Fuel control system, staged switching method, warming control method, and monitoring method

Abstract

This invention provides a fuel control system, a staged switching method, a heating control method, and a monitoring method, relating to the field of aero-engine combustor performance testing. The fuel control system includes a main fuel supply line for supplying fuel to the system. A first fuel supply branch is connected to the main fuel supply line, and at least a first regulating valve, a first fuel flow meter, and a first heater are installed on the branch. A first fuel supply branch is connected to the main fuel supply line, and its outlet is connected to the test specimen. At least a first switching valve and a second fuel flow meter are installed on the branch. The inlet of a first return fuel branch is connected between the main and branch fuel supply lines, and its outlet is connected to the main fuel supply line. At least a second regulating valve and a second switching valve are installed on the return fuel branch. The first fuel supply branch, the first fuel supply branch, and the first return fuel branch cooperate to provide a first fuel flow rate to the test specimen.

Description

Technical Field

[0001] This invention relates to the field of performance testing of aero-engine combustion chambers, and particularly to a fuel control system, a staged switching method, a heating control method, and a monitoring method. Background Technology

[0002] Civil aviation engines undergo a "takeoff-climb-idle-cruise" flight cycle throughout their flight. During this cycle, the combustion chamber, a core component, must repeatedly open and close the main combustion stage. After these multiple on / off cycles, fuel nozzles are prone to coking and carbon buildup, leading to decreased engine power, increased fuel consumption, engine vibration and unstable idling, starting difficulties, worsened emissions, and shortened engine life. These issues severely impact the engine's safety, economy, environmental friendliness, and reliability. Therefore, during the combustion chamber design verification phase, simulated main combustion stage on / off tests are necessary to verify the fuel nozzles' anti-coking capabilities.

[0003] Simulated main combustion stage switching tests typically require controlling the fuel temperature within the range of 70℃ to 140℃ and simulating the switching cycle of the main combustion stage by controlling the fuel supply flow rate in the fuel supply circuit in stages. Currently, simulated main combustion stage switching tests face the following technical challenges: First, the fuel system should have the function of graded switching to enable rapid adjustment and switching of fuel flow between "target value 1" and "target value 2". Existing process solutions mostly use manual adjustment of target flow or valve opening to achieve graded fuel switching, which results in long switching time, unstable adjustment of transition conditions, and easy misoperation leading to engine shutdown, affecting the safety and reliability of the test.

[0004] Secondly, the temperature of the heated fuel should remain stable during rapid flow rate changes. Heating fuel typically employs electric heaters or oil baths, which offer advantages such as rapid heating and stable temperature control for fuel with a constant flow rate. However, in conditions with frequent changes in fuel flow, the equipment's high heat storage capacity can lead to temperature fluctuations and unstable control, increasing waiting time and reducing experimental efficiency. Furthermore, for safety reasons, electric heaters and oil baths should be placed far from the test specimen. Since the heated fuel enters the test specimen through a supply line, heat loss along this line causes a deviation between the controlled temperature and the actual oil temperature, increasing the difficulty of adjustment. Summary of the Invention

[0005] The purpose of this invention is at least to provide a fuel control system, a staged switching method, a heating control method, and a monitoring method.

[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0007] One embodiment of the present invention provides a fuel control system for simulating a main combustion stage switching test, the fuel control system comprising: The fuel supply main is used to supply fuel to the fuel control system.

[0008] The first fuel supply branch is connected to the main fuel supply line. The first fuel supply branch is equipped with at least a first regulating valve, a first fuel flow meter and a first heater.

[0009] The first fuel supply branch is connected to the first fuel supply sub-branch. The outlet of the first fuel supply branch is connected to the test piece. At least one first switch valve and one second fuel flow meter are installed on the first fuel supply branch.

[0010] The first return oil branch line has its inlet connected between the first oil supply branch line and the first oil supply branch line, and its outlet connected to the main oil supply line. At least the first and second regulating valves and the first and second switching valves are installed on the first return oil branch line.

[0011] The second fuel supply branch is connected to the main fuel supply branch. The second fuel supply branch is equipped with at least a second regulating valve, a second fuel flow meter and a second heater.

[0012] The second fuel supply branch is connected to the second fuel supply sub-branch. The outlet of the second fuel supply branch is connected to the test piece. At least a second switch valve and a second fuel flow meter are installed on the second fuel supply branch.

