A design method for emergency depressurization in aircraft

Abstract

This invention proposes a design method for emergency depressurization in an aircraft. The aircraft includes a cockpit (1), a pressurized cabin area (2), a non-pressurized cabin area (4), and a tail section (5). The method includes the following steps: S1, setting a pressurized end frame (3) for emergency depressurization opening at the interface between the pressurized cabin area (2) and the non-pressurized cabin area (4); S2, setting a pressurized cabin door (3-1), an emergency depressurization port cover (3-2), and a full latch and handle (3-3) on the pressurized end frame (3); S3, when the aircraft experiences an uncontrollable situation, opening the emergency depressurization port cover (3-2) to discharge the gas in the pressurized cabin area (2) into the non-pressurized cabin area (4); S4, when the pressure difference between the pressurized cabin area (2) and the non-pressurized cabin area (4) is equal, arranging for emergency evacuation. The invention requires minimal modification to the aircraft, and the emergency depressurization design does not directly communicate with the atmosphere, avoiding potential flight attitude instability issues, making it safer, simpler, and easier to implement.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design and relates to an emergency depressurization design method for an aircraft in-flight emergency evacuation system. Background Technology

[0002] Flight testing is the process of testing a product under real flight conditions. Flight testing is complex, involves numerous test flights, and carries a high risk of accidents, especially when performing high-risk maneuvers such as envelope expansion, flutter, and stall. Therefore, adequate safety measures must be in place on the test aircraft to ensure the safety of the test crew in the event of uncontrollable aircraft conditions.

[0003] According to Article 21.35 of CCAR-21-R3 "Regulations on the Conformity Assessment of Civil Aviation Products and Components", the applicant "shall prove that sufficient measures have been taken during each flight test to enable the flight test crew to evacuate the aircraft in an emergency..."; and Section 7.2 of AC-21-AA-2008-213 "Procedures for Issuing Special Flight Permits for Research and Development Flight Tests and Verification Flight Tests" stipulates that when issuing a special flight permit, "the exits for emergency evacuation of the flight test crew shall be checked...". Therefore, when an aircraft is conducting flight tests, it is necessary to establish an emergency evacuation system to ensure that the flight test crew can safely and quickly evacuate the aircraft in the event of an uncontrollable situation.

[0004] The emergency disembarkation system mainly consists of emergency disembarkation exits, emergency disembarkation paths, emergency disembarkation channels, emergency disembarkation auxiliary facilities, emergency disembarkation alarms and feedback, emergency depressurization, and emergency disembarkation life-saving equipment.

[0005] During an emergency evacuation, the aircraft is flying at high altitude, and there is a large pressure difference between the pressurized cabin where the test flight crew is located and the outside. If the emergency exit is opened directly without depressurization, the huge pressure difference may have an irreversible impact on the crew's health. Therefore, it is necessary to first depressurize the cabin to make the pressure difference between the inside and outside of the cabin equal before the emergency evacuation can proceed.

[0006] Currently, most aircraft emergency depressurization systems, both domestically and internationally, utilize explosive devices installed at weak points in the aircraft's fuselage structure. These devices are then used to depressurize the aircraft through explosive depressurization hatches. However, explosive depressurization has several drawbacks: 1) the explosion may damage other parts of the aircraft structure or onboard equipment, affecting subsequent flight safety; 2) the trajectory of the depressurization hatch after the explosion is uncertain, potentially causing secondary hazards; 3) the rapid pressure change after the explosion may lead to flight instability; and 4) if the blast port is close to the crew, it poses a safety hazard. Considering these reasons and the aircraft's design characteristics, a depressurization hatch can be installed at the interface between the pressurized and non-pressurized areas. This hatch can be mechanically opened to release pressurized gas into the non-pressurized area (the area open to the atmosphere), thus achieving emergency depressurization. This emergency depressurization method effectively solves the safety hazards of explosive depressurization, requires minimal modification to the aircraft structure, is simple to implement, and better meets the requirements for emergency depressurization. Summary of the Invention

[0007] The purpose of this invention is:

[0008] An emergency depressurization design method is proposed that can solve the safety hazards of traditional explosive depressurization, while being simple to implement and requiring minimal modification to the aircraft.

