A closed-loop control method for the total inlet temperature of a jet precooling system

Abstract

The present application belongs to the field of aircraft engine jet precooling technology, and particularly relates to a closed-loop control method for the total temperature at the inlet of a jet precooling system, wherein step S1: calculating the expected value of the total temperature at the inlet of the engine according to the aircraft Mach number; step S2: obtaining the measured value T2 of the total temperature at the inlet collected by the total temperature sensor, and performing advance correction on the measured value T2 of the total temperature at the inlet to obtain the equivalent temperature T 2mod , equivalent temperature T 2mod The temperature deviation value DeltaT2mod is obtained by subtracting the expected value of the inlet total temperature; Step S3: The temperature deviation value is used to calculate the current water supply expected value WwDem through the PID algorithm; Step S4: The water spraying amount of the sprinkler is controlled according to the current water supply expected value WwDem; By introducing the inlet total temperature advance correction algorithm, the sensor measurement delay problem is solved, and the closed-loop water volume is accurately controlled to avoid overheating or excessive cooling.

Description

Technical Field

[0001] The present application belongs to the technical field of jet precooling of aircraft engines, and in particular relates to a closed-loop control method for the total temperature at the inlet of a jet precooling system. Background Art

[0002] The Aero Engine Research Institute of China is actively carrying out research on key technologies of jet pre-cooling engines. Using a certain type of engine as a platform, it has completed ground verification of the jet pre-cooling engine at a ground heating of 316.7°C, verifying the technical feasibility of jet pre-cooling to expand the turbine engine envelope.

[0003] In recent years, extensive research has been conducted both domestically and internationally on the expansion of jet precooling for turbine engines. This involves installing a water spray precooling device in the inlet duct, injecting atomized liquid water into the inlet. This, through the principle of heat absorption through water vaporization, reduces the total engine inlet temperature, thereby increasing the aircraft's flight speed while maintaining the turbine engine's geometric, pressure, temperature, and speed limits. The basic principles for increasing thrust using jet precooling technology are: first, water evaporation cools the airflow in the inlet duct, reducing its temperature, increasing the fan speed, and increasing density, thereby increasing the air flow entering the engine and boosting thrust. Second, while the increase in engine thrust is primarily due to the reduction in air temperature, the vaporization of water injected into the inlet duct also contributes to an additional thrust increase. Third, the increased moisture content of the working fluid increases the gas constant, which in turn increases the working fluid's heat capacity, increasing the engine's exhaust velocity, and thus increasing specific thrust.

[0004] Jet pre-cooling systems are used to cool high-temperature air at high Mach numbers. The primary medium is water. The ultimate goal of controlling the water volume is to ensure that the total inlet temperature meets the set target, ensuring high control accuracy without overheating or excessive cooling.

[0005] Therefore, it is very necessary to design a closed-loop control method for the total temperature at the inlet of the jet precooling system.

[0006] Currently, in the closed-loop water volume calculation for jet precooling, there is no advance correction method for the inlet total temperature. The time response constant caused by the sensor's own characteristics is not taken into account, which will cause delays in the calculation of the controlled water volume and easily cause the inlet total temperature to overheat or overcool. Summary of the Invention

[0007] In order to solve the above problems, the present application provides a closed-loop control method for the total temperature at the inlet of a jet precooling system, comprising:

[0008] Step S1: Calculate the expected value of the total temperature at the engine inlet according to the aircraft Mach number;

[0009] Step S2: Obtain the measured value T2 of the inlet total temperature collected by the inlet total temperature sensor, and perform advance correction on the measured value T2 of the inlet total temperature to obtain the equivalent temperature T 2mod, equivalent temperature T 2mod The temperature deviation value DeltaT2 mod is obtained by subtracting the expected value of the inlet total temperature;

[0010] Step S3: The temperature deviation value is calculated by PID algorithm to obtain the current water supply expected value WwDem;

[0011] Step S4: Control the water spraying amount of the water spraying device according to the current expected water supply value WwDem.

[0012] Preferably, the equivalent method of measuring the total inlet temperature T2 is:

[0013] The time response constant a of the inlet total temperature sensor is equivalent to the first-order inertia link, and the actual value of the inlet total temperature T 2真 After equivalent, the measured value of the inlet total temperature T2 is obtained. The transfer function of the inlet total temperature sensor is:

[0014] The method for advance correction includes:

[0015] The measured value of the inlet total temperature T2 is equivalent to T2mod after advance correction, and its advance correction transfer function is:

[0016]

[0017] Among them, b is the constant corresponding to the filtering method, and s is the Laplace operator.

