A method and device for controlling the left-boundary afterburner connection of a turbofan engine at high altitude

Abstract

The present application belongs to the field of engine testing technology, and specifically relates to a method and device for controlling afterburner connection at the high altitude left boundary of a turbofan engine. The method comprises step S1, determining whether the aircraft is at the high altitude left boundary based on the aircraft altitude parameter and speed parameter; step S2, determining that the high-pressure conversion speed, the high-pressure physical speed, the afterburner connection stability approximate parameter, and the duration of the throttle being pushed through the afterburner domain all exceed the set value, then performing afterburner fueling; step S3, continuously monitoring the afterburner fueling time, and performing afterburner ignition when the afterburner fueling time reaches the specified required value and the afterburner connection stability approximate parameter reaches the given threshold value; step S4, continuously monitoring whether there is a flame in the afterburner combustion chamber, and performing afterburner continuous flame control after a delay based on the monitoring result. The present application shortens the afterburner connection time, gives full play to the afterburner combustion chamber connection performance, and shortens the dispersion of the afterburner connection time.

Description

Technical Field

[0001] The present application belongs to the field of engine control technology, and specifically relates to a method and device for controlling the left-boundary afterburner connection of a turbofan engine at high altitude. Background Art

[0002] A low-bypass-ratio afterburning turbofan engine should be able to connect the afterburner combustion chamber and operate stably within the afterburner connection envelope, thereby increasing the exhaust temperature and speed, achieving thrust growth, and meeting the aircraft's maneuverability and flight performance requirements.

[0003] The afterburner connection control logic design is the prerequisite for ensuring the reliable operation of the afterburner. Under normal temperature and pressure and high temperature and high pressure conditions, the afterburner connection ability is relatively strong, the flame propagation speed is fast, and the fuel supply and ignition control can be carried out normally. However, under the left boundary conditions of high altitude, as the flight altitude increases and the flight speed decreases, the atmospheric environment pressure and temperature drop, the afterburner inlet conditions deteriorate sharply. In addition, the individual differences in the engine performance and the dispersion of the fuel supply quality make it difficult to connect the afterburner, affecting the normal use of the aircraft.

[0004] A currently used high-altitude left-boundary afterburner connection design method is to perform fuel supply and ignition delay control: 1. During the engine main engine acceleration process, monitor the rising trend of the turbine expansion ratio. When it reaches a given threshold value, enter delay control; 2. After a delay of t1 seconds, perform afterburner fuel supply control; 3. After a delay of t2 seconds, perform afterburner ignition control; 4. Perform afterburner continuous flame and subsequent fuel supply control to achieve maximum thrust state. The control logic diagram during afterburner connection is as follows Figure 1 shown.

[0005] The existing afterburner connection control method can improve the afterburner connection capability under high-altitude left boundary conditions, but it has the following major disadvantages:

[0006] 1. To improve afterburner engagement reliability, afterburner engagement time is sacrificed, reducing aircraft maneuverability. Existing afterburner engagement control methods essentially delay afterburner fuel supply and ignition, further increasing the engine state, improving afterburner combustion chamber inlet conditions, and enhancing afterburner engagement reliability. However, due to the limitations of delayed fuel supply and ignition time, the engine afterburner engagement time is significantly increased. Compared with non-delayed control methods, the afterburner engagement time increases by 1 to 2 times, reducing the engine thrust response speed and restricting the aircraft's maneuverability.

[0007] 2. The afterburner connection capability is not fully utilized. The existing delayed fuel supply and ignition control method uses a time delay method, passively waiting for the afterburner inlet conditions to be established. Although it is compatible with most engines, the optimality of this compatibility has not been effectively verified. At the end of the delay time, it only indicates that afterburner connection can be performed at this moment, but it does not represent the boundary conditions for reliable afterburner ignition. This approach is also inconsistent with the forward design process. A control method that actively identifies the main engine state parameters should be established. When the afterburner connection boundary conditions are met, the afterburner connection control is actively performed to fully utilize the afterburner connection performance.