[0013] The second return oil branch has its inlet connected between the second oil supply branch and the second oil supply line, and its outlet connected to the main oil supply line. At least a second regulating valve and a second switching valve are installed on the second return oil branch.

[0014] The first fuel supply branch, the first fuel supply line, and the first return line work together to provide the test specimen with a first fuel flow rate. The second fuel supply branch, the second fuel supply line, and the second return line work together to provide the test specimen with a second fuel flow rate.

[0015] In some embodiments, a first heating tape is also provided on the first oil supply branch for heating the first oil supply branch.

[0016] A second heating cable is also installed on the second oil supply branch to heat the second oil supply branch.

[0017] In some embodiments, the oil supply main includes an oil tank, an oil pump, and a protection circuit. The protection circuit is used to maintain the pressure at the outlet of the oil pump. The protection circuit is connected between the outlet of the oil pump and the inlet of the oil tank. The protection circuit is equipped with at least an overflow valve and a third switching valve.

[0018] In some embodiments, a first pressure gauge is installed at the outlet of the oil tank, and a second pressure gauge and a third pressure gauge are installed at the two inlets of the test piece, respectively. The first oil supply pressure difference detected by the first pressure gauge and the second pressure gauge, together with the oil supply flow rate of the first oil supply branch, are used to evaluate the health status of the test piece. The second oil supply pressure difference detected by the first pressure gauge and the third pressure gauge, together with the oil supply flow rate of the second oil supply branch, are used to evaluate the health status of the test piece.

[0019] One embodiment of the present invention provides a fuel flow rate staged switching method. The fuel control system includes a control module, which is used to execute the fuel flow rate staged switching method. The fuel flow rate staged switching method includes: Set the first regulating valve and the second regulating opening to make the fuel flow of the first fuel flow meter and the second fuel flow meter reach the maximum fuel consumption of the current test.

[0020] Adjust the opening of the first and second regulating valves to make the fuel flow of the first and second fuel flow meters reach the first and second target values ​​respectively, and then shut off the main combustion stage.

[0021] Increase or decrease the opening of the first and second regulating valves to make the fuel flow of the first and second fuel flow meters reach the third and fourth target values ​​respectively, and the main combustion stage opens.

[0022] One embodiment of the present invention provides a fuel heating control method. The fuel control system includes a control module for executing the fuel heating control method. The fuel heating control method includes: Set the first regulating valve and the second regulating opening to make the fuel flow of the first fuel flow meter and the second fuel flow meter reach the maximum fuel consumption of the current test.

[0023] Control the first and second switching valves to open, adjust the opening degree of the first and second regulating valves, and control the oil supply flow and oil supply pressure to reach the target value.

[0024] Based on the maximum fuel consumption and target fuel temperature of the test, the total heating power required for the test is determined, and the heating power of the first heater and the second heater is gradually increased to the total heating power using a preset power gradient.

[0025] In some embodiments, a first heating tape is further provided on the first return oil branch for heating the first return oil branch. A second heating tape is further provided on the second return oil branch for heating the second return oil branch. The fuel heating control method includes: When the fuel temperature of the first fuel supply branch and the second fuel supply branch is close to the target fuel temperature but less than the target fuel temperature, the first and second heating cables are controlled to open, and the temperatures of the first and second heating cables are set to be close to the target fuel temperature but greater than the target fuel temperature.

[0026] One embodiment of the present invention provides a combustion chamber nozzle health monitoring method. The aforementioned fuel control system includes a control module, which is used to execute the combustion chamber nozzle health monitoring method. The combustion chamber nozzle health monitoring method includes: Set monitoring parameters, including nozzle flow rate, which is related to the fuel supply pressure differential and fuel supply flow rate.

[0027] The health status of the nozzle is determined by setting a threshold, including a first limit value and a second limit value. The first limit value is greater than the initial flow rate measured when the combustion chamber nozzle leaves the factory, and the second limit value is less than the initial flow rate. The range between the first limit value and the second limit value is defined as the normal range, the range greater than the first limit value is defined as the abnormal range, and the range less than the second limit value is defined as the coking range.

[0028] Monitor the first oil supply differential pressure and the oil supply flow rate of the first oil supply branch, as well as the second oil supply differential pressure and the oil supply flow rate of the second oil supply branch, to determine the health status of the nozzle.

