A method and system architecture for thermal management design of an engine fuel oil system

Abstract

The application belongs to the field of gas turbine engines, and is a method and system architecture for thermal management of an engine fuel-oil system. The highest inlet fuel temperature T1 and the inlet fuel temperature T2 corresponding temperature resistance values are obtained through simulation calculation, and by comparing with the temperature resistance limit values, the over-temperature position in the typical position of the fuel-oil system is obtained. Then, an oil return pipeline is opened between the low-pressure pump of the oil system and the fuel tank, a heat return oil electromagnetic valve and an auxiliary fuel-oil radiator are installed on the oil return pipeline, an air-fuel radiator is arranged between the auxiliary fuel-oil radiator and the oil tank, and the temperature of the temperature measuring point in the oil system and the fuel system is obtained in real time through the temperature measuring point. When the temperature is over, the fuel circuit or the oil circuit is effectively cooled. The engine fuel system and the oil system have enhanced ability to withstand the increase of the inlet fuel temperature, and the thermal management ability of the engine fuel-oil system is improved to adapt to the state change of the engine.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of gas turbine engines, and particularly relates to a method and system architecture for thermal management of an engine fuel-oil system. BACKGROUND

[0002] With the improvement of aircraft performance, the heat dissipation of its electromechanical system increases significantly. The heat sinks on the aircraft include fuel and ram air. However, due to the requirement of aircraft stealth, the introduction of ram air from outside the aircraft is limited, and the application of aircraft composite materials reduces the ability of fuel to dissipate heat outward through the tank structure. Therefore, the aircraft can only use more fuel heat sinks, which makes the engine fuel inlet temperature continue to rise. At the same time, the aircraft transfers part of the heat dissipation of the electromechanical system components to the engine fuel system for heat dissipation. Due to the existence of fuel coking problems, the heat dissipation of fuel is limited. In addition, the engine itself is difficult to dissipate heat from the oil system, and the heat from the aircraft further brings new challenges to the comprehensive thermal management of the engine fuel-oil system.

[0003] Figure 1 A schematic diagram of the existing engine fuel-oil system is given. Figure 1 A schematic diagram of the flow path of a typical engine fuel system is given. The fuel from the tank enters the engine first and mixes with the return oil inside the engine. Then it enters the low-pressure pump to complete the first step of pressurization, and then enters the high-pressure pump to complete the second step of pressurization. The high-pressure fuel passes through the regulating device and the fuel-oil heat exchanger, and finally enters the combustion chamber for combustion. The regulating device measures the fuel entering the combustion chamber according to the demand of the combustion chamber, and the remaining fuel returns to the low-pressure pump through the actuator mechanism. The fuel-oil heat exchanger can realize the cooling of the fuel to the oil, and ensure that the engine oil does not overheat.

[0004] Therefore, it is necessary to design a thermal management architecture that meets the needs of the aircraft and the engine under the condition of the increase of the engine fuel inlet temperature and the certain fuel heat sink. SUMMARY

[0005] The purpose of the present application is to provide a method and system architecture for thermal management of an engine fuel-oil system, to solve the problem that the existing fuel system has poor ability to withstand high-temperature fuel at the inlet, which affects the safe operation of the engine.

[0006] The technical solution of the present application is: a method and system architecture for thermal management of an engine fuel-oil system, comprising:

[0007] obtaining the highest inlet fuel temperature T1 that the engine can withstand and the engine inlet fuel temperature T2 after the engine inlet fuel temperature is increased;

[0008] The simulation calculation of the fuel-oil system thermal management of the engine under the condition of the highest imported fuel oil temperature T1 is carried out, and the first temperature-resistant value of the typical position of the fuel-oil system under the condition of the fuel oil temperature T1 is determined; the simulation calculation of the fuel-oil system thermal management of the engine under the condition of the imported fuel oil temperature T2 is carried out, and the second temperature-resistant value of the typical position of the fuel-oil system under the condition of the fuel oil temperature T2 is determined;

[0009] The temperature-resistant limit value at the typical position of the fuel-oil system is obtained according to the existing data, compared with the second temperature-resistant value, and the over-temperature position in the typical position of the fuel-oil system is obtained; the temperature measuring point is arranged in the over-temperature position in the fuel-oil system, and is monitored; at least one temperature measuring point is arranged in the fuel-oil system;

