A method for quickly filling a large-cavity forced fuel pipeline

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a large-cavity afterburner fuel pipeline rapid filling method. The application changes a scheme of filling afterburner fuel distributors according to a traditional afterburner fuel distributioner control afterburner fuel manifold filling into a control scheme of filling according to a digital electronic control metering oil rapid filling. Meanwhile, through a nozzle area A8 pre-discharge, the afterburner each road filling process Pt6 drop quantity and Pt6 rise quantity after the filling completion are ensured to meet the afterburner connection time, the afterburner flame and the influence quantity of the afterburner on the surge margin in the controllable range. In addition, a disposal logic of a large EPR misadjustment in the afterburner connection process is arranged to reduce the parameter fluctuation quantity. The above measures have important roles for safely, rapidly and reliably connecting the afterburner, reducing the parameter fluctuation quantity in the afterburner connection process, and have very important significance for realizing the engine afterburner connection index, realizing the stable work requirements in the flight range and the like.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a method for rapid filling of a large-volume afterburning fuel line. Background Technology

[0002] Once the hardware design of an afterburning turbofan engine is finalized, developing a scientific afterburner engagement control scheme is crucial for ensuring rapid, smooth, and reliable afterburner engagement. Modern engines have a very wide afterburner engagement range, with some engines even requiring afterburner engagement capability across almost the entire flight range. When afterburner engagement control is not optimized, significant fluctuations in engine process parameters occur during afterburner engagement. This can range from minor fluctuations in critical parameters such as exhaust pressure (Pt6) and thrust, to more serious issues like unreliable afterburner engagement within the required range, or a substantial decrease in the surge margin of compression components (primarily the fan), potentially even triggering surge. These factors severely endanger the operational safety of the engine and aircraft, and are a major contributing factor to flight safety accidents.

[0003] Therefore, developing a reasonable afterburner activation scheme is of great significance for reliable afterburner activation, reducing the surge margin decrease during afterburner activation, and improving operational effectiveness.

[0004] During the booster connection process, the matching degree between the booster fuel supply and the nozzle area is required to be high. The larger the filling volume of each booster (zone) pipeline, the shorter the booster connection time, and the smaller the parameter fluctuation amplitude requirement, the greater the difficulty of matching the two will be.

[0005] Currently, domestically produced third-generation turbofan engines have relatively long afterburner engagement times and all employ a mechanical-hydraulic afterburner fuel distributor for automatic afterburner fuel filling (this accessory can automatically and rapidly fill the afterburner line with non-metered fuel when afterburner engagement conditions are met, and automatically stops after filling). The presence of the afterburner fuel distributor shortens the afterburner fuel main filling time and reduces the possibility of parameter fluctuations, compression component surge margin loss, or afterburner stall caused by overfilling or underfilling of the line. Matching the fuel and nozzle area during afterburner engagement is relatively easy; without software measures to suppress parameter fluctuations, the engine exhaust pressure Pt6 fluctuation amplitude during afterburner engagement is sufficient to meet the requirement of no more than 8%. With engine upgrades, advanced engines have adopted full authority numerical control systems, eliminating the afterburner fuel distributor, and the afterburner line filling mode has changed from mechanical hydraulic system control to digital electronic control. Simultaneously, due to increased engine thrust and larger line cavity, shorter afterburner engagement times and smaller parameter fluctuation amplitudes (no more than 5%) are required, and existing designs clearly cannot meet these new requirements. There are no reports from abroad that can be used as a reference.

