Aeroengine airborne starting method and system

Abstract

A method and system for airborne engine start in flight. The method includes determining that at least one of the aircraft engines of an aircraft in flight is flameout in flight, determining that the aircraft is outside a start envelope, using airflow from an air source to drive a starter to turn a high pressure rotor of the flameout engine, determining that the aircraft is within the start envelope, and performing an airborne start procedure in accordance with an aircraft flight manual.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of aero-engines, and in particular to a method and system for in-flight starting of an aero-engine. BACKGROUND

[0002] During the operation of an aircraft, the engine may be subject to unexpected disturbances (e.g. fuel contamination, loss of power, extreme weather or crew error operation, etc.) and may be subject to in-flight flameout or be forced to flameout for a short time due to other reasons. In order to ensure the flight power and safe operation of the aircraft, the engine needs to be in-flight started. The in-flight starting of the engine usually includes starter-assisted starting and windmill starting. Whether it is starter-assisted starting or windmill starting, the rotor speed needs to be increased to above the lower limit of the in-flight starting speed, so as to achieve in-flight ignition starting.

[0003] When the aircraft engine is subject to in-flight flameout, the engine may fail to be successfully ignited and started due to various reasons due to its design characteristics and special operating environment, which endangers flight safety.

[0004] The present disclosure is improved in view of, but not limited to, the above factors. SUMMARY

[0005] To this end, the present disclosure provides a method and system for in-flight starting of an aero-engine. In the technical solution of the present disclosure, after determining that the engine is subject to in-flight flameout based on flight parameters and engine operating parameters, the starter continuously drives the high-pressure rotor of the flameout engine, so that the speed of the high-pressure rotor is maintained within a predetermined speed range, and more cold gas is driven into the inner flow passage, so that better cold gas effect is obtained inside, and the engine in-flight starting failure caused by rotor blocking or rotor locking is prevented. Thus, the method and system of the present disclosure solve the problem of engine in-flight starting failure caused by rotor locking or rotor blocking by using existing aircraft equipment (such as auxiliary power units, other engines that have not been subject to flameout, etc.), without increasing the requirement for additional equipment. At the same time, the method and system of the present disclosure effectively improve the success rate of engine in-flight starting and improve flight safety.

[0006] According to a first aspect of the present disclosure, a method for in-flight starting of an aero-engine is provided, comprising: determining that at least one of the aero-engines of an aircraft in flight is subject to in-flight flameout; determining that the aircraft is outside a starting envelope; using airflow from an air source to drive a starter to rotate a high-pressure rotor of the aero-engine subject to in-flight flameout; determining that the aircraft enters the starting envelope; and performing an in-flight starting procedure according to an aircraft flight manual.

[0007] According to one embodiment, determining whether an aircraft engine has experienced in-flight engine failure includes determining whether the aircraft engine has experienced in-flight engine failure based on the aircraft's engine speed and exhaust temperature.

[0008] According to another embodiment, determining that the aircraft is outside the start-up envelope includes making the determination based on the aircraft's current flight speed and flight altitude.

[0009] According to yet another embodiment, using an airflow from an air source to drive a starter motor includes opening a valve between the air source and the starter motor to allow airflow from the air source to be delivered to the starter motor.

[0010] According to yet another embodiment, the method further includes fully opening the valve to increase the rotational speed of the high-pressure rotor at the fastest possible rate.

[0011] According to yet another embodiment, the method further includes controlling the opening of the valve in response to the rotational speed of the high-pressure rotor, so that the rotational speed of the high-pressure rotor is maintained within a predetermined rotational speed range.

[0012] According to another embodiment, controlling the opening of the valve to maintain the rotational speed of the high-pressure rotor within the predetermined rotational speed range includes: reducing the opening of the valve when the rotational speed of the high-pressure rotor exceeds the upper limit of the predetermined rotational speed range; and increasing the opening of the valve when the rotational speed of the high-pressure rotor is below the lower limit of the predetermined rotational speed range.

[0013] According to yet another embodiment, the reduction and / or increase of the valve opening is performed in predetermined steps or continuously.

[0014] According to another embodiment, the method further includes opening the valve to a predetermined opening degree below full opening, the predetermined opening degree being associated with a predetermined speed range and airflow pressure.

[0015] According to another embodiment, the predetermined opening degree is determined by searching a lookup table using the airflow pressure and the predetermined rotational speed range as keywords.

[0016] According to yet another embodiment, the gas source is selected from either the aircraft's ignition-activated aero-engine or its APU.