[0010] The oil return pipeline is arranged between the low-pressure pump of the oil system and the fuel tank, the hot oil return electromagnetic valve and the auxiliary fuel-oil radiator are arranged on the oil return pipeline, and the heat dissipation area of the auxiliary fuel-oil radiator is determined; the outlet of the fuel-oil radiator in the oil flow path is connected with the auxiliary fuel-oil radiator; the air-fuel radiator is arranged between the auxiliary fuel-oil radiator and the oil tank;

[0011] The temperature of the temperature measuring point in the oil system and the fuel-oil system is obtained in real time, the temperature of the temperature measuring point is compared with the temperature-resistant limit value, whether the temperature of the temperature measuring point reaches the temperature-resistant limit value is judged, if yes, the hot oil return electromagnetic valve is opened, the oil return pipeline is started, the engine performs hot oil return to the aircraft, the engine hot oil return flow required for cooling the oil is calculated according to the temperature of the temperature measuring point, the opening degree of the hot oil return electromagnetic valve is determined and the opening degree of the hot oil return electromagnetic valve is automatically controlled, until the temperature of the temperature measuring point of the fuel-oil system is lower than the temperature-resistant limit value;

[0012] The total income of the aircraft fuel-oil system thermal management is evaluated, whether the total income of the aircraft fuel-oil system thermal management is positive is judged, if not, the efficiency of the air-fuel radiator or the auxiliary fuel-oil radiator is increased, until the total income of the aircraft fuel-oil system thermal management is positive.

[0013] Preferably, the calculation formula of the outlet fuel oil temperature Tr2 of the auxiliary fuel-oil radiator is:

[0014] Tr2=(Th1-Tr1)*η1+Tr1

[0015] In the formula, Tr1 is the inlet fuel oil temperature of the auxiliary fuel-oil radiator, Tr2 is the outlet fuel oil temperature of the auxiliary fuel-oil radiator, and Th1 is the inlet oil temperature of the auxiliary fuel-oil radiator.

[0016] Preferably, the calculation formula of the engine hot oil return flow Wr is:

[0017]

[0018] In the formula, Wh is the lubricating oil flow rate of the auxiliary fuel lubricating oil radiator, Cph is the lubricating oil constant-pressure specific heat, Th2 is the outlet lubricating oil temperature of the auxiliary fuel lubricating oil radiator, and Cpr is the fuel constant-pressure specific heat.

[0019] Preferably, the method for obtaining the heat dissipation area of the auxiliary fuel lubricating oil radiator is as follows: given the heat dissipation efficiency of the auxiliary fuel lubricating oil radiator, a simulation calculation model of the auxiliary fuel lubricating oil radiator and the hot oil return electromagnetic valve is established, the maximum inlet fuel temperature and the maximum inlet lubricating oil temperature of the auxiliary fuel lubricating oil radiator are determined according to the simulation calculation results of the fuel lubricating oil system thermal management of the engine under the condition of the inlet fuel temperature T2, and the heat dissipation area of the auxiliary fuel lubricating oil radiator under the condition of the maximum inlet temperature of the auxiliary fuel lubricating oil radiator and the effective heat dissipation of the maximum inlet lubricating oil temperature of the auxiliary fuel lubricating oil radiator is determined by the logarithmic mean temperature difference method, which is taken as the heat dissipation area of the auxiliary fuel lubricating oil radiator structure.

[0020] Preferably, the method for obtaining the heat dissipation area of the air fuel radiator is as follows: according to the maximum inlet fuel temperature and the maximum inlet lubricating oil temperature of the auxiliary fuel lubricating oil radiator, the efficiency of the air fuel radiator is given, and the ram air flow rate and the ram air temperature are set, the outlet maximum fuel temperature of the auxiliary fuel lubricating oil radiator is calculated by the performance-unit method, and then the heat dissipation area of the air fuel radiator is determined according to the efficiency of the air fuel radiator.

[0021] Preferably, the method for evaluating the total benefit of the aircraft fuel system thermal management is as follows: temperature sensors are arranged at the inlet of the fuel tank, the inlet and outlet of the air fuel radiator, the real-time temperature of each temperature sensor is obtained, and the heat Qfin discharged by the engine fuel inlet, the heat Qr returned to the aircraft by the hot oil return interface, and the heat Qs discharged by the air fuel radiator through the ram air are calculated, and then the evaluation formula is:△Q=Qfin-(Qr-Qs).

