Aerial starting method and system for aero-engine

Abstract

The invention relates to an aero-engine air starting method and system. The method includes: determining that at least one of aero-engines of an aircraft in flight is off in the air; determining that the aircraft is outside a starting envelope; the starter is driven by air flow from an air source, so that a high-pressure rotor of the aero-engine which is shut down in the air rotates; determining that the aircraft enters the starting envelope; and executing an air start procedure according to the aircraft flight manual.

Description

Technical Field

[0001] The present disclosure relates to the field of aircraft engines, and in particular to an in-air starting method and system for aircraft engines. Background Art

[0002] During the operation of an aircraft, the engine may flame out in the air if it encounters unexpected disturbances (such as fuel contamination, loss of power, extreme weather or crew erroneous operation, etc.), or it may be forced to flame out for a short period of time due to other reasons. In order to ensure the flight power and safe operation of the aircraft, the engine needs to be started in the air. The methods of starting the engine in the air usually include 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 air starting speed to achieve air ignition starting.

[0003] When an aircraft engine stalls in the air, due to its own design features and special operating environment, the engine may not be able to ignite and start successfully for various reasons, endangering flight safety.

[0004] The present disclosure has been improved with respect to but not limited to the above-mentioned factors. Summary of the invention

[0005] To this end, the present disclosure provides an aircraft engine air start method and system. In the technical solution of the present disclosure, after determining that the engine is flameout in the air based on flight parameters and engine operating parameters, the high-pressure rotor of the flameout engine is continuously driven by the starter, so that the rotation speed of the high-pressure rotor is maintained within a predetermined rotation speed range, thereby driving more cold air gas into the internal flow channel, so that the interior obtains a better cooling effect, and prevents the engine from failing to start in the air due to rotor blockage or rotor lock. Therefore, the method and system of the present disclosure only use existing aircraft equipment (such as auxiliary power units, other engines that are not flameouted, etc.) to solve the problem that rotor lock or rotor blockage may cause the failure of the engine to start in the air, without increasing the demand for additional equipment. At the same time, the method and system of the present disclosure effectively improve the success rate of the engine air start and improve flight safety.

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

[0007] According to an embodiment, determining whether the aircraft engine has flamed out in mid-air includes determining whether the aircraft engine has flamed out in mid-air based on a rotation speed and an exhaust temperature of the aircraft engine.

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

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

[0010] According to yet another embodiment, the method further comprises fully opening the valve so that the rotation speed of the high-pressure rotor is increased at the fastest rate.

[0011] According to yet another embodiment, the method further comprises 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 so that the rotational speed of the high-pressure rotor is maintained within the predetermined speed range includes: when the rotational speed of the high-pressure rotor exceeds the upper limit of the predetermined speed range, reducing the opening of the valve; and when the rotational speed of the high-pressure rotor is lower than the lower limit of the predetermined speed range, increasing the opening of the valve.

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

[0014] According to yet another embodiment, the method further comprises opening the valve to a predetermined opening degree less than fully open, the predetermined opening degree being associated with a predetermined speed range and air flow pressure.

[0015] According to yet another embodiment, the predetermined opening degree is searched from a lookup table using the air flow pressure and the predetermined rotation speed range as keywords.

[0016] According to yet another embodiment, the air source is one selected from an unextinguished aircraft engine and an APU of the aircraft.

[0017] According to another embodiment, the method further includes: determining the airflow pressure of the aircraft engine that is not turned off; if the airflow pressure is higher than a predetermined threshold, selecting the aircraft engine that is not turned off as the air source; otherwise, selecting the APU as the air source.

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

[0019] According to an embodiment, the air source is one selected from an unextinguished aircraft engine and an APU of the aircraft.

[0020] According to another embodiment, the engine control system is further arranged to: determine the airflow pressure of the aircraft engine that is not turned off; if the airflow pressure is higher than a predetermined threshold, select the aircraft engine that is not turned off as the air source; otherwise select the APU as the air source.

[0021] According to another embodiment, opening the valve to use the 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 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 another embodiment, opening the valve to use the airflow from the air source to drive the starter includes: opening the valve to a predetermined opening degree lower than fully open, wherein the predetermined opening degree is associated with a predetermined speed range and an airflow pressure, and wherein the predetermined opening degree is obtained by looking up from 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 the present disclosure, there is provided an aircraft, comprising a system according to any one of claims 13-18.

