A method for controlling the flow of water in a multi-pipe water flow system of an aircraft engine jet pre-cooling system

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a method for controlling water flow of a multi-pipeline ejection pre-cooling system of an aero-engine. The water flow of the multi-pipeline is allocated by a digital electronic controller, and each pipeline is independently controlled. The given value of the water supply is calculated by means of temperature deviation, closed-loop control is realized, and the fitting degree of the water injection amount and the required cooling amount is improved. Through the feedback of the inlet temperature, the dependence on the control accuracy of the water metering valve can be reduced. Even if the metered water is inaccurate, it can be compensated through temperature closed-loop adjustment, the industrial requirements of the valve and the electro-hydraulic servo valve are reduced, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aero-engines, and particularly relates to a method for controlling water flow of a multi-pipeline of a jet pre-cooling system of an aero-engine. BACKGROUND

[0002] China Aero-engine Research and Manufacturing Co., Ltd. actively carries out key technology research on jet pre-cooling engines, and completes jet pre-cooling ground verification of an engine under ground warming of 316.7 ℃, which verifies the technical feasibility of jet pre-cooling extended turbine engine envelope.

[0003] In recent years, a large amount of researches have been carried out on jet pre-cooling extended envelope of turbine engines at home and abroad, that is, a water spraying pre-cooling device is installed in an air inlet, and atomized liquid water is sprayed into the air inlet, the principle of water vaporization heat absorption is used to reduce the engine inlet total temperature, and the flight speed of the aircraft is increased without changing the geometric limit, pressure limit, temperature limit and speed limit of the turbine engine. The basic principle of the engine using jet pre-cooling technology to increase the thrust is as follows: first, the water evaporation cools the airflow in the air inlet, the airflow temperature is lowered, the fan equivalent speed is increased, the density is increased, the air flow entering the engine is increased, and the thrust is also increased; second, although the increase of the engine thrust is mainly caused by the decrease of the air temperature, the water vaporization sprayed into the air inlet also increases the thrust; third, the moisture content of the working medium is increased, the gas constant is increased, the heat capacity of the working medium is increased, the exhaust velocity of the engine is increased, and the unit thrust is increased.

[0004] The turbine engine of a hypersonic aircraft needs to use jet pre-cooling technology to expand the envelope to cope with high-temperature inflow problems, and the success or failure of the jet pre-cooling system directly determines the ability of the engine to expand the envelope, and is one of the core key technologies of space engines. The jet pre-cooling system is used to cool high-temperature air under high Mach number, and the main medium is water. If the water flow is large, only a single pipeline needs to be designed as a large diameter to meet the requirements, but due to the standardization and engineering practicality of the pipeline, a large diameter pipeline is generally not used. Therefore, when the required water flow is large, a multi-pipeline water supply mode can be used.

[0005] Therefore, it is necessary to propose a multi-pipeline water supply control method for the jet pre-cooling system, 1) the jet pre-cooling system of the current aero-engine generally uses a single pipeline water supply mode, and an open-loop calculation method is adopted for water quantity control, that is, the fan inlet equivalent flow, the fan inlet total pressure and the fan inlet total temperature are used to calculate the given value of the water quantity, and then the water quantity control is realized. This method calculates the relationship between the water spraying quantity and the temperature reduction, and cannot represent the actual corresponding relationship between the water spraying quantity and the temperature reduction.

[0006] 2) Because the water flow needs to be accurately metered to ensure the required cooling effect, the metering valve control precision requirement for water is very high, which increases the manufacturing difficulty and control complexity. SUMMARY

[0007] To solve the above problems, the application provides a control method for water flow of a multi-pipeline jet pre-cooling system of an aero-engine, comprising:

[0008] Step S1: calculating an expected value T2Dem of the engine inlet total temperature according to the aircraft Mach number,

[0009] Step S2: comparing the expected value T2Dem with the inlet total temperature T2 实际值 to obtain a deviation value DeltaT2;

[0010] Step S3: calculating a current water supply expected value WwDem based on the deviation value DeltaT2;

[0011] Step S4: dividing the current water supply expected value WwDem into multiple water supply zones, and calculating a water supply expected value of each water supply zone based on the water flow and the valve opening calibration line of each water supply zone;

[0012] Step S5: calculating a water quantity control current of each water supply zone based on the deviation value of the water supply expected value of each water supply zone and the metering valve line displacement sensor acquisition value;

[0013] Step S6: controlling the opening of the metering valve based on the water quantity control current of each water supply zone through the electro-hydraulic servo valve, and realizing the control of the engine inlet multi-pipeline water flow through the opening of the metering valve and the jet pre-cooling controller of each zone.

[0014] Preferably, the current water supply expected value WwDem is obtained by an outer loop PID controller, and the water quantity control current of each water supply zone is obtained by an inner loop PID controller of each water supply zone.