[0022] As a specific embodiment, an improved engine fuel lubricating oil system thermal management system architecture includes an air fuel radiator, an auxiliary fuel lubricating oil radiator, and a hot oil return electromagnetic valve, the inlet of the hot oil return electromagnetic valve is arranged between the low-pressure pump and the high-pressure pump, the outlet of the hot oil return electromagnetic valve is connected to the fuel inlet of the auxiliary fuel lubricating oil radiator, the lubricating oil inlet of the auxiliary fuel lubricating oil radiator is connected to the lubricating oil outlet of the fuel lubricating oil radiator, the fuel outlet of the auxiliary fuel lubricating oil radiator is connected to the inlet of the air fuel heat exchanger, the outlet of the air fuel radiator is connected to the fuel tank, and temperature measuring points are arranged between the lubricating oil outlet of the auxiliary fuel lubricating oil radiator and the low-pressure pump and the high-pressure pump.

[0023] The engine fuel-oil system thermal management design method and system architecture of the application first obtains the temperature resistance values corresponding to the maximum inlet fuel temperature T1 and the inlet fuel temperature T2 through simulation calculation, compares them with the temperature resistance limit values, and obtains the over-temperature position in the typical position of the fuel-oil system. Then, an oil return pipeline is opened between the low-pressure pump of the oil system and the fuel tank, a heat return oil electromagnetic valve and an auxiliary fuel-oil radiator are installed on the oil return pipeline, an air-fuel radiator is arranged between the auxiliary fuel-oil radiator and the oil tank, and the temperature of the temperature measuring point in the oil system and the fuel system is obtained in real time through the temperature measuring point. When the temperature is too high, the fuel circuit or the oil circuit is effectively cooled. The engine fuel system can resist the increase of the inlet fuel temperature, the engine oil system can resist the increase of the inlet fuel temperature, and the thermal management capability of the engine fuel-oil system can adapt to the change of the engine state. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions provided by the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0025] Figure 1 A typical engine fuel system flow path schematic diagram in the background art;

[0026] Figure 2 A whole process schematic diagram of the application;

[0027] Figure 3 An engine fuel-oil thermal management system architecture diagram of the application;

[0028] Figure 4 A flow path schematic diagram of the auxiliary fuel-oil radiator of the application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0030] An engine fuel-oil system thermal management design method, as shown in Figure 2 includes the following steps:

[0031] Step S100, obtaining the maximum inlet fuel temperature T1 that the engine can withstand and the engine inlet fuel temperature T2 after the engine inlet fuel temperature is increased, T2 < T1.

[0032] The highest import fuel temperature T1 and the engine import fuel temperature T2 can be obtained by existing data acquisition, and the engine outlet fuel temperature after the engine fuel import temperature is raised cannot be obtained, so further analysis is needed.

[0033] In step S200, the engine fuel oil system thermal management simulation calculation under the highest import fuel temperature T1 is carried out, the first temperature resistance value of the typical position of the fuel oil system under the fuel temperature T1 is determined, the engine fuel oil system thermal management simulation calculation under the import fuel temperature T2 is carried out, and the second temperature resistance value of the typical position of the fuel oil system under the fuel temperature T2 is determined.

[0034] When the thermal management simulation calculation is carried out, the calculation result is compared with the test data to ensure that the thermal management simulation calculation error of the typical position of the fuel oil system is not more than 5 DEG C.

[0035] The simulation calculation result of the engine at any typical position under the import fuel temperature T1 and the import fuel temperature T2 represents the working temperature range of each typical position. The working temperature ranges under the two temperatures have the same temperature range, and also have different temperature ranges, and the temperature range of a typical position under the import fuel temperature T2 may exceed the temperature range of the typical position under the highest import fuel temperature T1.

[0036] In step S300, the temperature resistance limit value of the typical position of the fuel oil system is obtained according to the existing data, the existing data includes the oil system instruction manual, theoretical analysis and experimental research, and the second temperature resistance value is compared to obtain the over-temperature position in the typical position of the fuel oil system. The over-temperature position may exist under the T1 and T2 temperatures.