[0025] Aspects generally include methods, apparatus, systems, computer program products, and processing systems substantially as described herein with reference to and as illustrated by the accompanying figures.

[0026] The foregoing has broadly outlined the features and technical advantages of examples according to the present disclosure so that the following detailed description can be better understood. Additional features and advantages will be described hereinafter. The disclosed concepts and specific examples can be easily used as the basis for modifying or designing other structures for implementing the same purpose as the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, both in terms of their organization and method of operation, and the associated advantages will be better understood by considering the following description in conjunction with the accompanying drawings. Each of the accompanying drawings is provided for illustration and description purposes and does not define limitations on the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to understand in detail the manner in which the above-stated features of the present disclosure are used, the above briefly summarized content may be described in more detail with reference to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only certain typical aspects of the present disclosure and should not be considered to limit its scope, as the description may allow for other equally effective aspects. The same reference numerals in different drawings may identify the same or similar elements.

[0028] Figure 1 is a flow chart of a method for improving the quality of aviation product technical publications according to an example of an embodiment of the present disclosure;

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

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

[0031] Figure 4 is a schematic diagram of an aircraft according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] Terminology explanation:

[0033] Rotor lock: refers to the rotor speed dropping to zero after the engine is shut down or turned off in the air, and it still cannot rotate under windmill or auxiliary starting.

[0034] Rotor block: refers to the phenomenon that the rotor speed is reduced in the windmill state due to the load of engine accessories connected and the high friction of the rotor / stator.

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

[0036] The inventors recognize that when an aircraft engine flames out in the air, the engine may fail to ignite and start successfully due to various reasons due to its own design features and special operating environment, endangering flight safety. The inventors recognize that the engine may experience rotor lock or rotor block, resulting in the engine rotor speed being lower than the lower limit of the air starting speed, especially in the case of dual engine failure. If the engine cannot be restarted due to rotor lock or blockage, it will have catastrophic consequences for the flight safety of the aircraft.

[0037] The inventors also recognized that modern turbofan engines have a large bypass ratio, usually above 5. Since the internal air flow accounts for a small proportion, in order to ensure normal ignition and starting, a larger windmill speed is required to provide sufficient air flow to drive the engine rotor. When starting without auxiliary devices, this means that a higher airspeed is required. The combustion flame in the annular combustion chamber is irregular, and it is difficult to form a stable flame under the conditions of high-speed and low-temperature airflow in the air, which is not conducive to starting. Design features such as the high-pressure ratio compressor lead to a reduction in the air starting envelope, which increases the time required to restart, resulting in an increased risk of rotor lock or blockage of the engine during the air start process, reducing the success rate of air starts and endangering flight safety.

[0038] To this end, the present disclosure provides an aircraft engine air start method and system. In the technical solution of the present disclosure, after determining that the engine is flameout in the air based on flight parameters and engine operating parameters, the high-pressure rotor of the flameout engine is continuously driven by the starter, so that the rotation speed of the high-pressure rotor is maintained within a predetermined rotation speed range, thereby driving more cold air gas into the internal flow channel, so that the interior obtains a better cooling effect, and prevents the engine from failing to start in the air due to rotor blockage or rotor locking.

[0039] Therefore, the method and system of the present disclosure only utilize existing aircraft equipment (such as auxiliary power units, other engines that are not turned off, etc.) to solve the problem that rotor lock or rotor blocking may cause engine air start failure without adding additional equipment requirements. At the same time, the method and system of the present disclosure effectively improves the success rate of engine air start and improves flight safety.

[0040] The detailed description set forth below 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 may 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 may be practiced without these specific details.

[0041] Reference below Figure 1 , which shows a flow chart of a method 100 for starting an aircraft engine in the air according to an exemplary embodiment of the present disclosure.

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

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

[0044] In another embodiment of the present disclosure, determining whether the aircraft engine flameout occurs in mid-air may include determining whether the aircraft engine flameout occurs in mid-air based on the aircraft engine speed, exhaust temperature, flight altitude, etc. In this embodiment, the 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 may be used to determine the occurrence of the engine flameout in mid-air, which will not be described in detail herein.