[0009] The technical solution of this invention is:

[0010] The emergency depressurization system design of this invention mainly involves setting an emergency depressurization opening at the interface between the pressurized and unpressurized areas of the aircraft. The emergency depressurization port cover is opened mechanically to release pressurized gas into the unpressurized area of ​​the aircraft, utilizing the connection between the unpressurized compartment and the atmosphere to achieve emergency depressurization. The emergency depressurization system design specifically includes the following:

[0011] (1) Design of emergency pressure relief opening location

[0012] For pressurized aircraft operating at high altitudes, the fuselage is generally divided into three sections: the cockpit, passenger cabin (or through cabin), and tail compartment. The cockpit and passenger cabin, where people move around, are generally designed as pressurized sections, while the tail compartment, which serves as an equipment bay or other function, is generally designed as a non-pressurized section. The pressurized and non-pressurized compartments are generally separated by a pressurized end frame or pressurized door. Based on the present invention, the emergency depressurization opening can be designed on such pressurized end frame or pressurized door structures.

[0013] During high-altitude flight, the pressure in the non-pressurized cabin is similar to atmospheric pressure because it is not pressurized. The pressure in the pressurized cabin is generally 2400m atmospheric pressure, so the pressure in the pressurized cabin is higher than that in the non-pressurized cabin. In case of emergency evacuation, the emergency depressurization opening on the pressurized end frame or pressurized cabin door can be opened, and the pressure difference between the pressurized and non-pressurized cabins can be used to release the gas in the pressurized cabin into the non-pressurized cabin, thereby achieving emergency depressurization of the pressurized cabin.

[0014] (2) Emergency pressure relief opening size

[0015] According to the structural design principles of the pressurized chamber, the maximum perforation area that it can withstand is HO (m²). 2 It can be calculated using the following formula:

[0016] H O =PA S

[0017] In the formula:

[0018] P=(A S / 580)+0.024

[0019] AS is the maximum cross-sectional area (m²) of the pressurized casing perpendicular to the longitudinal axis. 2 ).

[0020] The emergency depressurization system needs to depressurize quickly in the air. Based on the above formula, the maximum area of ​​the emergency depressurization opening in the aircraft pressurized cabin can be obtained. Combined with the design type and spatial location of the depressurization port cover, the size of the depressurization opening can be determined.

[0021] (3) Emergency pressure relief port cover design

[0022] The emergency pressure relief cover is designed to open mechanically. To reduce the operating force required by the test flight crew, the operating force for opening the cover can be reduced by increasing the lever arm of the cover handle.

[0023] (4) Design of emergency ventilation openings in non-pressurized compartments

[0024] Based on the emergency depressurization system design of this invention, for non-pressurized compartments that do not require pressurization, emergency ventilation openings need to be installed on the fuselage skin to ensure that the aircraft fuselage structure can withstand deformation caused by changes in temperature and pressure difference. The emergency ventilation openings are generally located on the top or upper side of the fuselage and can be designed in the form of "cat ears" or louvers.

[0025] (5) Analysis of the pressure-bearing capacity of the structure in the non-pressurized zone

[0026] Because a large amount of gas is released from the pressurized compartment into the non-pressurized area within a very short time, it is necessary to assess the structural pressure-bearing capacity based on the pressure difference and pressure change rate curves of the non-pressurized compartment during emergency depressurization. This ensures that the non-pressurized area structure does not suffer damage that could affect flight safety before the test flight crew evacuates the aircraft in an emergency. Since the non-pressurized area is designed with vents connecting to the atmosphere, and the aircraft structure itself has a leakage rate not exceeding 460 kg / h, under normal circumstances, the emergency depressurization gas will not cause damage to the non-pressurized area structure.

[0027] By determining and designing the above parameters, the emergency depressurization design of the aircraft test flight emergency exit system can be completed.

[0028] The advantages and beneficial effects of this invention are:

[0029] The emergency depressurization design method of this invention discharges pressurized cabin gas into a non-pressurized area connected to the atmosphere through a mechanically opened emergency depressurization port, thereby achieving emergency depressurization. This invention, while meeting the emergency depressurization requirements of aircraft, solves the safety hazards caused by traditional explosive depressurization; this invention only involves structural modifications, the system is simple and easy to implement, and requires minimal changes to the aircraft; the emergency depressurization design of this invention does not directly connect to the atmosphere, avoiding potential flight attitude instability problems; compared with other methods, this invention is safer, simpler, easier to implement, and does not generate secondary risks. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Fuselage compartment diagram;

[0032] Figure 2 Schematic diagram of the pressurization end frame and emergency pressure relief opening;

[0033] Figure 3 Schematic diagram of the emergency ventilation opening in the stern compartment;

[0034] Figure 4 Pressure and differential pressure change rate curves of the non-pressurized chamber.

