Method for regulating and controlling main fuel oil of variable cycle engine

Abstract

The invention belongs to the field of engine design, and particularly relates to a variable cycle engine main fuel regulation and control method which comprises the steps that a main fuel control rule framework is designed based on critical mach numbers of all feature heights, and main fuel control rules of different bypass ratio states under all the feature heights are designed; main fuel control rule optimization design is carried out in the state switching period, and a main fuel design rule in the state switching period is obtained; when the rotating speed of the fan is limited and the flow is reduced, matching design is carried out on the main fuel control rule, and a main fuel design rule in the flow reduction period is obtained; and the correction amount determined by the test is added on the main fuel oil design rule of the full working envelope, and the main fuel oil self-adaptive control rule is obtained. The blank in the field of variable-cycle engine full-envelope, multi-working-mode and full-thrust-state main fuel regulation and control design is filled up, self-adaptive regulation and control of main fuel of the variable-cycle engine are achieved, and the design capacity of an aero-engine is improved.

Description

Technical Field

[0001] This application belongs to the field of engine design, and specifically relates to a method for main fuel regulation in a variable cycle engine. Background Technology

[0002] Variable cycle engines operate in two modes: high bypass ratio and low bypass ratio. In throttling mode, the engine typically operates at the high bypass ratio to achieve the lowest possible fuel consumption. In intermediate and higher Mach numbers, the engine operates at the low bypass ratio to achieve the highest possible thrust. Simultaneously, in the low Mach number range, the engine operates at the low bypass ratio, resulting in a high overall pressure ratio and a high engine temperature rise ratio (the ratio of turbine inlet temperature to engine inlet temperature). As the Mach number increases, the turbine inlet temperature gradually approaches its maximum limit, making it impossible to maintain the maximum calorimetric flow rate using the low bypass ratio mode. Therefore, in the high Mach number range, the engine operates at the high bypass ratio to shift the calorimetric flow rate inflection point later, thereby maximizing thrust performance.

[0003] The conventional main fuel control method for turbofan engines cannot take into account changes in bypass ratio at different stages. If the optimal bypass ratio is determined simply by the thrust magnitude, sudden changes in parameters such as thrust and flow rate may occur, which is very detrimental to aircraft attitude control and engine aerodynamic stability.

[0004] Currently, the main fuel control methods for aero engines are primarily applicable to conventional cycle engines such as turbojet and turbofan engines. However, given the multi-operating-mode characteristics of variable-cycle aero engines, existing methods cannot fully leverage the performance advantages of variable-cycle engines and have the following drawbacks:

[0005] 1. Conventional turbojet and turbofan engines have only one operating mode and their operating characteristics are basically fixed. Variable cycle engines have multiple operating modes and their operating characteristics are variable. The existing main fuel control architecture cannot express the main fuel control requirements of variable cycle engines.

[0006] 2. Existing main fuel control methods cannot achieve the design of main fuel control laws for variable cycle engines that take into account multiple performance objectives and different operating modes under different flight conditions.

[0007] Therefore, how to achieve more effective main fuel regulation in variable cycle engines is a problem that needs to be solved. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a main fuel control method for a variable cycle engine, thereby resolving the problem that the operating modes of conventional turbojet and turbofan engines are difficult to apply to variable cycle engines.

[0009] The technical solution of this application is: a method for main fuel regulation of a variable cycle engine, comprising:

[0010] Select several feature heights, divide the height direction into multiple intervals, and determine the height direction layering scheme;

[0011] Determine the critical Mach number for each characteristic altitude and establish an adaptive main fuel control architecture: When the flight Mach number is less than the critical Mach number, if the throttle lever angle is less than PLA4, the engine adopts a high bypass ratio main fuel supply pattern; if the throttle lever angle is greater than PLA4, the engine adopts a low bypass ratio main fuel supply pattern. When the flight Mach number is greater than the critical Mach number, the engine adopts a high bypass ratio fuel supply pattern regardless of the throttle lever position. PLA4 is the throttle lever angle corresponding to the engine's intermediate state.

[0012] Based on the main fuel adaptive regulation architecture, main fuel control laws for different altitudes were designed.

[0013] During the state switching between the two bypass ratios, the main fuel control law and the adjustable geometric control law are combined and optimized to obtain the main fuel design law during the state switching period.

[0014] During the flow-limited period, the main fuel control law is matched and designed for the period when the converted flow is lower than the design value, so as to obtain the main fuel design law during the flow-limited period.

[0015] The design rules for main fuel during state transitions and flow-limited periods at different altitudes are obtained to obtain the design rules for main fuel at all altitudes of the full envelope. Experimentally determined corrections are added to the design rules for main fuel at all altitudes of the full envelope to obtain the adaptive control rules for main fuel.