[0045] After determining that an engine in-flight flameout has occurred, method 100 may include, at block 120 , determining that the aircraft is outside of a start-up envelope.

[0046] The inventors have realized that after the engine flameout occurs in the air, the engine enters the windmilling state. Starting the engine in the windmilling state is not successful under all flight conditions. The air start of the engine is possible only when the aircraft is within the starting envelope.

[0047] For example, the higher the flight altitude of the aircraft, the lower the pressure and temperature of the air at the combustion chamber inlet, and the more difficult it is to ignite the combustion chamber; the higher the flight speed of the aircraft, the greater the airflow speed at the combustion chamber inlet, the more difficult it is to ignite the mixture of fuel and air, and the engine cannot start. In addition, if the flight speed of the aircraft is too low, the windmill speed is too low. If the fuel supply is low, the turbine output power may be insufficient, resulting in speed suspension during the start process and start failure; if the fuel supply is increased, the temperature before the turbine may be too high or the high-pressure compressor may stall. Therefore, when the flight speed of the aircraft is too low, the engine cannot start in the windmill state. This is the minimum speed boundary for the engine to start in the air in the windmill state. After the flight speed is lower than this boundary, the engine needs to be started with the assistance of a starter to increase the starting speed and starting acceleration capability of the engine. There is also a lower limit to the flight speed that can be reliably started with the assistance of a starter. If the flight speed is lower than this lower limit, the engine speed is too low, or the fuel pressure pumped out by the fuel pump is too low, the fuel cannot be atomized and is difficult to ignite, or the engine may start in a windmill state at the low flight speed boundary, and problems such as speed suspension, excessive temperature before the turbine, and high-pressure compressor stall may occur during the engine starting process.

[0048] Thus, in one embodiment of the present disclosure, determining that the aircraft is outside the start-up envelope may include making a determination based on the current flight speed and flight altitude of the aircraft. Figure 2 FIG. 2 shows a schematic diagram of a starting envelope 200 according to an embodiment of the present disclosure. Figure 2 In the area "enclosed" by the starting envelope 200 and the speed axis), an air start of the engine is possible. Figure 2 A starting envelope 200 of a specific shape is shown, and those skilled in the art will appreciate that the starting envelope may have any suitable shape, which varies with aircraft and engines and will not be described in detail herein.

[0049] The inventors recognize that the methods of starting (or restarting) an engine in the air usually include starter-assisted starting and windmill starting. Whether it is starter-assisted starting or windmill starting, it is necessary to increase the rotor speed to above the lower limit of the air starting speed, so as to achieve air ignition and starting. When an aircraft engine flames out in the air, the engine may experience rotor lock or rotor block due to its own design features and special operating environment, causing the engine rotor speed to be lower than the lower limit of the air starting speed. The engine will not be able to successfully ignite and start, especially in the case of dual engine failure. The engine cannot be restarted due to the rotor jam problem, which will have catastrophic consequences for the flight safety of the aircraft. At the same time, if the crew members are not clearly aware of the impending or already occurring rotor lock condition, they will not be able to make correct judgments and countermeasures, which will also lead to flight accidents.

[0050] So, continue to refer to Figure 1 The method 100 may include, at block 130, using the airflow from the air source to drive the starter to rotate the high-pressure rotor of the aircraft engine that has been shut down in the air. In this way, the high-pressure rotor of the engine is continuously driven by the starter, so that the rotation speed of the high-pressure rotor is maintained at a relatively high state (higher than the windmill speed), thereby driving more cooling gas into the internal flow passage of the engine, so that the engine can obtain a better cooling effect, and slow down or prevent the occurrence of rotor blockage or rotor lock.

[0051] In one embodiment of the present disclosure, using the airflow from the air source to drive the starter may include opening the valve between the air source and the starter so that the airflow from the air source can be delivered to the starter. Further according to this embodiment, method 100 may first fully open the valve so that the rotation speed of the high-pressure rotor is increased at the fastest rate. For example, after the valve is fully opened (in other words, the valve opening reaches 100%), the maximum airflow flow from the air source will be delivered to the starter to drive the starter to operate, and the operating starter will then rotate the high-pressure rotor of the engine through a transmission device (e.g., a transmission shaft). In this way, the high-pressure rotor can reach a higher speed in the shortest time.

