An aero-engine fuel warming device and control method

Abstract

The application belongs to the field of engine test equipment control, and particularly relates to an aero-engine fuel warming device and a control method. When the fuel warming test is performed, the fuel is pressurized by a centrifugal oil pump group, enters a turbine flowmeter, and is warmed in a warmer. The warmer adopts a PID control algorithm to ensure that the hot oil temperature after the warmer outlet remains constant. The heated hot oil enters a three-way regulating valve, a branch is added in front of the three-way regulating valve, a high-temperature centrifugal oil pump group, a flowmeter and a check valve are arranged on the branch, an internal hot oil circulation is formed, part of the fuel in a hot oil supply pipeline is supplied to the front of the flowmeter, the hot oil supply pipeline flow rate is increased, the temperature loss is reduced, and a temperature control method adopts PID control combined with automatic control. Compared with the original fuel warming control system, when the fuel flow is stable, the outlet temperature control precision is within ±1.5℃, when the fuel flow changes, the outlet temperature control precision is within ±5℃, and the stable time is not greater than 60 seconds.

Description

Technical Field

[0001] This application belongs to the field of engine test equipment control, and specifically relates to an aircraft engine fuel heating device and control method. Background Technology

[0002] According to the requirements of the "General Specifications for Aircraft Turbojet and Turbofan Engines" (GJB241A-2010), the maximum allowable fuel inlet temperature for continuous engine operation should not be lower than 93℃. To meet the fuel heating test requirements of a certain aircraft engine, the fuel heating device should have the following functions:

[0003] 1) The outlet oil temperature is between room temperature and 93℃, and the oil temperature can be controlled according to the test requirements;

[0004] 2) When the fuel flow rate is stable during the fuel heating test, the temperature control accuracy is within ±1.5℃. During the fuel flow rate change process, the temperature control accuracy is within ±5℃, and the stabilization time is no more than 60 seconds.

[0005] Currently, fuel heating systems for aero engines primarily utilize electric heaters. These heaters are mainly controlled by relays and PID controllers. However, these methods only meet the control requirements of simple temperature control systems. For temperature control systems with characteristics such as control lag and time-varying temperatures, their adaptability and reliability are weak, making it difficult to meet control requirements. Since the fuel temperature control object in fuel heating systems is a typical first-order lag element, a single control method cannot rapidly change the fuel temperature during testing as required. Therefore, current fuel heating systems mainly use PID control combined with manual adjustment to control the outlet fuel temperature. Summary of the Invention

[0006] To address the aforementioned problems, this application provides an aircraft engine fuel heating device, comprising:

[0007] Hot oil passage, cold oil passage, and mixing passage;

[0008] in,

[0009] The hot oil passage, from inlet to outlet, includes: a centrifugal oil pump unit, a volumetric flow meter, a pressure sensor, a temperature sensor, a heater, another pressure sensor, and another temperature sensor. A return oil branch is connected in parallel after the temperature sensor at the heater outlet and before the volumetric flow meter. This return oil branch includes a centrifugal oil pump unit, a volumetric flow meter, and a check valve to return the hot oil from the heater outlet to the heater inlet. A pressure sensor and a temperature sensor are also installed after the return oil branch.

[0010] The cold oil passage has a centrifugal oil pump set, a pressure sensor, and a temperature sensor sequentially from the inlet to the outlet.

[0011] The hot oil passage and the cold oil passage are mixed by an electric three-way regulating valve and enter the mixing passage. The outlet of the mixing passage is connected to the test specimen. The mixing passage is equipped with a volumetric flow meter, a pressure sensor, and a temperature sensor.

[0012] A temperature control method for an aircraft engine fuel heating device, comprising using the aforementioned aircraft engine fuel heating device, collecting the measured mixing temperature T'2, and setting the set temperature T2 of the mixing passage outlet as required by the test.

[0013] Based on the engine inlet change rate, the system is divided into steady-state control and dynamic control. When the system is in the steady-state control process:

[0014] When |T2-T'2|≤a, the three-way regulating valve will not be adjusted during this control cycle;

[0015] When |T2-T'2|>a, calculate the theoretical hot oil flow rate Q0 that makes the set temperature T2 equal to the measured mixing temperature T'2, and adjust the opening of the three-way regulating valve by the difference ΔQ between the theoretical hot oil flow rate Q0 and the measured hot oil flow rate Q'0.