[0017] According to another embodiment, the method further includes: determining the airflow pressure of the unextinguished aero-engine; if the airflow pressure is higher than a predetermined threshold, selecting the unextinguished aero-engine as the air source; otherwise, selecting the APU as the air source.

[0018] According to a second aspect of this disclosure, a system for in-flight starting of an aircraft engine is provided, comprising: a starter motor coupled to a high-pressure rotor of the aircraft engine via a transmission mechanism; an air source coupled to the starter motor via a valve; and an engine control system; the engine control system being arranged to: determine that at least one of the aircraft engines has failed in-flight; determine that the aircraft is outside the starting envelope; open the valve to use an airflow from the air source to drive the starter motor to rotate the high-pressure rotor of the failed aircraft engine; determine that the aircraft has entered the starting envelope; and execute an in-flight starting procedure according to the aircraft flight manual.

[0019] According to one embodiment, the gas source is selected from either the aircraft's ignition engine or its APU.

[0020] According to another embodiment, the engine control system is further configured to: determine the airflow pressure of the undisturbed aircraft engine; if the airflow pressure is higher than a predetermined threshold, select the undisturbed aircraft engine as the air source; otherwise, select the APU as the air source.

[0021] According to yet another embodiment, opening the valve to use airflow from the air source to drive the starter includes: fully opening the valve to increase the speed of the high-pressure rotor at the fastest possible rate; and controlling the opening of the valve in response to the speed of the high-pressure rotor to maintain the speed of the high-pressure rotor within a predetermined speed range.

[0022] According to yet another embodiment, opening the valve to use airflow from the air source to drive the starter includes: opening the valve to a predetermined opening degree below full opening, the predetermined opening degree being associated with a predetermined speed range and airflow pressure, and wherein the predetermined opening degree is obtained by looking up a lookup table based on the airflow pressure and the predetermined speed range.

[0023] According to yet another embodiment, the engine control system is a full authority digital engine control system.

[0024] According to a third aspect of this disclosure, an aircraft is provided, comprising the system according to any one of claims 13-18.

[0025] The aspects generally include, as substantially as described herein with reference to the accompanying drawings and as explained by the drawings, methods, apparatus, systems, computer program products, and processing systems.

[0026] The foregoing has broadly outlined the features and technical advantages of the examples according to this disclosure so that the following detailed description may be better understood. Additional features and advantages will be described thereafter. The disclosed concepts and specific examples can be readily used as the basis for modifying or designing other structures for implementing the same purposes as this disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, in both their organization and manner of operation, and their associated advantages, will be better understood by considering the following description in conjunction with the accompanying drawings. Each drawing is provided for illustrative and descriptive purposes and does not define any limitation on the claims. Attached Figure Description

[0027] To gain a more detailed understanding of the features described above in this disclosure, reference can be made to various aspects of the above-briefly summarized content, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and should not be considered as limiting its scope, as other equivalent aspects are permissible in this description. Identical reference numerals in different drawings may identify the same or similar elements.

[0028] Figure 1 This is a flowchart illustrating an example of a method for improving the quality of aviation product technical publications according to an embodiment of this disclosure;

[0029] Figure 2 This is a schematic diagram of the starting envelope according to an embodiment of the present disclosure;

[0030] Figure 3 This is a schematic diagram of an in-flight starting system for an aircraft engine according to an embodiment of the present disclosure; and

[0031] Figure 4 This is a schematic diagram of an aircraft according to an embodiment of the present disclosure. Detailed Implementation

[0032] Terminology Explanation:

[0033] Rotor lock-up: refers to a situation where the rotor speed drops to zero after the engine is shut off in the air or turned off, and it still cannot rotate even with a fan or auxiliary start.

[0034] Rotor stall: refers to the phenomenon that the rotor speed decreases in windmill mode due to the load connected to the engine accessories and the high friction and rubbing between the rotor and stator.

[0035] Aircraft Flight Manual (AFM): Contains information required to operate a specific type of aircraft. A typical flight manual includes operating limitations, normal / abnormal / emergency operating procedures, performance data, and load information.

[0036] The inventors recognized that when an aircraft engine experiences in-flight engine failure, due to its inherent design features and unique operating environment, the engine may fail to ignite and restart for various reasons, jeopardizing flight safety. The inventors particularly recognized that rotor lock-up or rotor stalling can cause the engine rotor speed to drop below the minimum in-flight starting speed. Especially in the event of dual engine failure, if the engines cannot restart due to rotor lock-up or stalling, it will have catastrophic consequences for aircraft flight safety.