[0015] Preferably, the outer loop PID controller adopts an incremental control method.

[0016] Preferably, the outer loop PID controller adopts a discrete PID parameter design method, which discretizes the continuous quantity to obtain the outer loop calculation formula as follows:

[0017]

[0018] wherein, k p_out is the outer loop proportional coefficient, T i_out is the outer loop integral constant, K d_out is the outer loop differential constant, and the As an operator, if the data record acquisition period is consistent with the algorithm operation period, then Ts = 1.

[0019] Preferably,

[0020]

[0021] Preferably, the calculation formula of the inner loop PID controller controlled by the proportional integral derivative control law is:

[0022]

[0023] Preferably, the calculation formula of the inner loop PID controller controlled by the proportional integral control law is:

[0024]

[0025] Preferably, the water supply zone water supply expected value calculation method is:

[0026] Obtain the maximum water supply Ww of each water supply zone max i Where i is the serial number of the water supply zone, i = 1, 2, 3…N, obtain the previous water supply expected value WwDem, when The first n-1 water supply zones are operated at the maximum water supply, and the water supply of the nth water supply zone is Where the n+1th to Nth water supply zones are in the closed state.

[0027] The advantages of the present application include: 1) through the digital electronic controller, the water flow of multiple pipelines is allocated and each pipeline is independently controlled. The given value of the water supply is calculated by the temperature deviation, realizing closed loop control and improving the coincidence degree of the water spray and the required cooling amount.

[0028] 2) Through the feedback of the inlet temperature, the dependence on the control accuracy of the water metering valve can be reduced. Even if the metered water is not accurate, it can be compensated through temperature closed loop adjustment, reducing the industrial requirements of the valve and the electro-hydraulic servo valve, and reducing the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the three-pipeline water supply control architecture of the jet pre-cooling system of a preferred embodiment of the present application;

[0030] Figure 2 is a schematic diagram of the water flow closed loop control architecture. DETAILED DESCRIPTION

[0031] In order to make the technical solutions of the present application and their advantages clearer, the technical solutions of the present application will be further clearly and completely described below in conjunction with the drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application, which are used to explain the present application, but not to limit the present application. It should be noted that, for the purpose of description, only parts related to the present application are shown in the drawings, and other related parts can be referred to the general design. In the case of no conflict, the embodiments in the present application and the technical features in the embodiments can be combined to obtain new embodiments.

[0032] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of the present application should be the general meanings understood by the general technical personnel in the field of the present application. The words indicating the direction or position relationship such as "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inner", "outer" and the like used in the description of the present application are only used to indicate the relative direction or position relationship, but not to imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and the relative position relationship may also change accordingly when the absolute position of the described object changes, therefore it cannot be understood as a limitation on the present application. The "first", "second", "third" and the like used in the description of the present application are only for the purpose of description, to distinguish different components, and cannot be understood as indicating or implying relative importance. The "one", "an" or "the" and the like used in the description of the present application should not be understood as an absolute limitation on the quantity, but should be understood as the existence of at least one. The "including" or "containing" and the like used in the description of the present application means that the elements or objects appearing before the word are covered by the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0033] In addition, it should be noted that, unless otherwise specified and limited, the "installation", "connection", "connection" and the like used in the description of the present application should be understood in a broad sense, for example, the connection can be fixed connection, or detachable connection, or integral connection; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, or the communication between two elements, the person skilled in the art can understand the specific meaning of the present application according to the specific situation.

[0034] In order to solve the problem of high temperature flow for hypersonic aircraft turbine engine, jet precooling technology is needed to expand the line, and the success of jet precooling system directly determines the capacity of engine expansion line, which is one of the core key technologies of space engine. The jet precooling device and water supply system are composed of spray rod and nozzle, water supply pipeline, controller, water pump, regulating valve, sensor and other components. For example Figure 1As shown, taking three-way pipeline water supply as an example, the control loop of the jet pre-cooling control system is a water supply flow control loop of a first area, a second area and a third area. The jet pre-cooling control device adopts a double-redundancy electro-hydraulic servo valve to control a metering valve, selects a double-redundancy linear displacement sensor to feed back the position of the metering valve, and adopts a double-redundancy pressure sensor to measure the water supply pressure before and after the metering valve, so as to realize the control of the water supply flow together with the jet pre-cooling controller.

[0035] The valve opening is controlled according to the set flow, and the cooling effect generated by the actual water supply is fed back to the jet pre-cooling digital electronic controller through the inlet total temperature sensor. The controller controls the valve opening in real time according to the deviation to make the water flow in a closed-loop regulation state, so as to meet the cooling requirement. The advantage is that the water flow is controlled through temperature closed loop, and the water flow set value automatically changes with the temperature difference, so the control is accurate.