[0052] In a preferred embodiment of the present disclosure, considering that too high a speed of the starter will cause the temperature of the starter to be too high, thereby increasing the loss of the starter and reducing the life of the starter, the method 100 can also control the air flow from the air source after the speed of the high-pressure rotor reaches a certain value so that the starter no longer receives the maximum air flow, so that it no longer rotates at the maximum possible power to prevent the starter temperature from being too high. Thus, in this example, the method 100 may include controlling the opening of the valve in response to the speed of the high-pressure rotor so that the speed of the high-pressure rotor is maintained within a predetermined speed range. According to this example, the predetermined speed range may be a range of 10-15% of the rated speed of the high-pressure rotor of the engine. It will be understood that this speed range is only an example, and those skilled in the art can set any suitable speed range, which will not be repeated here. In another embodiment of the present 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 speed of the high-pressure rotor is 10.1% of the rated speed, it can also be considered that it meets 10% of the rated speed.

[0053] Further according to this embodiment, controlling the opening of the valve so that the rotational speed of the high-pressure rotor is maintained within a predetermined speed range may include: reducing the opening of the valve when the rotational speed of the high-pressure rotor exceeds the upper limit of the predetermined speed range; and increasing the opening of the valve when the rotational speed of the high-pressure rotor is lower than the lower limit of the predetermined speed range. In this embodiment, the reduction and / or increase of the opening of the valve may be carried out according to a predetermined step size, such as reducing or increasing by 1%, 1.5%, etc. each time. After each adjustment of the valve opening, wait for a predetermined time, and then continue to adjust based on the rotational speed of the high-pressure rotor. It will be understood that the predetermined step size may be any suitable value. Alternatively, the reduction and / or increase of the opening of the valve may be carried out continuously, such as reducing or increasing the valve opening at a rate of 0.1% per second. Regardless of how the valve opening is adjusted, once the rotational speed of the high-pressure rotor falls within the predetermined speed range, the valve opening is stopped from being adjusted so that the rotational speed of the high-pressure rotor is stabilized within this speed range.

[0054] In another embodiment of the present disclosure, the valve is not fully opened at the beginning, but the valve can be opened to a predetermined opening according to a predetermined speed range and a gas flow pressure from an air source. In this embodiment, this predetermined opening is associated with a predetermined speed range and a gas flow pressure, so that at this predetermined opening, the speed of the engine high-pressure rotor will inevitably fall within the predetermined speed range. According to this embodiment, the relationship between the valve opening and the speed of the high-pressure rotor and the gas flow pressure from the gas source can be collected during factory testing, and the relationship can be made into a lookup table to be stored in an onboard storage device of the aircraft. Thus, the method 100 using the gas flow from the gas source to drive the starter can optionally include opening the valve to a predetermined opening lower than fully opened, and the predetermined opening is associated with a predetermined speed range and a gas flow pressure. Moreover, the predetermined opening can be found from a lookup table based on the gas flow pressure and the predetermined speed range. It will be understood that a suitable predetermined opening can be derived from the lookup table by interpolation, nearest value, etc. For example, in the case where the lookup table only includes the predetermined openings corresponding to the airflow pressures of 2.5 bar and 2.6 bar, for the airflow pressure of 2.58 bar, the predetermined opening corresponding to the 2.6 bar claim can be selected according to the closest value method, or any suitable interpolation algorithm can be applied to the two predetermined openings corresponding to the airflow pressures of 2.5 bar and 2.6 bar to calculate the appropriate opening. Subsequently, the method 100 can continuously monitor the speed of the high-pressure rotor of the engine and dynamically adjust the valve opening to maintain the speed of the high-pressure rotor within the predetermined speed range.

[0055] In another embodiment of the present disclosure, the air source may be any suitable airflow source, for example, it may be one selected from an unextinguished aircraft engine and an APU of the aircraft. Considering that the unextinguished aircraft engine itself also needs to work normally, and turning on the cross bleed air (i.e., using the unextinguished aircraft engine as the air source) will have a certain impact on the unextinguished aircraft engine, so in order to prevent adverse effects on the aircraft engine that is still working normally, the method 100 may also include first determining the airflow pressure of the unextinguished aircraft engine of the aircraft, and only selecting the unextinguished aircraft engine as the air source when the airflow pressure is higher than a predetermined threshold. In this way, the problem of rotor blocking or locking can be solved without turning on an auxiliary device (e.g., APU).

