A control method for water flow of an aero-engine jet pre-cooling system

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a control method for water flow of an ejection pre-cooling system of an aero-engine. The temperature and pressure values of water in a pipe before a nozzle are collected by a sensor. Based on the collected temperature and pressure values, a judging program is used to judge whether the water in the pipe before the nozzle is in a liquid phase, a gas phase or a gas-liquid mixed phase. Corresponding programs are called based on the judging result to control the water flow, so that the state of the water in the pipe before the nozzle is judged, and then the water flow is controlled.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a method for controlling the water flow rate of an aero-engine jet precooling system. Background Technology

[0002] The China Aero Engine Research Institute actively carried out research on key technologies for jet precooled engines. Using a certain type of engine as a platform, it completed the ground verification of the whole engine under ground heating of 316.7℃, verifying the technical feasibility of jet precooling to extend the envelope of the turbine engine.

[0003] In recent years, extensive research has been conducted both domestically and internationally on jet precooling expansion envelopes for turbine engines. This involves installing a water-jet precooling device in the air intake, injecting atomized liquid water into the intake, and reducing the overall engine inlet temperature through the principle of water vaporization and heat absorption. This increases the aircraft's flight speed without altering the turbine engine's geometric, pressure, temperature, and speed limitations. The basic principles of increasing thrust using jet precooling technology are as follows: First, water evaporation cools the airflow in the intake, lowering its temperature, increasing the fan's converted speed, increasing density, and increasing the airflow into the engine, thus increasing thrust. Second, although the increase in engine thrust is mainly due to the decrease in air temperature, the vaporization of water injected into the intake also contributes to the additional thrust. Third, the increased moisture content of the working fluid increases the gas constant and the working fluid's heat capacity, leading to increased engine exhaust velocity and increased thrust per unit area.

[0004] Jet precooling systems are used to cool high-temperature air at Mach numbers, with water as the primary medium. When air pressure decreases at high altitudes, the boiling point of water decreases, and the temperature rises at high Mach numbers, easily causing the water in the pipes to boil, resulting in a water-water vapor coexistence state. The cooling capacity differs depending on whether the water in the pipes is in a purely liquid, gas-liquid coexistence, or purely gaseous state. Maximum cooling effect is achieved when the water is in a liquid state before the nozzle; however, due to environmental factors, a larger volume of water is required to achieve the same cooling effect as pure liquid water when the water is in a gas-liquid coexistence or purely gaseous state.

[0005] Therefore, in order to achieve the corresponding cooling effect, it is essential to determine the state of the water and control the water volume in the jet precooling system.

[0006] Currently, the jet precooling technology for cooling aero-engines mainly calculates and controls the cooling effect of liquid water, without considering the state of water that has already vaporized in the pipeline before the nozzle. Vaporized water and liquid water have different cooling effects, which will lead to a decrease in the cooling effect. Summary of the Invention

[0007] To solve the above problems, the present application provides a method for controlling the water flow rate of an aeroengine jet pre-cooling system, including:

[0008] Step S1: Collect the temperature and pressure values of the water in the pipeline before the nozzle through a sensor;

[0009] Step S2: Based on the collected temperature and pressure values, use a judgment program to judge whether the water in the pipeline before the nozzle is in the liquid phase, gas phase or gas-liquid mixed phase;

[0010] Step S3: Based on the judgment result, call the corresponding program to control the water flow rate; specifically, when the water in the pipeline before the nozzle is in the liquid phase, call the liquid-phase control program to control the water flow rate, when the water in the pipeline before the nozzle is in the gas phase, call the gas-phase control program to control the water flow rate, when the water in the pipeline before the nozzle is in the gas-liquid mixed phase, call the gas-liquid mixed-phase program to control the water flow rate, when the water in the pipeline before the nozzle is...

[0011] Preferably, the judgment program is:

[0012] Establish a thermodynamic parameter equation P = f(T) for water vapor in a saturated state with respect to temperature and pressure;

[0013] Let the collected temperature value be T0 and the collected pressure value be P0;

[0014] When f(T0) < P0, the water in the pipeline before the nozzle is in the gas phase;

[0015] When f(T0) = P0, the water in the pipeline before the nozzle is in the gas-liquid mixed phase;

[0016] When f(T0) > P0, the water in the pipeline before the nozzle is in the liquid phase.