[0035] in:

[0036] 1: Cockpit;

[0037] 2: Pressurized cabin area;

[0038] 3: Pressure boosting end frame;

[0039] 3-1: Pressurized compartment door; 3-2: Emergency depressurization port cover; 3-3: Full latch and handle;

[0040] 4: Non-pressurized area of ​​the cabin;

[0041] 5: Tail compartment; 5-1: Emergency ventilation opening. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] The emergency depressurization design method of this invention involves installing an emergency depressurization port cover at the interface between the pressurized and unpressurized areas of the aircraft. This cover is opened mechanically to release pressurized gas into the unpressurized area, utilizing the connectivity between the unpressurized compartment and the atmosphere to achieve emergency depressurization. The main contents of the emergency depressurization design method of this invention include:

[0045] (1) Determining the location of the emergency depressurization opening: The depressurization opening should be located at the interface between the pressurized and non-pressurized compartments of the aircraft. The opening should be open and easy to operate.

[0046] (2) Determination of emergency depressurization opening size: The opening size can be calculated based on the formula for the maximum opening area that the aircraft pressurization chamber can withstand;

[0047] (3) Emergency pressure relief cap design: The cap is designed as a mechanical cap, which can increase the lever arm of the handle to reduce the operating force of the cap;

[0048] (4) Emergency depressurization time: The emergency depressurization time can be calculated by modeling based on the boundary conditions of the aircraft emergency descent profile and the altitude requirements of the parachute jump.

[0049] (5) Analysis of the structural pressure-bearing capacity of the non-pressurized area: The structural pressure-bearing capacity is assessed based on the pressure difference and pressure change rate curves of the non-pressurized compartment during emergency depressurization to ensure that it will not affect the subsequent emergency evacuation of the test flight crew. This invention solves the safety hazards caused by traditional explosive depressurization while meeting the emergency depressurization requirements of the aircraft; this invention only involves structural modification, the system is simple and easy to implement, and the modification to the aircraft is minimal; the emergency depressurization design of this invention does not directly communicate with the atmosphere, avoiding the potential flight attitude instability problems; compared with other methods, this invention is safer, simpler, easier to implement, and does not generate secondary risks.

[0050] The following is a case study of the emergency depressurization design of an emergency evacuation system for a certain type of aircraft during flight testing. The specific implementation process is as follows:

[0051] 1) Design of emergency pressure relief opening location

[0052] The fuselage section of a certain type of aircraft is divided into the cockpit 1, pressurized through-cabin area 2, unpressurized through-cabin area 4, and tail compartment 5, as shown in the attached diagram. Figure 1 As shown in the diagram. The cockpit and pressurized access area are pressurized compartments, while the non-pressurized access area and stern compartment are non-pressurized compartments. The pressurized end frame 3 serves as the interface between the pressurized and non-pressurized compartments. A pressurized compartment door 3-1 is installed on the pressurized end frame 3, and an emergency depressurization port cover 3-2 is designed on the door, as shown in the attached diagram. Figure 2 As shown, there are no obstructions around the opening, the space is open and easy to operate, and there is no airborne equipment that could affect flight safety in the area directly opposite the opening, so there are no safety hazards.

[0053] 2) Emergency pressure relief opening dimensions

[0054] Based on the calculation formula for the maximum opening area HO that the pressurization chamber can withstand, the emergency depressurization opening area is no greater than 0.194 m². Considering the spatial location and structural design, the following is provided on the pressurization chamber door 3-1: Figure 2 The emergency pressure relief port cover 3-2 shown has an opening size of 330mm×128mm and an area of ​​0.042m2, which meets the design requirements.

[0055] 3) Emergency pressure relief port cover design

[0056] As attached Figure 2 As shown, an emergency depressurization port cover 3-2 is installed on the pressurization cabin door. The cover is equipped with a safety pin and a handle 3-3. In case of emergency depressurization, first pull out the pin, and then grasp the handle 3-3 and apply force in the direction of travel to open the emergency depressurization valve and complete the emergency depressurization.

