Method and system for predicting maximum speed of power turbine after engine loses load

Abstract

The present application relates to a kind of engine loses load power turbine maximum speed prediction method and system, belong to aviation gas turbine engine field including the following steps: obtaining the pressure signal of the compressor outlet of engine, the pressure signal of the main oil line of fuel distribution device and the pressure signal of the auxiliary oil line of fuel distribution device;Maximum state simulation overspeed test is carried out to engine, and the fuel law of engine maximum state overspeed is obtained according to test result;The power turbine speed of different time points in the maximum state overspeed process of engine is calculated by section iteration, and the relationship between power turbine speed and time is obtained;According to the relationship between power turbine speed and time, the maximum power turbine speed of engine maximum state overspeed process is obtained.The present application fully considers the response time of overspeed protection system, fuel attenuation law and torque variation law, and can accurately predict the maximum speed of engine broken shaft.

Description

Technical Field

[0001] This invention belongs to the field of aero gas turbine engines, and specifically relates to a method and system for predicting the maximum speed of the power turbine after the engine loses load. Background Technology

[0002] Torque shaft failure in turboshaft engines is a common form of turbine loss of load. At the moment of shaft failure, the continued production of high-energy combustion gases by the gas generator can cause the turbine to over-rev, potentially leading to turbine blade or disc breakage and jeopardizing flight safety. To protect the structural integrity and flight safety of turboshaft engines, they are designed with a turbine over-rev protection system. However, due to the response time of this system, the actual maximum over-revving speed is higher than the over-rev protection value.

[0003] Existing technologies predict the maximum speed of a power turbine when it loses load by assuming that the gas generator output energy remains constant and calculating based on the relationship between gas turbine output energy and aerodynamic torque, and between power turbine speed and acceleration. In reality, after the power turbine loses load, the over-rev protection system reduces fuel flow, thereby reducing the gas generator output energy. This assumption does not match reality and introduces errors. Existing technologies assume that the maximum speed has been reached when the over-rev protection system responds. However, in actual operation, the fuel cut-off or reduction requires a certain amount of time, during which the engine speed continues to rise. Therefore, this calculation method does not fully consider the fuel decay pattern and contains errors. Existing fuel flow meters are installed in the inlet pipe of the test bench and measure flow using a low sampling rate (below 20Hz) data acquisition system. However, this method cannot reflect the actual flow rate entering the engine combustion chamber during the transition state. Therefore, this method has errors and lag in fuel flow measurement and cannot accurately obtain the true pattern of fuel flow rate after fuel cut-off.

[0004] Therefore, it is evident that existing technologies cannot accurately predict the maximum speed in the event of an engine shaft breakage. Summary of the Invention

[0005] To address the above problems, this invention provides a method for predicting the maximum speed of a power turbine after an engine loses load, comprising the following steps:

[0006] Acquire the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device;

[0007] Conduct simulated over-revving tests under maximum engine conditions, and obtain the fuel consumption patterns under maximum engine over-revving conditions based on the test results;

[0008] The power turbine speed at different time points during the engine's maximum overspeed process is calculated in a piecewise iterative manner to obtain the relationship between the power turbine speed and time.

[0009] Based on the relationship between the power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained.

[0010] Furthermore, the simulated over-rotation test includes the following steps:

[0011] Start the engine and run it to maximum speed; the running time is 3-5 minutes.

[0012] The test bench equipment is used to control the over-revving fuel release valve of the fuel distribution device until the fuel supply to the engine is completely cut off.

[0013] The pressure signals at the compressor outlet, the main oil circuit, and the auxiliary oil circuit of the fuel distribution device of the engine at maximum over-speed were obtained using test bench equipment, and the variation of these signals with the fuel cut-off time was observed.

[0014] Based on the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device, the fuel flow rate of the main oil circuit and the auxiliary oil circuit of the fuel distribution device is calculated to obtain the over-rev fuel pattern.