[0017] Preferably, the method for visually establishing the judgment program is:

[0018] Plot the thermodynamic parameter equation into the first quadrant of a rectangular coordinate system to obtain a saturated vapor curve;

[0019] Divide the two regions formed by the boundary lines of the temperature value range, the boundary lines of the pressure value range and the saturated vapor curve into a liquid-phase region and a gas-phase region, and the region above the saturated vapor curve is the gas-liquid mixed-phase region;

[0020] Plot the collected temperature and pressure values in the form of coordinates into the rectangular coordinate system, and judge the state of the water in the pipeline before the nozzle in the corresponding region by judging the region where the coordinates of the collected temperature and pressure values fall.

[0021] Preferably, the control program for controlling the water flow rate is:

[0022] Outer-loop control includes: calculating the expected value of the engine inlet total temperature based on the aircraft Mach number.

[0023] T2Dem is used to calculate the deviation DeltaT2 between the actual T2 value collected by the inlet total temperature sensor and the expected value T2Dem of the engine inlet total temperature; based on the deviation DeltaT2, the expected value Ww Dem of the current water supply is calculated using a PID algorithm.

[0024] The inner loop control includes: calculating the current valve expected value LwDem based on the current expected water supply value and the valve opening calibration line; obtaining the valve opening deviation value by subtracting the current valve expected value LwDem from the value Lw collected by the metering valve linear displacement sensor; calculating the water flow control current ILW after PID algorithm; and controlling the valve opening and thus the water flow rate by controlling the water flow control current ILW.

[0025] Preferably, in the gas-liquid mixed-phase process, the expected value of the initial water supply for the gas-liquid mixed water is...

[0026] WwpDem;

[0027] WwpDem(k)=FDBS1*WwDem(k);

[0028] Where: FDBS1 represents the magnification factor, with a default value of 1.5 and an adjustable range of (0-10);

[0029] In the gas phase control program, the expected value of the pre-supply of gaseous water is WwpDemxz;

[0030] WwpDemxz(k)=FDBS2*WwDem(k);

[0031] Wherein: FDBS2 represents the magnification factor, with a default value of 5 and an adjustable range of (0-10).

[0032] Preferably, in the gas phase control program, the water flow control current ILW needs to be compensated and corrected.

[0033] ILWXZ(k)=FDBS3*ILW(k);

[0034] Where: FDBS2 represents the amplification factor, with a default value of 1.1 and an adjustable range of (0-10); ILWXZ is the water volume control current in the gas phase control program.

[0035] Preferably, when the water in the pipeline changes from a gas-liquid mixture or a gas phase to a liquid phase, a certain delay is made before switching back to the liquid water control mode.

[0036] Preferably, the delay time is set to 1 second.

[0037] The advantages of this application include: taking environmental factors into account, using algorithms to determine the state of water, and precisely controlling the amount of water in the pipeline before the nozzle that is in a liquid, gaseous, or gas-liquid coexistence state, thereby achieving faster cooling and temperature reduction across the entire envelope. Attached Figure Description

[0038] Figure 1 This is a flowchart of the water flow control method for the jet precooling system of an aero-engine in this application;

[0039] Figure 2 This is a schematic diagram of a water and steam state determination model. Detailed Implementation

[0040] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some 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 related to this application are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0041] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer," etc., used in this application description to indicate relative direction or positional relationship are used only to indicate relative orientation or positional relationship, and do not imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, and therefore should not be construed as a limitation on this application. The terms "first," "second," "third," and similar terms used in this application description are used only for descriptive purposes to distinguish different components, and should not be construed as indicating or implying relative importance. The terms "a," "one," or "the," etc., used in this application description should not be construed as an absolute limitation on quantity, but should be construed as indicating the existence of at least one. The terms "including," "comprising," etc., used in this application description mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects.

[0042] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, terms such as “installation,” “connection,” and “linkage” used in the description of this application should be interpreted broadly. For example, a 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 or an indirect connection through an intermediate medium; or it can be a connection within two components. Those skilled in the art can understand its specific meaning in this application according to the specific circumstances.

[0043] This application takes a hypersonic aircraft turbine engine as an example. To cope with the problem of high-temperature incoming flow, a jet precooling technology is required to expand the engine envelope. The success or failure of the jet precooling system directly determines the engine's expansion capability and is one of the core technologies of aerospace engines. The jet precooling device and water supply system consist of components such as a spray bar and nozzle, water supply pipeline, controller, water pump, regulating valve, and sensors.

[0044] Step 1:

[0045] Establish a calculation model for the thermodynamic physical properties of water and water vapor, and write the thermodynamic parameter equations for water and water vapor as a function of temperature and pressure using a programming language. For example... Figure 1 As shown, a saturated vapor line divides the entire region into two parts: the area to the left of the saturated vapor line represents liquid water, and the area to the right represents water vapor. Falling on the saturated vapor line indicates a state of coexistence of water and vapor.