[0018] Preferably, the calculation method of the lead correction transfer function is:

[0019] After discretizing the Laplace operator s of the lead correction transfer function, we can obtain:

[0020]

[0021] Wherein, T represents the operation cycle;

[0022] Substituting the discretized Laplace operator s into the lead correction transfer function yields:

[0023]

[0024] Among them, U(z) represents the input amount of the current cycle, U(z)z -1 represents the input amount of the previous cycle, Y(z)z -1 Indicates the output of the previous cycle;

[0025] Reverse transform formula (3) to get

[0026]

[0027] Where u(k) represents the input of the current cycle, u(k-1) represents the input of the previous cycle, y(k-1) represents the output of the previous cycle, and y(k) represents the output of the current cycle.

[0028] The value of the time response constant a of the imported total temperature sensor is obtained through sensor experimental testing;

[0029] The constant b corresponding to the filtering method is selected through the filtering algorithm.

[0030] Preferably, the method for selecting the constant b corresponding to the filtering method includes:

[0031] Get the filtering formula:

[0032] y(k)=c·y(k-1)+(1-c)u(k) (5);

[0033] The transfer function of the imported total temperature sensor is Obtained by z-transform

[0034]

[0035] Comparing formula (5) with formula (6), we can obtain:

[0036]

[0037] Wherein, c represents the filtering coefficient, and c is a number less than 1. When c=0.9, it indicates that the filtering method is 1-9 filtering, and when c=0.8, it indicates that the filtering method is 2-8 filtering.

[0038] Preferably, the current water supply expected value WwDem is calculated as:

[0039]

[0040] k p_out is the outer ring proportional coefficient, T i_out is the outer loop integration constant, T d_out is the outer loop differential constant, and k is the current cycle.

[0041] Preferably, the water spraying device includes a nozzle, a metering valve for controlling the flow rate of the nozzle, and an electro-hydraulic servo valve for controlling the opening of the metering valve.

[0042] Preferably, the specific steps of controlling the water spraying amount of the water spraying device according to the current expected value of the water supply amount include:

[0043] Calculate the current expected valve opening value through the current expected water supply value and the valve opening calibration line;

[0044] The displacement deviation value is obtained by subtracting the current expected value of the valve opening from the value collected by the metering valve linear displacement sensor. The displacement deviation value is calculated by the PID algorithm to obtain the water volume control current. The water volume control current acts on the electro-hydraulic servo valve to control the metering valve opening, thereby realizing the control of the water supply.

[0045] The advantages of this application include: by introducing the inlet total temperature advance correction algorithm, the sensor measurement delay problem is solved, the closed-loop water volume is accurately controlled, and overheating or excessive cooling is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of a water flow closed-loop control architecture in a preferred embodiment of the present application;

[0047] Figure 2 Schematic diagram of the advance correction link in a preferred embodiment of the present application. DETAILED DESCRIPTION

[0048] To make the technical solution and its advantages of the present application clearer, the technical solution of the present application will be described in further detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application and are only used to explain the present application, not to limit the present application. It should be noted that, for ease of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0049] In addition, unless otherwise defined, the technical or scientific terms used in the description of this application should have the ordinary meanings understood by those of ordinary skill in the art to which this application belongs. The words "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer" used in the description of this application are only used to indicate relative directions or positional relationships, and do not imply that the device or component must have a specific orientation, be constructed, or operate in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. Therefore, they should not be understood as limitations on this application. The words "first," "second," "third," and similar terms used in the description of this application are used only for descriptive purposes to distinguish different components and should not be understood to indicate or imply relative importance. The words "one," "an," or "the" used in the description of this application should not be understood as absolute limitations on quantity, but should be understood as meaning the presence of at least one. The words "include" or "comprises" used in the description of this application mean that the element or object listed before the word includes the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0050] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "install", "connect", "connect" 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, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection between two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0051] This application solves the problem of sensor measurement delay by introducing an inlet total temperature advance correction algorithm and achieves precise control of closed-loop water volume.

[0052] To address high-temperature inflow, hypersonic aircraft turbine engines require jet pre-cooling technology for expansion. The success of the jet pre-cooling system directly determines the engine's expansion capability and is a key technology for aerospace engines. The jet pre-cooling device and water supply system consists of a spray boom and nozzle, water supply piping, controller, water pump, regulating valve, sensor, and other components.

[0053] Water flow closed-loop control architecture: The valve opening is controlled according to the set flow rate. The cooling effect of the actual water supply is fed back to the jet pre-cooling digital electronic controller via an imported total temperature sensor. The controller then adjusts the valve opening in real time based on the deviation, maintaining a closed-loop regulation of water flow to meet cooling requirements. This architecture offers the advantage of controlling water flow through a closed-loop temperature control, with the setpoint automatically changing with temperature differences, ensuring precise control.