[0057] 4) Design of emergency ventilation openings for non-pressurized compartments

[0058] To ensure that the non-pressurized fuselage structure can withstand deformation caused by environmental changes such as temperature and air pressure during normal flight and emergency depressurization, an emergency ventilation vent 5-1 is installed on the upper side of the rear section 5 of the tail section of a certain type of aircraft, as shown in the attached diagram. Figure 3 As shown. During the emergency depressurization process, when the emergency depressurization port cover 3-2 is opened by the handle 3-3, the high-pressure gas in the pressurized area 2 of the cabin is discharged into the non-pressurized area 4 of the cabin through the emergency depressurization opening. After passing through the emergency ventilation port 5-1 located on the upper side of the tail compartment 5, the gas is finally discharged from the fuselage, thereby achieving the purpose of emergency depressurization of the pressurized compartment.

[0059] Emergency ventilation opening 5-1 measures 335mm × 60mm and features a symmetrical design. To prevent rainwater and marine water from entering, it is designed as a louvered structure with a U-shaped tube.

[0060] 5) Analysis of the structural bearing capacity in the non-pressurized zone

[0061] According to the extreme working conditions, based on the attached Figure 4 The pressure and differential pressure change rate curves of the non-pressurized compartment, based on structural strength assessment, indicate that the emergency depressurization gas will not have a destructive impact on the non-pressurized compartment structure, will not cause significant deformation, and will not affect the subsequent emergency evacuation of the test flight crew. Figure 4 The horizontal axis represents time (in seconds), and the vertical axis represents pressure (kPa) and real-time pressure (kPa / s).

[0062] It should be noted that the above process operations can be combined to varying degrees. For the sake of brevity, the implementation methods of various combinations will not be elaborated here. Those skilled in the art can flexibly adjust the order of the above operation steps or flexibly combine the above steps according to actual needs.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A design method for emergency depressurization in flight, wherein the aircraft includes: The method comprises a cockpit (1), a pressurized through-cabin area (2), a non-pressurized through-cabin area (4), and a stern compartment (5), characterized in that the method includes the following steps: S1, a pressurized end frame (3) for emergency depressurization opening is set at the interface between the pressurized cabin area (2) and the non-pressurized cabin area (4) of the aircraft. S2, a pressurization chamber door (3-1), an emergency depressurization port cover (3-2), and a full latch and handle (3-3) are provided on the pressurization end frame (3). S3, when the aircraft is in an uncontrollable situation, open the emergency depressurization port cover (3-2) and discharge the gas in the cabin pressurization area (2) into the cabin non-pressurization area (4). S4, when the pressure difference between the pressurized waiting area (2) and the non-pressurized open area (4) is equal, arrange for emergency evacuation; in step S2: Based on the formula for the maximum opening area that an aircraft pressurized compartment can withstand, and combined with the design type and spatial location of the pressure relief cover, the dimensions of the emergency pressure relief cover (3-2) are derived; The maximum hole area H that the emergency pressure relief cap (3-2) can withstand. O (m) 2 Calculate using the following formula: A O = OFF S In the formula: P = (A S / 580)+0.024 A S The maximum cross-sectional area (m²) of the pressurized housing perpendicular to the longitudinal axis 2 ).

2. The method according to claim 1, characterized in that... It also includes: Maximum hole area H O Not greater than 0.194m 2 .

3. The method according to claim 1, characterized in that... It also includes: The opening size of the emergency pressure relief cap (3-2) is 330mm × 128mm.

4. The method according to claim 1, characterized in that... It also includes: The structural pressure bearing capacity is assessed based on the pressure difference and pressure change rate curve of the non-pressurized area (4) during emergency depressurization, so that the highest point of the pressure difference and pressure change rate curve of the non-pressurized area (4) is within the safe range.

5. The method according to claim 1, characterized in that... It also includes: Set the stern compartment (5) as a non-pressurized compartment that does not require pressurization; An emergency ventilation opening (5-1) is installed on the fuselage skin of the tail section (5).

6. The method according to claim 4, characterized in that... ,in: Emergency ventilation openings (5-1) are located on the top or upper side of the unit and are designed in the form of "cat ears" or louvers.

7. The method according to claim 1, characterized in that... It also includes: The emergency pressure relief port cover (3-2) is designed to be located outside the fuselage skin.

8. The method according to any one of claims 1-7, characterized in that... In step S2: The emergency pressure relief cap (3-2) is designed as a mechanical cap and an additional handle lever arm is added to reduce the operating force of the cap.

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