A method for designing overall parameters of a scaled-down technology demonstrator for a jet aircraft using liquid hydrogen fuel

Abstract

The present invention aims at the scale verification demand of liquid hydrogen fuel jet aircraft and proposes a method for designing the overall parameters of a scale technology verification machine of a jet aircraft using liquid hydrogen fuel. The method first estimates the take-off weight of the scale technology verification machine, then calculates the minimum wing reference area required to meet the estimated take-off weight of the scale technology verification machine, and determines the preliminary scale ratio. The aerodynamic force and moment coefficient of the corrected scale technology verification machine are then used for verification. After that, the volume of the liquid hydrogen storage tank is calculated, and it is verified whether the liquid hydrogen storage tank can be arranged in the scale technology verification machine under the current scale ratio. If so, the scale ratio is obtained, otherwise the take-off weight of the scale technology verification machine is re-estimated. The present invention can provide support for further developing the overall design of the scale verification machine.

Description

Technical Field

[0001] The present invention relates to the technical field of scaled aircraft design, and in particular to a method for designing overall parameters of a scaled technology verification machine for a jet aircraft using liquid hydrogen fuel. Background Art

[0002] Using liquid hydrogen as jet fuel is one of the future trends in green aviation. Liquid hydrogen offers significant advantages as a jet fuel. First, it is a clean energy source, producing only water as a combustion product, leaving no environmental impact. Second, liquid hydrogen has a high energy density. While its volumetric energy density is low, its gravimetric energy density is high, meaning it can provide more energy for the same weight. Furthermore, liquid hydrogen is widely available and can be produced sustainably through methods such as water electrolysis.

[0003] The difficulty with liquid hydrogen fuel lies in its need to be stored as a cryogenic liquid in heavy tanks. Therefore, the design of a liquid hydrogen-fueled jet aircraft requires a focus on the overall layout, liquid hydrogen system, and onboard liquid hydrogen tank solutions. To fully validate these design proposals, a scaled-down demonstrator aircraft must be developed and tested to verify the feasibility of the hydrogen-fueled powertrain design and the overall design of the liquid hydrogen-fueled jet aircraft.

[0004] Since the onboard liquid hydrogen storage tank is an important part of the liquid hydrogen fuel jet aircraft, and the volume and layout of the liquid hydrogen storage tank are important factors that affect the overall layout of the liquid hydrogen fuel jet aircraft compared to traditional fuel aircraft, therefore, in the scale verification, it is necessary to first determine the appropriate scale to accurately verify the impact of the onboard liquid hydrogen tank solution on the overall solution of the liquid hydrogen fuel jet aircraft. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention is based on the overall design scheme of a jet aircraft using liquid hydrogen fuel and the design scheme of liquid hydrogen and power system, clarifies the verification requirements of the scaled verification machine, proposes an overall parameter design method for a scaled technology verification machine of a jet aircraft using liquid hydrogen fuel, determines the scale of the scale, and thus enables further development of the overall scheme design of the scaled verification machine.

[0006] The technical solution of the present invention is:

[0007] A method for designing overall parameters of a scaled-down technology demonstrator for a jet aircraft using liquid hydrogen fuel comprises the following steps:

[0008] Step 1: Calculate the maximum allowable takeoff weight of the scaled technology demonstrator based on the weight and thrust of the hydrogen-fueled engine selected in the overall design of the liquid hydrogen-fueled jet aircraft. Estimate the takeoff weight of the scaled technology demonstrator based on the requirement that it should not exceed the maximum allowable takeoff weight, the constraints of the prototype selected in the overall design of the liquid hydrogen turbofan regional airliner, the set scale ratio, and the minimum takeoff weight constraint of the scaled technology demonstrator.

[0009] Step 2: Based on the aerodynamic force and moment coefficient data of the prototype aircraft, and in accordance with the set safe takeoff speed and safe angle of attack of the scaled-down technology demonstrator aircraft, aerodynamic calculations are performed to determine the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology demonstrator aircraft.

