for cooling.

2. The indirectly cooled regenerative water-enhanced turbofan engine according to claim 1, characterized in that: The inlet of the steam turbine is connected to the cold end outlet of the steam generator through a connecting pipeline; The outlet of the steam turbine is connected to the combustion chamber or the high- and low-pressure turbines through pipelines; The water pump is connected to the condensation outlet of the liquid water through a pipeline, compresses the liquid water to a supercritical pressure higher than 23 MPa, and is powered by a low-pressure shaft motor; The hot end of the steam generator is connected to the hot end of the condenser through a countercurrently arranged heat exchanger flow channel to improve heat exchange efficiency.

3. The indirectly cooled regenerative water-enhanced turbofan engine according to claim 1, characterized in that: The high-pressure components include: a high-pressure turbine and a high-pressure compressor connected by a high-pressure shaft; The low-pressure component includes: a low-pressure turbine and a low-pressure compressor connected by a low-pressure shaft, and the low-pressure shaft is also connected to a low-pressure shaft motor to provide driving force for the water pump; The heat exchange component includes: a steam generator and a condenser, which realizes the conversion of condensed water into supercritical water vapor through a flow channel and transmits it to a steam turbine.

4. The indirectly cooled regenerative water-enhanced turbofan engine according to claim 1, characterized in that: The condenser is installed under the wing of the aircraft, closely fitting with the wing skin, and is cooled by utilizing the natural heat dissipation characteristics of the aircraft skin; The condensed water is separated into gas and liquid by a gas-liquid separator installed at the outlet of the condenser. The liquid water is connected to the water pump inlet through a flow channel and is pressurized and circulated for use, thereby improving the engine cycle efficiency.

5. The indirectly cooled regenerative water-enhanced turbofan engine according to claim 1, characterized in that: The control module monitors the content of gaseous water and liquid water in real time through a sensor installed at the outlet of the steam turbine; Based on the sensor feedback data, the water injection device is controlled to inject precise amounts of steam into the high and low pressure turbines for cooling or into the combustion chamber to optimize combustion efficiency, thereby dynamically optimizing the engine operating performance.

6. The indirectly cooled regenerative water-enhanced turbofan engine according to claim 1, characterized in that: The heat exchanger is made of high-temperature aviation alloy material, and the arrangement of the heat exchange flow channel is to meet the high-efficiency heat exchange performance; The water pump is integrated with other engine components, and its volume and mass are optimized to fit the space and weight limitations of aircraft engines; The water pump is installed at the shaft power transmission position of the low-pressure shaft and is rigidly fixed with other components through a compact bracket, thereby ensuring the compactness of the engine structure and the stability of the system.

7. An operating method of an indirect cooling and regenerative water-enhanced turbofan engine, characterized in that: The method comprises the following steps: Step 1: Compressed Air External air enters the turbofan engine through the air inlet, and enters the combustion chamber after being compressed step by step by the fan, booster compressor and high-pressure compressor. Step 2: Burning and Expansion High-pressure air is mixed with fuel and supercritical steam in the combustion chamber to generate high-temperature and high-pressure combustion gas, which enters the high-pressure turbine and the low-pressure turbine to expand and perform work; Step 3: Steam Cycle The high-temperature combustion gas enters the hot end of the steam generator after the turbine, heats the high-pressure water at the cold end, and generates supercritical steam; Step 4: Steam Utilization and Recovery The supercritical water vapor is cooled by the steam turbine, part of the steam is injected into the combustion chamber to participate in combustion or the turbine for cooling, and the remaining water vapor is cooled and recovered into liquid water in the condenser, which is pressurized by the water pump and then enters the steam generator again, forming a closed cycle.

8. The operating method of the indirectly cooled regenerative water-enhanced turbofan engine according to claim 7, characterized in that: The method comprises: The dual process of heating assembly and liquid nitrogen cooling assembly is adopted, specifically: During the first assembly, the transfer positioning block and the rotor shaft are combined by means of heated interference fit; During the second assembly, the limit pins are assembled by cooling with liquid nitrogen to avoid damage to the first assembly structure.

9. The operating method of the indirectly cooled regenerative water-enhanced turbofan engine according to claim 7, characterized in that: The method comprises: The sensor monitors the gaseous water and liquid water content at the steam turbine outlet in real time, and controls the water spray device to spray steam into the combustion chamber or high and low pressure turbines according to the optimal water spray amount, thereby improving the engine combustion efficiency and cooling effect.

10. The operating method of the indirectly cooled regenerative water-enhanced turbofan engine according to claim 7, characterized in that: The method comprises: The remaining energy of the high-temperature gas after expansion in the low-pressure turbine is recovered through the steam generator, and the condensed water is heated to generate supercritical steam; The heat exchange efficiency is optimized through a countercurrent heat exchanger. At the same time, the condenser is arranged under the aircraft wing, and the skin is used for heat dissipation to achieve efficient recovery and reuse of condensed water.

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