[0016] When the system is in a dynamic control process, the theoretical hot oil flow rate Q0 is calculated to make the set temperature T2 equal to the measured mixing temperature T'2, and the opening of the three-way regulating valve is adjusted by the difference ΔQ between the theoretical hot oil flow rate Q0 and the measured hot oil flow rate Q'0.

[0017] Preferably, a is 0.5.

[0018] Preferably, the theoretical hot oil flow rate Q0 and the theoretical cold oil flow rate Q1 are calculated as follows:

[0019] Based on the energy conservation principles of the hot oil passage, cold oil passage, and mixing passage:

[0020] Cρ0Q0T0+Cρ1Q1T1=Cρ2Q2T2;

[0021] In the formula, C is the specific heat capacity of the oil, T0 is the hot oil temperature, which is obtained by a temperature sensor, ρ0 is the oil density at temperature T0, T1 is the cold oil temperature, which is obtained by a temperature sensor, ρ1 is the oil density at temperature T1, Q1 is the theoretical cold oil flow rate at temperature T1, and ρ2 is the oil density at temperature T2.

[0022] According to the law of conservation of mass, the relationship between fuel flow rates before and after blending is as follows:

[0023] ρ0Q0+ρ1Q1=ρ2Q2

[0024] Given that the required fuel flow rate for the test is the mixing flow rate Q2, if the mixing temperature is to reach the set temperature T2, the required theoretical hot oil flow rate Q0 at the theoretical hot oil temperature T0 and the theoretical cold oil flow rate Q1 at the theoretical cold oil temperature T1 are respectively:

[0025]

[0026] Preferably, during steady-state control, the measured hot oil flow rate Q'0 is taken as the average value of the volumetric flow meter (3) in the mixing passage within a certain period before the control cycle; during dynamic control, the measured hot oil flow rate Q'0 is taken as the average value of the volumetric flow meter (3) in the mixing passage within the control cycle t, and the control cycle t is greater than the adjustment response cycle of the three-way regulating valve.

[0027] Preferably, the method for judging steady-state control and dynamic control is as follows: the outlet flow of the fuel heating device system is mainly controlled by the opening degree of the engine inlet valve. When the rate of change of the engine inlet valve opening α ≥ 1° / s, the system is considered to be in a dynamic control process. If the rate of change of the engine inlet valve opening α < 1° / s, the system is considered to be in a steady-state control process.

[0028] The advantages of this application include:

[0029] 1) It can automatically control the outlet oil temperature of the fuel heating device;

[0030] 2) When the fuel flow rate is stable, the outlet temperature control accuracy is within ±1.5℃; when the fuel flow rate changes, the outlet temperature control accuracy is within ±5℃, and the stabilization time is no more than 60 seconds.

[0031] 3) Add a branch line before the three-way regulating valve, and install a high-temperature centrifugal oil pump set, flow meter, and check valve on the branch line to form a hot oil internal circulation. Supply part of the fuel in the hot oil supply pipeline to the flow meter, increase the flow rate of the hot oil supply pipeline, and reduce temperature loss.

[0032] 4) The control algorithm is simple and easy to understand, and easy to operate. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a preferred embodiment of an aircraft engine fuel heating device according to this application;

[0034] Figure 2 This is a flowchart of a preferred embodiment of the temperature control method for an aircraft engine fuel heating device. Detailed Implementation

[0035] 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.

[0036] 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.

[0037] 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.

[0038] like Figure 1 As shown, an aircraft engine fuel heating device includes:

[0039] The system includes a hot oil passage, a cold oil passage, and a mixing passage. The hot oil passage, from inlet to outlet, consists of: a centrifugal oil pump assembly 1, a volumetric flow meter 3, a pressure sensor 4, a temperature sensor 5, a heater 6, and a return oil branch connected in parallel after the temperature sensor 5 at the outlet of the heater 6 and before the volumetric flow meter 3. The return oil branch includes the centrifugal oil pump assembly 1, the volumetric flow meter 3, and a check valve 2, which allow the hot oil from the outlet of the heater 6 to flow back to the inlet of the heater 6. The pressure sensor 4 and the temperature sensor 5 are also installed after the return oil branch.

