A control method for flow peak problem in zone switching of jet precooling water supply system

Abstract

The present application belongs to the field of aero-engine technology, and particularly relates to a method for controlling flow spikes in zone switching of a jet pre-cooling water supply system. The method designs a state flow to realize the switching relationship between the various states, and designs different limiting rates and flow distribution methods in different states. The relationship between the states that allow switching is set, and in the process of gradually reducing the water supply in the three zones with a large flow rate, the spike problem that occurs during zone switching is effectively suppressed. This is conducive to accurate water supply design during the project development process and meets the needs of developing a water supply control plan.

Description

Technical Field

[0001] The present application belongs to the field of aero-engine technology, and in particular relates to a method for controlling flow peak problems in zone switching of a jet pre-cooling water supply system. Background Art

[0002] In recent years, a lot of research has been carried out at home and abroad on the expansion line of jet precooling of turbine engines, that is, installing a water spray precooling device in the inlet duct, spraying atomized liquid water into the inlet duct, absorbing heat through water evaporation, and reducing the total temperature of the engine inlet.

[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 basic principle of the engine using jet pre-cooling technology to increase thrust is: first, water evaporation cools the airflow in the inlet duct, reducing the airflow temperature, increasing the fan conversion speed, increasing the density, increasing the air flow entering the engine, and also increasing the thrust; second, although the increase in engine thrust is mainly caused by the decrease in air temperature, the vaporization of water injected into the inlet duct also increases the thrust; third, the moisture content of the working fluid increases, the gas constant increases, the heat capacity of the working fluid increases, the engine exhaust velocity increases, and the unit thrust increases.

[0005] The jet pre-cooling water supply system needs to be implemented separately through 2-3 zones to ensure that the total water supply is implemented according to the desired water supply plan. Since the total water supply range is large, it is necessary to switch and control in several zones. Assume that the water supply is divided into 3 zones, namely Zone I, Zone II, and Zone III, and the three zones are metered separately. When the water supply is small, Zone I is supplied with water, and Zones II and III are not supplied with water. When the water supply gradually increases, Zone II is put into operation. When the water supply further increases, Zone III is put into operation. In order to ensure the cooling effect of the water spray, when the water supply area is switched, the water supply flow distribution ratio of each zone is adjusted accordingly, resulting in a relatively large fluctuation in the water supply flow when the zone switching occurs.

[0006] The jet pre-cooling water supply control system is a newly developed one. At present, when the three zones are put into operation, in order to ensure that the total amount of water supply remains unchanged and to achieve a better spray control effect, when zone II is put into operation, zone I and zone II share the water supply demand evenly. That is, when the zone water supply is switched, the following figure appears ( Figure 1 )

[0007] In fact, Figure 1 It is just the expected value of water supply in three zones. Due to the limitation of actual product characteristics, the water supply function of each zone, whether it is put into operation or withdrawn from operation, cannot be completed instantly within one cycle. Instead, it is a gradual transition process. Figure 2 shown.

[0008] The current solution has disadvantages: the expected water supply and the actual water supply will be different. Figure 2 The spike disturbance shown is undesirable for the demand of precise control of water supply and the demand of conducting a preliminary investigation of water supply control plan during the development process.

[0009] To address this issue, during the development process, we implemented a limit on the rate of change of the given water supply during zone switching. This has impacted the quality of water supply control, as well as the design and verification of water supply plans. However, due to the complex switching logic, different zones require different flow rate limits when switching, and simply limiting the rate of change of the given flow in each zone is inadequate. Summary of the Invention

[0010] In order to solve the above problems, the present application provides a control method for the flow spike problem of zone switching in a jet precooling water supply system, which is used to control the water supply of multiple water supply zones, including zone I, zone II and zone III. The control method is controlled by state, and includes:

[0011] State 0, Zones I, II, and III are not working;

[0012] State 1, zone I working;

[0013] State 2, Zones I and II are working;

[0014] State 3, working in Zones I, II and III;

[0015] It also includes

[0016] State 12 when switching from state 1 to state 2. In state 12, the water supply decrease rate of zone I is set to be consistent with the water supply increase rate of zone II, and the water supply limit rate is C;

[0017] In state 21 when state 2 switches to state 1, the water supply increase rate of zone I is set to be consistent with the water supply decrease rate of zone II, and the water supply limit rate is C;

[0018] In state 23 when switching from state 2 to state 3, the water supply of zone I and zone II are set to have the same decreasing rate, with the limiting rate being C / 2. The water supply increasing rate of zone III is set, with the limiting rate of zone III being C.