[0037] The inventors also recognized that modern turbofan engines have high bypass ratios, typically above 5. Due to the smaller proportion of airflow within the combustion chamber, a higher turbine speed is needed to provide sufficient airflow to drive the engine rotor in order to ensure proper ignition and starting. Without auxiliary starting devices, this translates to a higher airspeed. The irregular combustion flame in the annular combustion chamber makes it difficult to form a stable flame under high-speed, low-temperature airflow conditions, hindering starting. Furthermore, the design features of high-pressure compressors result in a narrow in-flight starting envelope, increasing the time required for restarting. This increases the risk of rotor lock-up or stalling during in-flight starting, reducing the success rate of in-flight starts and jeopardizing flight safety.

[0038] Therefore, this disclosure provides an in-flight starting method and system for an aircraft engine. In the technical solution of this disclosure, after determining that the engine has shut down in-flight based on flight parameters and engine operating parameters, the high-pressure rotor of the shut-down engine is continuously driven by a starter motor to maintain the rotational speed of the high-pressure rotor within a predetermined range. This drives more cool gas into the internal flow channel, thereby achieving a better cooling effect inside the engine and preventing in-flight start failure due to rotor obstruction or rotor lock-up.

[0039] Therefore, the method and system of this disclosure solve the problem of engine in-flight start failure caused by rotor lock-up or rotor jamming using only existing aircraft equipment (such as auxiliary power units, other engines that are not shut down), without increasing the need for additional equipment. At the same time, the method and system of this disclosure effectively improve the success rate of engine in-flight start and enhance flight safety.

[0040] The detailed description that follows, taken in conjunction with the accompanying drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein can be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details.

[0041] The following is for reference. Figure 1 The diagram illustrates a flowchart of a method 100 for in-flight starting of an aircraft engine according to an example embodiment of the present disclosure.

[0042] like Figure 1 As shown, method 100 may include, in block 110, determining that at least one of the aircraft engines of an aircraft in flight has shut down in mid-air.

[0043] In one embodiment of this disclosure, the aircraft may include two or more aircraft engines. In this example, one or more of the aircraft's aircraft engines may experience in-flight engine failure (i.e., in-flight shutdown). It will be understood that in-flight engine failure refers to the phenomenon of an engine stopping working during flight, rather than an engine failure on the ground.

[0044] In another embodiment of this disclosure, determining whether an aircraft engine has experienced in-flight engine failure may include determining whether an in-flight engine failure has occurred based on the aircraft's engine speed, exhaust temperature, flight altitude, etc. In this embodiment, engine speed may include fan speed, high-pressure rotor speed, low-pressure rotor speed, etc. Those skilled in the art will understand that any other suitable parameters and conditions can be used to determine the occurrence of an engine in-flight failure, which will not be elaborated upon here.

[0045] After determining that an engine has failed in mid-air, method 100 may include, in block 120, determining that the aircraft is outside the start-up envelope.

[0046] The inventors recognized that after an in-flight engine failure, the engine enters a windmill operating state. Starting the engine in this windmill state is not possible under all flight conditions. In-flight engine starting is only possible when the aircraft is within its starting envelope.

[0047] For example, the higher the aircraft's altitude, the lower the pressure and temperature of the air at the combustion chamber inlet, making it more difficult to ignite the fuel-air mixture; the higher the aircraft's speed, the greater the airflow velocity at the combustion chamber inlet, making it even more difficult to ignite the fuel-air mixture, and preventing the engine from starting. Furthermore, if the aircraft's speed is too low, the turbine speed will be too low, and if the fuel supply is low, insufficient turbine output power may occur, leading to speed hangs during starting and failure to start; increasing the fuel supply may result in excessively high turbine inlet temperature or high-pressure compressor stall. Therefore, when the aircraft's speed is too low, the engine cannot start in windmill mode. This is the minimum speed boundary for engine in-flight starting in windmill mode. Below this boundary, the engine requires starter motor assistance to increase the engine's starting speed and acceleration capability. There is also a lower limit to the flight speed at which a starter motor can reliably start the engine. If the flight speed is below this lower limit, the engine speed will be too low, or the fuel pressure from the fuel pump will be too low, the fuel will not be able to atomize and will be difficult to ignite, or similar to starting the engine at a low flight speed boundary in windmill mode, problems such as speed suspension, excessively high turbine inlet temperature and high pressure compressor stall will occur during the engine start-up process.