[0046] The equation for the saturated vapor line is:

[0047]

[0048] In the formula: p* = 1 MPa; T* = 1 K;

[0049] Coefficients in the formulas in Table 1

[0050]

[0051]

[0052] Step Two:

[0053] Formula (1) is a control equation based on temperature and pressure calculations. After the temperature and pressure collected by the sensor are transmitted to the controller, the controller calculates the values ​​according to the program and then applies them in real time. Figure 1 A state point is generated. If the state point is in the liquid phase region, the liquid phase region control program is called; if the state point is in the gas phase region, the gas phase region control program is called; if the state point falls exactly on the control equation line (saturated vapor line), it is in a state of coexistence of water and water vapor, and the liquid-gas coexistence line control program is called.

[0054] Therefore, temperature and pressure can be used to determine whether water and water vapor are in a liquid phase, a gas phase, or a gas-liquid mixture.

[0055] Step 3:

[0056] The system uses temperature and pressure calculations to determine whether the water in the pre-nozzle pipeline is in a liquid, gaseous, or gas-liquid mixture state, and selects the appropriate control algorithm accordingly. The jet precooling water flow control structure is a dual closed-loop structure.

[0057] a) When water is in a liquid state, the basic control algorithm is used, as follows:

[0058] 1) Calculation method for outer ring water volume:

[0059] The expected value of the engine inlet total temperature is calculated based on the aircraft's Mach number, i.e., the outer loop setpoint (T2Dem). The deviation value (DeltaT2) is obtained by subtracting the actual T2 value collected by the inlet total temperature sensor. The deviation value is then used to calculate the expected value of the current water supply using a PID algorithm.

[0060] 2) Calculation method for inner ring valve opening:

[0061] The current valve expected value (LwDem), i.e. the inner loop setpoint (LwDem), is calculated by the water flow and valve opening calibration line. The deviation value obtained by subtracting the value collected by the metering valve linear displacement sensor (Lw) is then calculated by the PID algorithm to obtain the water flow control current (ILW).

[0062] 3) Valve activation:

[0063] The current is applied to the electro-hydraulic servo valve to control the opening of the metering valve (Lw), thereby controlling the water supply.

[0064] b) When water is in a gas-liquid mixed state, the algorithm is as follows:

[0065] 1) Calculation method for outer ring water volume:

[0066] The expected water supply value calculated by the basic control algorithm is amplified by a factor.

[0067] WwpDem(k)=FDBS1*WwDem(k) (7)

[0068] Where: FDBS1 represents the magnification factor, with a default value of 1.5 and an adjustable range of (0-10);

[0069] WwDem represents the expected water supply value calculated using the basic control algorithm.

[0070] 2) Calculation method for inner ring valve opening:

[0071] The current valve expected value (LwDem), i.e. the inner loop setpoint (LwDem), is calculated by the water flow and valve opening calibration line. The deviation value obtained by subtracting the value collected by the metering valve linear displacement sensor (Lw) is then calculated by the PID algorithm to obtain the water flow control current (ILW).

[0072] 3) Valve activation:

[0073] The current is applied to the electro-hydraulic servo valve to control the opening of the metering valve (Lw), thereby controlling the water supply.

[0074] c) When water is in a gaseous state, the algorithm is as follows:

[0075] 1) The calculation method for the outer ring water volume is as follows:

[0076] The expected water supply value calculated by the basic control algorithm is amplified by a factor.

[0077] WwpDemxz(k)=FDBS2*WwDem(k) (8)

[0078] Where: FDBS2 represents the magnification factor, with a default value of 5 and an adjustable range of (0-10);

[0079] WwDem represents the expected water supply value calculated using the basic control algorithm.

[0080] 2) Calculation method for inner ring valve opening:

[0081] The current valve expected value (LwDem), i.e. the inner loop setpoint (LwDem), is calculated by the water flow and valve opening calibration line. The deviation value obtained by subtracting the value collected by the metering valve linear displacement sensor (Lw) is then calculated by the PID algorithm to obtain the water flow control current (ILW).

[0082] Based on the calculated water flow control current (ILW), a control current compensation correction is performed to maximize the compensation for the latent heat loss caused by premature water vaporization. The compensation correction method is as follows:

[0083] ILWXZ(k)=FDBS3*ILW(k) (9)

[0084] Where: FDBS2 represents the magnification factor, with a default value of 1.1 and an adjustable range of (0-10);

[0085] 3) Valve activation:

[0086] The current is applied to the electro-hydraulic servo valve to control the opening of the metering valve (Lw), thereby controlling the water supply.