[0015] Furthermore, the variation patterns of the compressor outlet pressure signal, the main oil circuit pressure signal, and the auxiliary oil circuit pressure signal of the engine at maximum over-revving state with the fuel cut-off time are expressed as follows:

[0016] P fz =f1(t), P ff =f2(t), P s3 =f3(t)

[0017] In the formula, P fz P is the pressure signal for the main oil circuit of the fuel distribution device. ff P is the pressure signal for the auxiliary oil circuit of the fuel distribution device. s3 This is the pressure signal at the compressor outlet of the engine.

[0018] Furthermore, the calculation formula for the over-revving fuel consumption law is expressed as follows:

[0019]

[0020] W f =W fz +W ff =f4(t)

[0021] In the formula, Wfz W represents the fuel flow rate in the main oil circuit of the fuel distribution device. ff W is the fuel flow rate in the auxiliary oil circuit of the fuel distribution device. f denoted as the total fuel flow rate into the engine combustion chamber, b is the main fuel circuit flow coefficient, d is the auxiliary fuel circuit flow coefficient, and c is the correction coefficient.

[0022] Furthermore, the relationship between the power turbine speed and time is expressed as follows:

[0023] N p =f6(t).

[0024] Furthermore, the calculation formula for segmented iterative calculation of the power turbine speed at different time points during the maximum overspeed process of the engine is expressed as follows:

[0025] Np x+1 =Np x +a x *T0 / n

[0026] In the formula, a is the acceleration of the power turbine rotor; T0 is the total duration of the overrun process; and n is the number of segments in the total duration of the overrun process.

[0027] Furthermore, the formula for calculating the acceleration of the power turbine rotor is expressed as follows:

[0028]

[0029] In the formula, T is the aerodynamic torque during the dynamic process; k1 is the moment of inertia of the power turbine rotor system; N p This refers to the speed of the power turbine.

[0030] Furthermore, the formula for calculating the aerodynamic torque of the dynamic process is expressed as follows:

[0031]

[0032] In the formula, N p Pdn represents the turbine speed; Pdn represents the engine's equivalent power.

[0033] Furthermore, the formula for calculating the equivalent power of the engine is expressed as follows:

[0034] Pdn=f(W f N p f5(t)

[0035] In the formula, W f N is the total fuel flow rate into the engine combustion chamber. p This refers to the speed of the power turbine.

[0036] A system for predicting the maximum speed of a power turbine after engine loss of load includes:

[0037] Acquisition module: used to acquire the pressure signal at the compressor outlet of the engine, the pressure signal of the main oil circuit of the fuel distribution device, and the pressure signal of the auxiliary oil circuit of the fuel distribution device;

[0038] Test module: Used to conduct simulated over-revving tests under maximum engine conditions, and to obtain the fuel consumption patterns under maximum engine over-revving conditions based on the test results;

[0039] Calculation module: Performs piecewise iterative calculations on the power turbine speed at different time points during the engine's maximum overspeed process to obtain the relationship between power turbine speed and time;

[0040] Turbine speed module: Based on the relationship between power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1) This invention fully considers the response time of the overspeed protection system, the fuel decay law and the torque change law, and can accurately predict the maximum speed in the event of engine shaft failure.

[0043] 2) This invention utilizes test bench equipment to obtain the pressure signal at the compressor outlet of the engine at maximum over-speed, the pressure signal of the main oil circuit of the fuel distribution device, and the pressure signal of the auxiliary oil circuit of the fuel distribution device as a function of fuel cut-off time, thus fully considering the response time of the over-speed protection system.

[0044] 3) This invention performs segmented iterative calculations on the power turbine speed at different time points during the engine's maximum overspeed process to obtain the relationship between the power turbine speed and time, thereby deriving the maximum power turbine speed during the engine's maximum overspeed process, thus taking into account the law of torque change.

[0045] 4) This invention conducts a simulated over-revving test under the maximum engine condition and obtains the fuel consumption law under the maximum engine over-revving condition based on the test results, thus taking into account the fuel degradation law.