[0019] In state 32 when state 3 switches to state 2, the water supply increase rate of zone I and zone II is set to be the same, and the limit rate is C / 2. The water supply decrease rate of zone III is set, and the water supply limit rate of zone III is C;

[0020] Design direct switching logic from state 0 to state 1, state 0 to state 2, and state 0 to state 3 without slope limitation.

[0021] Preferably, zone I is the same as zone II, and the maximum water supply of zone III is twice that of zones I and II.

[0022] Preferably, the method for determining the value of the water supply limit rate C includes:

[0023] Obtain the water supply increase rate limit I_up and the water supply decrease rate limit I_down in zone I when the water supply relationship between zone I and zone II is switched;

[0024] Obtain the water supply increase rate limit II_up and the water supply decrease rate limit II_down in zone II when the water supply relationship between zone I and zone II is switched;

[0025] Set the rate limit value A=min(I_up, I_down, II_up, II_down) when switching between zone I and zone II.

[0026] Obtain the water supply increase rate limit III_up and the water supply decrease rate limit III_down in zone III when the water supply relationship between zones II and III is switched;

[0027] Set the rate limit value B = min(II_up, II_down, III_up, III_down) when switching between zone II and zone III;

[0028] Then C=min(A, B).

[0029] Preferably, according to the increase in water supply flow, state 0, state 1, state 2 and state 3 are gradually switched in sequence. In state 2, area I and area II jointly supply water, and the water supply flow ratio is 1:1; in state 3, area I, area II and area III jointly supply water, and the ratio is 1:1:2 respectively.

[0030] The advantages of this application include: Through simulation testing, it has effectively suppressed the spike problem that occurs when switching zones during the gradual reduction of water supply in three zones with high flow rates. This facilitates precise water supply design during project development and meets the needs of developing water supply control plans. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of an ideal control plan when switching between three zones in the background technology;

[0032] Figure 2 This is a schematic diagram of the actual water supply curve when the three zones are switched in the background technology;

[0033] Figure 3 Schematic diagram of traffic spike phenomenon that occurs during partition switching in the background technology;

[0034] Figure 4 Flowchart of the control method for the zone switching flow peak problem of the jet pre-cooling water supply system of the present application;

[0035] Figure 5 Verification of the effectiveness of the control method for the zone switching flow peak problem of the jet precooling water supply system of this application. DETAILED DESCRIPTION

[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] Assume that the water supply zone switching algorithm switches at 1.5 kg / s and 3 kg / s, respectively. When the flow rate is less than 1.5 kg / s, only Zone I receives water. When the water flow rate is greater than 1.5 kg / s and less than 3 kg / s, Zones I and II share water in a 1:1 ratio. When the water flow rate is greater than 3 kg / s, Zones I, II, and III share water in a 1:1:2 ratio. Existing methods directly adjust the water supply flow rate according to the zoned water supply plan when switching occurs.

[0040] 1. The threshold C of the proposed small disturbance switching method to prevent the spike problem is selected as follows:

[0041] 1) Through the analysis of experimental data, when the water supply relationship between zone I and zone II is switched, the water supply increase rate limit of zone I is I_up, and the water supply decrease rate limit of zone I is I_down;

[0042] 2) Through the analysis of experimental data, when the water supply relationship between zone I and zone II is switched, the water supply increase rate limit of zone II is II_up, and the water supply decrease rate limit of zone II is II_down;

[0043] 3) When switching between zone I and zone II, select the rate limit value A = min(I_up, I_down, II_up, II_down);

[0044] 4) Through the analysis of experimental data, when the water supply relationship between zone II and zone III is switched, the water supply increase rate limit of zone III is set as III_up, and the water supply decrease rate limit of zone III is set as III_down;

[0045] 5) When switching between zone II and zone III, select the rate limit value B = min(II_up, II_down, III_up, III_down);

[0046] 6) C = min(A, B) Formula (1)

[0047] 2. The small disturbance switching method uses state control. The specific method is as follows: Figure 4 As shown:

[0048] 1) Set state 1, state 2, state 3. In state 1, only zone I works; in state 2, zone I and zone II work; in state 3, zone I, zone II and zone III work;

[0049] 2) Initially, it is set to state 0. In state 0, all three zones are not working;

[0050] 3) When switching between state 1 and state 2, set state 12 (representing the switching process from state 1 to state 2), and perform slope limiting during the switching process. The falling rate of zone 1 and the rising rate of zone II are consistent, and the limiting rate C (obtained by formula (1)) is used;

[0051] 4) When switching between state 1 and state 2, set state 21 (representing the switching process from state 2 to state 1), and perform slope limiting during the switching process. The rising rate in zone I and the falling rate in zone II are consistent, and the limiting rate C (obtained by formula (1)) is used.