[0040] The cold oil passage has a centrifugal oil pump set 1, a pressure sensor 4, and a temperature sensor 5 sequentially from the inlet to the outlet.

[0041] The hot oil and cold oil paths are mixed by an electric three-way regulating valve 7 and enter the mixing path. The outlet of the mixing path is connected to the test specimen. A volumetric flow meter 3, a pressure sensor 4, and a temperature sensor 5 are connected to the mixing path. During the fuel heating test, the fuel is pressurized by a centrifugal oil pump unit, passes through a turbine flow meter, and enters the heater for heating. The heater uses a PID control algorithm to ensure that the hot oil temperature after the heater outlet remains constant. The heated oil enters the three-way regulating valve. Due to the long distance between the heater and the three-way regulating valve, there is a significant temperature loss. Therefore, a branch is added before the three-way regulating valve, equipped with a high-temperature centrifugal oil pump unit, a flow meter, and a check valve, forming an internal hot oil circulation. This supplies some of the fuel from the hot oil supply pipeline to the flow meter, increasing the flow rate in the hot oil supply pipeline and reducing temperature loss. Another path of low-temperature fuel is pressurized by the centrifugal oil pump unit to the three-way regulating valve. The ratio of cold oil to hot oil is controlled by manually adjusting the three-way regulating valve to achieve the required fuel temperature for the test.

[0042] The simplified schematic diagram of the new fuel heating device system is the same as that of the original heating device, but the temperature control method adopts a combination of PID control and automatic control. This invention first establishes a mathematical model of the temperature control object of the fuel heating device, then proposes the temperature control logic of the fuel heating device, then explains the data processing method of the fuel heating device, and finally develops an automatic temperature control algorithm for the fuel heating device.

[0043] I. Mathematical Model of Temperature Control Object in Fuel Heating Device

[0044] The fuel heating device obtains fuel at the required temperature by mixing hot and cold oil. The core control component is a three-way regulating valve; adjusting the valve's opening controls the mixing ratio of hot and cold oil, thus ensuring the mixing temperature meets requirements. Assuming the pressure drop within the mixing device and external heat exchange are negligible, the energy conservation equation is:

[0045] Cρ0Q0T0+Cρ1Q1T1=Cρ2Q2T2 (1)

[0046] In the formula, C is the specific heat capacity of the oil, T0 is the hot oil temperature, which is obtained by a temperature sensor, ρ0 is the oil density at temperature T0, T1 is the cold oil temperature, which is obtained by a temperature sensor, ρ1 is the oil density at temperature T1, Q1 is the theoretical cold oil flow rate at temperature T1, and ρ2 is the oil density at temperature T2.

[0047] According to the law of conservation of mass, the relationship between fuel flow rates before and after blending is as follows:

[0048] ρ0Q0+ρ1Q1=ρ2Q2 (2)

[0049] Simplifying Equations 1-2, given that the required fuel flow rate for the experiment is the mixing flow rate Q2, and to achieve a mixing temperature of T2, the theoretically calculated hot oil flow rate Q0 at temperature T0 and the theoretically calculated cold oil flow rate Q1 at temperature T1 are respectively:

[0050]

[0051] The hot oil flow rate Q'0 can be measured at the flow meter measuring point on the fuel heating device. By comparing the measured hot oil flow rate Q'0 with the theoretical hot oil flow rate Q0, the three-way regulating valve is adjusted in real time to make the real-time measured hot oil flow rate Q'0 equal to the theoretical hot oil flow rate Q0, and the measured cold oil flow rate Q'1 equal to the theoretical cold oil flow rate Q1, so that the mixing temperature reaches the required temperature T2 of the test.

[0052] II. Temperature Control Logic of Fuel Heating Device

[0053] This invention controls fuel temperature by comparing the difference ΔQ = Q'0 - Q0 between the measured hot oil flow rate Q'0 and the theoretical hot oil flow rate Q0. To balance the stability and rapid response of the control system, this invention divides the fuel heating device into two states: First, when the flow rate is stable, the opening of the three-way regulating valve is only related to the measured temperature T'2 and the set temperature T2, which is a steady-state control process. Second, when the system flow rate changes, the opening of the three-way regulating valve is related to the flow rate change, as well as the measured temperature T'2 and the set temperature T2, which is a dynamic control process. Therefore, different control algorithms are used for dynamic control and steady-state control.