[0010] Selecting a wing reference area for the scaled-down technology verification aircraft in accordance with the minimum wing reference area requirement, and determining a scale ratio based on the wing reference area of ​​the scaled-down technology verification aircraft and the wing reference area of ​​the prototype aircraft, in combination with the set scale ratio constraint requirements;

[0011] Step 3: Based on the scale ratio determined in step 2 and the aerodynamic force and moment coefficient data of the prototype, after Reynolds number correction, the aerodynamic force and moment coefficient data of the scaled-down technology verification aircraft are obtained;

[0012] Verify using the aerodynamic force and moment coefficients of the scaled technology demonstrator: Using the aerodynamic force and moment coefficient data of the scaled technology demonstrator and in accordance with the set safe takeoff speed and safe angle of attack of the scaled technology demonstrator, calculate whether the scaled technology demonstrator can meet the estimated takeoff weight requirement of the scaled technology demonstrator. If yes, proceed to the subsequent steps. If not, return to step 2 and reselect the wing reference area of ​​the scaled technology demonstrator.

[0013] Step 4: Calculate the liquid hydrogen load required for the scaled-down technology verification aircraft to complete the flight mission based on the aerodynamic and torque coefficient data of the scaled-down technology verification aircraft, the set flight mission profile of the scaled-down technology verification aircraft, and the hydrogen consumption rate of the hydrogen-fired engine selected in Step 1.

[0014] Step 5: Determine the volume of the liquid hydrogen storage tank according to the liquid hydrogen loading amount calculated in step 4;

[0015] Step 6: Based on the volume of the liquid hydrogen storage tank obtained in step 5, determine whether the liquid hydrogen storage tank can be arranged in the scaled-down technology verification aircraft at the current scaled-down ratio; if so, obtain the scaled-down ratio; if not, first adjust the layout positions of the remaining system components in the scaled-down technology verification aircraft to determine whether space for the liquid hydrogen storage tank can be obtained. If it still cannot be obtained, re-estimate the take-off weight of the scaled-down technology verification aircraft under the requirement of not exceeding the maximum allowable take-off weight, and then return to step 2 until the liquid hydrogen storage tank can be arranged in the scaled-down aircraft.

[0016] According to a further preferred embodiment, in steps 2 and 3, the aerodynamic force and torque coefficient data of the prototype are the aerodynamic force and torque coefficients of the prototype under a set configuration; the set configuration is determined according to the set flight mission profile of the scaled-down technology verification aircraft.

[0017] According to a further preferred embodiment, the flight mission profile of the scaled-down technology verification aircraft requires a maximum flight altitude of more than 200 meters and a flight time of more than 5 minutes.

[0018] In a further preferred embodiment, the set configuration adopts a take-off configuration.

[0019] As a further preferred solution, in step 3, the scaled-down verification machine is also aerodynamically modified, and the aerodynamic force and torque coefficient data of the modified scaled-down verification machine are used for verification.

[0020] According to a further preferred embodiment, in step 4, the liquid hydrogen loading amount required for the scaled-down technology verification aircraft to complete the flight mission includes the hydrogen consumption during normal flight and the emergency redundancy.

[0021] Beneficial effects

[0022] Aiming at the scale verification requirements of liquid hydrogen fueled jet aircraft, the present invention proposes a method for designing overall parameters of a scale technology verification machine for a jet aircraft using liquid hydrogen fuel, so as to determine the scale ratio, thereby enabling further overall scheme design of the scale verification machine, and then fully verifying the overall layout scheme, liquid hydrogen system scheme and onboard liquid hydrogen storage tank scheme of the jet aircraft using liquid hydrogen fuel through test flights.