[0054] The jet pre-cooling water flow control structure is a double closed loop structure. Figure 1 As shown, the algorithm logic is:

[0055] Step S1: Calculate the expected value of the total temperature at the engine inlet according to the aircraft Mach number;

[0056] Step S2: Obtain the measured value T2 of the inlet total temperature collected by the inlet total temperature sensor, and perform advance correction on the measured value T2 of the inlet total temperature to obtain the equivalent temperature T 2mod , equivalent temperature T 2mod The temperature deviation value DeltaT2 mod is obtained by subtracting the expected value of the inlet total temperature;

[0057] Step S3: The temperature deviation value is calculated by PID algorithm to obtain the current water supply expected value WwDem;

[0058] Step S4: Control the water spraying amount of the water spraying device according to the current expected water supply value WwDem.

[0059] In some optional embodiments, the equivalent method for measuring the total inlet temperature T2 is:

[0060] The time response constant a of the inlet total temperature sensor is equivalent to the first-order inertia link, and the actual value of the inlet total temperature T 2真 After equivalent, the measured value of the inlet total temperature T2 is obtained. The transfer function of the inlet total temperature sensor is:

[0061] The method of advance correction is as follows: Figure 2 Shown, including:

[0062] The measured value of the inlet total temperature T2 is equivalent to T after advance correction. 2mod , its lead correction transfer function is:

[0063]

[0064] Among them, b is the constant corresponding to the filtering method, and s is the Laplace operator.

[0065] In some optional implementations, the lead correction transfer function is calculated as follows:

[0066] After discretizing the Laplace operator s of the lead correction transfer function, we can obtain:

[0067]

[0068] Wherein, T represents the operation cycle;

[0069] Substituting the discretized Laplace operator s into the lead correction transfer function yields:

[0070]

[0071] Among them, U(z) represents the input amount of the current cycle, U(z)z -1 represents the input amount of the previous cycle, Y(z)z -1 Indicates the output of the previous cycle;

[0072] Reverse transform formula (3) to get

[0073]

[0074] Where u(k) represents the input of the current cycle, u(k-1) represents the input of the previous cycle, y(k-1) represents the output of the previous cycle, and y(k) represents the output of the current cycle.

[0075] The value of the time response constant a of the imported total temperature sensor is obtained through sensor experimental testing;

[0076] The constant b corresponding to the filtering method is selected through the filtering algorithm.

[0077] In some optional implementations, the method for selecting the constant b corresponding to the filtering method includes:

[0078] Get the filtering formula:

[0079] y(k)=c·y(k-1)+(1-c)u(k) (5);

[0080] The transfer function of the imported total temperature sensor is Obtained by z-transform

[0081]

[0082] Comparing formula (5) with formula (6), we can obtain:

[0083]

[0084] Wherein, c represents the filter coefficient, and c is a number less than 1. When c=0.9, it indicates that the filtering method is 1-9 filtering, and when c=0.8, it indicates that the filtering method is 2-8 filtering;

[0085] After correction, T2 is closer to the actual T2 temperature of the engine inlet total temperature. 2Mod Participate in closed-loop calculation of water volume.

[0086] Among them, the calculation formula for the current expected value of water supply WwDem is:

[0087] According to the aircraft Mach number, the expected value of the total temperature of the engine inlet is calculated, that is, the outer loop given value (T 2Dem ), and then calculate T based on the actual value of T2 collected by the imported total temperature sensor according to the advance correction transfer function 2Mod , T 2Dem With T 2Mod The difference is calculated to get the deviation value (DeltaT2mod); the deviation value is calculated by PID algorithm to get the expected value of current water supply.

[0088] According to the PID control principle:

[0089]

[0090] Where: k p_out 、T i_out 、T d_out They are the outer loop proportional coefficient, outer loop integral constant and outer loop differential constant respectively;

[0091]

[0092] K d_out (k) = K p_out (k)×T d_out (k) (10)

[0093]

[0094] According to formulas (9) and (10), formula (11) is obtained, which is the form of Kp, Ki, and Kd.

[0095] When using the traditional discrete PID parameter design method, the continuous quantity is discretized and the closed-loop water volume calculation formula is obtained as follows:

[0096]

[0097] k p_out is the outer ring proportional coefficient, T i_out is the outer loop integration constant, T d_out is the outer loop differential constant, and k is the current cycle.