[0037] Temperature measuring points are set at the over-temperature positions in the fuel oil system and monitored, at least one temperature measuring point is set in the fuel system and the oil system to judge whether there is over-temperature in a state of the over-temperature position, if there is over-temperature, the thermal management of the application is triggered.

[0038] In combination with Figure 3 , in step S400, an oil return pipeline is opened between the low-pressure pump of the oil system and the fuel tank, a heat return electromagnetic valve and an auxiliary fuel oil radiator are installed on the oil return pipeline, the heat dissipation area of the auxiliary fuel oil radiator is determined, the outlet of the fuel oil radiator in the oil flow path is connected with the auxiliary fuel oil radiator, and an air fuel radiator is arranged between the auxiliary fuel oil radiator and the oil tank.

[0039] In the fuel circuit, fuel flows out from the fuel tank, and then enters the hot return fuel solenoid valve through the aircraft heating element and the low pressure pump. The hot return fuel solenoid valve has an opening angle adjustment function, which can adjust the flow of fuel. Then the fuel enters the fuel side of the auxiliary fuel-oil radiator. In the oil circuit, high-temperature oil enters the oil side of the fuel-oil radiator, exchanges heat with the fuel, and then enters the oil side of the auxiliary fuel-oil radiator, exchanges heat with the fuel, and forms low-temperature fuel and flows out.

[0040] When there is an over-temperature position in the oil circuit, the temperature of the oil after heat exchange in the fuel-oil radiator will be higher than that of the fuel on the fuel side of the auxiliary fuel-oil radiator. Therefore, the fuel will cool the oil, and the oil will reach the normal working temperature.

[0041] When there is an over-temperature position in the fuel circuit, the fuel flowing out of the auxiliary fuel-oil radiator enters the air-fuel radiator. The air-fuel radiator cools the fuel by using ram air. The cooled fuel flows back to the fuel tank.

[0042] When there are over-temperature positions in both the fuel circuit and the oil circuit, the auxiliary fuel-oil radiator cools the oil, and the air-fuel radiator cools the fuel, thereby effectively cooling the over-temperature fuel or oil.

[0043] In order to ensure the cooling quality, the air-fuel radiator and the auxiliary fuel-oil radiator each need sufficient heat dissipation area to effectively dissipate heat when the over-temperature reaches the maximum value. Therefore, the heat dissipation area of the air-fuel radiator and the auxiliary fuel-oil radiator needs to be planned respectively.

[0044] The method for obtaining the heat dissipation area of the auxiliary fuel-oil radiator is as follows: given the heat dissipation efficiency of the auxiliary fuel-oil radiator, which is usually not less than 60%, a simulation calculation model of the auxiliary fuel-oil radiator and the hot return fuel solenoid valve is established. According to the simulation calculation results of the fuel-oil system thermal management of the engine under the condition of the imported fuel temperature T2, the maximum inlet fuel temperature and the maximum inlet oil temperature of the auxiliary fuel-oil radiator are determined. Combined with the heat dissipation efficiency of the auxiliary fuel-oil radiator and through the logarithmic mean temperature difference method, the heat dissipation area of the auxiliary fuel-oil radiator is determined when the maximum inlet oil temperature of the auxiliary fuel-oil radiator is effectively cooled under the maximum inlet temperature of the auxiliary fuel-oil radiator. The heat dissipation area is used as the heat dissipation area of the auxiliary fuel-oil radiator structure.

[0045] The method for obtaining the heat dissipation area of the air-oil radiator is as follows: according to the maximum inlet fuel temperature and the maximum inlet lubricating oil temperature of the auxiliary fuel-oil radiator, the efficiency of the air-oil radiator is given, which is usually not less than 30%, and the ram air flow and the ram air temperature are set, the maximum outlet fuel temperature of the auxiliary fuel-oil radiator is calculated by the performance-unit method, and then the heat dissipation area of the air-oil radiator is determined according to the efficiency of the air-oil radiator.

[0046] Generally, the higher the efficiency of the radiator, the larger the volume of the radiator and the heavier the mass of the radiator. Considering the installation space and mass limitation of the radiator, the optimal design scheme of the auxiliary fuel-oil radiator and the air-oil radiator is determined, and then the design scheme of the engine fuel-oil thermal management system is formed.