[0023] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0025] Figure 1 : Schematic diagram of the takeoff configuration of the scale verification aircraft at a scale of 1:4;

[0026] Figure 2 : Aerodynamic forces and moment coefficients of the scaled-down verification aircraft after modification; (a) Comparison of lift coefficient curves before and after modification, (b) Comparison of lift-to-drag ratio curves before and after modification, (c) Comparison of moment coefficient curves before and after modification;

[0027] Figure 3 : Schematic diagram of the overall layout of the scaled verification machine platform;

[0028] Figure: 1. Multi-function air data sensor; 2. Network switch; 3. Integrated avionics computer; 4. Secondary link terminal; 5. Air data computer; 6. Integrated inertial navigation system; 7. Wireless altimeter host; 8. High-voltage power battery; 9. Main link terminal; 10. Onboard battery; 11. First altimeter antenna; 12. Satellite positioning antenna; 13. Nosewheel steering servo; 14. Nose landing gear; 15. First main link antenna; 16. Surveillance camera; 17. Hydrogen storage tank; 18. Second altimeter antenna; 19. Secondary link antenna; 20. Electric low-temperature regulating valve V03; 21. Electric low-temperature regulating valve V04; 22. Hydrogen concentration sensor; 23. Electric heater; 24. Second main link antenna; 25. Main landing gear; 26. Hydrogen control box; 27. Hydrogen delivery pipeline and control cables; 28. Engine controller, igniter, and oil pump; 29. ​​Engine; 30. Oil tank; 31. Drain pipe.

[0029] Figure 4 : Model diagram of liquid hydrogen delivery system;

[0030] Figure 5 : Power energy system layout diagram. DETAILED DESCRIPTION

[0031] The following describes in detail embodiments of the present invention. The embodiments are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.

[0032] This embodiment takes the liquid hydrogen turbofan regional passenger aircraft as the research object. During the development process of this type of aircraft, the focus is on the overall layout plan, liquid hydrogen system plan and onboard liquid hydrogen storage tank plan of the liquid hydrogen turbofan regional aircraft. In order to fully verify these design plans, it is necessary to carry out the development and test flight of a scaled-down verification aircraft of the liquid hydrogen turbofan regional aircraft to verify the feasibility of the design of the hydrogen energy power plan and the feasibility of the overall plan of the liquid hydrogen turbofan regional aircraft.

[0033] To develop a scaled-down verification aircraft for a liquid hydrogen turbofan regional aircraft, it is necessary to determine the scaled-down ratio based on the overall design plan of the liquid hydrogen turbofan regional passenger aircraft and the design plan of the liquid hydrogen and power system, thereby laying a foundation for subsequent research. To this end, this embodiment proposes a method for designing the overall parameters of a scaled-down verification aircraft for a liquid hydrogen turbofan regional aircraft, including the following steps:

[0034] Step 1: Estimate the takeoff weight of the scaled technology demonstrator aircraft.

[0035] Since a hydrogen-fired engine has been selected for the overall design of the liquid hydrogen turbofan regional airliner, and the same hydrogen-fired engine is installed on the scaled-down technology verification aircraft, the maximum allowable take-off weight of the scaled-down technology verification aircraft can be calculated based on the weight and thrust of the selected hydrogen-fired engine and in accordance with the known aircraft design performance calculation method.

[0036] The takeoff weight of the scaled technology demonstrator is estimated based on the requirement of no more than the maximum allowable takeoff weight, the selected prototype aircraft in the overall design plan for the liquid hydrogen turbofan regional airliner, the set scale ratio constraints, and the minimum takeoff weight constraint for the scaled technology demonstrator. In this embodiment, the selected prototype aircraft is the ARJ21; the scale ratio constraint is: scale ratio ≥ 1:5; and the minimum takeoff weight constraint for the scaled technology demonstrator is: takeoff weight ≤ 250 kg.

[0037] Step 2: Based on the aerodynamic force and moment coefficient data of the prototype, and in accordance with the set safe takeoff speed and safe angle of attack of the scaled-down technology verification aircraft, aerodynamic calculations can be performed to obtain the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology verification aircraft.

