Overall parameter design method for scaling technical verification machine of jet aircraft using liquid hydrogen fuel

Abstract

According to the overall parameter design method for the scaling technical verification machine of the jet aircraft using the liquid hydrogen fuel, the scaling verification requirement of the jet aircraft using the liquid hydrogen fuel is met, firstly, the take-off weight of the scaling technical verification machine is estimated, and then the minimum wing reference area needed by the estimated take-off weight of the scaling technical verification machine is calculated; the method comprises the following steps: calculating the volume of a liquid hydrogen storage tank, determining an initial scaling ratio, checking by using the corrected aerodynamic force and torque coefficients of a scaling technical verification machine, calculating the volume of the liquid hydrogen storage tank, verifying whether the liquid hydrogen storage tank can be arranged in the scaling technical verification machine under the current scaling ratio, if so, obtaining the scaling ratio, and if not, determining the scaling ratio. Otherwise, the take-off weight of the aircraft is verified by re-estimating the scaling technology. The method can provide support for further development of the overall scheme design of the scaling verification machine.

Description

Technical Field

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

[0002] Using liquid hydrogen as jet fuel is one of the development trends of green flight in the future. Liquid hydrogen as jet fuel has significant characteristics and advantages. First, liquid hydrogen is a clean energy source, and its combustion product is only water, which is pollution-free to the environment. Secondly, liquid hydrogen has a high energy density. Although its volume energy density is low, its weight energy density is high, which means that liquid hydrogen can provide more energy at the same weight. In addition, liquid hydrogen has a wide range of sources and can be produced by methods such as electrolysis of water, which is sustainable.

[0003] The difficulty of liquid hydrogen fuel is that it must be stored in a heavy tank in the form of a cryogenic liquid. Therefore, the design of a liquid hydrogen fuel jet aircraft needs to focus on the overall layout plan, the liquid hydrogen system plan, and the onboard liquid hydrogen storage tank plan. In order to fully verify these design plans, it is necessary to carry out the development and test flight of a scaled verification aircraft of a liquid hydrogen fuel jet 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 fuel 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, 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 view of 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 a scaled verification machine, proposes an overall parameter design method for a scaled technology verification machine of a jet aircraft using liquid hydrogen fuel, and determines the scale of the scale, so as to further carry out the overall design of the scaled verification machine.

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

[0007] A method for designing overall parameters of a jet aircraft scale technology verification machine using liquid hydrogen fuel comprises the following steps:

[0008] Step 1: Calculate the maximum allowable takeoff weight of the scaled technology verification aircraft based on the weight and thrust of the hydrogen-fueled engine selected in the overall design of the jet aircraft using liquid hydrogen fuel; estimate the takeoff weight of the scaled technology verification aircraft based on the requirement of not exceeding the maximum allowable takeoff weight, the prototype selected in the overall design of the liquid hydrogen turbofan regional airliner, the set scale ratio constraint requirements and the minimum takeoff weight constraint requirements of the scaled technology verification aircraft;

[0009] 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, the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology verification aircraft can be obtained through aerodynamic calculation;

[0010] According to the minimum wing reference area requirement, the wing reference area of ​​the scaled technology verification aircraft is selected, and the scaled ratio is determined according to the wing reference area of ​​the scaled technology verification aircraft and the wing reference area of ​​the prototype aircraft, and in combination with the set scaled ratio constraint requirement;

[0011] Step 3: According to 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 machine are obtained;

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

[0013] Step 4: Calculate the amount of liquid hydrogen required for the scaled-down technology verification aircraft to complete the flight mission based on the aerodynamic force and moment 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-burning 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: Determine whether the liquid hydrogen storage tank can be arranged in the scaled-down technology verification machine at the current scaled-down ratio based on the volume of the liquid hydrogen storage tank obtained in step 5; 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 machine to determine whether space for the liquid hydrogen storage tank can be obtained; if still not, re-estimate the take-off weight of the scaled-down technology verification machine 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 machine.

[0016] According to a further preferred embodiment, in step 2 and step 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 a 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] According to a further preferred embodiment, in step 3, the scaled-down verification machine is also subjected to aerodynamic modification, and the aerodynamic force and moment coefficient data of the scaled-down verification machine after modification are used for verification.