[0006] Currently, the existing third-generation afterburning turbofan aero engines in China use a mechanical-hydraulic afterburning fuel distributor to fill the afterburning fuel manifold. When the throttle lever angle and engine speed meet the afterburning activation conditions, the afterburning line can be automatically filled at high speed using non-metered fuel, and automatically stopped after it is full. This shortens the afterburning fuel manifold filling time and reduces parameter fluctuations caused by overfilling or underfilling of the line, as well as the possibility of surge margin loss of compression components or afterburning shutdown. Summary of the Invention

[0007] To address the aforementioned problems, this application provides a method for rapid filling of a large-capacity afterburning fuel line, comprising:

[0008] The external throttle lever angle position controlled by the pilot is obtained, and the internal throttle lever controlling the fuel flow moves toward the external throttle lever angle position; when the afterburner is engaged, each afterburner fuel manifold is filled with fuel in the corresponding order and fuel supply filling coefficient. When each afterburner fuel manifold is filled, the throttle lever is locked in a given position, and the nozzle area is increased according to a preset value.

[0009] Once the corresponding afterburner fuel manifold is filled, the built-in throttle lever is released from its current position lock. After unlocking, the nozzle area and afterburner fuel supply increase in a matching manner according to a given pattern, and the built-in throttle lever moves according to a preset throttle lever speed limit scheme.

[0010] Preferably, the given position of the built-in throttle lever lock and the preset value of the increase in nozzle area ensure that the decrease in engine exhaust pressure Pt6 is within the specified range, and the instantaneous increase in engine exhaust pressure Pt6 is within the specified range when each afterburner fuel main is overfilled.

[0011] Preferably, the preset value of the nozzle area increase ensures that the decrease in engine exhaust pressure Pt6 after the increase is no more than 4%, and the instantaneous increase in engine exhaust pressure Pt6 when each afterburner fuel manifold is overfilled is no more than 5%.

[0012] Preferably, the preset throttle lever rate limiting scheme includes: when the throttle lever angle PLA is between 75° and 80°, the built-in throttle lever rate is maintained at 60° / s; when the throttle lever angle PLA is between 83° and 90°, the built-in throttle lever rate is maintained at 23° / s; when the throttle lever angle PLA is between 93° and 105°, the built-in throttle lever rate is maintained at 15° / s; when the throttle lever angle PLA is between 107° and 110°, the built-in throttle lever rate is maintained at 60° / s; and the throttle lever rate between adjacent intervals is smoothly transitioned by 2° to 3°.

[0013] Preferably, during the power-on process, when the difference between the given value and the feedback value of the engine pressure ratio EPR is greater than a given threshold, the throttle lever angle is locked; when the deviation between the given value and the feedback value of the engine pressure ratio EPR is less than the given threshold, the throttle lever angle is unlocked.

[0014] Preferably, the filling status of each afterburner fuel main is determined based on the increase in the oil pressure measurement values ​​Pjl2 and Pjl3 of the second fuel main and the third fuel main during the filling process.

[0015] The advantages of this application include: the present invention changes the traditional scheme of controlling the filling of each fuel main of the afterburner by the fuel distributor to a control scheme of rapid filling of metered fuel by digital electronic control;

[0016] At the same time, by pre-releasing the nozzle area A8, the amount of Pt6 falling during the filling process of each afterburner and the amount of Pt6 rising after filling are ensured, so as to keep the afterburner connection time, afterburner flame connection and the impact of afterburner on surge margin within a controllable range.

[0017] In addition, a handling logic is set up to deal with large EPR misalignment during the force connection process, reducing parameter fluctuations.

[0018] The above measures play an important role in ensuring safe, rapid, and reliable afterburner engagement and reducing parameter fluctuations during afterburner engagement. They are of great significance for achieving engine afterburner engagement targets and other tactical and technical targets such as stable operation within the flight range. Attached Figure Description

[0019] Figure 1 This is a schematic diagram showing the relationship between the afterburner fuel supply coefficient and the throttle angle in this application.

[0020] Figure 2 This is a schematic diagram showing the change in nozzle throat area with throttle angle. Detailed Implementation

[0021] 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.

[0022] This application provides a method for rapid filling of a large-capacity afterburning fuel line, including:

[0023] The external throttle lever angle position controlled by the pilot is obtained, and the internal throttle lever controlling the fuel flow moves toward the external throttle lever angle position; when the afterburner is engaged, each afterburner fuel manifold is filled with fuel in the corresponding order and fuel supply filling coefficient. When each afterburner fuel manifold is filled, the throttle lever is locked in a given position, and the nozzle area is increased according to a preset value.