[0008] 3. Large dispersion in afterburner engagement time. Engine state dispersion is an objective law. Different engines have inherent variations in main engine acceleration performance. This, combined with fuel supply deviations in the low-flow section at the left edge of the high altitude, external factors such as off-standard days, Reynolds numbers, aircraft power extraction, and bleed air separation, as well as fan / compressor / turbine matching deviations, results in a large dispersion in the turbine expansion ratio response speed. This results in large variations in the time it takes for the engine to reach the afterburner fuel supply threshold, leading to large dispersion in afterburner engagement time. Summary of the Invention

[0009] In order to solve one of the above problems, the present application provides a method and device for controlling the left-boundary afterburner connection of a turbofan engine at high altitude, which actively identifies whether afterburner connection is required based on the host state parameters, thereby improving the afterburner connection response speed, fully utilizing the afterburner combustion chamber connection performance, and reducing the dispersion of the afterburner connection time.

[0010] In a first aspect, the present application provides a method for controlling the left-boundary afterburner connection of a turbofan engine at high altitude, mainly comprising:

[0011] Step S1: Determine whether the aircraft is at the high altitude left boundary according to the aircraft altitude parameter and speed parameter;

[0012] Step S2: If the high-pressure converted speed, the high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters, and the duration of the throttle being pushed through the afterburner region all exceed set values, then afterburner fuel supply is performed;

[0013] Step S3: continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches a specified required value and the afterburner connection stability approximate parameter reaches a given threshold value;

[0014] Step S4: Continuously monitor whether there is flame in the afterburner chamber, and perform afterburner continuous flame control after a delay based on the monitoring result.

[0015] Preferably, step S1 further comprises:

[0016] Obtaining a flight altitude or engine cabin pressure and a flight speed; if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, determining that the aircraft is at the left altitude boundary, where the first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h;

[0017] If the flight speed cannot be obtained, the compressor outlet pressure is obtained. If the flight altitude is greater than or equal to the first preset value, or the engine cabin pressure is less than or equal to the second preset value, and the compressor outlet pressure is less than or equal to a fourth preset value, it is determined that the aircraft is at the high altitude left boundary. The fourth preset value is determined by the whole aircraft performance simulation model. The fourth preset value determined by the whole aircraft performance simulation model refers to the maximum compressor outlet pressure determined under the specified altitude, speed and total pressure loss conditions.

[0018] Preferably, in step S2, when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the afterburner connection stability approximate parameter is greater than or equal to 0.9 times the afterburner reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the afterburner domain is greater than or equal to the seventh preset value, afterburner fuel supply is performed, wherein the fifth preset value, the sixth preset value and the seventh preset value are all determined by the whole machine performance transition state simulation model, and the afterburner reliable connection boundary uses the whole machine performance simulation model to calculate the maximum state afterburner connection stability approximate parameter S under the specified altitude, speed and total pressure loss conditions, and take a set multiple of S as the afterburner reliable connection boundary, and the set multiple is 0.6 to 0.8 times.

[0019] Preferably, in step S3, the boost fueling time is continuously monitored. If the boost fueling time reaches an eighth preset value and the boost connection stability approximate parameter is greater than or equal to the boost reliable connection boundary, boost ignition is performed. Otherwise, boost ignition is performed after the boost fueling time reaches a ninth preset value. The eighth preset value is determined by the boost fueling line length ÷ the fuel supply flow rate × the fuel supply line area. The ninth preset value is 2 to 5 times the eighth preset value.

[0020] Preferably, in step S4, if flame is detected in the afterburner, afterburner continuous flame control is performed after the current afterburner fuel supply state continues for a tenth preset time; otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state continues for an eleventh preset time, wherein the tenth preset time is determined by the circumference of the afterburner main stabilizer divided by the flame propagation speed, the flame propagation speed ranges from 2 m / s to 3 m / s, and the eleventh preset time is 2 to 5 times the tenth preset time.

[0021] A second aspect of the present application provides a turbofan engine high-altitude left boundary afterburner connection control device, mainly comprising:

[0022] A high-altitude left boundary condition determination module is used to determine whether the aircraft is at the high-altitude left boundary based on the aircraft altitude parameters and speed parameters;

[0023] The afterburner fuel supply condition determination module is used to determine that the high-pressure converted speed, high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters and the duration of the throttle being pushed through the afterburner range all exceed the set values, and then afterburner fuel supply is performed;

[0024] Afterburner ignition condition determination module, used to continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches the specified required value and the afterburner connection stability approximate parameter reaches a given threshold value;

[0025] The afterburner continuous flame control condition determination module is used to continuously monitor whether there is a flame in the afterburner combustion chamber, and perform afterburner continuous flame control after a delay based on the monitoring results.