[0029] In some embodiments, the combustion chamber nozzle health monitoring method includes: The monitoring parameters include the amplitude of the pulsating pressure vibration inside the flame tube, setting the threshold for judging the health status of the nozzle, including a third limit value. If the third limit value is greater than the stable value of the pulsating pressure inside the flame tube, the amplitude of the pulsating pressure vibration inside the flame tube is monitored to determine the health status of the nozzle.

[0030] In some embodiments, the combustion chamber nozzle health monitoring method includes: The monitoring parameters include nozzle wall temperature, setting thresholds for determining nozzle health status, including a fourth limit value. If the fourth limit value is greater than the constant value of nozzle wall temperature, the nozzle wall temperature is monitored, and the health status of the nozzle is determined.

[0031] The beneficial effects that this invention can achieve are at least as follows: 1. A two-stage heating strategy is adopted to effectively compensate for pipeline heat loss, and the temperature control accuracy is improved to ±5K; 2. Enables rapid and stable flow switching without sudden pressure changes during the switching process, avoiding the risk of engine shutdown; 3. Enables online monitoring of nozzle health status, providing early warning of coking risks without disassembly. Attached Figure Description

[0032] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals. Wherein: Figure 1 This is a connection block diagram of a fuel control system according to some embodiments.

[0033] Figure 2 This is a schematic diagram illustrating the monitoring status of nozzle flow rate according to some embodiments.

[0034] Figure 3 This is a schematic diagram of the monitoring status of pulsating pressure inside the flame tube, as shown in some embodiments. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0036] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions.

[0037] It is understood that the technical terms that may be used in the description of this specification, such as “center,” “longitudinal,” “lateral,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the implementation method and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the invention.

[0038] It should be noted that the use of terms such as "first" and "second" to define features in this document is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, these terms have no special meaning and should not be construed as limiting the scope of protection of this invention. As shown in this specification and claims, the terms "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural, unless the context clearly indicates otherwise. Generally, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements.

[0039] In the description of this specification, it should also be noted that, unless otherwise expressly specified or limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium, or a connection within two components, etc. Those skilled in the art can understand the specific meaning of the above terms in this specification according to the specific circumstances.

[0040] This specification presents a fuel control system and corresponding methods for flow rate stage switching, fuel heating control, and combustion chamber nozzle health monitoring. These methods can simultaneously achieve three objectives: rapid and stable flow rate switching, precise control of heated fuel temperature, and online diagnosis of nozzle health status. This comprehensively improves the efficiency, safety, and data reliability of simulated main combustion stage switching tests.

[0041] The fuel control system provided in the embodiments of this specification for simulating the main combustion stage switch test adopts a dual-path independent fuel supply + return fuel regulation architecture, which can realize independent control of the two fuel supply parameters without interference, and is suitable for the test requirements of multi-path combustion chamber nozzles.

[0042] like Figure 1 As shown, the fuel control system includes a fuel supply main circuit, which serves as the fuel supply source for the fuel control system and provides the subsequent branch circuits with base fuel that meets the required pressure and flow rate.

[0043] In some embodiments, the fuel supply main includes a fuel tank 1, a fuel pump 2, and a protection circuit. The fuel tank 1 stores the fuel required for the entire test process. The fuel pump 2 pressurizes the atmospheric pressure fuel in the fuel tank to the required test pressure level, providing high-pressure fuel to the test specimen. The inlet of the protection circuit is connected to the outlet of the fuel pump, and the outlet of the protection circuit is connected to the inlet of the fuel tank. The protection circuit is used to maintain a stable pressure at the outlet of the fuel pump. In some embodiments, the fuel supply main includes a fuel source, which is connected to the fuel tank 1 via a regulating valve 9. The regulating valve 9 is used to control and regulate the fuel supply from the fuel source to the fuel tank 1.

[0044] Specifically, an overflow valve 26 and a third switching valve 18 are installed on the protection circuit. When the oil pump outlet pressure is higher than the preset limit value, the overflow valve 26 automatically releases pressure to protect the oil pump 2 and downstream pipeline equipment.

[0045] Downstream of the main oil supply line are two identical oil supply links, namely the first oil supply branch and the second oil supply branch.