[0038] In this embodiment, since the flight mission profile of the scaled-down technology demonstrator requires a maximum flight altitude exceeding 200 meters and a flight time exceeding 5 minutes, the scaled-down technology demonstrator is fixed in the takeoff configuration for safety, economy, and structural considerations. Compared to the cruise configuration, the takeoff configuration has a higher available lift coefficient, significantly reducing takeoff and landing speeds and improving takeoff and landing safety. Compared to the cruise and landing configurations, the takeoff configuration has a higher stall angle of attack and a larger safe flight angle of attack margin, which improves flight safety. Compared to the landing configuration, the takeoff configuration has a higher lift-to-drag ratio, requiring less maximum engine thrust and reducing hydrogen fuel consumption. By keeping the takeoff configuration fixed throughout the flight, servos are not required for the inner and outer flaps; only angle blocks are required to secure the flaps to the main wing. This saves the procurement cost of four servos per aircraft, eliminates the complex flap kinematic mechanism, significantly reduces aircraft processing and manufacturing difficulties, and improves aircraft reliability.

[0039] Therefore, based on the aerodynamic force and moment coefficient data under the prototype's takeoff configuration, in accordance with the set safe takeoff speed and safe angle of attack, and according to the known aircraft lift calculation formula, the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology verification aircraft is calculated.

[0040] The wing reference area of ​​the scaled-down technology verification aircraft is selected in accordance with the minimum wing reference area requirement; the scaled-down ratio is determined based on the wing reference area of ​​the scaled-down technology verification aircraft and the wing reference area of ​​the prototype aircraft, and in combination with the set scaled-down ratio constraint requirements.

[0041] In this embodiment, the wing reference area of ​​the final selected scaled technology verification aircraft is 4.99125m 2 , while the wing reference area of ​​the prototype ARJ21 is 79.86m 2 , thus determining the scale ratio to be 1:4, which meets the set scale ratio constraint requirements. The main dimensional parameters of the prototype and scale verification machine under this scale ratio are shown in the following table:

[0042]

[0043] Step 3: Based on the scale ratio determined in step 2 and the aerodynamic force and moment coefficients of the prototype, the aerodynamic force and moment coefficients of the scaled-down technology verification machine are obtained after Reynolds number correction.

[0044] Since the prototype and the scaled-down technology verification machine are of different sizes, the aerodynamic force and torque coefficient data of the prototype cannot be equivalent to the aerodynamic force and torque coefficient data of the scaled-down technology verification machine due to the influence of the Reynolds number. Therefore, according to the scale ratio determined in step 2, the Reynolds number correction is performed by a known method to obtain the aerodynamic force and torque coefficient data of the scaled-down technology verification machine.

[0045] Furthermore, since the scaled-down verification aircraft adopts a takeoff configuration, and considering the actual processing and use requirements of the scaled-down verification aircraft, as well as the risk of possible weight gain, aerodynamic modifications were also made to the scaled-down verification aircraft based on the prototype:

[0046] 1. Modify the slat shape and increase the slat angle to improve the stall angle of attack and the slat channel air intake efficiency;

[0047] 2. Modify the leading edge of the main wing to reduce the peak of the main wing head and improve the air intake efficiency of the slats;

[0048] 3. Modify the flap compartment shape to make it easier to process, and increase the flap deflection angle to improve the linear lift coefficient;

[0049] 4. Move the wings downward to reduce the obstruction of the center wing box to the interior space of the fuselage and reduce the height of the landing gear;

[0050] 5. Increase the leading edge radius of the winglet to enhance the winglet's anti-separation capability at high angles of attack;

[0051] 6. Increase the leading edge radius of the horizontal tail to enhance its ability to resist separation at high angles of attack;

[0052] 7. Increase the leading edge radius of the nacelle rack to enhance the rack's anti-separation capability;

[0053] 8. Trim the trailing edge of the nacelle pylon to prevent it from being eroded by the high-temperature jet of the engine;

[0054] 9. Modify the original fairing to make it easier to process and manufacture;

[0055] 10. Modify the tail shape to increase the ground contact angle of the entire aircraft (while reducing the height of the landing gear).