[0046] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart of the method for predicting the maximum speed of the power turbine after the engine loses load according to the present invention is shown;

[0049] Figure 2 The diagram shows the variation of the pressure signal at the compressor outlet, the pressure signal in the main oil circuit of the fuel distribution device, and the pressure signal in the auxiliary oil circuit of the fuel distribution device with the fuel cut-off time when the engine is at its maximum over-speed.

[0050] Figure 3 A schematic diagram of the fuel consumption pattern during over-revving is shown;

[0051] Figure 4 A schematic diagram showing the variation of the engine's equivalent power is shown.

[0052] Figure 5 A schematic diagram showing the relationship between the speed of a power turbine and time;

[0053] Figure 6 A schematic diagram of the fuel distribution device and the test bench equipment is shown.

[0054] Figure 7 A block diagram of the power turbine maximum speed prediction system after engine loss of load according to the present invention is shown. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Example 1

[0057] Figure 1 A flowchart illustrating the method for predicting the maximum speed of the power turbine after the engine loses load according to the present invention is shown. Figure 1 As shown, a method for predicting the maximum speed of a power turbine after an engine loses load includes the following steps:

[0058] Acquire the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device;

[0059] Conduct simulated over-revving tests under maximum engine conditions, and obtain the fuel consumption patterns under maximum engine over-revving conditions based on the test results;

[0060] The power turbine speed at different time points during the engine's maximum overspeed process is calculated in a piecewise iterative manner to obtain the relationship between the power turbine speed and time.

[0061] Based on the relationship between the power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained.

[0062] In some embodiments, the conditions for performing piecewise iterative calculations of the power turbine speed at different time points during the engine's maximum overspeed process are as follows:

[0063] The transient analysis of the aerodynamic torque of the power turbine during over-rotation was performed using a steady-state analysis method.

[0064] During over-revving, the slow-response power turbine constant speed system has no effect on the fuel decay pattern.

[0065] Specifically, a power turbine speed constant speed system with a slow response time refers to a system that regulates fuel supply by controlling the opening of the fuel pump regulator needle, hence the slower response time.

[0066] In some embodiments, the simulated overrun test includes the following steps:

[0067] Start the engine and run it to maximum speed; the running time is 3-5 minutes.

[0068] The test bench equipment is used to control the over-revving fuel release valve of the fuel distribution device until the fuel supply to the engine is completely cut off.

[0069] The pressure signals at the compressor outlet, the main oil circuit, and the auxiliary oil circuit of the fuel distribution device of the engine at maximum over-speed were obtained using test bench equipment, and the variation of these signals with the fuel cut-off time was observed.

[0070] Based on the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device, the fuel flow rate of the main oil circuit and the auxiliary oil circuit of the fuel distribution device is calculated to obtain the over-rev fuel pattern.

[0071] In some embodiments, the criterion for determining whether the engine's fuel supply is completely cut off is that the pressure signals of both the main fuel circuit and the auxiliary fuel circuit of the fuel distribution device are less than the pressure signal at the engine compressor outlet.

[0072] Figure 2 This diagram illustrates the variation of pressure signals at the compressor outlet, the main fuel line, and the auxiliary fuel line of the engine at maximum over-revving with the fuel cut-off time. Figure 2 As shown, in some embodiments, the variation patterns of the compressor outlet pressure signal, the main oil circuit pressure signal, and the auxiliary oil circuit pressure signal of the fuel distribution device with the fuel cut-off time for the engine at maximum overspeed are expressed as follows:

[0073] P fz =f1(t), P ff =f2(t), P s3 =f3(t)

[0074] In the formula, P fz P is the pressure signal for the main oil circuit of the fuel distribution device. ff P is the pressure signal for the auxiliary oil circuit of the fuel distribution device. s3 This is the pressure signal at the compressor outlet of the engine.

[0075] Figure 3 A schematic diagram illustrating the over-revving fuel consumption pattern is shown. For example... Figure 3 As shown, in some embodiments, the calculation formula for the over-revving fuel pattern is expressed as:

[0076]

[0077] W f =W fz +W ff =f4(t)

[0078] In the formula, W fz W represents the fuel flow rate in the main oil circuit of the fuel distribution device. ff W is the fuel flow rate in the auxiliary oil circuit of the fuel distribution device. f denoted as the total fuel flow rate into the engine combustion chamber, b is the main fuel circuit flow coefficient, d is the auxiliary fuel circuit flow coefficient, and c is the correction coefficient.