[0016] The adaptive control law of the main fuel is verified, the engine parameters are calculated by selecting the test points, and it is determined whether the engine parameters meet the index requirements. If so, the design is completed.

[0017] Preferably, the specific method for combining and optimizing the main fuel control law with the adjustable geometric control law is as follows:

[0018] By coordinating the relative conversion speed of the fan with the angles of the fan's inlet guide vanes and adjustable stator vanes, two bypass ratio transition stages are obtained. The engine inlet flow and thrust are controlled to remain continuous and without conflict during the transition stages of the two bypass ratios.

[0019] Preferably, the specific method for matching design of the main fuel control law during periods when the converted flow rate is lower than the design value is as follows:

[0020] After the engine inlet temperature increases and the engine flow rate is limited, different adjustable geometric parameters are set, including the adjustable fan guide vane angle, the adjustable fan stator vane angle, the high-pressure compressor guide vane angle, the nozzle area, the duct ejector opening, and the adjustable turbine blade angle. Select any one or more adjustable geometric parameters, keep the other adjustable geometric parameters unchanged, and adjust the selected adjustable geometric parameters in sequence according to the set step size within the design range to determine the engine thrust under different adjustable geometric parameters. Then select the optimal thrust and calculate the engine converted flow rate under the optimal thrust.

[0021] Preferably, the main fuel adaptive control law is as follows:

[0022] ;

[0023] in, Engine speed, This is the fuel control coefficient. For the throttle lever angle, This refers to the total temperature at the engine inlet. This represents the atmospheric static pressure at different flight altitudes. This is a correction amount.

[0024] Preferably, the specific method for determining whether the engine parameters meet the target requirements is as follows:

[0025] A certain number of steady-state performance test points are selected on the engine. The engine performance parameters and aerodynamic stability parameters of the steady-state performance test points are calculated. The difference ratio between the engine performance parameters and aerodynamic stability parameters and the corresponding indicators is calculated by absolute value calculation. When the difference ratio is less than a certain value, it is judged that the indicator requirements are met; otherwise, the main fuel control law state switching period and flow restriction period are redesigned until the indicator requirements are met.

[0026] Preferably, the critical Mach number is obtained by calculating the thrust characteristics corresponding to the two bypass ratio states separately, and then calculating the intersection of the thrust characteristics corresponding to the two bypass ratio states.

[0027] The variable cycle engine main fuel control method of this application has the following advantages:

[0028] Through innovative designs such as highly hierarchical adaptation, stable flow control during transition phases, active adjustment for flow-limited conditions, adaptive law quantification, and closed-loop verification, deep matching between main fuel control and multiple engine operating modes has been achieved.

[0029] The variable cycle engine is significantly superior to conventional single-mode control methods in terms of mode switching, performance maintenance under flow-limited conditions, and engine flow matching, fully releasing the performance advantages of "low fuel consumption and high thrust" of the variable cycle engine.

[0030] It fills the gap in the design of main fuel regulation for variable cycle engines across the entire envelope, multiple operating modes, and all thrust states. It realizes adaptive regulation of main fuel for variable cycle engines, enhances the design capabilities of aero engines, especially the design capabilities of control laws for next-generation engines, and has extremely high value. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall process of this application;

[0032] Figure 2 This is a schematic diagram showing the thrust characteristics under two bypass ratio conditions in this application;

[0033] Figure 3 This is a schematic diagram showing the inlet critical temperature under different altitude conditions in this application;

[0034] Figure 4 This is a schematic diagram of the engine inlet flow characteristics for this application;

[0035] Figure 5 This is a schematic diagram of the rotational speed and geometric matching design during the state transition period of this application;

[0036] Figure 6 This is a schematic diagram comparing the thrust characteristics before and after the design of this application;

[0037] Figure 7 This is a schematic diagram of the main fuel adaptive control architecture of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] The first aspect of this application provides a main fuel control method for a variable cycle engine. Compared with conventional turbofan engines, it is necessary to focus on the bypass ratio state switching logic and the matching design that cannot maintain the design value during the state switching period and the conversion flow period.

[0040] like Figure 1 As shown, it includes the following steps:

[0041] Step S100: Select several feature heights, divide the height direction into multiple intervals, and determine the height direction layering scheme.

[0042] Considering that ambient temperature and pressure vary with altitude, the optimal main fuel control law can be matched for different altitudes. Therefore, it is necessary to select several characteristic altitudes H1, H2, H3, H4, ... and divide the altitude direction into several intervals, with the same main fuel control law executed in each interval.

[0043] Step S200: Determine the critical Mach number for each characteristic altitude and establish a main fuel adaptive control architecture: When the flight Mach number is less than the critical Mach number, if the throttle lever angle is less than PLA4, the engine adopts a high bypass ratio main fuel supply pattern; if the throttle lever angle is greater than PLA4, the engine adopts a low bypass ratio main fuel supply pattern. When the flight Mach number is greater than the critical Mach number, the engine adopts a high bypass ratio fuel supply pattern regardless of the throttle lever position. PLA4 is the throttle lever angle corresponding to the engine's intermediate state.