[0024] Once the corresponding afterburner fuel manifold is filled, the built-in throttle lever is released from its current position lock. After unlocking, the nozzle area and afterburner fuel supply increase in a matching manner according to a given pattern, and the built-in throttle lever moves according to a preset throttle lever speed limit scheme.

[0025] The methods for determining the fuel supply filling coefficient for each route include:

[0026] 1. Determine the volume of each fuel manifold in the afterburner and allocate the filling time appropriately according to the total afterburner connection time requirement. Typically, afterburner engines supply fuel through 4-5 fuel manifolds. Taking a 4-way afterburner engine as an example, the volume of each fuel manifold is shown in Table 1. The filling time allocated to each fuel manifold in the afterburner according to the ground afterburner connection time requirement is shown in Table 1 (the proportion of filling time allocation for each fuel manifold in the air is determined with reference to ground condition time).

[0027] Table 1. Fuel mains capacity for each afterburner line

[0028]

[0029] 2. Develop a suitable booster oil supply scheme for full-coverage lines.

[0030] 1) Within the envelope, define the fuel supply fill factor for each booster path in the zoned configuration.

[0031] To reduce the fluctuation amplitude of the engine exhaust pressure Pt6 parameter caused by overfilling of the fuel manifold and to avoid excessive loss of surge margin leading to surge, fuel filler coefficients for each afterburner path were established within the envelope (based on height and total intake pressure)—the fuel filler coefficients PCT1, PCT2, PCT3, and PCT4 for afterburner paths I, II, III, and IV (i.e., the percentage of filler fuel to the total afterburner fuel volume). The fuel manifold filler coefficients given for afterburner path I are shown in Table 2.

[0032] The oil supply filling coefficient setting should be able to take into account the need for pipeline filling time and prevent excessive loss of the surge margin of the compression components in case of overfilling.

[0033] Table 2 Filling coefficients for Afterburner I

[0034]

[0035] 2) When filling each fuel main, lock the throttle lever to the given position, and at the same time, pre-release the nozzle area appropriately to ensure that the decrease in Pt6 after pre-release is within the specified range (not greater than 4%). At the same time, ensure that the instantaneous increase in Pt6 during PCT1, PCT2, PCT3, and PCT4 filling is within the specified range (not greater than 5%).

[0036] 3) Pressure measurement is performed using large oil volume distribution manifolds such as Pjl2 and Pjl3;

[0037] The fuel main is determined to be full based on the increase in the filling process of Pjl2 and Pjl3. After full filling, the throttle lever is released from its current position lock. After unlocking, the nozzle area and fuel supply increase in a matching manner according to a given pattern.

[0038] The preset throttle lever speed limiting scheme includes:

[0039] Normally, the throttle lever angle and afterburner fuel supply change linearly under afterburner conditions, and the nozzle area adapts to the fuel supply. To make the afterburner activation relatively "smooth," this patent has developed a suitable throttle rate limiting scheme based on the afterburner activation time requirements. When the throttle is quickly pushed up, the afterburner fuel supply and nozzle feedforward are controlled at a limited rate, reducing the impact of untimely nozzle area adjustment and large parameter fluctuations during the transition process. See Table 3 for details.

[0040] Table 3 Throttle lever speed limiting scheme

[0041]

[0042] Furthermore, a handling logic for large EPR misalignment has been added to reduce parameter fluctuations and improve afterburner engagement capability. During afterburner engagement, when the difference between the engine pressure ratio (EPR) setpoint and the feedback value deviates significantly, the nozzle throat area A8 deviates from the required value, causing changes in the main engine status and resulting in parameter fluctuations. To mitigate this issue, a separate handling logic for large EPR deviations has been implemented: when the deviation between the EPR setpoint and the feedback value exceeds a given threshold, the throttle lever angle is locked; when the deviation falls below the given threshold, the throttle lever angle is unlocked. This measure alleviates the large EPR misalignment problem, reduces parameter fluctuations, and improves afterburner engagement capability.