[0026] Preferably, the fueling condition determination module includes:

[0027] an altitude and speed determination unit, configured to obtain a flight altitude or an engine cabin pressure and a flight speed, and determine that the aircraft is at the left altitude boundary if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, where the first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h; or

[0028] The altitude and compressor parameter determination unit is used to obtain the compressor outlet pressure when the flight speed cannot be obtained. If the flight altitude is greater than or equal to the first preset value, or the engine cabin pressure is less than or equal to the second preset value, and the compressor outlet pressure is less than or equal to the fourth preset value, it is determined that the aircraft is at the high altitude left boundary. The fourth preset value is determined by the whole aircraft performance simulation model. The fourth preset value determined by the whole aircraft performance simulation model refers to the maximum state compressor outlet pressure determined under the specified altitude, speed and total pressure loss conditions.

[0029] Preferably, in the boost fueling condition determination module, boost fueling is performed when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the boost connection stability approximate parameter is greater than or equal to 0.9 times the boost reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the boost domain is greater than or equal to the seventh preset value. The fifth preset value, the sixth preset value and the seventh preset value are all determined by the whole machine performance transition state simulation model, and the boost reliable connection boundary uses the whole machine performance simulation model to calculate the maximum state boost connection stability approximate parameter S under the specified altitude, speed and total pressure loss conditions, and take a set multiple of S as the boost reliable connection boundary, and the set multiple is 0.6 to 0.8 times.

[0030] Preferably, the afterburner ignition condition determination module continuously monitors the afterburner fuel supply time. If the afterburner fuel supply time reaches an eighth preset value and the afterburner connection stability approximate parameter is greater than or equal to the afterburner reliable connection boundary, afterburner ignition is performed. Otherwise, afterburner ignition is performed after the afterburner fuel supply time reaches a ninth preset value. The eighth preset value is determined by afterburner fuel supply line length ÷ fuel supply flow rate × fuel supply line area. The ninth preset value is 2 to 5 times the eighth preset value.

[0031] Preferably, in the afterburner continuous flame control condition determination module, if flame is detected in the afterburner, afterburner continuous flame control is performed after the current afterburner fuel supply state continues for a tenth preset time; otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state continues for an eleventh preset time, wherein the tenth preset time is determined by the circumference of the afterburner main stabilizer divided by the flame propagation speed, the flame propagation speed ranges from 2m / s to 3m / s, and the eleventh preset time is 2 to 5 times the tenth preset time.

[0032] The present application shortens the afterburner connection time, fully utilizes the afterburner combustion chamber connection performance, and shortens the dispersion of the afterburner connection time. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the existing boost-on logic control.

[0034] Figure 2 This is a flow chart of a preferred embodiment of the high-altitude left-boundary afterburner connection control method of the turbofan engine of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0036] First, let's discuss the flight envelope. The flight envelope is one of many indicators used to comprehensively evaluate an aircraft's flight performance. It consists of a very simple two-dimensional curve, with flight speed on the horizontal axis and altitude on the vertical axis. The left boundary of the flight envelope represents the aircraft's minimum speed at any altitude. This speed is entirely determined by the aircraft's overall aerodynamic characteristics. In layman's terms, it represents the minimum speed at which the aircraft can maintain level flight at a given altitude. Below this speed, the aircraft enters a stall state, with the lift generated on the wings less than the aircraft's weight. Conversely, the right boundary represents the maximum speed the aircraft can reach at full acceleration at a given altitude. This speed depends on the engine thrust and the aircraft's own aerodynamic characteristics. At the maximum speed, the maximum thrust output by the aircraft's engine is exactly equal to the aircraft's aerodynamic drag at that speed, a speed the aircraft cannot exceed.

[0037] The purpose of this application is to connect the afterburner to achieve afterburner drive under the left boundary conditions of the flight envelope.