[0044] The critical Mach number is determined by calculating the thrust characteristics for the two bypass ratio states separately. The intersection of the thrust characteristics for the two bypass ratio states is the critical Mach number. Figure 2 As shown. And the critical Mach number corresponding to the feature height in step S100 is determined respectively, as follows: Figure 3 As shown.

[0045] Step S300, matching design during state transition:

[0046] Based on the adaptive control architecture of main fuel, main fuel control laws for different heights are designed respectively; during the state switching period of the two bypass ratios, the main fuel control laws and adjustable geometric control laws are combined and optimized to obtain the main fuel design law during the state switching period.

[0047] Specifically: taking the characteristic height H1 as an example, the main fuel control law is designed directly using the thrust magnitude as the criterion, resulting in the engine's converted flow characteristics and thrust characteristics, such as... Figures 4-6 As shown, both flow rate and thrust exhibit significant fluctuations before and after the bypass ratio is adjusted.

[0048] This is highly detrimental to aircraft attitude control and engine aerodynamic stability. Therefore, it is necessary to conduct matching design based on the main fuel supply pattern during state transitions, specifically:

[0049] exist Figure 4Two bypass ratio transition stages are set at point ①, allowing the intake airflow to change continuously. Specifically, this is achieved by coordinating the fan's relative calculated speed with the angles of the fan's inlet guide vanes and adjustable stator vanes. This ensures that the engine inlet airflow remains continuous and does not conflict during the transition between the two bypass ratios. Figure 5 As shown.

[0050] Step S400, Matching design during traffic-constrained periods:

[0051] During periods of flow restriction, a matching design is carried out for the main fuel control law during periods when the converted flow exceeds the design value, thereby obtaining the main fuel design law during periods of flow restriction.

[0052] The calculated flow rate cannot maintain the match with the design value during the flight Mach number period. When the flight Mach number is high, the engine speed and temperature reach their limits, causing the calculated flow rate to fail to maintain the design value. Moreover, as the flight Mach number increases, the deviation between the calculated flow rate and the design value becomes greater. Figure 4 As shown in Figure ②, after the converted flow rate deviates from the design value, the corresponding optimal control law will also change. Compared with conventional turbofan engines, variable cycle engines have a large number of adjustable geometric parameters, providing room for adjustment of the control law for optimal matching.

[0053] Therefore, it is necessary to carry out matching design for the main fuel supply pattern during periods when the converted flow rate cannot maintain the design value:

[0054] Specifically, after the engine inlet temperature increases, different adjustable geometric parameters are set, including the adjustable fan guide vane angle, the adjustable fan stator vane angle, the high-pressure compressor guide vane angle, the nozzle area, the duct ejector opening, and the turbine adjustable blade angle. Any one or more adjustable geometric parameters are selected, while keeping the other adjustable geometric parameters unchanged. Within the design range, the selected adjustable geometric parameters are adjusted sequentially according to the set step size to determine the engine thrust under different adjustable geometric parameters, and then the optimal thrust is selected.

[0055] Step S500, Design Result:

[0056] The design rules for main fuel during state transitions and flow-limited periods at different altitudes are obtained to obtain the design rules for main fuel at all altitudes of the full envelope. Experimentally determined corrections are added to the design rules for main fuel at all altitudes of the full envelope to obtain the adaptive control rules for main fuel.

[0057] With the main fuel adaptive control law determined, the main fuel flow of the variable cycle engine is controlled according to the engine speed, taking into account the critical Mach number Ma corresponding to different altitude conditions. cr Different values ​​require the introduction of altitude H correction into the main fuel control law. Flight altitude can be determined using ambient pressure P. s0Replacement. At the same time, considering that the actual performance of a real engine under different operating conditions will inevitably deviate to some extent from its design, a correction amount is added to the basic control rules to adapt to the actual main fuel control requirements after engine testing.

[0058] Combination Figure 7 The adaptive control law for the main fuel is obtained as follows:

[0059] ;

[0060] in, Engine speed, This is the fuel control coefficient. For the throttle lever angle, This refers to the total temperature at the engine inlet. This represents the atmospheric static pressure at different flight altitudes. This is a correction amount.

[0061] Step S600, Result Verification:

[0062] The adaptive control law of the main fuel is verified, the engine parameters are calculated by selecting the test points, and it is determined whether the engine parameters meet the index requirements. If so, the design is completed.