[0046] The first fuel supply branch is connected to the outlet of the main fuel supply line. The first fuel supply branch is equipped with a first fuel flow meter 14, a first regulating valve 10 and a first heater 7. The first regulating valve 10 is used to regulate the fuel supply flow of the first fuel supply branch. The first fuel flow meter 14 is used to monitor the fuel supply flow of the first fuel supply branch in real time. The first heater 7 is used to centrally heat the fuel in the first fuel supply branch and raise the fuel temperature to close to the test target temperature.

[0047] The downstream of the first fuel supply branch is divided into two paths. One path is the first fuel supply branch, whose outlet is connected to the first fuel inlet of the test piece. At least a first switching valve 21 and a first and second fuel flow meter 16 are installed on the first fuel supply branch. The first switching valve 21 is used to control the on / off state of the branch, and the first and second fuel flow meter 16 is used to monitor the actual fuel flow rate entering the test piece in real time. The other path is the first return fuel branch, whose inlet is connected to the connection node between the first fuel supply branch and the first fuel supply branch. The outlet of the first return fuel branch flows back to the fuel tank 1 of the main fuel supply line. At least a first and second regulating valve 12 and a first and second switching valve 19 are installed on the first return fuel branch. The first and second regulating valve 12 is used to regulate the return fuel flow rate, thereby indirectly adjusting the fuel flow rate entering the first fuel supply branch. The first and second switching valve 19 is used to control the on / off state of the first return fuel branch.

[0048] The second fuel supply branch connects to the main fuel supply line. At least a second regulating valve 11, a second fuel flow meter 15, and a second heater 8 are installed on the second fuel supply branch. Downstream of the second fuel supply branch connects to the second fuel supply sub-branch and the second return fuel sub-branch. The outlet of the second fuel supply sub-branch connects to the second fuel inlet of the test piece. At least a second switching valve 22 and a second fuel flow meter 17 are installed on the second fuel supply sub-branch. The inlet of the second return fuel sub-branch connects to the second fuel supply branch. The outlet of the second return fuel sub-branch flows back to the fuel tank 1. At least a second regulating valve 13 and a second switching valve 20 are installed on the second return fuel sub-branch. The second switching valve 20 is used to control the on / off state of the second return fuel sub-branch.

[0049] By coordinating the first fuel supply branch, the first fuel supply line, and the first return line, a precisely adjustable first fuel flow rate can be independently provided to the test specimen; by coordinating the second fuel supply branch, the second fuel supply line, and the second return line, a precisely adjustable second fuel flow rate can be independently provided to the test specimen. The two adjustment processes do not interfere with each other, and can simulate different fuel supply parameters of the main combustion stage under different operating conditions.

[0050] In some embodiments, a first heating tape 27 is further provided on the first fuel supply branch, and a second heating tape 28 is further provided on the second fuel supply branch. These provide auxiliary heating to the fuel supply branches (including the first and second fuel supply branches) to compensate for heat loss during fuel transportation and maintain stable fuel temperature. For example, the first heating tape 27 and the second heating tape 28 are respectively attached to the outer walls of the first and second fuel supply branches to compensate for heat loss during fuel transportation.

[0051] In some embodiments, the fuel control system further includes multiple pressure detection elements. A first pressure gauge is installed at the fuel tank outlet, and a second and a third pressure gauge are respectively installed at the two inlets of the test piece. The pressure difference detected by the first and second pressure gauges is the fuel supply pressure differential of the first fuel supply branch. This pressure differential, in conjunction with the fuel supply flow rate of the first fuel supply branch, can be used to assess the health status of the corresponding fuel line of the test piece. The pressure difference detected by the first and third pressure gauges is the fuel supply pressure differential of the second fuel supply branch. This pressure differential, in conjunction with the fuel supply flow rate of the second fuel supply branch, can be used to assess the health status of another fuel line of the test piece, allowing for the acquisition of nozzle operating status data without disassembling the test piece. A fourth pressure gauge is installed at the fuel pump outlet to monitor the pressure at the fuel pump outlet.

[0052] In some embodiments, such as Figure 1 As shown, the fuel control system also includes multiple temperature detection elements. In some embodiments, the fuel control system further includes multiple filters, such as a first filter 3, a second filter 4, a third filter 5, and a fourth filter 6. These filters are respectively located downstream of the fuel tank 1, downstream of the fuel pump 2, downstream of the first fuel supply branch, and downstream of the second fuel supply branch. They have a filtration accuracy of 5 μm and are used to filter particulate matter in the fuel tank and impurities such as coking inside the fuel heater, protecting downstream equipment and the test nozzle from clogging.