[0048] Therefore, in one embodiment of this disclosure, determining that an aircraft is outside its start-up envelope may be made based on the aircraft's current flight speed and altitude. For example, Figure 2 A schematic diagram of a starting envelope 200 according to an embodiment of the present disclosure is shown. Within the starting envelope 200 (i.e. Figure 2 In the area "enclosed" by the starting envelope 200 and the speed axis, in-flight starting of the engine is possible. Although Figure 2 A starting envelope 200 of a specific shape is shown. Those skilled in the art will understand that the starting envelope can have any suitable shape, which varies depending on the aircraft and engine, and will not be elaborated further here.

[0049] The inventors recognized that in-flight engine restarting (or re-starting) typically involves starter-assisted starting and windmill starting. Both methods require increasing the rotor speed to above the minimum in-flight starting speed to achieve in-flight ignition. When an aircraft engine experiences in-flight engine failure, due to its design features and the specific operating environment, rotor lock-up or rotor jamming may occur, causing the engine rotor speed to fall below the minimum in-flight starting speed. This prevents successful ignition and restarting, especially in the event of dual engine failure. The inability to restart due to rotor jamming can have catastrophic consequences for flight safety. Furthermore, if the crew is not aware of the impending or already occurring rotor lock-up, they will be unable to make correct judgments and take appropriate action, potentially leading to a flight accident.

[0050] Therefore, continue to refer to Figure 1 Method 100 may include, in block 130, using an airflow from an air source to drive a starter motor to rotate the high-pressure rotor of an in-flight engine that has been shut down. In this way, by continuously driving the high-pressure rotor of the engine through the starter motor, the high-pressure rotor speed is maintained at a high level (above windmill speed), thereby driving more cool air into the engine's internal flow channels, thus achieving better cooling inside the engine and mitigating or preventing rotor stalling or rotor lock-up.

[0051] In one embodiment of this disclosure, using airflow from an air source to drive the starter motor may include opening a valve between the air source and the starter motor to allow airflow from the air source to be delivered to the starter motor. Further according to this embodiment, method 100 may first fully open the valve to allow the high-pressure rotor speed to increase at the fastest possible rate. For example, after the valve is fully open (in other words, the valve opening is 100%), the maximum airflow rate from the air source will be delivered to the starter motor to drive it to operate, and the operating starter motor will then rotate the engine's high-pressure rotor via a transmission device (e.g., a driveshaft). This allows the high-pressure rotor to reach a higher speed in the shortest possible time.

[0052] In a preferred embodiment of this disclosure, considering that excessively high starter speed will lead to excessively high starter temperature, thereby increasing starter wear and reducing starter life, method 100 may further control the air flow rate from the air source after the high-pressure rotor speed reaches a certain value so that the starter no longer receives the maximum air flow rate, thereby no longer rotating at the maximum possible power to prevent the starter temperature from becoming too high. Thus, in this example, method 100 may include controlling the valve opening in response to the high-pressure rotor speed to maintain the high-pressure rotor speed within a predetermined speed range. According to this example, the predetermined speed range may be 10-15% of the rated speed of the engine's high-pressure rotor. It will be understood that this speed range is merely an example, and those skilled in the art can set any suitable speed range, which will not be elaborated here. In another embodiment of this disclosure, the predetermined speed range may include only a single value, such as 10%, 12%, etc., of the rated speed. In this embodiment, an appropriate error range may be allowed; for example, if the high-pressure rotor speed is 10.1% of the rated speed, it may also be considered to meet 10% of the rated speed.

[0053] Further according to this embodiment, controlling the valve opening to maintain the high-pressure rotor speed within a predetermined speed range may include: reducing the valve opening when the high-pressure rotor speed exceeds the upper limit of the predetermined speed range; and increasing the valve opening when the high-pressure rotor speed is below the lower limit of the predetermined speed range. In this embodiment, the reduction and / or increase of the valve opening may be performed in predetermined steps, such as reducing or increasing by 1%, 1.5%, etc., each time. After each adjustment of the valve opening, a predetermined time is waited, and then adjustments are continued based on the high-pressure rotor speed. It will be understood that the predetermined step size can be any suitable value. Alternatively, the reduction and / or increase of the valve opening may be performed continuously, for example, reducing or increasing the valve opening at a rate of 0.1% per second. Regardless of how the valve opening is adjusted, once the high-pressure rotor speed falls within the predetermined speed range, the adjustment of the valve opening is stopped so that the high-pressure rotor speed is stabilized within this speed range.