[0063] Preferably, the specific method for determining whether the engine parameters meet the target requirements is as follows:

[0064] A certain number of steady-state performance test points are selected on the engine. The steady-state performance parameters and aerodynamic stability parameters of the steady-state performance test points are calculated. The difference ratio between the engine performance parameters and aerodynamic stability parameters and the corresponding indicators is calculated by absolute value calculation. If the difference ratio is less than a certain value, it is determined that the indicator requirements are met; otherwise, the process returns to step S300 to redesign the state switching and flow restriction process within the main fuel control law until the indicator requirements are met.

[0065] In summary, this application has the following advantages:

[0066] Through innovative designs such as highly hierarchical adaptation, stable performance control during state switching, flow-limited thrust optimization, and iterative verification, a main fuel adaptive control architecture was established, achieving deep matching between main fuel control and multiple engine operating modes and performance targets.

[0067] It fills the gap in the design of main fuel regulation for variable cycle engines across the entire envelope, multiple operating modes, and all thrust states. It realizes adaptive regulation of main fuel for variable cycle engines, enhances the design capabilities of aero engines, especially the design capabilities of control laws for next-generation engines, and has extremely high value.

[0068] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of main fuel regulation for a variable cycle engine, characterized in that, The method comprises the following steps: selecting several characteristic altitudes, dividing the altitude direction into multiple intervals, and determining an altitude direction layering scheme; determining critical Mach numbers of the characteristic altitudes, and establishing a main fuel self-adaptive control architecture: when the flight Mach number is less than the critical Mach number, if the throttle lever angle is less than PLA4, the engine adopts a main fuel supply law of the large-bypass-ratio mode, and if the throttle lever angle is greater than PLA4, the engine adopts a main fuel supply law of the small-bypass-ratio mode; when the flight Mach number is greater than the critical Mach number, no matter where the throttle lever is located, the engine adopts a main fuel supply law of the large-bypass-ratio mode; PLA4 is the throttle lever angle corresponding to the intermediate state of the engine; designing main fuel control laws of different altitudes based on the main fuel self-adaptive control architecture; combining and optimizing the main fuel control law and the adjustable geometry control law during the state switching of the two bypass ratios to obtain a main fuel design law during the state switching; during the flow limitation, matching design is carried out on the main fuel control law during the period when the converted flow is lower than the design value to obtain a main fuel design law during the flow limitation; obtaining the main fuel design laws during the state switching and the flow limitation of different altitudes to obtain main fuel design laws of all altitudes of the full envelope; adding a correction amount determined by tests to the main fuel design laws of all altitudes of the full envelope to obtain a main fuel self-adaptive control law; verifying the main fuel self-adaptive control law, selecting assessment points for engine parameter calculation, and judging whether the engine parameters meet the index requirements; if yes, the design is completed.

2. The variable cycle engine main fuel regulation method of claim 1 wherein, The specific method of combining and optimizing the main fuel control law and the adjustable geometry control law is: adjusting the fan relative converted speed and the angles of the fan inlet guide vanes and the adjustable stator vanes to obtain two bypass ratio transition stages, and keeping the engine inlet flow and the thrust continuous and non-conflicting during the two bypass ratio transition stages.

3. The variable cycle engine main fuel regulation method of claim 1 wherein, The specific method of matching design on the main fuel control law during the period when the converted flow is lower than the design value is: after the engine inlet temperature increases and the engine flow is limited, different adjustable geometry parameters are set, including the fan adjustable guide vane angle, the fan adjustable stator vane angle, the high-pressure compressor guide vane angle, the nozzle area, the bypass ejector opening degree and the turbine adjustable blade angle; selecting any one or more adjustable geometry parameters, keeping the remaining adjustable geometry parameters unchanged, adjusting the selected adjustable geometry parameters in the design range according to the set step, determining the thrust of the engine under different adjustable geometry parameters, and then selecting the best thrust to calculate the converted flow of the engine under the best thrust.

4. The variable cycle engine main fuel regulation method of claim 1 wherein, The main fuel self-adaptive control law is: ； wherein, is the engine speed, is the fuel regulation coefficient, is the throttle lever angle, is the engine inlet total temperature, is the atmospheric static pressure corresponding to different flight altitudes, is the correction amount.

5. The variable cycle engine main fuel regulation method of claim 1 wherein, The specific method of judging whether the engine parameters meet the index requirements is: Select a certain number of steady-state performance test points on the engine, calculate the engine performance parameters and aerodynamic stability parameters of the steady-state performance test points, use the absolute value calculation method to calculate the difference ratio of the engine performance parameters and aerodynamic stability parameters and the corresponding indicators, when the difference ratio is less than a certain value, it is judged that the index requirement is met; otherwise, the main fuel control law state switching period and the flow limiting period are redesigned until the index requirement is met.

6. The variable cycle engine main fuel regulation method of claim 1 wherein, By calculating the thrust characteristics corresponding to the two duct ratios respectively, and then calculating the intersection point of the thrust characteristics corresponding to the two duct ratios as the critical Mach number.

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