[0053] In some embodiments, the fuel control system is further provided with multiple check valves. For example, the first check valve 23 is provided at the outlet of the fuel pump 2 to prevent backflow of fuel into the fuel line; the second check valve 24 and the third check valve 25 are respectively provided at the outlets of the two fuel supply branches to prevent fuel in the test piece from flowing back into the fuel line.

[0054] In some embodiments, the fuel cooler 29 is located at the common end of the first return oil branch and the second return oil branch. Specifically, the fuel cooler 29 is a water-cooled cooler used to cool the return oil, keeping the return oil temperature below 40°C to prevent the fuel tank temperature from rising.

[0055] The embodiments in this specification adopt a dual-path fuel supply architecture. If the test specimen has multiple fuel supply requirements, a corresponding number of fuel supply links can be connected in parallel. The parameter adjustment of a single branch has no effect on other branches. If there is a large flow rate and a wide range of fuel supply requirements, the fuel pump's fuel supply capacity can be increased accordingly, and multiple fuel flow meters with different ranges can be connected in parallel on the branch to meet the accurate measurement requirements of different flow ranges.

[0056] Based on the aforementioned fuel control system, this invention also provides a fuel flow rate staged switching method, executed by a control module included in the fuel control system, which enables rapid and smooth flow rate switching during the main combustion stage switching process. The fuel flow rate staged switching method specifically includes the following steps: Test parameters are preset as follows: When the main stage is closed, the flow rates of the first and second oil supply branches are the first and second target values, respectively, and this state is maintained for a first duration; when the main stage is open, the flow rates of the first and second oil supply branches are the third and fourth target values, respectively, and this state is maintained for a second duration.

[0057] Pre-adjustment stage: Control the opening of the first regulating valve 10 and the second regulating valve 11 to stabilize the detection values ​​of the first fuel flow meter 14 and the second fuel flow meter 15 at the maximum fuel consumption of this test, keep the total flow of the two fuel supply links constant, and provide a stable fuel base for subsequent flow switching.

[0058] Simulate the main combustion stage shutdown condition: Adjust the opening of the first and second regulating valves 12 and 13 to adjust the return oil flow rate so that the detection values ​​of the first and second fuel flow meters 16 and 17 reach the first target value and the second target value respectively. This condition corresponds to the fuel supply flow rate of the engine main combustion stage shutdown state, and maintain this state for a preset first duration.

[0059] Simulate the main combustion stage opening condition: Continue to increase or decrease the opening of the first and second regulating valves 12 and 13, and change the fuel supply flow of the fuel supply branch only by adjusting the return oil flow, so that the detection values ​​of the first and second fuel flow meters 16 and 17 reach the third and fourth target values ​​respectively. This condition corresponds to the fuel supply flow of the engine main combustion stage in the open state, and maintain this state for the preset second duration.

[0060] In some embodiments, the actuation rates of the first and second regulating valves 12 and 13 are controlled according to the flow rate variation range during the main combustion stage switching process, ensuring that the switching response speed meets the test requirements while avoiding pressure fluctuations caused by sudden flow changes. In some embodiments, the valve opening degree, state holding time, and number of cycles corresponding to the target flow rate are preset, and the control module automatically performs simulations of multiple switching cycles without manual intervention.

[0061] During the flow switching process in the embodiments of this specification, the total flow of the fuel supply main is always maintained at the maximum fuel consumption of the test. The flow of the fuel supply branch is supplied only through the regulating valve on the return branch, and there is no pressure change, which meets the requirements of the simulated main combustion stage switch test.