[0047] In step S500, the temperatures of the temperature measuring points in the lubricating oil system and the fuel system are obtained in real time through the temperature measuring points, the temperatures of the temperature measuring points are compared with the temperature resistance limit value, it is judged whether the temperature of the temperature measuring point reaches the temperature resistance limit value, if yes, the hot oil return electromagnetic valve is opened, the oil return pipeline is started, the engine performs hot oil return to the aircraft, the engine hot oil return flow required for cooling the lubricating oil is calculated through the temperature of the temperature measuring point, the opening of the hot oil return electromagnetic valve is determined and the opening of the hot oil return electromagnetic valve is automatically controlled until the temperatures of the temperature measuring points of the fuel-oil system are all lower than the temperature resistance limit value.

[0048] Preferably, the calculation formula of the outlet fuel temperature Tr2 of the auxiliary fuel-oil radiator is as follows:

[0049] Tr2=(Th1-Tr1)*η1+Tr1

[0050] In the formula, Tr1 is the inlet fuel temperature of the auxiliary fuel-oil radiator, Tr2 is the outlet fuel temperature of the auxiliary fuel-oil radiator, and Th1 is the inlet lubricating oil temperature of the auxiliary fuel-oil radiator.

[0051] In combination Figure 4 The calculation formula of the engine hot oil return flow Wr required for cooling the lubricating oil is calculated by the energy conservation formula as follows:

[0052]

[0053] In the formula, Wh is the lubricating oil flow of the auxiliary fuel-oil radiator, Cph is the specific heat of the lubricating oil at constant pressure, Th2 is the outlet lubricating oil temperature of the auxiliary fuel-oil radiator, and Cpr is the specific heat of the fuel at constant pressure.

[0054] Step S600, the total benefit of the aircraft fuel system thermal management is evaluated, and it is judged whether the total benefit of the aircraft fuel system thermal management is positive, if not, the efficiency of the air fuel radiator or the auxiliary fuel oil radiator is increased until the total benefit of the aircraft fuel system thermal management is positive. When it is negative, it means that the auxiliary fuel oil radiator and the air fuel radiator are difficult to effectively cool the over-temperature, which will cause the continuous rise of the temperature of the fuel circuit or the oil circuit.

[0055] The method for evaluating the total benefit of the aircraft fuel system thermal management is that temperature sensors are arranged at the inlet of the fuel tank, the inlet and outlet of the air fuel radiator, the real-time temperature of each temperature sensor is obtained, and the heat Qfin discharged by the aircraft through the engine fuel inlet, the heat Qr returned to the aircraft by the engine through the hot oil return interface, and the heat Qs discharged by the air fuel radiator through the ram air are calculated, and then the evaluation formula is: AQ=Qfin-(Qr-Qs).

[0056] Wherein Qfin=(Wr+Wz)*Cpr*(T2-T1)

[0057] Qr=Wr*Cpr*(Tr2-T1)

[0058] Qs=Wr*Cpr*(Tr2-Tr3)

[0059] In the formula, Wz is the fuel flow entering the main combustion chamber, and Tr3 is the outlet fuel temperature of the air fuel radiator.

[0060] If the evaluation result of the total benefit of the aircraft fuel system thermal management is negative, the initial setting efficiency value of the air fuel radiator and the auxiliary fuel oil radiator needs to be adjusted, and the design iteration is carried out. Generally, the higher the efficiency, the larger the heat exchange area, and the greater the weight, the greater the design difficulty. The higher the efficiency of the auxiliary fuel oil radiator, the higher the hot oil return temperature Tr2 of the fuel, which is beneficial to the total benefit of the aircraft fuel system thermal management AQ but is not conducive to the oil cooling; the higher the efficiency of the air fuel radiator, the lower the hot oil return temperature Tr3 of the fuel, which is beneficial to the total benefit of the aircraft fuel system thermal management AQ.