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

[0021] Beneficial Effects

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

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through 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 easily understood from the description of the embodiments in conjunction with the following drawings, in which:

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

[0026] Figure 2 : Aerodynamic force and moment coefficient 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] In the figure: 1. Multifunctional atmospheric data sensor; 2. Network switch; 3. Integrated avionics computer; 4. Secondary link terminal; 5. Atmospheric data computer; 6. Combined inertial navigation; 7. Wireless altimeter host; 8. High-voltage power battery; 9. Main link terminal; 10. Airborne battery; 11. First altimeter antenna; 12. Satellite positioning antenna; 13. Nose wheel steering servo; 14. Front landing gear; 15. First main link antenna; 16. Monitoring 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 cable; 28. Engine controller, igniter and lubricating oil pump; 29. ​​Engine; 30. Lubricating oil tank; 31. Exhaust pipeline;

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

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

[0031] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not 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 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 machine for a liquid hydrogen turbofan regional aircraft, it is necessary to determine the scaled-down ratio based on the overall design scheme of the liquid hydrogen turbofan regional aircraft and the design scheme of the liquid hydrogen and power system, so as to lay a foundation for subsequent research. To this end, this embodiment proposes an overall parameter design method for a scaled-down verification machine for a liquid hydrogen turbofan regional aircraft, including the following steps:

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

[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 technology verification aircraft, the maximum allowable take-off weight of the scaled technology verification aircraft can be calculated based on the weight and thrust of the selected hydrogen-fired engine in accordance with the known aircraft design performance calculation method.

[0036] According to the requirement of not more than the maximum allowable takeoff weight, the prototype selected by the overall design plan of the liquid hydrogen turbofan regional airliner, the set scale ratio constraint requirements and the minimum takeoff weight constraint requirements of the scaled technology verification aircraft, the takeoff weight of the scaled technology verification aircraft is estimated. In this embodiment, the selected prototype is ARJ21; the scale ratio constraint is: scale ratio ≥ 1:5; the minimum takeoff weight constraint of the scaled technology verification aircraft is: takeoff weight ≮ 250kg.

[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 technology verification aircraft, through aerodynamic calculations, the minimum wing reference area required to meet the estimated takeoff weight of the scaled technology verification aircraft can be obtained.

[0038] In this embodiment, since the flight mission profile of the scaled technology verification aircraft requires a maximum flight altitude of more than 200 meters and a flight time of more than 5 minutes, the scaled technology verification aircraft is fixed to the take-off configuration from the perspectives of safety, economy, and structural characteristics: relative to the cruise configuration, the take-off configuration has a large available lift coefficient, which can significantly reduce the take-off and landing speed and improve the take-off and landing safety; relative to the cruise configuration and the landing configuration, the take-off configuration has a large stall angle of attack and a large safe flight angle of attack boundary, which is conducive to improving flight safety; relative to the landing configuration, the take-off configuration has a large lift-to-drag ratio, requires less maximum engine thrust, and consumes less hydrogen fuel; if the flight is fixed to the take-off configuration throughout the entire flight, there is no need to use servos on the inner and outer flaps, and only the flaps need to be fixed to the main wing with angle blocks. In this way, a single aircraft can save the purchase cost of 4 servos, while removing the complex flap motion mechanism, significantly reducing the difficulty of aircraft processing and manufacturing, and improving 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 based on 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 reduction ratio to be 1:4, which meets the set reduction ratio constraint requirements. The main dimensional parameters of the prototype and the scaled verification machine under this reduction 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 moment coefficient data of the prototype cannot be equivalent to the aerodynamic force and moment 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 moment coefficient data of the scaled-down technology verification machine.

[0045] Furthermore, since the scaled-down verification aircraft adopts the take-off configuration, considering the actual processing and use requirements of the scaled-down verification aircraft, as well as the risk of possible weight increase, the scaled-down verification aircraft was also aerodynamically modified 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, reduce the peak value of the main wing head, and improve the air intake efficiency of the slat channel;

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

[0049] 4. Move the wing downward to reduce the obstruction of the central wing box to the internal space of the fuselage, and at the same time reduce the height of the landing gear;

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

[0051] 6. Increase the leading edge radius of the horizontal tail to enhance the horizontal tail's 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. Cut the trailing edge of the nacelle bracket to prevent it from being burned 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 better at a large lift coefficient; the longitudinal static stability before and after the modification is about 40%, and the pitch moment after the modification can be maintained in an approximately linear segment to 16°.