[0062] Based on the aforementioned fuel control system, this invention also provides a fuel heating control method, executed by the control module of the fuel control system, which can achieve precise temperature control of the heated fuel, reduce heat loss during transportation, and ensure stable fuel temperature at the test specimen inlet. The fuel heating control method specifically includes the following steps: Preparation before the test: Check that the fuel quantity in fuel tank 1 meets the test requirements. After passing through the first filter 3 and fuel pump 2, the fuel flows back to fuel tank 1 through the protection circuit, and enters the fuel supply link through another route. By adjusting the speed of fuel pump 2 or adjusting the opening of overflow valve 26, the fuel pressure after pumping can be increased or decreased. Next, open the first and second switch valves 19 and 20, the first and second regulating valves 12 and 13 (initial opening set to 100%), the first regulating valve 10 and 11 of the return fuel branch, so that the high-pressure fuel after pumping flows through the first fuel flow meter 14 and 15, the first regulating valve 10 and 11, the first heater 7 and 8, and then flows through the first and second switch valves 19 and 20, the first and second regulating valves 12 and 13 of the return fuel branch and the fuel cooler 29 before entering fuel tank 1, establishing a stable circulation fuel circuit.

[0063] Flow pre-adjustment: Adjust the opening of the first regulating valve 10 and the second regulating valve 11 to stabilize the detection values ​​of the first fuel flow meter 14 and the second fuel flow meter 15 at the maximum fuel consumption of the current test; open the first switching valve 21 and the second switching valve 22 of the fuel supply branch, and slowly reduce the opening of the first regulating valve 12 and the second regulating valve 13 to stabilize the fuel supply flow and fuel supply pressure of the fuel supply branch at the target values ​​of the main combustion stage in the closed state.

[0064] Heater heating: Based on the maximum fuel consumption and target fuel temperature for the current test, calculate the total heating power required for the test, and gradually increase the heating power of the first heater 7 and the second heater 8 in a preset power gradient (e.g., 10% of the total power). After each power increase, wait for the fuel temperature to stabilize (e.g., temperature rise less than 1K / min) before making the next power adjustment to avoid an abnormal increase in fuel pressure due to an excessively large power gradient.

[0065] In some embodiments, when the fuel temperature of the first fuel supply branch and the second fuel supply branch is close to but lower than the target fuel temperature (e.g., below the target temperature range of 0K to 10K), the first heating cable 27 and the second heating cable 28 are activated, and the temperature of the heating cables is set to be close to but higher than the target fuel temperature (e.g., above the target temperature range of 0K to 5K) to compensate for heat loss of fuel during pipeline transportation. If the fuel supply temperature still does not reach the target value, the set temperature of the heating cables can be gradually increased according to a certain temperature gradient (e.g., 5K) until the fuel supply temperature meets the test requirements.

[0066] After the test, first shut off the first heating cable 27 and the second heating cable 28, then gradually reduce the power of the first heater 7 and the second heater 8 to 0 according to the preset power gradient. After the fuel temperature in the heater drops below 40°C, then shut off the first switch valve 21 and the second switch valve 22, the first regulating valve 10 and the second regulating valve 11 in sequence, and finally stop the oil pump 2 to prevent high-temperature fuel from stagnating and coking in the pipeline.

[0067] The first heater 7 and the second heater 8 described in this specification always heat the system to the maximum test flow rate. The heater power remains stable during flow rate switching, avoiding temperature fluctuations under variable flow conditions. Furthermore, the two-stage heating strategy of centralized heater heating and heat tracing cable supplementation effectively compensates for heat loss along the pipeline extension, providing accurate control of the fuel temperature supplied to the test specimen. The stepped power adjustment method avoids sudden changes in temperature and pressure, effectively protecting the heaters and pipeline equipment and extending the system's service life.

[0068] Existing technologies lack characteristic parameters and evaluation criteria for online diagnosis of combustion chamber nozzle health status during testing. It is necessary to disassemble the test specimen after the test for non-destructive testing such as borehole probing and CT to obtain information on coking conditions. This makes it impossible to assess nozzle health status in real time or monitor and predict the degree of performance degradation online. Therefore, this specification provides a combustion chamber nozzle health monitoring method based on the aforementioned fuel control system with pressure detection elements. This method is executed by the control module of the fuel control system and can achieve online diagnosis during testing, promptly detecting early nozzle abnormalities. The combustion chamber nozzle health monitoring method specifically includes the following steps: Threshold preset: Monitoring parameters are preset, with the core parameter being the nozzle flow rate. The formula for calculating the nozzle flow rate is FN = m / √(ΔP), where m is the real-time fuel supply flow rate of the fuel supply branch, and ΔP is the fuel supply pressure difference of the corresponding fuel supply link. The nozzle flow rate parameter directly reflects changes in the nozzle's flow characteristics. The combustion chamber nozzle is initially measured at the factory. If the nozzle flow rate FN decreases, typically a decrease of more than 15%, it can be diagnosed as coking and blockage inside the fuel nozzle. If the nozzle flow rate FN increases, typically an increase of more than 10%, it can be diagnosed as an abnormality in the fuel nozzle.

