A nozzle throat area adjustment method based on fan pressure ratio closed-loop control

Abstract

The present application belongs to the technical field of nozzle control of aviation turbofan engines, and specifically relates to a nozzle throat area adjustment method based on fan pressure ratio closed-loop control, comprising: step one, calculating the corresponding fan pressure ratio pifDem at different aviation turbofan engine intake temperatures and low-pressure conversion speeds according to the nozzle throat area design rule; step two, when the aviation turbofan engine is working, according to the corresponding fan pressure ratio pifDem at different aviation turbofan engine intake temperatures and low-pressure conversion speeds, closed-loop controlling the nozzle throat area S, adjusting the pressure ratio pif when the fan is working, and controlling the aviation turbofan engine.

Description

Technical Field

[0001] The present application belongs to the technical field of nozzle control of aviation turbofan engines, and specifically relates to a nozzle throat area adjustment method based on closed-loop control of fan pressure ratio. Background Art

[0002] In order to reduce the detectability of aircraft, a large amount of bypass air is currently used to cool the nozzle in the design of aviation turbofan engines. The bypass air cooling air flows from the afterburner heat shield into the nozzle heat shield and flows out from the air film holes on the nozzle heat shield to form a cooling air film to cool the nozzle. The cooling air exists not only from the nozzle inlet to the nozzle throat, but also from the nozzle throat to the nozzle outlet.

[0003] The nozzle flow coefficient is the ratio of the effective flow area of ​​the nozzle throat to the mechanical area of ​​the nozzle, and it changes with changes in the cooling air mixing loss. Turbofan engines require a large amount of external cooling air to cool the nozzle throughout the engine's operation, and this external cooling air can change in real time, causing changes in the cooling air mixing loss and, in turn, the nozzle flow coefficient to change.

[0004] When the cooling air mixing loss is large, the air flow pressure in the nozzle is low and the required effective flow area is large. At this time, if the nozzle mechanical area is kept unchanged, it is equivalent to reducing the effective flow area of ​​the nozzle throat and the nozzle flow coefficient becomes smaller, which will cause the fan working line to move up; when the cooling air mixing loss is small, the air flow pressure in the nozzle is high and the required effective flow area is small. At this time, if the nozzle mechanical area is kept unchanged, it is equivalent to increasing the effective flow area of ​​the nozzle throat and the nozzle flow coefficient becomes larger, which will cause the fan working line to move down, such as Figure 2 As shown in the figure, this phenomenon is common in the small nozzle state in the left half of the flight envelope of aviation turbofan engines where the inlet pressure is lower.

[0005] If the fan working line moves downward, the fan stability margin and fan efficiency will be reduced, thereby increasing the exhaust temperature of the aviation turbofan engine and may cause the aviation turbofan engine to enter an unstable working area; if the fan working line moves downward, the fan pressure ratio will be reduced, thereby reducing the overall thrust of the aviation turbofan engine, affecting the performance of the aircraft.

[0006] Currently, most approaches use closed-loop control of the turbofan engine's pressure ratio (the ratio of the turbofan engine's exhaust pressure to its inlet pressure) to maintain the fan operating line at its design state. With this technical solution, if the compressor pressure ratio and turbine expansion ratio are at their design states, the fan pressure ratio will also be at their design state. However, due to individual differences in turbofan engines and performance degradation, the compressor pressure ratio and turbine expansion ratio often deviate from their design states. At this point, if closed-loop control of the turbofan engine's pressure ratio is still applied, the fan pressure ratio will deviate from its design state, resulting in changes in the overall engine matching.

[0007] This application is proposed in view of the above-mentioned technical defects. Summary of the Invention

[0008] The purpose of this application is to provide a nozzle throat area adjustment method based on fan pressure ratio closed-loop control to overcome or alleviate at least one of the known technical defects.

[0009] The technical solution of this application is:

[0010] A nozzle throat area adjustment method based on fan pressure ratio closed-loop control, comprising:

[0011] Step 1: Calculate the corresponding fan pressure ratio pifDem under different aviation turbofan engine inlet temperatures and low-pressure conversion speeds according to the nozzle throat area design rules;

[0012] Step 2: When the aviation turbofan engine is working, the nozzle throat area S is controlled in a closed loop according to the corresponding fan pressure ratio pifDem at different aviation turbofan engine inlet temperatures and low-pressure converted speeds, and the pressure ratio pif when the fan is working is adjusted to control the aviation turbofan engine.

[0013] According to at least one embodiment of the present application, in the above-mentioned nozzle throat area adjustment method based on fan pressure ratio closed-loop control, in step one, the overall performance calculation model of the aviation turbofan engine is used to calculate the corresponding fan pressure ratio pifDem under different aviation turbofan engine inlet temperatures and their low-pressure converted speeds, and calculate the corresponding bypass ratio B and flow rate W.