[0079] Figure 5 A schematic diagram showing the relationship between the speed of a power turbine and time. (Example) Figure 5 As shown, in some embodiments, the relationship between the power turbine speed and time is expressed as:

[0080] N p =f6(t).

[0081] In some embodiments, the calculation formula for segmented iterative calculation of the power turbine speed at different time points during the engine's maximum overspeed process is expressed as follows:

[0082] Np x+1 =Np x +a x *T0 / n

[0083] In the formula, a is the acceleration of the power turbine rotor; T0 is the total duration of the overrun process; and n is the number of segments in the total duration of the overrun process.

[0084] Specifically, once the total fuel flow into the engine combustion chamber reaches zero, the engine's gas generator ceases to output energy; therefore, the starting point is set to W. f The time when the time equal to 0 is the total duration T0, that is, the total duration of the overspeed process is T0. The overspeed process T0 is divided into n segments, and the calculation is performed segment by segment with T0 / n as a segment. The acceleration of the power turbine rotor obtained after using the initial parameters of each segment is regarded as the average acceleration of that segment. The power turbine speed of each segment is equal to the power turbine speed of the previous segment plus the power turbine rotor acceleration multiplied by the time. That is, the power turbine speed of the xth segment is expressed as:

[0085] Np x+1 =Np x +a x *T0 / n

[0086] From this, the relationship between the power turbine speed and time, N, is obtained. p =f6(t), and the maximum power turbine speed during the over-rotation process is obtained.

[0087] In some embodiments, the piecewise iterative calculation process of the power turbine speed includes an initial value of the power turbine speed, and the formula for calculating the initial value of the power turbine speed is expressed as:

[0088] Np1 = Np0 + a1 * T0 / n

[0089] In some embodiments, the formula for calculating the acceleration of the power turbine rotor is expressed as:

[0090]

[0091] In the formula, T is the aerodynamic torque during the dynamic process; k1 is the moment of inertia of the power turbine rotor system; N p This refers to the speed of the power turbine.

[0092] In some embodiments, the formula for calculating the aerodynamic torque of the dynamic process is expressed as:

[0093]

[0094] In the formula, N p Pdn represents the turbine speed; Pdn represents the engine's equivalent power.

[0095] Figure 4 A schematic diagram illustrating the variation of the engine's equivalent power is shown. For example... Figure 4 As shown, in some embodiments, the formula for calculating the equivalent power of the engine is expressed as:

[0096] Pdn=f(W f N p f5(t)

[0097] In the formula, W f N is the total fuel flow rate into the engine combustion chamber. p This refers to the speed of the power turbine.

[0098] Specifically, the engine performance model is established using the component-level modeling method for turboshaft engines. This involves iteratively solving a set of simultaneous cubic equations based on the characteristics of each engine component, inlet and outlet conditions, and equilibrium conditions to obtain the engine's maximum steady-state performance. Transient state simulation is then performed based on this model, according to W... f =f4(t) is used to adjust the fuel supply and obtain the relationship between the engine's equivalent power Pdn and time.

[0099] Specifically, adjusting the fuel supply involves inputting the fuel flow rate into the engine performance model, which then calculates the engine's equivalent power.

[0100] Specifically, the component-level modeling object is a single-rotor turboshaft engine with a free turbine. The engine is divided into multiple sub-components for calculation. A common working equation is established through the aerodynamic and thermodynamic relationships between the components, and the engine performance is calculated based on the common operating point obtained from the solution. This is existing technology and will not be elaborated further.

[0101] Specifically, since the engine performance model uses a power turbine characteristic diagram, which includes the power turbine efficiency at different power turbine speeds, the power turbine efficiency, blade airflow friction, impeller aerodynamic drag, and bearing friction are all considered in the component-level model when calculating the output power at different power turbine speeds, and are not calculated separately. The power turbine efficiency here already takes into account blade airflow friction, impeller aerodynamic drag, and bearing friction.