[0054] During steady-state control, if the difference in ΔQ is small, it indicates that the blended fuel has reached the set temperature T2. In this case, the opening of the three-way regulating valve only needs fine-tuning or even no adjustment. If the difference in ΔQ is large, it indicates that the measured temperature T'2 differs significantly from the set temperature T2. In this case, the opening of the three-way regulating valve should be adjusted to ensure that the measured hot oil flow rate Q'0 quickly reaches the theoretical hot oil flow rate Q0. Furthermore, during steady-state control, if the difference between the measured temperature T'2 and the set temperature T2 is within 0.5℃, the opening of the three-way regulating valve is not adjusted. This increases the stability of the control algorithm while still meeting the temperature control accuracy requirements.

[0055] In dynamic control, ΔQ is affected by many factors and the system is more complex. Therefore, the opening of the three-way regulating valve should be adjusted according to ΔQ at any time, and no temperature dead zone should be set.

[0056] Method for judging steady-state control and dynamic control: The outlet flow of the fuel heating device system is mainly controlled by the opening of the engine inlet valve. If the rate of change of the engine inlet valve opening α ≥ 1° / s, the system is considered to be in a dynamic control process. If the rate of change of the engine inlet valve opening α < 1° / s, the system is considered to be in a steady-state control process.

[0057] III. Data Processing Methods for Fuel Heating Devices

[0058] During the experiment, the temperature control program of the fuel heating device mainly controls the opening of the three-way regulating valve by comparing the theoretical flow rate and the measured flow rate. Therefore, the accuracy of the flow rate data directly affects the control precision. The fuel heating system uses an FM high-temperature flow meter for flow measurement. Due to practical engineering reasons, flow measurement will have random errors, i.e., the measured values ​​will fluctuate, which will reduce the stability and accuracy of the control system. Therefore, the collected data needs to be processed. An effective method to eliminate random errors is the mean method, but the mean method cannot reflect the true changes in the measured values. To solve this problem, different data processing methods need to be used when the flow rate is stable and when the flow rate changes.

[0059] The longer the sampling period for steady-state control, the closer the average value is to the true value. Considering that the period of stable flow rate during each test is over 200 seconds, the flow rate measurement value for steady-state control is the average value of the first 10 seconds of that control period. For dynamic control, the measured flow rate value is the average value within that control period t. Considering practical engineering applications, the control period t should be slightly longer than the adjustment response period of the three-way control valve to increase valve life and system control stability. When transitioning from steady-state control to dynamic control, the data processing method used for dynamic control is adopted; when transitioning from dynamic control to steady-state control, the flow rate measurement value is the average flow rate from the point of transition to that moment.

[0060] IV. Automatic Temperature Control Algorithm for Fuel Heating Device

[0061] The fuel heating device control system uses a Siemens PLC and is programmed with WinCC. The temperature control process of the fuel heating device during the experiment is as follows:

[0062] 1) First, set the required outlet temperature T2 for the test, and collect the measured hot oil temperature T'0, measured cold oil temperature T'1, measured mixing temperature T'2, measured hot oil flow rate Q'0 and mixed flow rate Q2 of the fuel heating device in real time.

[0063] 2) Then determine whether the system is in a steady-state control process or a dynamic control process. If the system is in a steady-state control process, determine the difference between the set test outlet temperature T2 and the measured mixing temperature T'2. If |T2-T'2|≤0.5, then the three-way regulating valve will not be adjusted in this control cycle; if |T2-T'2|>0.5, then obtain the theoretical hot oil flow rate Q0 and ΔQ through formula 1-3, and adjust the opening of the three-way regulating valve. If the system is in a dynamic control process, obtain the theoretical hot oil flow rate Q0 and ΔQ through formula 1-3, and adjust the opening of the three-way regulating valve according to the table.

[0064] 3) Repeat the above steps in the next control cycle.

[0065] The fuel heating control flowchart within a single control cycle is as follows: Figure 2 As shown.