[0056] However, if the airflow pressure from the aircraft engine that is not turned off is not higher than the predetermined threshold, the method 100 can select the APU as the air source. Of course, the method 100 can also use the APU as the air source by default, so that there is no need to make any determination on the airflow pressure of the aircraft engine that is not turned off.

[0057] Continue to refer Figure 1, the method 100 may include determining that the aircraft is within the start envelope at block 140 , and executing an in-flight start procedure in accordance with the aircraft flight manual at block 150 .

[0058] In yet another embodiment of the present disclosure, if the method 100 determines in frame 120 that the aircraft is not outside the start envelope, the method 100 may not perform the steps described in frames 130 and 140, but directly proceed to frame 150, where an air start procedure is performed according to the aircraft flight manual.

[0059] In this way, the method 100 disclosed in the present invention can open the valve between the gas source and the starter when the aircraft encounters an engine flameout at high altitude and drifts outside the starting envelope, and use the airflow from the gas source to drive the starter through the gas pipeline, so that the starter maintains the rotation of the engine high-pressure rotor through the transmission device, thereby maintaining the internal air flow speed, accelerating the heat dissipation inside the core engine, and avoiding the high-pressure rotor speed from continuously decreasing or even getting stuck. The engine high-pressure rotor maintains this speed until the aircraft enters the air starting envelope, so as to perform the air starting procedure according to the aircraft flight manual. Preferably, the predetermined speed range will not be selected to be too high or too low, because too low a speed will lead to insufficient cold air intake and fail to achieve the expected cooling effect; too high a speed will lead to too high a temperature of the starter, increase the starter loss, and reduce the life of the starter. In this way, the method disclosed in the present invention uses the airflow from the gas source to keep the high-pressure rotor of the engine at a certain speed after the aircraft encounters an engine shutdown in the air and before entering the starting envelope, thereby avoiding the risk of rotor locking or blocking.

[0060] refer to Figure 3 , which shows a schematic diagram of a system 300 for starting an aircraft engine in the air according to an exemplary 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. Figure 3 The system 300 is shown to include the above three components because these components are components related to the system of the present disclosure, but the system 300 may also include any other suitable components. Furthermore, the above components may also be split into any suitable subcomponents as long as they implement corresponding functions.

[0062] In one embodiment of the present disclosure, the starter 301 may be coupled to the high pressure rotor of the aircraft engine via a transmission mechanism. Figure 3 As shown, the starter 301 is coupled to the high pressure rotor 311 of the aircraft engine through the transmission mechanism 309. In this embodiment, the air source can be coupled to the starter through a valve. Figure 3As shown, the gas source 303 is coupled to the starter 301 through the valve 307. Of course, there is also an air flow channel (such as a valve 307) between the gas source 303 and the starter 301. Figure 3 313 in the figure), which is used to deliver the air flow from the air source 303 to the starter 301.

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

[0064] In another embodiment of the present disclosure, the air source 303 may be one selected from an aircraft engine that is not turned off and an APU. According to this embodiment, the engine control system 305 may also be arranged to: determine the airflow pressure of the aircraft engine that is not turned off; if the airflow pressure is higher than a predetermined threshold, select the aircraft engine that is not turned off as the air source; otherwise select the APU as the air source. Of course, the system 300 may also use the APU as the air source by default, so that there is no need to make any determination on the airflow pressure of the aircraft engine that is not turned off.

[0065] In another embodiment of the present disclosure, opening the valve 307 to drive the starter 301 with the airflow from the air source 303 may include: fully opening the valve 307 to increase the speed of the high-pressure rotor 311 at the fastest rate; and controlling the opening of the valve 307 in response to the speed of the high-pressure rotor 311 so that the speed of the high-pressure rotor 311 is maintained within a predetermined speed range. According to this embodiment, the engine control system 305 may be arranged to first fully open the valve to increase the speed of the high-pressure rotor at the fastest rate. For example, after the valve is fully opened (in other words, the valve opening reaches 100%), the maximum airflow flow from the air source will be delivered to the starter to drive the starter to operate, and the operating starter will then rotate the high-pressure rotor of the engine through a transmission device (e.g., a transmission shaft). In this way, the high-pressure rotor can reach a higher speed in the shortest time.