[0054] In another embodiment of this disclosure, the valve is not initially fully opened, but rather opened to a predetermined degree based on a predetermined speed range and the airflow pressure from the air source. In this embodiment, this predetermined opening degree is associated with a predetermined speed range and airflow pressure, such that at this predetermined opening degree, the speed of the engine's high-pressure rotor will necessarily fall within the predetermined speed range. According to this embodiment, the relationship between the valve opening degree and the high-pressure rotor speed, and the airflow pressure from the air source, can be collected during factory testing and stored in a lookup table in the aircraft's onboard storage device. Thus, method 100, using airflow from the air source to drive the starter, may optionally include opening the valve to a predetermined degree below full opening, said predetermined opening degree being associated with the predetermined speed range and airflow pressure. Furthermore, the predetermined opening degree can be looked up from the lookup table based on the airflow pressure and the predetermined speed range. It will be understood that a suitable predetermined opening degree can be derived from the lookup table using methods such as interpolation and closest values. For example, if the lookup table only includes predetermined openings corresponding to 2.5 bar and 2.6 bar airflow pressures, for a 2.58 bar airflow pressure, the predetermined opening corresponding to the 2.6 bar claim can be selected using the closest value method, or any suitable interpolation algorithm can be applied to the two predetermined openings corresponding to 2.5 bar and 2.6 bar airflow pressures respectively to calculate the appropriate opening. Subsequently, method 100 can continuously monitor the rotational speed of the engine high-pressure rotor and dynamically adjust the valve opening to maintain the rotational speed of the high-pressure rotor within a predetermined speed range.

[0055] In another embodiment of this disclosure, the air source can be any suitable airflow source, such as one selected from the aircraft's ignition engine and APU. Considering that the ignition engine itself also needs to operate normally, and that activating cross-bleed air (i.e., using the ignition engine as the air source) would have some impact on it, to prevent adverse effects on the still-operating engine, method 100 may further include first determining the airflow pressure of the aircraft's ignition engine, and selecting the ignition engine as the air source only if the airflow pressure is higher than a predetermined threshold. This allows the rotor jamming or lock-up problem to be resolved without activating auxiliary devices (e.g., the APU).

[0056] However, if the airflow pressure from the ignited aircraft engine does not exceed a predetermined threshold, method 100 may select the APU as the air source. Of course, method 100 may also default to using the APU as the air source, thus eliminating the need to make any determination regarding the airflow pressure of the ignited aircraft engine.

[0057] Continue to refer to Figure 1Method 100 may include determining in block 140 that the aircraft has entered the start-up envelope, and in block 150, performing an in-flight start-up procedure in accordance with the aircraft's flight manual.

[0058] In another embodiment of this disclosure, if in block 120, method 100 determines that the aircraft is not outside the start envelope, then method 100 may skip the steps described in blocks 130 and 140 and proceed directly to block 150, where the in-flight start procedure is performed according to the aircraft flight manual.

[0059] Thus, the method 100 of this disclosure can, when the aircraft experiences an engine failure at high altitude and drifts outside the starting envelope, open the valve between the air source and the starter motor, using airflow from the air source through the gas pipeline to drive the starter motor. This allows the starter motor to maintain the rotation of the engine's high-pressure rotor via a transmission device, thereby maintaining the internal airflow velocity, accelerating heat dissipation within the core engine, and preventing the high-pressure rotor speed from continuously decreasing or even seizing. The engine's high-pressure rotor maintains this speed until the aircraft enters the in-flight starting envelope, thus executing the in-flight starting procedure according to the aircraft's flight manual. Preferably, the predetermined speed range is not selected to be too high or too low, because too low a speed will result in insufficient cold air intake, failing to achieve the expected cooling effect; too high a speed will result in excessively high starter motor temperature, increasing starter motor wear and reducing starter motor life. In this way, the method of this disclosure, after the aircraft experiences an engine failure in flight but before entering the starting envelope, uses airflow from the air source to maintain a certain speed of the engine's high-pressure rotor, thus avoiding the risk of rotor lock-up or jamming.

[0060] refer to Figure 3 The diagram illustrates a schematic of an air-start system 300 for an aircraft engine according to an example embodiment of the present disclosure.