[0056] The aerodynamic force and moment coefficient data of the scaled-down verification machine after modification are obtained, such as Figure 2As shown in the figure, at the same angle of attack, the lift coefficient increases by 0.15 after the modification, the stall angle of attack exceeds 20°, and the maximum lift coefficient exceeds 2.43; the maximum reduction in the lift-to-drag ratio is about 0.5 at a small lift coefficient; in the expected lift coefficient range, the lift-to-drag ratio after the modification is equivalent to the original lift-to-drag ratio, and is even better at large lift coefficients; the longitudinal static stability is around 40% before and after the modification, and the pitching moment after the modification can be maintained in an approximately linear segment up to 16°.

[0057] Since the calculation in step 2 uses the aerodynamic force and moment coefficient data of the prototype, it is necessary to use the aerodynamic force and moment coefficients of the modified scaled technology verification aircraft for verification here: using the aerodynamic force and moment coefficients of the scaled technology verification aircraft, and then according to the set scaled technology verification aircraft safe takeoff speed and safe angle of attack, calculate whether the scaled technology verification aircraft can meet the estimated takeoff weight requirement of the scaled technology verification aircraft. If so, proceed to the subsequent steps. If not, return to step 2 and reselect the wing reference area of ​​the scaled technology verification aircraft.

[0058] The next step is to verify whether the reduction ratio meets the liquid hydrogen loading requirements.

[0059] Step 4: Based on the aerodynamic and torque coefficient data of the scaled-down technology verification aircraft, the set flight mission profile of the scaled-down technology verification aircraft, and the hydrogen consumption rate of the hydrogen-fired engine selected in Step 1; calculate the liquid hydrogen loading required for the scaled-down technology verification aircraft to complete the flight mission through the known flight performance calculation method, including the hydrogen consumption during normal flight and the emergency redundancy.

[0060] Step 5: According to a known method, determine the volume of the liquid hydrogen storage tank based on the liquid hydrogen loading amount calculated in step 4.

[0061] Step 6: Based on the volume of the liquid hydrogen storage tank obtained in step 5, determine whether the liquid hydrogen storage tank can be arranged in the scaled technology verification aircraft at the current scale ratio; if so, obtain the scale ratio; if not, first adjust the layout positions of the remaining system components in the scaled technology verification aircraft to determine whether space for the liquid hydrogen storage tank can be obtained. If it still cannot be obtained, re-estimate the take-off weight of the scaled technology verification aircraft according to the constraints of step 1, and then return to step 2 until the liquid hydrogen storage tank can be arranged in the scaled aircraft.

[0062] In this embodiment, it has been verified that the liquid hydrogen loading requirements can be met according to the scale ratio of 1:4. The overall layout diagram of the scale verification machine platform is as follows: Figure 3 As shown in the figure, the liquid hydrogen delivery system model is as follows: Figure 4 As shown, the power energy system is arranged as follows Figure 5As shown, the liquid hydrogen aircraft is designed to have a hydrogen pressure of 3MPa and a maximum hydrogen flow rate of 40g / s. The liquid hydrogen pump is placed in a liquid hydrogen storage tank with an internal pressure of 0.3MPa, ensuring a subcooling of 1K or more at the pump inlet. The liquid hydrogen is driven by the pump, with an outlet pressure of 3MPa, and is delivered to the engine through a low-temperature regulating valve. Simultaneously, a branch is vaporized in a self-pressurizing heat exchanger and then returned to the liquid hydrogen storage tank through a low-temperature regulating valve to maintain a stable pressure of 0.3MPa in the tank to ensure the internal pressure. To supply two engines, the main liquid hydrogen line is divided into two routes, each connected to the heat exchanger at the rear engine tail nozzle. A safety valve is installed on the pipeline, which is connected to the flame arrester via a discharge line. When the set pressure is reached, the hydrogen fuel is discharged into the external atmosphere after passing through the flame arrester, thus preventing overpressure.