[0036] The jet pre-cooling water flow control structure is a double-closed-loop structure, as shown in Figure 2 The water flow closed-loop control architecture is shown in the figure, and the architecture of only one area is drawn, and the architectures of the remaining areas are omitted. The jet pre-cooling water flow control structure is a double-closed-loop structure. The algorithm logic is that the expected value of the engine inlet total temperature, i.e. the outer ring given value (T2Dem), is calculated according to the aircraft Mach number, and the deviation value (DeltaT2) is obtained by subtracting the actual value T2 collected by the inlet total temperature sensor. The deviation value is calculated by the PID algorithm to obtain the current water supply expected value, and the current 1-area Lw1Dem expected value, 2-area Lw2Dem expected value and 3-area Lw3Dem expected value, i.e. the inner ring given value (Lw1Dem, Lw2Dem, Lw3Dem), are calculated through the 1-area water flow and valve opening calibration line, 2-area water flow and valve opening calibration line and 3-area water flow and valve opening calibration line respectively. The deviation values obtained by subtracting the 1-area metering valve linear displacement sensor collection value Lw1, 2-area metering valve linear displacement sensor collection value Lw2 and 3-area metering valve linear displacement sensor collection value Lw3 are calculated by the PID algorithm to obtain the 1-area water flow control current (ILW1), 2-area water flow control current (I2) and 3-area water flow control current (ILW3) respectively. The currents act on the electro-hydraulic servo valves of the three areas to control the openings of the metering valves (Lw1, Lw2, Lw3) of the three areas respectively, so as to realize the control of the water supply flow, and T2 is collected by the sensor and transmitted back to the controller to realize the closed loop.

[0037] The PID control principle is as follows:

[0038]

[0039] Wherein: k p_out , T i_out , T d_out are the outer ring proportional coefficient, the outer ring integral constant and the outer ring differential constant respectively.

[0040]

[0041] K d_out (k) = K p_out (k) x T d_out (k) (3)

[0042]

[0043] According to formula (2), (3) to get formula (4), namely Kp, Ki, Kd form.

[0044] For PID control method, divided into position and incremental, for T2 control method is proposed to use incremental control method.

[0045] 3.1 outer loop calculation method

[0046] For PID control method, divided into position and incremental, for T2 outer ring is proposed to use incremental control method.

[0047] Using discrete PID parameter design method, the continuous quantity is discretized, the outer loop calculation formula is as follows:

[0048]

[0049] + K d_out *[DeltaT2(k)-DeltaT2(k-1)] / Ts+WwDem(k-1)

[0050] The formula As an operator, if the data record acquisition period is consistent with the algorithm operation period, then Ts=1.

[0051] For T2 control outer loop control has two schemes:

[0052] a) scheme one is with differential form, the advantage is fast response, but easy to exist overshoot, the calculation formula is consistent with formula (5);

[0053] b) scheme two is not with differential form, namely KI control mode, the advantage is that the control water is more stable, the overshoot is smaller, but the response speed is slow, as shown in formula (6).

[0054]

[0055] 3.2 inner loop calculation method

[0056] The inner loop uses position control method, for T2 control inner loop control has two schemes:

[0057] a) Scheme one is with differential form, its advantage is fast response, but easy to exist overshoot, the calculation formula is shown in (7), (8), (9);

[0058] b) Scheme two is without differential form, namely KI control mode, its advantage is that the control water quantity is relatively stable, and the overshoot is small, but the response speed is slow, such as formula (10), (11), (12).

[0059]

[0060] Wherein IBalLw1, IBalLw2, IBalLw3 represent the balance current of electro-hydraulic servo valve.

[0061] According to the flow conservation principle and the flow of the throttling element, the nozzle flow can be calculated, and the calculation formula is as follows:

[0062]

[0063] Wherein: Q, volume flow; μ, flow coefficient; A, throttling area; ρ, liquid density; ΔP, throttling pressure difference;

[0064] The jet pre-cooling control device drives the electro-hydraulic servo valve according to the jet pre-cooling controller instruction, realizes the closed-loop control of the three-zone water supply flow independent of each other, realizes the flow metering of each zone through the feedback of the linear displacement sensor and the measurement of the pressure sensor before and after the metering valve, and allocates the flow of each zone after calculation by the digital electronic controller.