[0087] Step Four:

[0088] When the temperature and pressure inside the pipeline meet the conditions for water to be in a liquid state, the liquid water control mode is restored after a certain delay.

[0089] The delay time is set to 1 second (adjustable from 0 to 10 seconds).

[0090] This method can be directly applied to jet precooling systems for aero engines to achieve precise water volume control and enhance cooling effect, and has good market application prospects.

[0091] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of controlling water flow in an aircraft engine effusion precooling system, the method comprising: determining a water flow rate for the aircraft engine effusion precooling system; and adjusting the water flow rate based on a water flow rate error. The method comprises the following steps: Step S1: collecting the temperature and pressure values of the water in the pipe before the nozzle through a sensor; Step S2: judging the phase of the water in the pipe before the nozzle based on the collected temperature and pressure values through a judging program; Step S3: calling a corresponding program to control the flow of the water based on the judging result; The specific steps of Step S3 include: calling a liquid-phase control program to control the flow of the water when the water in the pipe before the nozzle is in a liquid phase, calling a gas-phase control program to control the flow of the water when the water in the pipe before the nozzle is in a gas phase, and calling a gas-liquid mixed-phase control program to control the flow of the water when the water in the pipe before the nozzle is in a gas-liquid mixed phase; The liquid-phase control program comprises the following steps: Outer loop control: calculating the expected value T2Dem of the engine inlet total temperature according to the Mach number of the aircraft, calculating the deviation value DeltaT2 between the actual value T2 collected by the inlet total temperature sensor and the expected value T2Dem of the engine inlet total temperature, and calculating the current water supply expected value WwDem based on the deviation value DeltaT2 through a PID algorithm; Inner loop control: calculating the current valve expected value LwDem based on the current water supply expected value and the valve opening calibration line, calculating the valve opening deviation value by subtracting the current valve expected value LwDem from the value Lw collected by the metering valve line displacement sensor, calculating the water supply control current ILW through a PID algorithm, and controlling the valve opening and the flow of the water through the water supply control current ILW; In the gas-liquid mixed-phase program, the front water supply expected value WwpDem of the gas-liquid mixed water; WwpDem(k)=FDBS1*WwDem(k); Wherein: FDBS1 represents the amplification factor, the default value is 1.5, and the adjustable range is 0-10; In the gas-phase control program, the front water supply expected value WwpDemxz of the gaseous water; WwpDemxz(k)=FDBS2*WwDem(k); Wherein: FDBS2 represents the amplification factor, the default value is 5, and the adjustable range is 0-10; In the gas-phase control program, the water supply control current ILW needs to be compensated and corrected; ILWXZ(k)=FDBS3*ILW(k); Wherein: FDBS2 represents the amplification factor, the default value is 1.1, and the adjustable range is 0-10, and ILWXZ is the water supply control current in the gas-phase control program; When the water in the pipe changes from the gas-liquid mixed phase or the gas phase to the liquid phase, a certain time delay is required to switch to the liquid water control mode.

2. The method of controlling water flow in an aircraft engine effusion precooling system of claim 1, wherein, The judging program comprises the following steps: Establishing a thermodynamic parameter equation P=f(T) about temperature and pressure when the water vapor is in a saturated state; Let the collected temperature value be T0 and the collected pressure value be P0; When f(T0)<P0, the water in the pipe before the nozzle is in a gas phase; When f(T0)=P0, the water in the pipe before the nozzle is in a gas-liquid mixed phase; When f(T0)<P0, the water in the pipe before the nozzle is in a liquid phase.

3. The method of controlling water flow in an aircraft engine effusion precooling system of claim 2, wherein, The visualization establishment method of the judging program comprises the following steps: Drawing the thermodynamic parameter equation into the first quadrant of the rectangular coordinate system to obtain a saturated vapor curve; The two regions formed by the temperature value range boundary line, the pressure value range boundary line and the saturated steam curve are divided into a liquid phase region and a gas phase region, and the region on the saturated steam curve is a gas-liquid mixed phase region; The collected temperature value and pressure value are plotted in the coordinate system in the form of coordinates, and the state of the water in the pipeline in front of the nozzle corresponding to the region is determined by judging the region where the collected temperature value and pressure value fall.

4. The method of controlling water flow in an aircraft engine effusion precooling system of claim 1, wherein, The delay time is set to 1s.

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