A method for improving the temperature control effect of jet precooling control system

Abstract

The present application belongs to the field of aero-engine control, and in particular relates to a method for improving the temperature control effect of a jet pre-cooling control system. The water spray control mode is divided into an open-loop mode and a closed-loop mode. The open-loop mode is difficult to guarantee the temperature control effect, while the closed-loop mode may have problems such as large overshoot and slow convergence. A method for switching from open-loop to closed-loop is proposed. This method uses the temperature open-loop control effect as effective information and corrects the initial value of the closed-loop control plan so that the initial value of the closed-loop control is closer to the expected effect. This method can solve the problems of large overshoot and slow convergence in the open-loop to closed-loop control, and improve the control effect of the temperature closed-loop control.

Description

Technical Field

[0001] The present application relates to the field of aero-engine control, and in particular to a method for improving the temperature control effect of a jet pre-cooling control system. Background Art

[0002] In recent years, a lot of research has been carried out at home and abroad on the expansion of the jet pre-cooling envelope of turbine engines. That is, a water spray pre-cooling device is installed in the air inlet duct, and atomized liquid water is sprayed into the air inlet duct. The heat is absorbed by water evaporation to reduce the total temperature of the engine inlet, thereby increasing the range of the engine flight envelope.

[0003] The jet pre-cooling engine is based on a mature aviation turbine engine and sprays water on the turbine engine. The geometric limitations, pressure limitations, temperature limitations and speed limitations of the original turbine engine remain unchanged.

[0004] The engine uses jet precooling technology to control the total intake air temperature. Currently, there are two control schemes: open-loop and closed-loop. Open-loop control controls the amount of water based on the total intake air temperature. In principle, the higher the total intake air temperature T2, the more water the jet precooling system injects. Open-loop water supply control schemes struggle to achieve the desired control effect. As the water supply increases, the evaporation rate decreases, requiring the aircraft to carry more water, which can impact combustion stability. Too little water supply can also undermine the desired effect. Closed-loop control relies on the total intake air temperature after water injection.

[0005] During the development process, the jet precooling control mode was divided into two options: open-loop control and closed-loop control. The control mode was selected through instructions. When switching from open-loop control to closed-loop control, it was hoped that the water flow rate would not experience sudden changes in order to minimize the impact of water supply disturbances on the combustion chamber. Summary of the Invention

[0006] In order to solve the above problems, the present application provides a method for improving the temperature control effect of the jet pre-cooling control system, which can be freely switched between open-loop and closed-loop modes, including:

[0007] The closed-loop water supply calculation module uses the expected total intake air temperature T2Dem as the control target and the actual temperature T2_h after the jet water is sprayed as the feedback value to perform closed-loop calculation to obtain the expected closed-loop water supply value WwDem_closed;

[0008] The open-loop water supply calculation module performs open-loop calculation based on the expected total intake temperature T2Dem and the temperature T2 before the jet water spray to obtain the expected open-loop water supply value WwDem_open;

[0009] A mode selection module, which selects a closed-loop water supply expected value or an open-loop water supply expected value as the water supply result expected value WwDem_a;

[0010] The switching process slope limiting function module corrects the expected value of the water supply result WwDem_a to the total expected value of water supply WwDem without sudden changes in water supply flow through slope limiting;

[0011] The jet water spray device sprays water to cool the turbine engine based on the total water supply expected value WwDem.

[0012] Preferably, the open-loop calculation formula is:

[0013] WwDem_open=fcn1(T2Dem, T2, P2).

[0014] Preferably, the closed-loop calculation method is:

[0015] Calculate the proportional term U_Kp and the integral term U_Ki based on the difference deltaT2 between the expected total intake air temperature T2Dem and the actual temperature T2_h after the water jet is sprayed;

[0016] The sum of the proportional term U_Kp and the integral term U_Ki is obtained to obtain the sum value Delta_U, and the sum value Delta_U is summed with the preset value U_PI_Pre to obtain the feedback sum value U_PI. The feedback sum value U_PI is limited by the boundary saturation limiter to finally obtain the closed-loop water supply expected value WwDem_closed.