[0098] Closed loop water flow calculation uses the T after lead correction 2mod It can avoid the hysteresis effect caused by the sensor time constant, so that the water supply calculation meets the current expectations and is accurately controlled.

[0099] In some optional embodiments, the water spraying device includes a nozzle, a metering valve for controlling the flow rate of the nozzle, and an electro-hydraulic servo valve for controlling the opening of the metering valve.

[0100] In some optional implementations, the specific steps of controlling the water spraying amount of the water spraying device according to the current expected water supply amount include:

[0101] Calculate the current expected valve opening value through the current expected water supply value and the valve opening calibration line;

[0102] The displacement deviation value is obtained by subtracting the current expected value of the valve opening from the value collected by the metering valve linear displacement sensor. The displacement deviation value is calculated by the PID algorithm to obtain the water volume control current. The water volume control current acts on the electro-hydraulic servo valve to control the metering valve opening, thereby realizing the control of the water supply.

[0103] The advantages of this application include: by introducing the inlet total temperature advance correction algorithm, the sensor measurement delay problem is solved, the closed-loop water volume is accurately controlled, and overheating or excessive cooling is avoided.

[0104] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A closed-loop control method for the total temperature at the inlet of a jet precooling system, characterized in that: include: Step S1: Calculate the expected value of the total temperature at the engine inlet according to the aircraft Mach number; Step S2: Obtain the measured value T2 of the inlet total temperature collected by the inlet total temperature sensor, and perform advance correction on the measured value T2 of the inlet total temperature to obtain the equivalent temperature T 2mod , equivalent temperature T 2mod The temperature deviation value DeltaT2mod is obtained by subtracting the expected value of the inlet total temperature; Step S3: The temperature deviation value is calculated by PID algorithm to obtain the current water supply expected value WwDem; Step S4: controlling the water spraying amount of the water spraying device according to the current expected water supply value WwDem; The equivalent method for measuring the total inlet temperature T2 is: The time response constant a of the inlet total temperature sensor is equivalent to the first-order inertia link, and the actual value of the inlet total temperature T 2真 After equivalent, the measured value of the inlet total temperature T2 is obtained. The transfer function of the inlet total temperature sensor is: The method for advance correction includes: The measured value of the inlet total temperature T2 is equivalent to T after advance correction. 2mod , its lead correction transfer function is: Among them, b is the constant corresponding to the filtering method, and s is the Laplace operator; The lead correction transfer function is calculated as: After discretizing the Laplace operator s of the lead correction transfer function, we can obtain: Wherein, T represents the operation cycle; Substituting the discretized Laplace operator s into the lead correction transfer function yields: Among them, U(z) represents the input amount of the current cycle, U(z)z -1 represents the input amount of the previous cycle, Y(z)z -1 Indicates the output of the previous cycle; Reverse transform formula (3) to get Where u(k) represents the input of the current cycle, u(k-1) represents the input of the previous cycle, y(k-1) represents the output of the previous cycle, and y(k) represents the output of the current cycle. The value of the time response constant a of the imported total temperature sensor is obtained through sensor experimental testing; The constant b corresponding to the filtering method is selected through the filtering algorithm; The selection methods of the constant b corresponding to the filtering method include: Get the filtering formula: y(k)=c·y(k-1)+(1-c)u(k) (5); The transfer function of the imported total temperature sensor is Obtained by z-transform By analogy between formula (5) and formula (6), we can obtain: Wherein, c represents the filter coefficient, and c is a number less than 1. When c=0.9, it indicates that the filtering method is 1-9 filtering, and when c=0.8, it indicates that the filtering method is 2-8 filtering; The calculation formula for the current expected value of water supply WwDem is: k p_out is the outer ring proportional coefficient, T i_out is the outer loop integration constant, T d_out is the outer loop differential constant, and k is the current cycle.

2. The closed-loop control method for the total temperature at the inlet of the jet precooling system according to claim 1, characterized in that: The water spraying device includes a nozzle, a metering valve for controlling the flow of the nozzle, and an electro-hydraulic servo valve for controlling the opening of the metering valve.

3. The closed-loop control method for the total temperature at the inlet of the jet precooling system according to claim 1, characterized in that: The specific steps of controlling the water spraying amount of the water spraying device according to the current expected value of water supply include: Calculate the current expected valve opening value through the current expected water supply value and the valve opening calibration line; The displacement deviation value is obtained by subtracting the current expected value of the valve opening from the value collected by the metering valve linear displacement sensor. The displacement deviation value is calculated by the PID algorithm to obtain the water volume control current. The water volume control current acts on the electro-hydraulic servo valve to control the metering valve opening, thereby realizing the control of the water supply.

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