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

[0067] Further according to this embodiment, controlling the opening of the valve so that the rotational speed of the high-pressure rotor is maintained within a predetermined speed range may include: reducing the opening of the valve when the rotational speed of the high-pressure rotor exceeds the upper limit of the predetermined speed range; and increasing the opening of the valve when the rotational speed of the high-pressure rotor is lower than the lower limit of the predetermined speed range. In this embodiment, the reduction and / or increase of the opening of the valve may be carried out according to a predetermined step size, such as reducing or increasing by 1%, 1.5%, etc. each time. After each adjustment of the valve opening, wait for a predetermined time, and then continue to adjust based on the rotational speed of the high-pressure rotor. It will be understood that the predetermined step size may be any suitable value. Alternatively, the reduction and / or increase of the opening of the valve may be carried out continuously, such as reducing or increasing the valve opening at a rate of 0.1% per second. Regardless of how the valve opening is adjusted, once the rotational speed of the high-pressure rotor falls within the predetermined speed range, the valve opening is stopped from being adjusted so that the rotational speed of the high-pressure rotor is stabilized within this speed range.

[0068] In another embodiment of the present disclosure, the valve is not fully opened at the beginning, but can be opened to a predetermined opening according to a predetermined speed range and the airflow pressure from the air source. In this embodiment, this predetermined opening is associated with a predetermined speed range and airflow pressure, so that at this predetermined opening, the speed of the high-pressure rotor of the engine will inevitably fall within the predetermined speed range. According to this embodiment, the relationship between the valve opening and the speed of the high-pressure rotor and the airflow pressure from the air source can be collected during factory testing, and it can be made into a lookup table to be stored in the onboard storage device of the aircraft. Thus, in this embodiment, opening the valve 307 to drive the starter 301 using the airflow from the air source 303 can include: opening the valve 307 to a predetermined opening lower than the fully opened, wherein the predetermined opening is associated with a predetermined speed range and the pressure of the airflow, and wherein the predetermined opening is found from the lookup table based on the airflow pressure and the predetermined speed range. It will be understood that a suitable predetermined opening can be derived from the lookup table by interpolation, nearest value, etc. For example, in the case where the lookup table only includes the predetermined openings corresponding to the airflow pressures of 2.5 bar and 2.6 bar, for the airflow pressure of 2.58 bar, the predetermined opening corresponding to the 2.6 bar claim can be selected according to the nearest value method, or any suitable interpolation algorithm can be applied to the two predetermined openings corresponding to the airflow pressures of 2.5 bar and 2.6 bar to calculate the appropriate opening. Subsequently, the system 300 can continuously monitor the speed of the high-pressure rotor of the engine and dynamically adjust the valve opening to maintain the speed of the high-pressure rotor within the predetermined speed range.

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

[0070] refer to Figure 4 , which 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 aircraft engine air starting system according to the above embodiments of the present disclosure, such as a combination of Figure 3 The system 300.

[0071] It will be understood that the term “high pressure rotor” is a commonly used term in the field of aircraft engines, ie a rotor in an aircraft engine that is subjected to and / or generates airflow at a higher pressure and rotates at a higher 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 accompanying 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 elements shown or described are also contemplated. In addition, examples using any combination or arrangement of those elements shown or described are also contemplated, or with reference to the 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 "including" and "comprising" are open ended, that is, systems, devices, articles, or processes having elements other than those elements listed after such terms in a claim are still deemed to fall within the scope of that claim. Furthermore, in the appended claims, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to indicate a numerical order to their objects.

[0075] In addition, the order of each operation explained in this specification is exemplary. In alternative embodiments, each operation can be performed in a different order than that shown in the drawings, and each operation can be combined into a single operation or split into more operations.