[0061] like Figure 3 As shown, system 300 may include a starter 301, an air source 303, and an engine control system 305. Although Figure 3 The system 300 is shown to include the three components described above because these components are relevant to the system of this disclosure, but the system 300 may also include any other suitable components. Furthermore, the aforementioned components may also be broken down into any suitable sub-components, as long as they perform the corresponding functions.

[0062] In one embodiment of this disclosure, the starter 301 can be coupled to the high-pressure rotor of the aircraft engine via a transmission mechanism. For example, as... Figure 3 As shown, the starter 301 is coupled to the high-pressure rotor 311 of the aircraft engine via a transmission mechanism 309. In this embodiment, the air source can be coupled to the starter via a valve. For example, as... Figure 3As shown, the air source 303 is coupled to the starter 301 via valve 307. Of course, there is also an airflow passage (such as...) between the air source 303 and the starter 301 via valve 307. Figure 3 (As shown by reference numeral 313 in the attached figure), it is used to deliver airflow from air source 303 to starter 301.

[0063] In yet another embodiment of this disclosure, the engine control system 305 may be arranged to: determine that at least one of the aircraft engines has failed in-flight; determine that the aircraft is outside the start-up envelope; open valve 307 to use airflow from air source 303 to drive starter 301 to rotate the high-pressure rotor 311 of the failed aircraft engine; determine that the aircraft has entered the start-up envelope; and execute an in-flight start-up procedure according to the aircraft flight manual.

[0064] In another embodiment of this disclosure, the air source 303 may be selected from the aircraft's ignition engine and APU. According to this embodiment, the engine control system 305 may also be arranged to: determine the airflow pressure of the ignition engine; select the ignition engine as the air source if the airflow pressure is higher than a predetermined threshold; otherwise, select the APU as the air source. Of course, the system 300 may also default to using the APU as the air source, thus eliminating the need to determine the airflow pressure of the ignition engine.

[0065] In another embodiment of this disclosure, opening valve 307 to use airflow from air source 303 to drive starter motor 301 may include: fully opening valve 307 to increase the speed of high-pressure rotor 311 at the fastest possible rate; and controlling the opening of valve 307 in response to the speed of high-pressure rotor 311 to maintain the speed of high-pressure rotor 311 within a predetermined speed range. According to this embodiment, engine control system 305 may be arranged to first fully open the valve to increase the speed of high-pressure rotor at the fastest possible rate. For example, after the valve is fully open (in other words, the valve opening is 100%), the maximum airflow from the air source is delivered to the starter motor to drive it, and the operating starter motor then rotates the high-pressure rotor of the engine via a transmission device (e.g., a driveshaft). This allows the high-pressure rotor to reach a higher speed in the shortest possible time.

[0066] In a preferred embodiment of this disclosure, considering that excessively high starter speed will lead to excessively high starter temperature, thereby increasing starter wear and reducing starter life, the engine control system 305 may also be arranged to control the air flow from the air source 303 after the high-pressure rotor 311 reaches a certain speed so that the starter 301 no longer receives the maximum air flow, thereby no longer rotating at the maximum possible power to prevent the starter temperature from becoming too high. Thus, in this example, the engine control system 305 may also be arranged to control the opening of the valve 307 in response to the high-pressure rotor 311 speed, so that the high-pressure rotor 311 speed is maintained within a predetermined speed range. According to this example, the predetermined speed range may be 10-15% of the rated speed of the engine's high-pressure rotor. It will be understood that this speed range is merely an example, and those skilled in the art can set any suitable speed range, which will not be elaborated here. In another embodiment of this disclosure, the predetermined speed range may include only a single value, such as 10%, 12%, etc., of the rated speed. In this embodiment, an appropriate error range can be allowed. For example, if the speed of the high-pressure rotor is 10.1% of the rated speed, it can also be considered to meet 10% of the rated speed.

[0067] Further according to this embodiment, controlling the valve opening to maintain the high-pressure rotor speed within a predetermined speed range may include: reducing the valve opening when the high-pressure rotor speed exceeds the upper limit of the predetermined speed range; and increasing the valve opening when the high-pressure rotor speed is below the lower limit of the predetermined speed range. In this embodiment, the reduction and / or increase of the valve opening may be performed in predetermined steps, such as reducing or increasing by 1%, 1.5%, etc., each time. After each adjustment of the valve opening, a predetermined time is waited, and then adjustments are continued based on the high-pressure rotor speed. It will be understood that the predetermined step size can be any suitable value. Alternatively, the reduction and / or increase of the valve opening may be performed continuously, for example, reducing or increasing the valve opening at a rate of 0.1% per second. Regardless of how the valve opening is adjusted, once the high-pressure rotor speed falls within the predetermined speed range, the adjustment of the valve opening is stopped so that the high-pressure rotor speed is stabilized within this speed range.