[0061] The application first obtains the maximum inlet fuel temperature T1 and the inlet fuel temperature T2 corresponding to the temperature resistance value through simulation calculation, compares the temperature resistance limit value, obtains the over-temperature position in the typical position of the fuel oil system, then opens the oil return pipeline between the low-pressure pump of the oil system and the fuel tank, installs the hot oil return electromagnetic valve and the auxiliary fuel oil radiator on the oil return pipeline, sets the air fuel radiator between the auxiliary fuel oil radiator and the oil tank, and obtains the temperature of the temperature measuring point in the oil system and the fuel system in real time through the temperature measuring point. When the temperature is too high, the fuel circuit or the oil circuit is effectively cooled.

[0062] The engine fuel system is enhanced in the ability to resist the temperature increase of the inlet fuel, and when the temperature of the inlet fuel of the engine is increased, the heat return port facing the aircraft is opened after the low pressure pump of the fuel system, and the heat return flow is controlled by the heat return electromagnetic valve, so that the temperature of the fuel system does not exceed the maximum tolerance temperature of the pump, the adjusting device and other fuel accessories.

[0063] The engine oil system is enhanced in the ability to resist the temperature increase of the inlet fuel, and when the temperature of the inlet fuel of the engine is increased, the auxiliary fuel and oil radiator is installed on the heat return oil pipeline facing the aircraft, and the oil is further cooled by the heat return oil, so that the temperature of the oil does not exceed the maximum tolerance temperature.

[0064] The engine fuel and oil system is enhanced in the heat management ability to adapt to the state change of the engine, and when the engine state is reduced to cause the fuel flow to suddenly decrease, the heat return oil facing the aircraft is opened to take away the waste heat of the oil system, so that the temperature of the oil does not exceed the maximum tolerance temperature.

[0065] The heat management benefit of the aircraft is enhanced, and through the reasonable design of the auxiliary fuel and oil radiator and the air fuel radiator, the aircraft can still discharge more heat when the heat return oil facing the aircraft is opened.

[0066] As a specific embodiment, the engine fuel and oil system heat management system architecture is also improved, which comprises an air fuel radiator, an auxiliary fuel and oil radiator and a heat return electromagnetic valve, the inlet of the heat return electromagnetic valve is arranged between the low pressure pump and the high pressure pump, the outlet of the heat return electromagnetic valve is connected with the fuel inlet of the auxiliary fuel and oil radiator, the oil inlet of the auxiliary fuel and oil radiator is connected with the oil outlet of the fuel and oil radiator, the fuel outlet of the auxiliary fuel and oil radiator is connected with the inlet of the air fuel radiator, the outlet of the air fuel radiator is connected with the fuel tank, and the oil outlet of the auxiliary fuel and oil radiator and the position between the low pressure pump and the high pressure pump are provided with temperature measuring points. The design can effectively cool the fuel circuit and the oil circuit without interfering with the normal fuel circuit and the oil circuit.

[0067] Finally, it should be pointed out that: first, in the description of the present application, it should be pointed out that unless otherwise specified and limited, the terms "installation", "connection", "connection" should be understood broadly, which can be mechanical connection or electrical connection, or the communication between two elements, or direct connection, "up", "down", "left", "right" and the like are only used to represent the relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may change;

[0068] Secondly: the present application discloses the structure involved in the embodiment of the present application, and other structures can refer to the general design, and the same embodiment and different embodiments of the present application can be combined with each other under the condition of no conflict.

[0069] Finally: the above only for the preferred embodiments of the present application, and not for limiting the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included in the scope of protection of the present application.