[0038] The first aspect of the present application provides a method for controlling the left boundary afterburner connection of a turbofan engine at high altitude, such as Figure 2 As shown, it mainly includes:

[0039] Step S1: Determine whether the aircraft is at the high altitude left boundary according to the aircraft altitude parameter and speed parameter;

[0040] Step S2: If the high-pressure converted speed, the high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters, and the duration of the throttle being pushed through the afterburner region all exceed set values, then afterburner fuel supply is performed;

[0041] Step S3: continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches a specified required value and the afterburner connection stability approximate parameter reaches a given threshold value;

[0042] Step S4: Continuously monitor whether there is flame in the afterburner chamber, and perform afterburner continuous flame control after a delay based on the monitoring result.

[0043] In some optional embodiments, step S1 further includes:

[0044] Obtain the flight altitude or engine cabin pressure and the flight speed. If the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, then it is determined that the aircraft is at the left boundary of the high altitude. The first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h.

[0045] If the flight speed cannot be obtained, the compressor outlet pressure is obtained. If the flight altitude is greater than or equal to the first preset value, or the engine cabin pressure is less than or equal to the second preset value, and the compressor outlet pressure is less than or equal to a fourth preset value, it is determined that the aircraft is at the high altitude left boundary. The fourth preset value is determined by the whole aircraft performance simulation model. The fourth preset value determined by the whole aircraft performance simulation model refers to the maximum compressor outlet pressure determined under the specified altitude, speed and total pressure loss conditions.

[0046] In this embodiment, the first method is preferably used to determine the high-altitude left boundary condition, that is, the flight altitude H ≥ A km (or the engine cabin pressure PH ≤ B kPa), and the flight speed V ≤ C km / h. When the engine cannot obtain the flight speed from the aircraft, the second method is used: the flight altitude H ≥ A km (or the engine cabin pressure PH ≤ B kPa), and the compressor outlet pressure P3 ≤ D kPa.

[0047] In this embodiment, the recommended flight altitude A is 12 km; the recommended cabin pressure B is 19.3 kPa; the recommended flight speed C is 400 km / h to 800 km / h; and the compressor outlet pressure D is calculated using the whole-machine performance simulation model under the conditions of a typical altitude E km, a flight speed C km / h, and a specified total inlet pressure loss, including the maximum compressor outlet pressure P3. The recommended typical altitude E is 15 km.

[0048] In some optional embodiments, in step S2, when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the afterburner connection stability approximate parameter is greater than or equal to 0.9 times the afterburner reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the afterburner domain is greater than or equal to the seventh preset value, afterburner fuel supply is performed, wherein the fifth preset value, the sixth preset value and the seventh preset value are all determined by the whole machine performance transition state simulation model, and the afterburner reliable connection boundary uses the whole machine performance simulation model to calculate the maximum state afterburner connection stability approximate parameter S under the specified altitude, speed and total pressure loss conditions, and take a set multiple of S as the afterburner reliable connection boundary, and the set multiple is 0.6 to 0.8 times.

[0049] Specifically, in this embodiment, the high-pressure converted speed n2r ≥ F%, and the afterburner connection stability approximate parameter S ≥ afterburner reliable connection boundary G×0.9; the high-pressure physical speed n2 ≥ H%; the throttle is pushed through the afterburner region and the duration reaches J s. The high-pressure converted speed F is calculated using the complete engine performance transition state simulation model. The high-pressure converted speed n2r is calculated when the engine accelerates from an idle state under the conditions of a typical altitude D km, a flight speed C km / h, and a specified total inlet pressure loss, and the afterburner connection stability approximate parameter S ≥ G × 0.9 is reached. The afterburner reliable connection boundary G needs to be obtained through special tests. The initial value design method of G is to use the complete engine performance simulation model to calculate the maximum state afterburner connection stability approximate parameter S × n (n ranges from 0.6 to 0.8, preferably 0.7) under the conditions of a typical altitude D km, a flight speed C km / h, and a specified total inlet pressure loss. The high-pressure physical speed H has the same value as F. The duration J is calculated using the complete engine performance transition state simulation model. The engine accelerates from an idle state under the conditions of a typical altitude D km, a flight speed C km / h, and a specified total inlet pressure loss. The time starts from the throttle entering the afterburner domain to the moment when the afterburner connection stability approximate parameter S ≥ G × 0.9.