[0014] According to at least one embodiment of the present application, in the above-mentioned nozzle throat area adjustment method based on fan pressure ratio closed-loop control, step 2 is specifically as follows:

[0015] The corresponding fan pressure ratio pifDem under different aviation turbofan engine intake temperatures and low-pressure converted speeds is input into the aviation turbofan engine controller. When the aviation turbofan engine is working, the corresponding fan pressure ratio pifDem is read from the aviation turbofan engine controller according to the aviation turbofan engine intake temperature and low-pressure converted speed, and the pressure ratio pif when the fan is working is calculated. Then, the nozzle throat area S is controlled by a closed-loop control method, and the pressure ratio pif when the fan is working is adjusted to be consistent with the corresponding fan pressure ratio pifDem.

[0016] According to at least one embodiment of the present application, in the above-mentioned nozzle throat area adjustment method based on fan pressure ratio closed-loop control, in step 2, the pressure ratio pif when the fan is working is calculated as follows:

[0017] pif=(P13*(B / (1+B))+P23*(1 / (1+B))) / P2;

[0018] in:

[0019] P13 is the total pressure at the fan outer duct outlet;

[0020] P23 is the total pressure at the fan outlet;

[0021] P2 is the fan inlet pressure.

[0022] According to at least one embodiment of the present application, in the above-mentioned nozzle throat area adjustment method based on fan pressure ratio closed-loop control, in step 2, the nozzle throat area S is controlled by a closed-loop control method to adjust the pressure ratio pif during fan operation to be consistent with the corresponding fan pressure ratio pifDem, specifically:

[0023] Calculate the deviation Δ between the fan pressure ratio pif during operation and the corresponding fan pressure ratio pifDem = pifDem - pif;

[0024] Calculate the control current using the PI control algorithm Among them, K p is the proportional control parameter, which is a constant; I 平衡 K is the balance current of the electro-hydraulic servo valve used to control the nozzle throat area and is a constant; i is the integral control parameter, which is a constant; For the points link;

[0025] The control current I is output to the electro-hydraulic servo valve for controlling the nozzle throat area actuator to control the nozzle throat area actuator, adjust the nozzle throat area S, gradually eliminate the deviation Δ, and make the pressure ratio pif when the fan is working consistent with the corresponding fan pressure ratio pifDem. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the changes in the fan working line of an aviation turbofan engine;

[0027] Figure 2 is a schematic diagram of a nozzle throat area adjustment method based on fan pressure ratio closed-loop control provided in an embodiment of the present application;

[0028] Figure 3 This is a logical diagram of controlling the nozzle throat area S using a closed-loop control method provided in an embodiment of the present application to adjust the pressure ratio pif during fan operation, which is consistent with the corresponding fan pressure ratio pifDem.

[0029] In order to better illustrate this embodiment, some components in the drawings may be omitted. This is only for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0030] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0031] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should have the usual meanings understood by those skilled in the art in the field to which this application belongs. The words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application means that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0032] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0033] A nozzle throat area adjustment method based on fan pressure ratio closed-loop control keeps the nozzle effective flow area unchanged, keeps the fan working line at the design state, and optimizes the matching of the entire aviation turbofan engine. Figure 2 shown.

[0034] Step 1: Based on the design rules of the nozzle throat area, calculate the corresponding fan pressure ratio pifDem and bypass ratio B under different aviation turbofan engine inlet temperatures and low-pressure conversion speeds.

[0035] The overall performance calculation model of aviation turbofan engines can be used to calculate the corresponding fan pressure ratio pifDem and bypass ratio B under different aviation turbofan engine inlet temperatures and low-pressure converted speeds, and the flow rate W can be calculated at the same time.

[0036] Step 2: When the aviation turbofan engine is working, the nozzle throat area S is controlled in a closed loop according to the corresponding fan pressure ratio pifDem at different aviation turbofan engine inlet temperatures and low-pressure converted speeds, and the pressure ratio pif when the fan is working is adjusted to control the aviation turbofan engine.

[0037] Specifically, the corresponding fan pressure ratio pifDem under different aviation turbofan engine intake temperatures and low-pressure converted speeds can be input into the aviation turbofan engine controller. When the aviation turbofan engine is working, the corresponding fan pressure ratio pifDem is read from the aviation turbofan engine controller according to the aviation turbofan engine intake temperature and low-pressure converted speed, and the pressure ratio pif when the fan is working is calculated. Then, the nozzle throat area S is controlled by a closed-loop control method, and the pressure ratio pif when the fan is working is adjusted to be consistent with the corresponding fan pressure ratio pifDem, that is, the effective flow area of ​​the nozzle is kept unchanged, the fan working line is kept in the design state, and the overall matching of the aviation turbofan engine is optimized.