[0017] Preferably,

[0018] The device for improving the temperature control effect of the jet pre-cooling control system, the preset value U_PI_Pre is selected by a previous value selection module, and the previous value selection module is selected according to the output value of the mode selection module;

[0019] When the open-closed loop switching mode model of the mode selection module is 1, the closed-loop water supply calculation module is used, and the preset value U_PI_Pre is the value WwDem_closed_Pre of the previous cycle of the closed-loop water supply expected value.

[0020] When the open-closed loop switching mode of the mode selection module is set to 0, the open-loop water supply calculation module is used, and the preset value U_PI_Pre is WwDem_open_a. WwDem_open_a is the output value WwDem_open of the expected open-loop water supply after being corrected by the temperature control effect correction algorithm module and then subjected to boundary saturation limitation.

[0021] The device for improving the temperature control effect of the jet pre-cooling control system, and the method for correcting the difference deltaT2 by the temperature control effect correction algorithm module include:

[0022] If deltaT2 >= A, then WwDem_open_out(k) = WwDem_open(k) + a;

[0023] If deltaT2 <= -A, then WwDem_open_out(k) = WwDem_open(k) - a;

[0024] If deltaT2 = B, then

[0025] WwDem_open_out(k) = WwDem_open(k) + b;

[0026] If deltaT2 > -A and if deltaT2 <= -B, then

[0027] WwDem_open_out(k) = WwDem_open(k) - b;

[0028] In other cases, WwDem_open_out(k) = WwDem_open(k)

[0029] where k is the current cycle; A is a preset first temperature threshold, B is a preset second temperature threshold B, a is a preset first compensation value, and b is a preset second compensation value.

[0030] Preferably, a boundary saturation limiter is provided at the output of the temperature control effect correction algorithm module

[0031] The advantages of this application include: it can avoid the problem of excessive overshoot caused by direct open-loop to closed-loop switching, and at the same time can meet the requirements of the response speed of the T2 closed-loop control. It realizes precise water supply in the jet pre-cooling water supply system, avoids waste of water supply in the jet pre-cooling water supply, thereby saving the water carrying capacity requirements of the aircraft and improving the control quality of the jet pre-cooling control system. Brief Description of the Drawings

[0032] Figure 1 is a logic block diagram of a jet pre-cooling control system according to a preferred embodiment of the present application;

[0033] Figure 2 Conventional PI control logic block diagram;

[0034] Figure 3 Closed-loop control algorithm logic block diagram with temperature control effect compensation;

[0035] Figure 4 Effect verification diagram of the method proposed in this application. Detailed Embodiments

[0036] 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.

[0037] 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.

[0038] 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.

[0039] like Figure 1 As shown, the present application provides a method for improving the temperature control effect of the jet precooling control system, a closed-loop water supply calculation module, which uses the expected value of the total intake temperature T2Dem as the control target and the actual temperature T2_h after the jet water is sprayed as the feedback value for closed-loop calculation to obtain the closed-loop water supply expected value WwDem_closed;

[0040] The open-loop water supply calculation module performs open-loop calculation based on the expected total intake temperature T2Dem and the temperature T2 before the jet water spray to obtain the expected open-loop water supply value WwDem_open;

[0041] A mode selection module, which selects a closed-loop water supply expected value or an open-loop water supply expected value as the water supply result expected value WwDem_a;

[0042] The switching process slope limiting function module corrects the expected value of the water supply result WwDem_a to the total expected value of water supply WwDem without sudden changes in water supply flow through slope limiting;

[0043] A jet water spray device sprays water to cool the turbine engine based on the total water supply desired value WwDem;