[0050] In this embodiment, the afterburner connection stability approximate parameter S is related to parameters such as the stabilizer slot width, inlet temperature, pressure, and outlet velocity of the afterburner combustion chamber. However, the corresponding measurement parameters are lacking under installed conditions, and other measurement parameters need to be used for approximate characterization, such as using the outlet pressure P6 after the last-stage turbine as a substitute.

[0051] In some optional embodiments, in step S3, the boost fueling time is continuously monitored. If the boost fueling time reaches an eighth preset value and the boost connection stability approximate parameter is greater than or equal to the boost reliable connection boundary, boost ignition is performed. Otherwise, boost ignition is performed after the boost fueling time reaches a ninth preset value. The eighth preset value is determined by the boost fueling pipeline length ÷ the fuel supply flow rate × the fuel supply pipeline area. The ninth preset value is 2 to 5 times the eighth preset value.

[0052] In some optional embodiments, in step S4, if flame is detected in the afterburner, afterburner continuous flame control is performed after the current afterburner fuel supply state continues for the tenth preset time; otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state continues for the eleventh preset time, wherein the tenth preset time is determined by the circumference of the afterburner main stabilizer divided by the flame propagation speed, the flame propagation speed ranges from 2m / s to 3m / s, and the eleventh preset time is 2 to 5 times the tenth preset time.

[0053] Advantages of this application include:

[0054] 1. Shortened the afterburner connection time.

[0055] The afterburner fuel supply delay and ignition delay in the original afterburner connection control method are cancelled, which reduces the invalid passive waiting time, improves the afterburner connection speed, and shortens the afterburner connection time.

[0056] 2. The afterburner connection performance is fully utilized.

[0057] Approximate parameters of afterburner connection stability were introduced as control conditions, and boundary conditions for reliable connection of the afterburner were established. Based on this, afterburner fuel supply and continuous flame control were carried out, and active connection control based on the engine main body state parameters was realized. When the afterburner inlet conditions reached the boundary, ignition control was immediately carried out to give full play to the connection performance of the afterburner.

[0058] 3. Shortened the dispersion of afterburner connection time.

[0059] Based on the boundary conditions for reliable afterburner engagement, fuel supply control is implemented in advance during the engine acceleration process, minimizing the dispersion of engagement times caused by variations in acceleration. Furthermore, using engine state parameters instead of the turbine expansion ratio as the fuel supply control condition mitigates engagement time variations caused by discrepancies in fan / compressor / turbine matching. These measures reduce dispersion in afterburner engagement times.

[0060] A second aspect of the present application provides a turbofan engine high-altitude left boundary afterburner connection control device corresponding to the above method, mainly comprising:

[0061] A high-altitude left boundary condition determination module is used to determine whether the aircraft is at the high-altitude left boundary based on the aircraft altitude parameters and speed parameters;

[0062] The afterburner fuel supply condition determination module is used to determine that the high-pressure converted speed, high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters and the duration of the throttle being pushed through the afterburner range all exceed the set values, and then afterburner fuel supply is performed;

[0063] Afterburner ignition condition determination module, used to continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches the specified required value and the afterburner connection stability approximate parameter reaches a given threshold value;

[0064] The afterburner continuous flame control condition determination module is used to continuously monitor whether there is a flame in the afterburner combustion chamber, and perform afterburner continuous flame control after a delay based on the monitoring results.

[0065] In some optional implementations, the fueling condition determination module includes:

[0066] an altitude and speed determination unit, configured to obtain a flight altitude or an engine cabin pressure and a flight speed, and determine that the aircraft is at the left altitude boundary if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, where the first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h; or

[0067] The altitude and compressor parameter determination unit is used to obtain the compressor outlet pressure when the flight speed cannot be obtained. If the flight altitude is greater than or equal to the first preset value, or the engine cabin pressure is less than or equal to the second preset value, and the compressor outlet pressure is less than or equal to the fourth preset value, it is determined that the aircraft is at the high altitude left boundary. The fourth preset value is determined by the whole aircraft performance simulation model. The fourth preset value determined by the whole aircraft performance simulation model refers to the maximum state compressor outlet pressure determined under the specified altitude, speed and total pressure loss conditions.