[0052] 5) Between state 2 and state 3, state 23 is set (representing the switching process from state 2 to state 3). During the switching process, slope limitation is performed. The falling rate in zone I is consistent with that in zone II, and the limiting rate is C / 2 (C is obtained by formula (1)). The rising rate in zone III is set, and the limiting rate is C.

[0053] 6) Between state 2 and state 3, state 32 is set (representing the switching process from state 3 to state 2). During the switching process, the slope is limited. The rising rate of zone I is consistent with the rising rate of zone II, and the limited rate is C / 2 (C is obtained by formula (1)). The falling rate of zone III is set, and the limited rate is C;

[0054] 7) Design direct switching logic from initial state 0 to state 1, state 0 to state 2, and state 0 to state 3, without rate limiting.

[0055] 3. Implementation logic of small disturbance switching method

[0056] Design state flow to realize the switching relationship between each state, and design different rate limits and traffic distribution methods in different states. The relationship between states that can be switched is as follows: Figure 4 An arrow indicates that a switch in that direction is allowed. For example, an arrow from state 1 to state 21 indicates that a switch from state 1 to state 21 is allowed. If there is no arrow between two states, this switch is not allowed.

[0057] like Figure 4 As shown, this patent proposes setting up 8 states, using different control plans for different states, so as to reduce the peak problem caused by the characteristics of the actuator when switching between zones, and not to impose restrictions on the water supply to the three zones in the initial state, so as to quickly achieve initial water supply.

[0058] 4 Simulation Verification

[0059] Design a simulation model and verify the algorithm proposed in this patent by simulation. Figure 1-3 Under the closed-loop control water supply demand shown, the control effect achieved by the method of this patent is shown in the figure below. Figure 5 The top graph shows a comparison of water flow control quality, while the bottom graph shows the actual switching control curve for the proposed algorithm. As can be seen, the spike problem in the top graph has been effectively resolved.

[0060] 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 method for controlling the flow peak problem of zone switching in a jet precooling water supply system, which is used to control the water supply of multiple water supply zones, including zone I, zone II and zone III, and is characterized in that: The control method is controlled by state, and includes: State 0, Zones I, II, and III are not working; State 1, zone I working; State 2, Zones I and II are working; State 3, working in Zones I, II and III; It also includes State 12 when switching from state 1 to state 2. In state 12, the water supply decrease rate of zone I is set to be consistent with the water supply increase rate of zone II, and the water supply limit rate is C; In state 21 when state 2 switches to state 1, the water supply increase rate of zone I is set to be consistent with the water supply decrease rate of zone II, and the water supply limit rate is C; In state 23 when switching from state 2 to state 3, the water supply of zone I and zone II are set to have the same decreasing rate, with the limiting rate being C / 2. The water supply increasing rate of zone III is set, with the limiting rate of zone III being C. In state 32 when state 3 switches to state 2, the water supply increase rate of zone I and zone II is set to be the same, and the limit rate is C / 2. The water supply decrease rate of zone III is set, and the water supply limit rate of zone III is C; Design direct switching logic from state 0 to state 1, state 0 to state 2, and state 0 to state 3 without rate limiting.

2. The method for controlling flow peak problem in zone switching of jet precooling water supply system according to claim 1, characterized in that: Zone I is the same as Zone II, and the maximum water supply of Zone III is twice that of Zone I and Zone II.

3. The method for controlling flow peak problem in zone switching of jet precooling water supply system according to claim 2, characterized in that: The methods for determining the water supply limit rate C include: Obtain the water supply increase rate limit I_up and the water supply decrease rate limit I_down for zone I when the water supply relationship between zone I and zone II is switched; Obtain the water supply increase rate limit II_up and the water supply decrease rate limit II_down in zone II when the water supply relationship between zone I and zone II is switched; Set the rate limit value A=min(I_up, I_down, II_up, II_down) when switching between zone I and zone II. Obtain the water supply increase rate limit III_up and the water supply decrease rate limit III_down in zone III when the water supply relationship between zones II and III is switched; Set the rate limit value B = min(II_up, II_down, III_up, III_down) when switching between zone II and zone III; Then C=min(A, B).

4. The method for controlling flow peak problem in zone switching of a jet precooling water supply system according to claim 2, characterized in that: According to the increase of water supply flow, the state 0, state 1, state 2 and state 3 are gradually switched in sequence. In state 2, area I and area II are supplied with water together, and the water supply flow ratio is 1:1; in state 3, area I, area II and area III are supplied with water together, and the ratios are 1:1:2 respectively.

Images