Claims

1. A method of thermal management design for an engine fuel oil system, characterized by, The method comprises the following steps: obtaining the highest inlet fuel temperature T1 that the engine can withstand and the engine inlet fuel temperature T2 after the engine inlet fuel temperature is raised; carrying out a simulation calculation of the fuel-oil system thermal management of the engine under the highest inlet fuel temperature T1 to determine the first temperature-resistant value of the typical position of the fuel-oil system under the fuel temperature T1, and carrying out a simulation calculation of the fuel-oil system thermal management of the engine under the inlet fuel temperature T2 to determine the second temperature-resistant value of the typical position of the fuel-oil system under the fuel temperature T2; comparing the temperature-resistant limit value at the typical position of the fuel-oil system obtained according to the existing data with the second temperature-resistant value to obtain the over-temperature position in the typical position of the fuel-oil system, setting a temperature measuring point at the over-temperature position in the fuel-oil system and monitoring the temperature measuring point, and setting at least one temperature measuring point in the fuel system and the oil system; opening an oil return pipeline between the low-pressure pump of the oil system and the fuel tank, installing a hot oil return electromagnetic valve and an auxiliary fuel-oil radiator on the oil return pipeline, determining the heat dissipation area of the auxiliary fuel-oil radiator, connecting the outlet of the fuel-oil radiator in the oil flow path with the auxiliary fuel-oil radiator, and setting an air-fuel radiator between the auxiliary fuel-oil radiator and the fuel tank; real-time obtaining the temperature of the temperature measuring point in the oil system and the fuel system through the temperature measuring point, comparing the temperature of the temperature measuring point with the temperature-resistant limit value, judging whether the temperature of the temperature measuring point reaches the temperature-resistant limit value, if yes, opening the hot oil return electromagnetic valve, starting the oil return pipeline, and the engine performing hot oil return to the aircraft, calculating the engine hot oil return flow required for cooling the oil through the temperature of the temperature measuring point, determining the opening degree of the hot oil return electromagnetic valve and automatically controlling the opening degree of the hot oil return electromagnetic valve until the temperature of the temperature measuring point of the fuel-oil system is lower than the temperature-resistant limit value; evaluating the total benefit of the aircraft fuel system thermal management, judging whether the total benefit of the aircraft fuel system thermal management is positive, if not, increasing the efficiency of the air-fuel radiator or the auxiliary fuel-oil radiator until the total benefit of the aircraft fuel system thermal management is positive; the method for evaluating the total benefit of the aircraft fuel system thermal management is that temperature sensors are arranged at the inlet of the fuel tank, the inlet and outlet of the air-fuel radiator, the real-time temperature of each temperature sensor is obtained, the heat Qfin discharged by the aircraft through the engine fuel inlet, the heat Qr returned to the aircraft by the engine through the hot oil return interface, and the heat Qs discharged by the air-fuel radiator through the ram air are calculated, and the evaluation formula is: ΔQ = Qfin-(Qr - Qs).

2. The engine fuel-oil system thermal management design method of claim 1, wherein, The outlet fuel temperature of the auxiliary fuel oil radiator The calculation formula is: ； wherein Tin is the inlet fuel temperature of the auxiliary fuel oil radiator, Tout is the outlet fuel temperature of the auxiliary fuel oil radiator, Tin is the inlet fuel temperature of the auxiliary fuel oil radiator, 3. The engine fuel oil system thermal management design method of claim 2, wherein, The engine hot oil flow rate The calculation formula is: ； wherein Cp is the specific heat of the lubricating oil, Cp is the specific heat of the lubricating oil, Cp is the specific heat of the lubricating oil, Cp is the specific heat of the lubricating oil.

4. The engine fuel oil system thermal management design method of claim 1, wherein, The method for obtaining the heat dissipation area of the auxiliary fuel oil radiator is as follows: given the heat dissipation efficiency of the auxiliary fuel oil radiator, a simulation calculation model of the auxiliary fuel oil radiator and the hot oil return electromagnetic valve is established, the maximum inlet fuel oil temperature and the maximum inlet lubricating oil temperature of the auxiliary fuel oil radiator are determined according to the simulation calculation result of the fuel oil system thermal management of the engine under the condition of the inlet fuel oil temperature T2, the heat dissipation area of the auxiliary fuel oil radiator under the maximum inlet temperature of the auxiliary fuel oil radiator and the maximum inlet lubricating oil temperature of the auxiliary fuel oil radiator for effective heat dissipation is determined by the logarithmic mean temperature difference method, and the heat dissipation area is taken as the heat dissipation area of the auxiliary fuel oil radiator structure.

5. The engine fuel oil system thermal management design method of claim 2 wherein, The method for obtaining the heat dissipation area of the air fuel oil radiator is as follows: according to the maximum inlet fuel oil temperature and the maximum inlet lubricating oil temperature of the auxiliary fuel oil radiator, the efficiency of the air fuel oil radiator is given, the ram air flow and the ram air temperature are set, the maximum outlet fuel oil temperature of the auxiliary fuel oil radiator is calculated by the performance-unit number method, and then the heat dissipation area of the air fuel oil radiator is determined according to the efficiency of the air fuel oil radiator.

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