[0068] In some optional embodiments, in the boost fueling condition determination module, boost fueling is performed when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the boost connection stability approximate parameter is greater than or equal to 0.9 times the boost reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the boost domain is greater than or equal to the seventh preset value, wherein the fifth preset value, the sixth preset value and the seventh preset value are all determined by the whole machine performance transition state simulation model, and the boost reliable connection boundary uses the whole machine performance simulation model to calculate the maximum state boost connection stability approximate parameter S under the specified altitude, speed and total pressure loss conditions, and take a set multiple of S as the boost reliable connection boundary, and the set multiple is 0.6 to 0.8 times.

[0069] In some optional embodiments, the afterburner ignition condition determination module continuously monitors the afterburner fuel supply time. If the afterburner fuel supply time reaches an eighth preset value and the afterburner connection stability approximate parameter is greater than or equal to the afterburner reliable connection boundary, afterburner ignition is performed. Otherwise, afterburner ignition is performed after the afterburner fuel supply time reaches a ninth preset value. The eighth preset value is determined by the afterburner fuel supply line length ÷ the fuel supply flow rate × the fuel supply line area. The ninth preset value is 2 to 5 times the eighth preset value.

[0070] In some optional embodiments, in the afterburner continuous flame control condition determination module, if flame is detected in the afterburner combustion chamber, afterburner continuous flame control is performed after the current afterburner fuel supply state continues for the tenth preset time; otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state continues for the eleventh preset time, wherein the tenth preset time is determined by the circumference of the afterburner combustion chamber main stabilizer divided by the flame propagation speed, the flame propagation speed range is 2m / s to 3m / s, and the eleventh preset time is 2 to 5 times the tenth preset time.

[0071] Although the present application has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements, which do not depart from the spirit of the present application, are within the scope of protection claimed in the present application.

Claims

1. A method for controlling the left boundary afterburner connection of a turbofan engine at high altitude, characterized in that: include: Step S1: Determine whether the aircraft is at the high altitude left boundary according to the aircraft altitude parameter and speed parameter; Step S2: If the high-pressure converted speed, the high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters, and the duration of the throttle being pushed through the afterburner region all exceed set values, then afterburner fuel supply is performed; Step S3: continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches a specified required value and the afterburner connection stability approximate parameter reaches a given threshold value; Step S4: continuously monitor whether there is flame in the afterburner chamber, and perform afterburner continuous flame control after a delay based on the monitoring result; Wherein, step S1 further includes: Obtaining a flight altitude or engine cabin pressure and a flight speed; if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, determining that the aircraft is at the left altitude boundary, where the first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h; If the flight speed cannot be obtained, the compressor outlet pressure is obtained. If the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the compressor outlet pressure is less than or equal to a fourth preset value, it is determined that the aircraft is at the high altitude left boundary. The fourth preset value is determined by the whole aircraft performance simulation model. The fourth preset value determined by the whole aircraft performance simulation model refers to the maximum compressor outlet pressure determined under the specified altitude, speed, and total pressure loss conditions. In step S2, when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the afterburner connection stability approximate parameter is greater than or equal to 0.9 times the afterburner reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the afterburner domain is greater than or equal to the seventh preset value, afterburner fuel supply is performed, wherein the fifth preset value, the sixth preset value and the seventh preset value are all determined by the whole machine performance transition state simulation model, and the afterburner reliable connection boundary uses the whole machine performance simulation model to calculate the maximum state afterburner connection stability approximate parameter S under the specified altitude, speed and total pressure loss conditions, and take a set multiple of S as the afterburner reliable connection boundary, and the set multiple is 0.6~0.8 times.

2. The method for controlling the left boundary afterburner connection of a turbofan engine at high altitude according to claim 1, characterized in that: In step S3, the afterburner fueling time is continuously monitored. If the afterburner fueling time reaches an eighth preset value and the afterburner connection stability approximate parameter is greater than or equal to the afterburner reliable connection boundary, afterburner ignition is performed. Otherwise, afterburner ignition is performed after the afterburner fueling time reaches a ninth preset value. The eighth preset value is determined by the afterburner fueling line length divided by the fueling flow rate multiplied by the fueling line area. The ninth preset value is 2 to 5 times the eighth preset value.