[0102] In some embodiments, an engine model is established using a common turboshaft engine component-level modeling method, and the engine equivalent power is calculated based on the total fuel flow into the engine combustion chamber and the power turbine speed.

[0103] Figure 6 A schematic diagram of the fuel distribution device and the test bench equipment is shown. Figure 6As shown, specifically, the test bench equipment includes a high-speed dynamic recorder, a first pressure sensor, a second pressure sensor, and a third pressure sensor. The electrical system of the high-speed dynamic recorder is electrically connected to the over-speed fuel cut-off solenoid valve of the fuel distribution device. The first pressure sensor is installed at the valve of the main fuel line of the fuel distribution device, the second pressure sensor is installed at the valve of the auxiliary fuel line of the fuel distribution device, and the third pressure sensor is installed at the compressor outlet. The first, second, and third pressure sensors are all electrically connected to the high-speed dynamic recorder, thereby transmitting the pressure signals from the main fuel line, auxiliary fuel line, and compressor outlet to the high-speed dynamic recorder.

[0104] Specifically, the sampling rate of the high-speed dynamic recorder is ≥1000Hz.

[0105] Figure 7 A block diagram of the power turbine maximum speed prediction system after engine loss of load according to the present invention is shown. Figure 7 As shown, a system for predicting the maximum speed of a power turbine after engine loss of load includes:

[0106] Acquisition module: used to acquire the pressure signal at the compressor outlet of the engine, the pressure signal of the main oil circuit of the fuel distribution device, and the pressure signal of the auxiliary oil circuit of the fuel distribution device;

[0107] Test module: Used to conduct simulated over-revving tests under maximum engine conditions, and to obtain the fuel consumption patterns under maximum engine over-revving conditions based on the test results;

[0108] Calculation module: Performs piecewise iterative calculations on the power turbine speed at different time points during the engine's maximum overspeed process to obtain the relationship between power turbine speed and time;

[0109] Turbine speed module: Based on the relationship between power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained.

[0110] Example 2

[0111] Based on Example 1, the super-rotation process is divided into n segments, where subscripts 1, 2, 3...n represent the starting parameters of each segment, and N... p0 Let the overspeed response speed of the engine's power turbine be the calculation process for the relationship between the power turbine speed and time, which is expressed as follows:

[0112] Pdn1=f(W f1 N p0 )=f(P fz1 P ff1 P s3-1 N p0 )

[0113]

[0114] Np1=N p0 +a1*T0 / n

[0115] Pdn2=f(W f2 N p1 )=f(P fz2 P ff2 P s3-2 N p1 )

[0116]

[0117] Np2 = Np1 + a2 * T0 / n

[0118] ...

[0119] Pdn n =f(W fn N pn-1 )=f(P fz n P ff n P s3-n N pn-1 )

[0120]

[0121] Np n =N pn-1 +a n *T0 / n

[0122] Specifically, 0-10ms is the first segment, and 10ms-20ms is the second segment. Based on the parameters at 0ms, the acceleration is calculated to be 30 revolutions / ms. Therefore, it is assumed that the power turbine speed increased by 300 revolutions after 10ms in the first segment.

[0123] Specifically, N p0 The overspeed response speed of the engine's power turbine is the same as the power turbine speed in Example 1.

[0124] test:

[0125] The maximum turbine speed under load loss was calculated for the turboshaft engine, and a table predicting the maximum speed under the condition of engine shaft failure was obtained. See Table 1.

[0126]

[0127] Table 1

[0128] As shown in Table 1, the maximum power turbine speed during the over-revving process is expected to be 127.52%, which accurately predicts the maximum speed in the event of engine shaft failure.