[0038] And calculate the pressure ratio pif when the fan is working, as follows:

[0039] pif=(P13*(B / (1+B))+P23*(1 / (1+B))) / P2;

[0040] in:

[0041] P13 is the total pressure at the fan duct outlet, which can be measured by an onboard sensor;

[0042] P23 is the total pressure at the fan outlet, which can be measured by an onboard sensor;

[0043] P2 is the fan inlet pressure, which can be measured by an onboard sensor;

[0044] The bypass ratio B can be calculated by dividing the external air flow by the internal air flow, or by using the calculated value in step 1.

[0045] When the onboard sensor only measures P13 or P23, the relationship between P13 and P23 can be obtained from the relevant calculation results in step 1, or the unmeasured parameters of P13 and P23 can be calculated based on the relationship between P13 and P23 obtained by the bench pressure sensor during the ground bench test.

[0046] The closed-loop control method is used to control the nozzle throat area S and adjust the fan pressure ratio pif during operation to be consistent with the corresponding fan pressure ratio pifDem, as shown in the following example: Figure 3 For details, please refer to the following:

[0047] Calculate the deviation Δ between the fan pressure ratio pif and the corresponding fan pressure ratio pifDem when the fan is working

[0048] =pifDem-pif;

[0049] Calculate the control current using the PI control algorithm Among them, K p is the proportional control parameter, which is a constant; I 平衡K is the balance current of the electro-hydraulic servo valve used to control the nozzle throat area and is a constant; i is the integral control parameter, which is a constant; For the points link;

[0050] The control current I is output to the electro-hydraulic servo valve for controlling the nozzle throat area actuator to control the nozzle throat area actuator, adjust the nozzle throat area S, gradually eliminate the deviation Δ, and make the pressure ratio pif when the fan is working consistent with the corresponding fan pressure ratio pifDem.

[0051] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0052] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A nozzle throat area adjustment method based on fan pressure ratio closed-loop control, characterized in that: include: Step 1: Calculate the corresponding fan pressure ratio pifDem under different aviation turbofan engine inlet temperatures and low-pressure conversion speeds according to the nozzle throat area design rules; Step 2: When the turbofan engine is operating, the nozzle throat area S is controlled in a closed loop according to the corresponding fan pressure ratio pifDem at different turbofan engine inlet temperatures and low-pressure converted speeds, and the pressure ratio pif when the fan is operating is adjusted to control the turbofan engine; Step 2 is as follows: The corresponding fan pressure ratio pifDem under different aviation turbofan engine intake temperatures and low-pressure converted speeds is input into the aviation turbofan engine controller. When the aviation turbofan engine is working, the corresponding fan pressure ratio pifDem is read from the aviation turbofan engine controller according to the aviation turbofan engine intake temperature and low-pressure converted speed, and the pressure ratio pif when the fan is working is calculated. Then, the nozzle throat area S is controlled by a closed-loop control method, and the pressure ratio pif when the fan is working is adjusted to be consistent with the corresponding fan pressure ratio pifDem.

2. The nozzle throat area adjustment method based on fan pressure ratio closed-loop control according to claim 1 is characterized in that: In step one, the overall performance calculation model of the aviation turbofan engine is used to calculate the corresponding fan pressure ratio pifDem under different aviation turbofan engine inlet temperatures and low-pressure conversion speeds, as well as the corresponding bypass ratio B and flow rate W.

3. The nozzle throat area adjustment method based on fan pressure ratio closed-loop control according to claim 2, characterized in that: In step 2, the pressure ratio pif when the fan is working is calculated as follows: pif=(P13*(B / (1+B))+P23*(1 / (1+B))) / P2; in: P13 is the total pressure at the fan outer duct outlet; P23 is the total pressure at the fan outlet; P2 is the fan inlet pressure.

4. The nozzle throat area adjustment method based on fan pressure ratio closed-loop control according to claim 3 is characterized in that: In step 2, the nozzle throat area S is controlled by a closed-loop control method to adjust the fan pressure ratio pif during operation to be consistent with the corresponding fan pressure ratio pifDem, specifically: Calculate the deviation Δ between the fan pressure ratio pif during operation and the corresponding fan pressure ratio pifDem = pifDem - pif; Calculate the control current using the PI control algorithm Among them, K p is the proportional control parameter, which is a constant; I 平衡 K is the balance current of the electro-hydraulic servo valve used to control the nozzle throat area and is a constant; i is the integral control parameter, which is a constant; For the points link; The control current I is output to the electro-hydraulic servo valve for controlling the nozzle throat area actuator to control the nozzle throat area actuator, adjust the nozzle throat area S, gradually eliminate the deviation Δ, and make the pressure ratio pif when the fan is working consistent with the corresponding fan pressure ratio pifDem.

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