[0063] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A method for designing overall parameters of a scaled-down technology demonstrator for a jet aircraft using liquid hydrogen fuel, characterized by: The following steps are involved: Step 1: Calculate the maximum allowable takeoff weight of the scaled technology demonstrator based on the weight and thrust of the hydrogen-fueled engine selected in the overall design of the liquid hydrogen-fueled jet aircraft. Estimate the takeoff weight of the scaled technology demonstrator based on the requirement that it should not exceed the maximum allowable takeoff weight, the constraints of the prototype selected in the overall design of the liquid hydrogen turbofan regional airliner, the set scale ratio, and the minimum takeoff weight constraint of the scaled technology demonstrator. Step 2: Based on the aerodynamic force and moment coefficient data of the prototype aircraft, and in accordance with the set safe takeoff speed and safe angle of attack of the scaled-down technology demonstrator aircraft, aerodynamic calculations are performed to determine the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology demonstrator aircraft. Selecting a wing reference area for the scaled-down technology verification aircraft in accordance with the minimum wing reference area requirement, and determining a scale ratio based on the wing reference area of ​​the scaled-down technology verification aircraft and the wing reference area of ​​the prototype aircraft, in combination with the set scale ratio constraint requirements; Step 3: Based on the scale ratio determined in step 2 and the aerodynamic force and moment coefficient data of the prototype, after Reynolds number correction, the aerodynamic force and moment coefficient data of the scaled-down technology verification aircraft are obtained; Verify using the aerodynamic force and moment coefficients of the scaled technology demonstrator: Using the aerodynamic force and moment coefficient data of the scaled technology demonstrator and in accordance with the set safe takeoff speed and safe angle of attack of the scaled technology demonstrator, calculate whether the scaled technology demonstrator can meet the estimated takeoff weight requirement of the scaled technology demonstrator. If yes, proceed to the subsequent steps. If not, return to step 2 and reselect the wing reference area of ​​the scaled technology demonstrator. Step 4: Calculate the liquid hydrogen load required for the scaled-down technology verification aircraft to complete the flight mission based on the aerodynamic and torque coefficient data of the scaled-down technology verification aircraft, the set flight mission profile of the scaled-down technology verification aircraft, and the hydrogen consumption rate of the hydrogen-fired engine selected in Step 1. Step 5: Determine the volume of the liquid hydrogen storage tank according to the liquid hydrogen loading amount calculated in step 4; Step 6: Based on the volume of the liquid hydrogen storage tank obtained in step 5, determine whether the liquid hydrogen storage tank can be placed in the scaled-down technology verification machine at the current scale; If it is possible, the scale ratio is obtained; if not, the layout positions of the remaining system components in the scaled technology verification aircraft are first adjusted to determine whether space is available for the layout of the liquid hydrogen storage tank. If it is still not available, the take-off weight of the scaled technology verification aircraft is re-estimated under the requirement of not exceeding the maximum allowable take-off weight, and then return to step 2 until the liquid hydrogen storage tank can be arranged in the scaled aircraft.

2. The overall parameter design method for a scaled-down technology demonstrator of a jet aircraft using liquid hydrogen fuel according to claim 1, characterized in that: In steps 2 and 3, the aerodynamic force and moment coefficient data of the prototype are the aerodynamic force and moment coefficients of the prototype in a set configuration; the set configuration is determined according to the set flight mission profile of the scaled technology verification aircraft.

3. The overall parameter design method for a scaled-down technology demonstrator of a jet aircraft using liquid hydrogen fuel according to claim 1 is characterized by: The flight mission profile of the scaled-down technology verification aircraft requires a maximum flight altitude of more than 200 meters and a flight time of more than 5 minutes.

4. The overall parameter design method for a scaled-down technology demonstrator of a jet aircraft using liquid hydrogen fuel according to claim 2, characterized in that: The set configuration adopts the take-off configuration.

5. The overall parameter design method for a scaled-down technology demonstrator of a jet aircraft using liquid hydrogen fuel according to claim 1 is characterized by: In step 3, the scaled-down verification aircraft was also aerodynamically modified, and the aerodynamic force and moment coefficient data of the modified scaled-down verification aircraft were used for verification.

6. The overall parameter design method for a scaled-down technology demonstrator of a jet aircraft using liquid hydrogen fuel according to claim 1 is characterized by: In step 4, the liquid hydrogen load required for the scaled-down technology verification aircraft to complete the flight mission includes the hydrogen consumption during normal flight and the emergency redundancy.

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