[0044] The above-mentioned open-loop module achieves rapid water supply, and the closed-loop module can increase control accuracy, but it also introduces the problem of sudden changes in water supply flow. This application further proposes a method for switching from open-loop to closed-loop, which can solve the problems of large overshoot and slow convergence speed in open-loop to closed-loop control, and improve the control effect of temperature closed-loop control. This method uses the temperature open-loop control effect as effective information and corrects the initial value of the closed-loop control plan, making the initial value of the closed-loop control closer to the desired effect, thereby achieving rapid convergence and improving the temperature control effect;

[0045] 1. Control Target

[0046] The target limit for the engine's total intake air temperature, T2Dem, is T2Dem. When the engine inlet total temperature exceeds T2Dem, water injection is intended to reduce it to below T2Dem. Therefore, to evaluate the effectiveness of temperature control, temperature measurements were taken before and after water injection. The temperature before injection is denoted by T2, and the temperature after injection is denoted by T2_h. In open-loop control, the value of T2_h is irrelevant; the total water supply volume is calculated based on T2Dem and T2. In closed-loop control, T2Dem is used as the target, and closed-loop control is performed by monitoring the effect of water injection, T2_h. If T2_h is less than T2Dem, water injection is not performed. If T2_h exceeds T2Dem, the closed-loop water supply flow rate is calculated based on the deviation. Therefore, open-loop water injection can result in T2_h being too low or too high. However, closed-loop water injection offers significantly better temperature control.

[0047] 2. Open-loop control plan calculation

[0048] Open-loop control plan, calculate the open-loop water supply expected value WwDem_open according to formula (1)

[0049] WwDem_open=fcn1(T2Dem, T2, P2) (1)

[0050] 3 Closed-loop control algorithm with temperature control effect compensation

[0051] Adopt incremental PI (proportional-integral) control algorithm. Conventional PI control logic is as follows Figure 2 As shown, the proportional term U_Kp and the integral term U_Ki are calculated based on the difference deltaT2 between T2Dem and T2_h. The proportional term U_Kp and the integral term U_Ki are summed to obtain the sum Delta_U. This sum Delta_U is then summed with the preset value U_PI_Pre to obtain the feedback sum U_PI. This feedback sum U_PI is then limited by the boundary saturation limiter to ultimately obtain the closed-loop water supply desired value WwDem_closed.

[0052] T2 closed-loop control deviation deltaT2 calculation formula

[0053] deltaT2(k)=T2_h(k)-T2Dem(k) (2)

[0054] Proportional term calculation formula

[0055] U_Kp(k)=Kp*(deltaT2(k)- deltaT2(k-1)) (3)

[0056] Integral term calculation formula

[0057] U_Ki(k) = Ki*deltaT2(k) (4)

[0058] Control quantity calculation formula

[0059] U_PI(k)=U_Kp(k) +U_Ki(k) (5)

[0060] U_PI_Pre(k)= U_PI(k-1) (6)

[0061] in,

[0062] The proposed algorithm with temperature control effect compensation is performed in the calculation link of U_PI_Pre. Figure 3 The processing shown.

[0063] Closed-loop control algorithm with temperature control effect compensation

[0064] 1) Open-closed loop switching mode model (0 represents open loop, 1 represents closed loop). If model = 1, the "previous value selection module" selects WwDem_closed;

[0065] 2) If model = 0, the "previous value selection module" selects WwDem_open_a;

[0066] 3) Correction algorithm with temperature control effect

[0067] If deltaT2 >= A, then WwDem_open_out(k) = WwDem_open(k) + a;

[0068] If deltaT2 <= -A, then WwDem_open_out(k) = WwDem_open(k) - a;

[0069] If deltaT2 = B, then

[0070] WwDem_open_out(k) = WwDem_open(k) + b;

[0071] If deltaT2 > -A and if deltaT2 <= -B, then

[0072] WwDem_open_out(k) = WwDem_open(k) - b;

[0073] In other cases, WwDem_open_out(k) = WwDem_open(k)

[0074] Where k is the current cycle; A is the preset first temperature threshold, B is the preset second temperature threshold B, a is the preset first compensation value, and b is the preset second compensation value