[0068] In another embodiment of this disclosure, the valve is not initially fully opened, but rather opened to a predetermined degree based on a predetermined speed range and the airflow pressure from the air source. In this embodiment, this predetermined opening degree is associated with a predetermined speed range and airflow pressure, such that at this predetermined opening degree, the speed of the engine's high-pressure rotor will necessarily fall within the predetermined speed range. According to this embodiment, the relationship between the valve opening degree and the high-pressure rotor speed, and the airflow pressure from the air source, can be collected during factory testing and stored in a lookup table in the aircraft's onboard storage. Thus, in this embodiment, opening valve 307 to use airflow from air source 303 to drive starter 301 may include opening valve 307 to a predetermined degree below full opening, wherein the predetermined opening degree is associated with a predetermined speed range and airflow pressure, and wherein the predetermined opening degree is obtained by looking up the value from the lookup table based on the airflow pressure and the predetermined speed range. It will be understood that a suitable predetermined opening degree can be derived from the lookup table using methods such as interpolation and closest values. For example, if the lookup table only includes predetermined openings corresponding to airflow pressures of 2.5 bar and 2.6 bar, for an airflow pressure of 2.58 bar, the predetermined opening corresponding to the 2.6 bar claim can be selected using the closest value method, or any suitable interpolation algorithm can be applied to the two predetermined openings corresponding to airflow pressures of 2.5 bar and 2.6 bar respectively to calculate a suitable opening. Subsequently, the system 300 can continuously monitor the rotational speed of the engine's high-pressure rotor and dynamically adjust the valve opening to maintain the high-pressure rotor's rotational speed within a predetermined range.

[0069] In yet another embodiment of this disclosure, the engine control system 305 may be a full authority digital engine control system.

[0070] refer to Figure 4 The illustration shows a schematic diagram of an aircraft 400 according to an exemplary embodiment of the present disclosure. In one embodiment, the aircraft 400 may include an in-flight engine start-up system as described in the above embodiments of the present disclosure, such as in conjunction with... Figure 3 The system 300 is described above.

[0071] It will be understood that the term "high-pressure rotor" is a common term in the field of aero-engines, referring to the rotor in an aero-engine that is subjected to and / or generates high-pressure airflow and rotates at a high speed.

[0072] In this disclosure, the terms "engine" and "aircraft engine" are used interchangeably.

[0073] The above detailed description includes references to the accompanying drawings, which form part of the detailed description. The drawings illustrate specific embodiments that can be practiced by way of illustration. These embodiments are also referred to herein as “examples.” Such examples may include elements other than those shown or described. However, examples including the shown or described elements are also contemplated. Furthermore, examples of any combination or arrangement of those elements shown or described are contemplated, or with reference to specific examples (or one or more aspects thereof) shown or described herein, or with reference to other examples (or one or more aspects thereof) shown or described herein.

[0074] In the appended claims, the terms “comprising” and “including” are open-ended, meaning that a system, apparatus, article of manufacture, or process containing elements other than those listed after such terms in a claim is still considered to fall within the scope of that claim. Furthermore, in the appended claims, the terms “first,” “second,” and “third,” etc., are used merely as designations and are not intended to indicate a numerical order of their contents.

[0075] Furthermore, the order of operations described in this specification is exemplary. In alternative embodiments, the operations may be performed in a different order than that shown in the accompanying drawings, and the operations may be combined into a single operation or broken down into more operations.

[0076] The above description is intended to be illustrative and not restrictive. For example, the examples described above (or one or more aspects thereof) may be used in conjunction with other embodiments. Other embodiments may be used by those skilled in the art after reviewing the above description. The abstract allows the reader to quickly determine the nature of this technical disclosure. This abstract is submitted and it is understood that it is not intended to interpret or limit the scope or meaning of the claims. Furthermore, in the above detailed description, various features may be grouped together to make this disclosure flow smoothly. However, the claims may not state every feature disclosed herein, as embodiments may characterize a subset of said features. Furthermore, embodiments may include fewer features than those disclosed in a particular example. Therefore, the appended claims are thus incorporated into the detailed description, with each claim existing independently as a separate embodiment. The scope of the embodiments disclosed herein should be determined by reference to the full scope of the appended claims and equivalents of such claims.