[0057] Since the calculation in step 2 uses the aerodynamic force and moment coefficient data of the prototype aircraft, 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 safe takeoff speed and safe angle of attack of the scaled technology verification aircraft, calculate whether the scaled technology verification aircraft can meet the estimated takeoff weight requirement of the scaled technology verification aircraft. If yes, 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, the volume of the liquid hydrogen storage tank is determined 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-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 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-down aircraft.

[0062] In this embodiment, it has been verified that the liquid hydrogen loading requirements can be met according to the 1:4 scale ratio. The overall layout diagram of the scale verification machine platform is as follows: Figure 3 As shown in Figure 2, the liquid hydrogen delivery system model is as follows: Figure 4 As shown, the power energy system is arranged as follows Figure 5As shown in the figure, the designed hydrogen delivery pressure of the liquid hydrogen aircraft is 3MPa, and the maximum hydrogen delivery flow rate is 40g / s. The liquid hydrogen pump is placed in the liquid hydrogen storage tank, and the pressure in the tank is 0.3MPa to ensure that the pressure at the inlet of the pump is 0.3MPa, and it has a supercooling degree of more than 1K. The liquid hydrogen is driven by the pump, and its outlet is 3MPa, and it is transported to the engine through a low-temperature regulating valve. At the same time, a branch is gasified by the self-pressurizing heat exchanger, and then returns to the liquid hydrogen storage tank through a low-temperature regulating valve to maintain the pressure in the tank stable at 0.3MPa to ensure the pressure in the storage tank. Because two engines are supplied, the main liquid hydrogen is divided into two routes, which are connected to the heat exchanger at the tail nozzle of the rear engine. A safety valve is configured on the pipeline, which is connected to the flame arrester through the discharge pipeline. When the set pressure is reached, the hydrogen fuel is discharged into the external atmosphere after the flame arrester, thereby avoiding overpressure.

[0063] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary 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 intent of the present invention.

Claims

1. A method for designing overall parameters of a scaled-down technology verification machine of a jet aircraft using liquid hydrogen fuel, characterized in that: The following steps are involved: Step 1: Calculate the maximum allowable takeoff weight of the scaled technology verification aircraft based on the weight and thrust of the hydrogen-fueled engine selected in the overall design of the jet aircraft using liquid hydrogen fuel; estimate the takeoff weight of the scaled technology verification aircraft based on the requirement of not exceeding the maximum allowable takeoff weight, the prototype selected in the overall design of the liquid hydrogen turbofan regional airliner, the set scale ratio constraint requirements and the minimum takeoff weight constraint requirements of the scaled technology verification aircraft; 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, the minimum wing reference area required to meet the estimated takeoff weight of the scaled-down technology verification aircraft can be obtained through aerodynamic calculation; According to the minimum wing reference area requirement, the wing reference area of ​​the scaled technology verification aircraft is selected, and the scaled ratio is determined according to the wing reference area of ​​the scaled technology verification aircraft and the wing reference area of ​​the prototype aircraft, and in combination with the set scaled ratio constraint requirement; Step 3: According to 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 machine are obtained; Use the aerodynamic force and moment coefficient of the scaled technology verification aircraft for verification: Use the aerodynamic force and moment coefficient data of the scaled technology verification aircraft and, in accordance with the set safe takeoff speed and safe angle of attack of the scaled technology verification aircraft, calculate whether the scaled technology verification aircraft can meet the estimated takeoff weight requirement of the scaled technology verification aircraft. If yes, proceed to the subsequent steps; if not, return to step 2 and reselect the wing reference area of ​​the scaled technology verification aircraft. Step 4: Calculate the amount of liquid hydrogen required for the scaled-down technology verification aircraft to complete the flight mission based on the aerodynamic force and moment 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-burning 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: According to 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 machine at the current scaled-down ratio; If possible, the scale ratio is obtained; 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 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 of a jet aircraft scale technology verification machine using liquid hydrogen fuel according to claim 1, characterized in that: In step 2 and step 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-down technology verification aircraft.

3. The overall parameter design method of a jet aircraft scale technology verification machine 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 of a jet aircraft scale technology verification machine using liquid hydrogen fuel according to claim 2 is characterized by: The set configuration adopts the take-off configuration.

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

6. The overall parameter design method of a jet aircraft scale technology verification machine using liquid hydrogen fuel according to claim 1 is characterized by: In step 4, the amount of liquid hydrogen 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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