[0069] like Figure 2 As shown, the first limit value 212 is set to 110% of the initial flow rate 211, and the second limit value 213 is set to 85% of the initial flow rate 211; the interval between the first limit value 212 and the second limit value 213 is defined as the normal interval, the interval greater than the first limit value 212 is the abnormal interval, and the interval less than the second limit value 213 is the coking interval.

[0070] Status determination: During the test, the oil supply flow rate of the first oil supply differential pressure and the first oil supply branch, and the oil supply flow rate of the second oil supply differential pressure and the second oil supply branch are monitored in real time. The nozzle flow rate of the corresponding oil circuit is calculated in real time, and the health status of the nozzle is judged according to the range of the flow rate. At the same time, the trend of the flow rate can be tracked. If the flow rate continues to approach the first limit value or the second limit value and there is no return trend, an early warning of early abnormality can be given.

[0071] In some embodiments, the amplitude of pulsating pressure vibration within the flame tube is included in the monitoring parameters, such as... Figure 3 As shown, a third limit value 31 is preset, which is greater than the stable amplitude of the pulsating pressure inside the flame tube. During the test, the vibration amplitude of the pulsating pressure inside the flame tube is monitored in real time. If the vibration amplitude continues to exceed the third limit value 31 (for example, for more than 10 seconds), the nozzle is determined to be in an abnormal health condition.

[0072] In some embodiments, nozzle wall temperature is included in the monitoring parameters, and a fourth limit value is preset, which is greater than the constant wall temperature under normal nozzle operation. During the test, the nozzle wall temperature is monitored in real time. If the wall temperature continues to rise without any downward trend, it is determined that the nozzle has a risk of coking.

[0073] The embodiments in this specification can obtain the health status of the nozzle online without disassembling the test specimen, and can monitor the performance degradation process of the nozzle in real time. If severe coking occurs during the test, the test can be terminated in time to avoid damage to the test specimen. The multi-dimensional evaluation system with multiple monitoring parameters can effectively distinguish different fault types such as coking and structural damage. It can realize early abnormality warning and provide data support for nozzle life prediction and structural optimization.

[0074] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

Claims

1. A fuel control system for simulating main combustion stage switching tests, characterized in that, The fuel control system includes: The fuel supply main is used to supply the fuel required by the fuel control system. The first fuel supply branch is connected to the main fuel supply line. At least a first regulating valve, a first fuel flow meter and a first heater are provided on the first fuel supply branch. The first fuel supply branch is connected to the first fuel supply sub-branch, and the outlet of the first fuel supply branch is connected to the test piece. At least a first switch valve and a first and second fuel flow meter are installed on the first fuel supply branch. The first return oil branch has its inlet connected between the first oil supply branch and the first oil supply branch, and its outlet connected to the main oil supply line. At least one first and two regulating valves and one first and two switching valves are provided on the first return oil branch. The second fuel supply branch is connected to the main fuel supply line. The second fuel supply branch is equipped with at least a second regulating valve, a second fuel flow meter and a second heater. The second fuel supply branch is connected to the second fuel supply sub-branch. The outlet of the second fuel supply branch is connected to the test piece. At least a second switch valve and a second fuel flow meter are installed on the second fuel supply branch. The second return oil branch has its inlet connected between the second oil supply branch and the second oil supply branch, and its outlet connected to the main oil supply line. At least a second regulating valve and a second switching valve are provided on the second return oil branch. The first fuel supply branch, the first fuel supply line, and the first return line cooperate to provide a first fuel flow to the test specimen; the second fuel supply branch, the second fuel supply line, and the second return line cooperate to provide a second fuel flow to the test specimen. A first heating cable is also provided on the first oil supply branch for heating the first oil supply branch; A second heating cable is also installed on the second oil supply branch for heating the second oil supply branch.

2. The fuel control system for simulating main combustion stage switching tests according to claim 1, characterized in that, The oil supply main circuit includes an oil tank, an oil pump, and a protection circuit. The protection circuit is used to maintain the pressure at the outlet of the oil pump. The protection circuit is connected between the oil pump outlet and the oil tank inlet. The protection circuit is equipped with at least an overflow valve and a third switching valve.