[0065] Water quantity control of each subarea:

[0066] Water quantity allocation method:

[0067] The jet pre-cooling control device realizes water flow control by using three metering valves, assuming that the maximum flow of each pipeline is 2 kg / s;

[0068] The water quantity is calculated by the temperature closed-loop method, when the demand water quantity is below 2 kg / s, the metering valve of the first pipeline is used, the valve opening is calculated according to the temperature closed-loop method, and the metering valves of the other two pipelines are in the closed state; when the demand water quantity is between 2 kg / s and 4 kg / s, the metering valve of the first pipeline is in the maximum state, the metering valve of the second pipeline is calculated according to the actual closed loop, and the metering valve of the third pipeline is in the closed state; when the demand water quantity is between 4 kg / s and 6 kg / s, the metering valves of the first and second pipelines are in the maximum state, and the metering valve of the third pipeline is calculated according to the actual closed loop;

[0069] The water supply expected value calculation method of the water supply subarea is:

[0070] The maximum water supply quantity Ww of each water supply subarea is obtainedmax i wherein i is the serial number of the water supply zone, i = 1, 2, 3…N, the previous water supply amount expectation value WwDem is obtained, when the previous n-1 water supply zones are operated at the maximum water supply amount, and the water supply amount of the nth water supply zone is wherein the n+1 to Nth water supply zones are in the closed state.

[0071] The specific implementation is:

[0072] The expectation value of the engine inlet total temperature is calculated according to the aircraft Mach number, that is, the outer ring given value (T2Dem), and the deviation value (DeltaT2) is obtained by the difference between the actual value T2 collected by the inlet total temperature sensor; the deviation value is calculated by the PID algorithm to obtain the current water supply amount expectation value.

[0073] 2) Inner ring valve opening calculation method:

[0074] The current valve expectation value (LwDem) is calculated by the water flow and valve opening calibration line, that is, the inner ring given value (LwDem), and the deviation value obtained by the difference between the metering valve line displacement sensor collection value (Lw) is calculated by the PID algorithm to obtain the water amount control current (ILW).

[0075] 3) Valve execution:

[0076] The current acts on the electro-hydraulic servo valve to control the opening of the metering valve (Lw), thereby realizing the control of the water supply amount.

[0077] The method can be directly applied in the aviation engine jet pre-cooling system, can meet the engineering actual requirements and improve the control precision of water flow, and has good market application prospect.

[0078] The present application allocates the water flow of multiple pipelines through a digital electronic controller, and each pipeline is independently controlled. The given value of the water supply amount is calculated by the temperature deviation, closed loop control is realized, and the degree of coincidence of the water injection amount and the required cooling amount is improved. Through the feedback of the inlet temperature, the dependence on the control precision of the water metering valve can be reduced, that is, even if the metered water is not accurate, it can be compensated through temperature closed loop adjustment, the industrial requirements of the valve and the electro-hydraulic servo valve are reduced, and the production cost is reduced.

[0079] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for controlling the flow of water in a multiple line water flow of an aircraft engine ejection pre-cooling system, characterized in that, Comprising: Step S1: calculating the expected value T2Dem of engine inlet total temperature according to the Mach number of the aircraft, Step S2: The desired value T2Dem is compared with the total temperature T2 实际值 The difference is the deviation DeltaT2; Step S3: calculating the current water supply expected value WwDem based on the deviation value DeltaT2; Step S4: dividing the current water supply expected value WwDem into multiple water supply zones, and calculating the water supply expected value of each water supply zone based on the water flow and the calibrated valve opening line of each water supply zone; Step S5: calculating the water quantity control current of each water supply zone through the deviation value of the water supply expected value of each water supply zone and the collected value of the metering valve line displacement sensor; Step S6: controlling the opening of the metering valve based on the water quantity control current of each water supply zone through the electro-hydraulic servo valve, and the opening of the metering valve and the jet pre-cooling controller of each zone jointly realize the control of the engine inlet multi-pipeline water flow; The current water supply expected value WwDem is calculated by an outer loop PID controller, and the water quantity control current of each water supply zone is calculated by an inner loop PID controller of each water supply zone; The water supply expected value calculation method of the water supply zone is: obtaining the maximum water supply amount Ww of each water supply partition max i wherein i is the serial number of the water supply partition, i = 1, 2, 3…N, obtaining the previous water supply amount expectation value WwDem, when the first n-1 water supply partitions are operated at the maximum water supply amount, and the water supply amount of the nth water supply partition is wherein the n+1th to Nth water supply partitions are in the closed state.

2. The method of claim 1, wherein, The outer loop PID controller adopts an incremental control method.

3. The method of claim 2, wherein the step of controlling the water flow rate in the multiple circuits of the jet pre-cooling system of the aero-engine is performed by the control unit. The outer loop PID controller adopts a discrete PID parameter design method, which discretizes the continuous quantity to obtain the outer loop calculation formula as follows: +K d_out *[DeltaT2(k)-DeltaT2(k-1)] / Ts+WwDem(k-1) where k p_out is the outer loop proportional coefficient, T i_out is the outer loop integral constant, K d_out is the outer loop derivative constant, and exists as an operator, and if the data record acquisition period and the algorithm operation period are consistent, then Ts = 1.

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