[0076] The above description is intended to be illustrative, 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, such as by a person of ordinary skill in the art, after reviewing the above description. The abstract allows the reader to quickly determine the nature of the present technology disclosure. The abstract is submitted, and it is understood that the abstract will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above specific embodiments, various features may be grouped together to make the disclosure fluent. However, the claims may not state every feature disclosed herein, because the embodiments may characterize a subset of the features. In addition, the embodiments may include fewer features than those disclosed in a particular example. Therefore, the attached claims are thus incorporated into the specific embodiments, and a claim exists independently as a separate embodiment. The scope of the embodiments disclosed herein should be determined with reference to the attached claims and the full scope of equivalents to which such claims are entitled.

Claims

1. A method for starting an aircraft engine in mid-air, comprising: Determining that at least one of the aircraft engines of an aircraft in flight has flamed out in mid-flight; determining that the aircraft is outside a starting envelope; Using air flow from an air source to drive a starter to rotate a high pressure rotor of an aircraft engine that has stalled in mid-air; determining that the aircraft enters the start-up envelope; and Perform air start procedures in accordance with the aircraft flight manual.

2. The method according to claim 1, characterized in that Determining whether an aircraft engine has flamed out in mid-air includes determining whether the aircraft engine has flamed out in mid-air based on the aircraft engine speed and exhaust temperature.

3. The method according to claim 1, characterized in that Determining that the aircraft is outside of a startup envelope includes making the determination based on a current flight speed and a flight altitude of the aircraft.

4. The method according to claim 1, characterized in that: Using the air flow from the air source to drive the starter includes opening a valve between the air source and the starter to enable the air flow from the air source to be delivered to the starter.

5. The method according to claim 4, characterized in that The method also includes fully opening the valve to increase the rotation speed of the high-pressure rotor at the fastest 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 so that the rotation speed of the high-pressure rotor is maintained within the predetermined rotation speed range includes: When the rotation speed of the high-pressure rotor exceeds the upper limit of the predetermined rotation speed range, reducing the opening of the valve; and When the rotation speed of the high-pressure rotor is lower than the lower limit of the predetermined rotation speed range, the opening of the valve is increased.

8. The method according to claim 7, characterized in that The reduction and / or increase of the opening of the valve is performed in a predetermined step size or continuously.

9. The method according to claim 4, characterized in that The method further includes opening the valve to a predetermined opening degree less than fully open, wherein the predetermined opening degree is associated with a predetermined speed range and air flow pressure.

10. The method according to claim 9, characterized in that The predetermined opening degree is searched from a lookup table using the air flow pressure and the predetermined rotation speed range as keywords.

11. The method according to claim 4, characterized in that The air source is one selected from an unextinguished aircraft engine and an APU of the aircraft.

12. The method according to claim 11, characterized in that Also includes: Determining the airflow pressure of the aircraft engine that is not turned off; When the airflow pressure is higher than a predetermined threshold, selecting the aircraft engine that has not been turned off as the air source; Otherwise, the APU is selected as the air source.

13. A system for starting an aircraft engine in mid-air, comprising: A starter, wherein the starter is coupled to a high-pressure rotor of an aircraft engine through a transmission mechanism; an air source, the air source being coupled to the starter via a valve; as well as Engine control systems; The engine control system is arranged to: determining that at least one of the aircraft engines has flamed out in mid-air; Make sure the aircraft is outside the starting envelope; Opening the valve to drive the starter using the air flow from the air source to rotate the high-pressure rotor of the aircraft engine that has been shut down in the air; determining that the aircraft enters the start-up envelope; and Perform air start procedures in accordance with the aircraft flight manual.

14. The system according to claim 13, characterized in that The air source is one selected from an unextinguished aircraft engine and an APU of the aircraft.

15. The system according to claim 14, characterized in that The engine control system is also arranged to: Determining the airflow pressure of the aircraft engine that is not turned off; When the airflow pressure is higher than a predetermined threshold, selecting the aircraft engine that has not been turned off as the air source; Otherwise, the APU is selected as the air source.

16. The system according to claim 13, characterized in that Opening the valve to use the air flow 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 rate; and The opening of the valve 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 rotational speed range.

17. The system according to claim 13, characterized in that Opening the valve to use the air flow from the air source to drive the starter includes: The valve is opened to a predetermined opening degree less than fully opened, the predetermined opening degree being associated with a predetermined speed range and an air flow pressure, and wherein the predetermined opening degree is looked up from a lookup table based on the air flow 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 a system according to any one of claims 13-18.

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