[0075] 5 Simulation verification

[0076] The method proposed in this invention is compared with two existing methods, and the simulation verification results are as Figure 4 shown. Open-loop control is performed from 0 to 50 s, and switched to closed-loop control at 50 s. The simulation setting is that the water supply given by the open-loop control plan is偏少, and the T2 control effect is not ideal. By switching to closed-loop control, the desired control target can be achieved. The three curves in the figure are respectively Method 1, the method of directly switching from open-loop to closed-loop; Method 2, the method of using the open-loop water supply as the previous value of the control quantity when switching from open-loop to closed-loop; Method 3 proposed in this patent is the method after correction by the closed-loop control algorithm with temperature control effect compensation. It can be seen that the method proposed in Method 3 can not only quickly achieve the T2 control target, but also avoid large water supply losses, reduce the demand for the aircraft's water load, and has high engineering application value.

[0077] 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 device for improving the temperature control effect of a jet precooling control system, characterized in that: including: a closed-loop water supply calculation module that performs closed-loop calculation with the expected total inlet temperature T2Dem as the control target and the actual temperature T2_h after jet water injection as the feedback value to obtain the expected value of closed-loop water supply WwDem_closed; an open-loop water supply calculation module that performs open-loop calculation with the expected total inlet temperature T2Dem and the temperature T2 before jet water injection to obtain the expected value of open-loop water supply WwDem_open; a mode selection module that selects either the expected value of closed-loop water supply or the expected value of open-loop water supply as the expected value of water supply result WwDem_a; a switching process slope limiting function module that modifies the expected value of water supply result WwDem_a to the total expected value of water supply WwDem without sudden change in water supply flow through slope limiting; a jet water injection device that sprays water to cool the turbine engine based on the total expected value of water supply WwDem; The closed-loop calculation method is as follows: According to the difference deltaT2 between the expected total inlet temperature T2Dem and the actual temperature T2_h after jet water injection, calculate the proportional term U_Kp and the integral term U_Ki; Sum the proportional term U_Kp and the integral term U_Ki to obtain the sum value Delta_U, sum the sum value Delta_U with the preset value U_PI_Pre to obtain the feedback sum value U_PI, and after the feedback sum value U_PI is limited by the boundary saturation limiter, finally obtain the expected value of closed-loop water supply WwDem_closed; The preset value U_PI_Pre is selected by a previous value selection module, and the previous value selection module selects according to the output value of the mode selection module; When the open / closed-loop switching mode model of the mode selection module is 1, the closed-loop water supply calculation module is adopted, and the preset value U_PI_Pre is the value of the previous cycle of the expected value of closed-loop water supply WwDem_closed_Pre; When the open / closed-loop switching mode model of the mode selection module is 0, the open-loop water supply calculation module is adopted, and the preset value U_PI_Pre is WwDem_open_a, and WwDem_open_a is the output value WwDem_open_out obtained after the expected value of open-loop water supply WwDem_open is corrected by the temperature control effect correction algorithm module and then limited by the boundary saturation; The method for the temperature control effect correction algorithm module to correct deltaT2 includes: If deltaT2 >= A, then WwDem_open_out(k) = WwDem_open(k) + a; If deltaT2 <= -A, then WwDem_open_out(k) = WwDem_open(k) - a; If deltaT2 = B, then WwDem_open_out(k) = WwDem_open(k) + b; If deltaT2 > -A and if deltaT2 <= -B, then WwDem_open_out(k) = WwDem_open(k) - b; In other cases, WwDem_open_out(k)=WwDem_open(k); Wherein, k is the current cycle; A is the preset first temperature threshold, B is the preset second temperature threshold B, a is the preset first compensation value, and b is the preset second compensation value.

2. The device for improving the temperature control effect of the jet precooling control system according to claim 1, characterized in that: The open-loop calculation formula is: WwDem_open=fcn1(T2Dem,T2,P2).

3. The device for improving the temperature control effect of the jet precooling control system according to claim 1, characterized in that: The output of the temperature control effect correction algorithm module is provided with a boundary saturation limiter.

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