3. The method for controlling the left boundary afterburner connection of a turbofan engine at high altitude according to claim 1, characterized in that: In step S4, if flame is detected in the afterburner, afterburner continuous flame control is performed after the current afterburner fuel supply state is continued for a tenth preset time. Otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state is continued for an eleventh preset time. The tenth preset time is determined by the circumference of the afterburner main stabilizer divided by the flame propagation speed. The flame propagation speed ranges from 2 m / s to 3 m / s. The eleventh preset time is 2 to 5 times the tenth preset time.

4. A turbofan engine high-altitude left boundary afterburner connection control device, characterized in that: include: A high-altitude left boundary condition determination module is used to determine whether the aircraft is at the high-altitude left boundary based on the aircraft altitude parameters and speed parameters; The afterburner fuel supply condition determination module is used to determine that the high-pressure converted speed, high-pressure physical speed, the ratio of the afterburner connection stability approximate parameters and the duration of the throttle being pushed through the afterburner range all exceed the set values, and then afterburner fuel supply is performed; Afterburner ignition condition determination module, used to continuously monitor the afterburner fuel supply time, and perform afterburner ignition when the afterburner fuel supply time reaches the specified required value and the afterburner connection stability approximate parameter reaches a given threshold value; Afterburner flame control condition determination module, used to continuously monitor whether there is flame in the afterburner combustion chamber, and perform afterburner flame control after a delay based on the monitoring results; Wherein, the boost fueling condition determination module includes: an altitude and speed determination unit, configured to obtain a flight altitude or an engine cabin pressure and a flight speed, and determine that the aircraft is at the left altitude boundary if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the flight speed is less than or equal to a third preset value, where the first preset value is 12 km, the second preset value is 19.3 kPa, and the third preset value is any value between 400 km / h and 800 km / h; or an altitude and compressor parameter determination unit, configured to obtain the compressor outlet pressure when the flight speed cannot be obtained, and determine that the aircraft is at the high altitude left boundary if the flight altitude is greater than or equal to a first preset value, or the engine cabin pressure is less than or equal to a second preset value, and the compressor outlet pressure is less than or equal to a fourth preset value, wherein the fourth preset value is determined by an entire aircraft performance simulation model. The fourth preset value determined by the entire aircraft performance simulation model refers to the maximum compressor outlet pressure determined under specified altitude, speed, and total pressure loss conditions; In the afterburner fueling condition determination module, afterburner fueling is performed when any of the following conditions is met: the high-pressure converted speed is greater than or equal to the fifth preset value and the afterburner connection stability approximate parameter is greater than or equal to 0.9 times the afterburner reliable connection boundary, or the high-pressure physical speed is greater than or equal to the sixth preset value, or the duration of the throttle being pushed through the afterburner domain is greater than or equal to the seventh preset value. The fifth preset value, the sixth preset value, and the seventh preset value are all determined by a whole-machine performance transition state simulation model. The afterburner reliable connection boundary uses the whole-machine performance simulation model to calculate the maximum state afterburner connection stability approximate parameter S under specified altitude, speed, and total pressure loss conditions, and a set multiple of S is taken as the afterburner reliable connection boundary, and the set multiple is 0.6 to 0.8 times.

5. The turbofan engine high altitude left boundary afterburner connection control device according to claim 4, characterized in that: In the afterburner ignition condition determination module, afterburner fuel supply time is continuously monitored. If the afterburner fuel supply time reaches an eighth preset value and the afterburner connection stability approximate parameter is greater than or equal to the afterburner reliable connection boundary, afterburner ignition is performed. Otherwise, afterburner ignition is performed after the afterburner fuel supply time reaches a ninth preset value. The eighth preset value is determined by afterburner fuel supply line length divided by fuel supply flow rate multiplied by fuel supply line area. The ninth preset value is 2 to 5 times the eighth preset value.

6. The turbofan engine high altitude left boundary afterburner connection control device according to claim 4, characterized in that: In the afterburner continuous flame control condition determination module, if flame is detected in the afterburner, afterburner continuous flame control is performed after the current afterburner fuel supply state continues for a tenth preset time; otherwise, subsequent fuel supply control is performed after the current afterburner fuel supply state continues for an eleventh preset time. The tenth preset time is determined by the circumference of the afterburner main stabilizer divided by the flame propagation speed, with the flame propagation speed ranging from 2 m / s to 3 m / s. The eleventh preset time is 2 to 5 times the tenth preset time.

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