[0043] The advantages of this application include: This invention replaces the traditional method of controlling the filling of each afterburner fuel manifold via a fuel distributor with a digital electronic control method for rapid fuel filling; simultaneously, by pre-releasing the nozzle area A8, it ensures the amount of Pt6 decrease during the filling process and the amount of Pt6 increase after filling, thus keeping the afterburner activation time, afterburner flame, and the impact of afterburner on surge margin within a controllable range; furthermore, it incorporates logic to handle large EPR misalignment during afterburner activation, reducing parameter fluctuations. These measures play a crucial role in ensuring safe, rapid, and reliable afterburner activation and reducing parameter fluctuations during afterburner activation, and are of great significance for achieving engine afterburner activation targets and stable operation requirements within the flight range.

[0044] 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 rapid filling of a large volume forced fuel line, characterized in that, The method comprises the following steps: An angle position of an external throttle lever operated by a pilot is acquired, and a built-in throttle lever controlling fuel flow is moved to the angle position of the external throttle lever; When the afterburner is turned on, each afterburner fuel manifold fills fuel according to a corresponding sequence and a filling coefficient, and the throttle lever is locked at a given position when each afterburner fuel manifold is filled, and the nozzle area is increased according to a preset value; After the corresponding afterburner fuel manifold is filled, the built-in throttle lever is unlocked from the current position, and after the unlocking, the nozzle area and the afterburner fuel are increased according to a given rule, and the built-in throttle lever is moved according to a preset throttle lever speed limit scheme; The given position of the built-in throttle lever and the preset value of the increased nozzle area ensure that the decrease amplitude of the engine exhaust pressure Pt6 is within a specified range, and when each afterburner fuel manifold is overfilled, the instantaneous engine exhaust pressure Pt6 increases by an amplitude within a specified range.

2. The method of quickly filling a large volume forced fuel line of claim 1, wherein, The filling coefficient of each afterburner fuel manifold is determined according to the flight altitude H and the engine inlet total pressure Pt2.

3. The method of quickly filling a large volume forced fuel line of claim 1, wherein, The preset value of the increased nozzle area ensures that the decrease amplitude of the engine exhaust pressure Pt6 after the increase is not greater than 4%, and when each afterburner fuel manifold is overfilled, the instantaneous engine exhaust pressure Pt6 increases by an amplitude not greater than 5%.

4. The method of quickly filling a large volume forced fuel line of claim 1, wherein, The preset throttle lever speed limit scheme comprises: when the throttle lever angle PLA is between 75° and 80°, the built-in throttle lever speed is kept at 60° / s; when the throttle lever angle PLA is between 83° and 90°, the built-in throttle lever speed is kept at 23° / s; when the throttle lever angle PLA is between 93° and 105°, the built-in throttle lever speed is kept at 15° / s; when the throttle lever angle PLA is between 107° and 110°, the built-in throttle lever speed is kept at 60° / s; the throttle lever speed of adjacent intervals is smoothly transitioned by 2° to 3°.

5. The method of quickly filling a large volume forced fuel line of claim 1, wherein, During the afterburner process, when the difference between the given value and the feedback value of the engine pressure ratio EPR is greater than a given threshold, the throttle lever angle is locked; when the difference between the given value and the feedback value of the engine pressure ratio EPR is less than a given threshold, the throttle lever angle is unlocked.

6. The method of quickly filling a large volume forced fuel line of claim 1, wherein, Whether each afterburner fuel manifold is filled is determined according to the increase of the second fuel manifold oil pressure measurement value Pjl2 and the third fuel manifold oil pressure measurement value Pjl3 during the filling process.

7. The large-volume forced fuel line quick-fill method of claim 1, wherein The filling coefficient of each afterburner fuel manifold is distributed according to the fuel manifold volume.

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