[0129] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features in the formulas; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the maximum speed of a power turbine after an engine loses load, characterized in that, Includes the following steps: Acquire the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device; Conduct simulated over-revving tests under maximum engine conditions, and obtain the over-revving fuel characteristics of engine over-revving under maximum engine conditions based on the test results; The power turbine speed at different time points during the engine's maximum overspeed process is calculated in a piecewise iterative manner to obtain the relationship between the power turbine speed and time. Based on the relationship between the power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained; The formula for calculating the over-revving fuel consumption law is as follows: W fz = b W ff = d W f = W fz +W ff = f 4(t) In the formula, W fz W represents the fuel flow rate in the main oil circuit of the fuel distribution device. ff W is the fuel flow rate in the auxiliary oil circuit of the fuel distribution device. f d represents the total fuel flow rate into the engine combustion chamber, where b is the main fuel circuit flow coefficient and d is the auxiliary fuel circuit flow coefficient. This is a correction factor; The calculation formula for segmented iterative calculation of the power turbine speed at different time points during the maximum overspeed process of the engine is expressed as follows: Np x+1 =Np x +a x T0 / n In the formula, a is the acceleration of the power turbine rotor; T0 is the total duration of the overrun process; n is the number of segments in the total duration of the overrun process; The formula for calculating the acceleration of the power turbine rotor is as follows: a= In the formula, For the aerodynamic torque of the dynamic process; The moment of inertia of the power turbine rotor system; This refers to the speed of the power turbine. The formula for calculating the aerodynamic torque in the dynamic process is as follows: T= In the formula, Pdn represents the engine's equivalent power output; (Note: The original text contains some inconsistencies and unclear grammatical structures. A more accurate translation would require the full context.) The formula for calculating the equivalent power of the engine is expressed as follows: = f (W f , )= f 5(t) wherein W f is the total fuel flow into the engine combustion chamber; N p is the power turbine rotational speed.

2. The method for predicting the maximum speed of the power turbine after engine loss of load according to claim 1, characterized in that, The simulated over-rotation test includes the following steps: Start the engine and run it to maximum speed; the running time is 3-5 minutes. The test bench equipment is used to control the over-revving fuel release valve of the fuel distribution device until the fuel supply to the engine is completely cut off. The pressure signals at the compressor outlet, the main oil circuit, and the auxiliary oil circuit of the fuel distribution device of the engine at maximum over-speed were obtained using test bench equipment, and the variation of these signals with the fuel cut-off time was observed. Based on the pressure signal from the compressor outlet of the engine, the pressure signal from the main oil circuit of the fuel distribution device, and the pressure signal from the auxiliary oil circuit of the fuel distribution device, the fuel flow rate of the main oil circuit and the auxiliary oil circuit of the fuel distribution device is calculated to obtain the over-rev fuel pattern.

3. The method for predicting the maximum speed of the power turbine after engine loss of load according to claim 2, characterized in that, The variation patterns of the compressor outlet pressure signal, the main oil circuit pressure signal, and the auxiliary oil circuit pressure signal of the engine at maximum overspeed with the fuel cut-off time are expressed as follows: = f 1(t), = f 2(t), = f 3(t) In the formula, This is the pressure signal for the main oil circuit of the fuel distribution device; For the pressure signal of the auxiliary oil circuit of the fuel distribution device; This is the pressure signal at the compressor outlet of the engine.

4. The method for predicting the maximum speed of the power turbine after engine loss of load according to claim 2, characterized in that, The relationship between the power turbine speed and time is expressed as follows: N p = f 6(t)。 5. A system for performing the method for predicting the maximum speed of a power turbine after engine loss of load as described in any one of claims 1-4, characterized in that, include: Acquisition module: used to acquire the pressure signal at the compressor outlet of the engine, the pressure signal of the main oil circuit of the fuel distribution device, and the pressure signal of the auxiliary oil circuit of the fuel distribution device; Test module: Used to conduct simulated over-revving tests under maximum engine conditions, and to obtain the fuel consumption patterns under maximum engine over-revving conditions based on the test results; Calculation module: Performs piecewise iterative calculations on the power turbine speed at different time points during the engine's maximum overspeed process to obtain the relationship between power turbine speed and time; Turbine speed module: Based on the relationship between power turbine speed and time, the maximum power turbine speed during the engine's maximum over-revving process is obtained.

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