Claims

1. A method for in-flight starting of an aircraft engine, comprising: Determine if at least one of the aircraft's engines in flight fails in mid-air; It was determined that the aircraft was outside the launch envelope; An airflow from an air source is used to drive the starter motor, which turns the high-pressure rotor of an aircraft engine that has shut down in mid-air. Determining that the aircraft enters the launch envelope; and Perform the in-flight start-up procedure according to the aircraft's flight manual.

2. The method according to claim 1, characterized in that, Determining whether an aircraft engine has experienced in-flight engine failure involves analyzing the engine's rotational speed and exhaust temperature.

3. The method according to claim 1, characterized in that, The determination that the aircraft is outside the launch envelope includes making the determination based on the aircraft's current flight speed and flight altitude.

4. The method according to claim 1, characterized in that, Using airflow from an air source to drive the starter motor involves opening a valve between the air source and the starter motor to allow airflow from the air source to be delivered to the starter motor.

5. The method according to claim 4, characterized in that, It also includes fully opening the valve to increase the speed of the high-pressure rotor at the fastest possible rate.

6. The method according to claim 5, characterized in that, It also includes controlling the opening of the valve in response to the rotational speed of the high-pressure rotor, so that the rotational speed of the high-pressure rotor is maintained within a predetermined rotational speed range.

7. The method according to claim 6, characterized in that, Controlling the opening of the valve to maintain the rotational speed of the high-pressure rotor within the predetermined speed range includes: When the rotational speed of the high-pressure rotor exceeds the upper limit of the predetermined rotational speed range, the opening degree of the valve is reduced; and When the rotational speed of the high-pressure rotor is lower than the lower limit of the predetermined rotational speed range, the opening degree of the valve is increased.

8. The method according to claim 7, characterized in that, The valve opening is reduced and / or increased in predetermined steps or continuously.

9. The method according to claim 4, characterized in that, It also includes opening the valve to a predetermined opening degree below full opening, the predetermined opening degree being associated with a predetermined speed range and airflow pressure.

10. The method according to claim 9, characterized in that, The predetermined opening degree is determined by searching a lookup table using the airflow pressure and the predetermined speed range as keywords.

11. The method according to claim 4, characterized in that, The gas source is selected from either the aircraft's ignition engine or its APU.

12. The method according to claim 11, characterized in that, Also includes: Determine the airflow pressure of the undisturbed aircraft engine; If the airflow pressure is higher than a predetermined threshold, the unextinguished aircraft engine is selected as the air source; Otherwise, the APU is selected as the gas source.

13. A system for in-flight starting of an aircraft engine, comprising: A starter motor, which is coupled to the high-pressure rotor of the aircraft engine via a transmission mechanism; An air source, which is coupled to the starter motor via a valve; as well as Engine control system; The engine control system is arranged as follows: Determine that at least one of the aircraft engines fails to fire in mid-air; Determine that the aircraft is outside the launch envelope; The valve is opened to use the airflow from the air source to drive the starter motor, thereby turning the high-pressure rotor of the aircraft engine that has been shut down in mid-air. Determining that the aircraft enters the launch envelope; and Perform the in-flight start-up procedure according to the aircraft's flight manual.

14. The system according to claim 13, characterized in that, The gas source is selected from either the aircraft's ignition engine or its APU.

15. The system according to claim 14, characterized in that, The engine control system is also arranged as follows: Determine the airflow pressure of the undisturbed aircraft engine; If the airflow pressure is higher than a predetermined threshold, the unextinguished aircraft engine is selected as the air source; Otherwise, the APU is selected as the gas source.

16. The system according to claim 13, characterized in that, Opening the valve to use an airflow from the air source to drive the starter includes: The valve is fully opened to allow the high-pressure rotor to increase its speed at the fastest possible rate; and The valve opening is controlled in response to the rotational speed of the high-pressure rotor so that the rotational speed of the high-pressure rotor is maintained within a predetermined speed range.

17. The system according to claim 13, characterized in that, Opening the valve to use an airflow from the air source to drive the starter includes: The valve is opened to a predetermined degree below full opening, the predetermined degree being associated with a predetermined speed range and an airflow pressure, wherein the predetermined degree is obtained by looking up a table based on the airflow pressure and the predetermined speed range.

18. The system according to claim 13, characterized in that, The engine control system is a full authority digital engine control system.

19. An aircraft comprising the system according to any one of claims 13-18.

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