3. The fuel control system for simulating main combustion stage switching tests according to claim 2, characterized in that, A first pressure gauge is installed at the outlet of the oil tank, and a second pressure gauge and a third pressure gauge are installed at the two inlets of the test piece, respectively. The first oil supply pressure difference detected by the first pressure gauge and the second pressure gauge, together with the oil supply flow rate of the first oil supply branch, are used to evaluate the health status of the test piece. The second oil supply pressure difference detected by the first pressure gauge and the third pressure gauge, together with the oil supply flow rate of the second oil supply branch, are used to evaluate the health status of the test piece.

4. A method for graded switching of fuel flow, characterized in that, The fuel control system according to any one of claims 1 to 3 includes a control module, the control module being used to execute a fuel flow rate staged switching method; the fuel flow rate staged switching method includes: Set the first regulating valve and the second regulating opening to make the fuel flow of the first fuel flow meter and the second fuel flow meter reach the maximum fuel consumption of the current test. Adjust the opening degree of the first and second regulating valves and the second regulating valve so that the fuel flow of the first and second fuel flow meters and the second fuel flow meter reaches the first target value and the second target value respectively, and the main combustion stage is shut off; Increase or decrease the opening of the first and second regulating valves and the second regulating valve, so that the fuel flow of the first and second fuel flow meters and the second fuel flow meter reach the third target value and the fourth target value respectively, and the main combustion stage opens.

5. A fuel heating control method, characterized in that, The fuel control system according to any one of claims 1 to 3 includes a control module, the control module being used to execute a fuel heating control method; the fuel heating control method includes: Set the first regulating valve and the second regulating opening to make the fuel flow of the first fuel flow meter and the second fuel flow meter reach the maximum fuel consumption of the current test. Control the first and second switching valves to open, adjust the opening degree of the first and second regulating valves, and control the oil supply flow and oil supply pressure to reach the target value; Based on the maximum fuel consumption and target fuel temperature of the current test, the total heating power required for the test is determined, and the heating power of the first heater and the second heater is gradually increased to the total heating power using a preset power gradient.

6. The fuel heating control method according to claim 5, characterized in that, The fuel heating control method includes: When the fuel temperature of the first fuel supply branch and the second fuel supply branch is close to the target fuel temperature but less than the target fuel temperature, the first heating tape and the second heating tape are turned on, and the temperature of the first heating tape and the second heating tape is set to be close to the target fuel temperature but greater than the target fuel temperature.

7. A method for monitoring the health of combustion chamber nozzles, characterized in that, The fuel control system of claim 3 includes a control module, the control module being used to execute a combustion chamber nozzle health monitoring method; the combustion chamber nozzle health monitoring method includes: Set monitoring parameters, including nozzle flow rate, which is related to the oil supply pressure differential and the oil supply flow rate; The health status of the nozzle is determined by setting a threshold, including a first limit value and a second limit value. The first limit value is greater than the initial flow rate measured when the combustion chamber nozzle leaves the factory, and the second limit value is less than the initial flow rate. The range between the first limit value and the second limit value is defined as the normal range, the range greater than the first limit value is defined as the abnormal range, and the range less than the second limit value is defined as the coking range. The health status of the nozzle is determined by monitoring the first oil supply pressure difference and the oil supply flow of the first oil supply branch, as well as the second oil supply pressure difference and the oil supply flow of the second oil supply branch.

8. The combustion chamber nozzle health monitoring method according to claim 7, characterized in that, The combustion chamber nozzle health monitoring method includes: The monitoring parameters include the amplitude of the pulsating pressure vibration inside the flame tube, and a threshold for determining the health status of the nozzle, including a third limit value. The third limit value is greater than the stable value of the pulsating pressure inside the flame tube. The amplitude of the pulsating pressure vibration inside the flame tube is monitored to determine the health status of the nozzle.

9. The combustion chamber nozzle health monitoring method according to claim 7, characterized in that, The combustion chamber nozzle health monitoring method includes: The monitoring parameters include nozzle wall temperature, and a threshold for determining the health status of the nozzle is set, including a fourth limit value. The fourth limit value is greater than the constant value of the nozzle wall temperature. The nozzle wall temperature is monitored to determine the health status of the nozzle.

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