[0066] Compared with the original fuel heating control system, the new control method has a simple and easy-to-understand algorithm, is easy to operate, can achieve automatic control, and has high control accuracy. When the fuel flow is stable, the outlet temperature control accuracy is within ±1.5℃, and when the fuel flow changes, the outlet temperature control accuracy is within ±5℃, and the stabilization time is no more than 60 seconds.

[0067] 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 temperature control method for an aircraft engine fuel heating device, characterized in that, The device includes: a hot oil passage, a cold oil passage, and a mixing passage; in, The hot oil passage, from inlet to outlet, includes: a centrifugal oil pump assembly (1), a volumetric flow meter (3), a pressure sensor (4), a temperature sensor (5), a heater (6), a pressure sensor (4), and a temperature sensor (5); a return oil branch is connected in parallel after the temperature sensor (5) at the outlet of the heater (6) and before the volumetric flow meter (3). The return oil branch includes a centrifugal oil pump assembly (1), a volumetric flow meter (3), and a check valve (2) that allows the hot oil at the outlet of the heater (6) to flow back to the inlet of the heater (6); a pressure sensor (4) and a temperature sensor (5) are also installed after the return oil branch. The cold oil passage has a centrifugal oil pump group (1), a pressure sensor (4), and a temperature sensor (5) sequentially from the inlet to the outlet. The hot oil passage and the cold oil passage are mixed by an electric three-way regulating valve (7) and enter the mixing passage. The outlet of the mixing passage is connected to the test piece. The mixing passage is connected to a volume flow meter (3), a pressure sensor (4) and a temperature sensor (5). The method includes: Collect measured mixing temperature Set the required temperature at the outlet of the mixing channel for the test. ; Based on the engine inlet change rate, the system is divided into steady-state control and dynamic control. When the system is in the steady-state control process: when If this occurs, the three-way regulating valve will not be adjusted during this control cycle; when When that time, calculate to make the set temperature Equal to the measured mixing temperature Theoretical hot oil flow rate at that time And through theoretical hot oil flow rate Compared with the measured hot oil flow rate difference Adjust the opening of the three-way regulating valve; When the system is in a dynamic control process, the set temperature is calculated. Equal to the measured mixing temperature Theoretical hot oil flow rate at that time And through theoretical hot oil flow rate Compared with the measured hot oil flow rate difference Adjust the opening of the three-way regulating valve.

2. The temperature control method for the aircraft engine fuel heating device as described in claim 1, characterized in that, a takes the value 0.

5.

3. The temperature control method for the aircraft engine fuel heating device as described in claim 1, characterized in that, Theoretical hot oil flow rate Theoretical cold oil flow rate The calculation method is as follows: Based on the energy conservation principles of the hot oil passage, cold oil passage, and mixing passage: ； In the formula, This is the specific heat capacity of the oil. The temperature of the hot oil is obtained through a temperature sensor. for Oil density at temperature The temperature of the cold oil is obtained through a temperature sensor. for Oil density at temperature for Theoretical cooling oil flow rate at temperature, for Oil density at temperature; According to the law of conservation of mass, the relationship between fuel flow rates before and after blending is as follows: ； Based on the known fuel flow rate required for the test, the mixture flow rate is... If the mixing temperature is to reach the set temperature The theoretical hot oil temperature is required. Theoretical hot oil flow rate With theoretical cooling oil temperature Theoretical cold oil flow rate They are respectively: 。 4. The temperature control method for the aircraft engine fuel heating device as described in claim 1, characterized in that, During steady-state control, the measured hot oil flow rate Take the average value of the volumetric flow meter (3) in the mixing path within a certain period before the control cycle; during dynamic control, measure the actual hot oil flow rate. Take the average value of the volumetric flow meter (3) in the mixing channel within the control period t, where the control period t is greater than the adjustment response period of the three-way regulating valve.

5. The temperature control method for the aircraft engine fuel heating device as described in claim 1, characterized in that, Method for judging steady-state control and dynamic control: The outlet flow of the fuel heating device system is mainly controlled by the opening of the engine inlet valve. When the rate of change of the engine inlet valve opening α ≥ 1° / s, the system is considered to be in a dynamic control process. If the rate of change of the engine inlet valve opening α < 1° / s, the system is considered to be in a steady-state control process.

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