An ECT flame monitoring sensor for fitting to an aeroengine combustion chamber

Abstract

The application discloses an ECT flame monitoring sensor attached to an aero-engine combustion chamber, which comprises an outer shielding layer, an outer electrode, an outer shielding electrode, an inner shielding layer, an inner electrode and an inner shielding electrode; the outer shielding layer is arranged on the outer side of the outer wall of the aero-engine combustion chamber and extends along the circumferential direction of the outer wall of the aero-engine combustion chamber to form a ring shape, a plurality of outer electrodes and outer shielding electrodes are arranged inside the outer shielding layer, a plurality of the outer electrodes are arranged along the circumferential direction of the outer shielding layer, and the outer shielding electrode is arranged between any two adjacent outer electrodes; the inner shielding layer is arranged on the inner side of the inner wall of the central transmission shaft chamber and extends along the inner circumferential direction of the inner wall of the central transmission shaft chamber to form a ring shape, a plurality of inner electrodes and inner shielding electrodes are arranged inside the inner shielding layer, a plurality of the inner electrodes are arranged along the circumferential direction of the inner shielding layer, and the inner shielding electrode is arranged between any two adjacent inner electrodes. The application is beneficial to improving the sensitivity of the sensitive field of the central area measurement and improving the measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of aero-engine combustion chamber monitoring, and in particular to an ECT flame monitoring sensor that fits into the combustion chamber of an aero-engine. Background Technology

[0002] With the increasing demand for aviation transportation technology, high thrust-to-weight ratio aero engines are gradually playing a crucial role. As a vital component of aero engines, the quality of the combustion chamber's outlet temperature distribution, especially the hot spot temperature, directly impacts turbine performance and the lifespan of hot-end components. Poor quality of the combustion chamber outlet temperature field can even lead to turbine blade burn-out and damage. Furthermore, under low-emission requirements, considering comprehensive indicators such as combustion efficiency, stability, and cleanliness, aero engines are typically designed to operate in a lean-burn state. During engine operation, the airflow velocity is extremely high, and the fuel residence time in the combustion chamber is on the order of milliseconds. This can easily lead to unstable flame combustion, causing fatigue damage to the equipment, reducing the reliability and lifespan of the burner, and in severe cases, even causing engine shutdown and in-flight accidents. Therefore, researching aero-engine combustion measurement technology to monitor the flame combustion state in real time is of great significance for suppressing unstable combustion, preventing engine shutdown, and controlling and protecting the engine's heat-sensitive components.

[0003] In existing technologies, the methods involved in conventional flame monitoring of aero-engine combustion chambers mainly include the following:

[0004] (1) Thermocouple technology

[0005] A thermocouple is formed by welding two different metal materials together. The two metals are welded together to form a circuit, forming a measuring end and a reference end. The measuring end is placed in the temperature measuring area, ensuring that it is exposed to the high-temperature gas flow. When the heat energy of the high-temperature gas is transferred to the measuring end of the thermocouple, based on the principle of thermoelectric effect, the temperature difference between the conductors of different materials will generate an electromotive force. The measured electromotive force signal is transmitted to the temperature conversion instrument or control system through the thermocouple wires. According to the known thermocouple characteristic curve, the system can calculate the corresponding temperature value. Thermocouple measurement requires the installation of multiple sensor probes to reflect changes in temperature and pressure in the flow field. When these sensors are placed in the flow field, they will cause disturbances to the flow field, resulting in measurement errors. Furthermore, as the power-to-weight ratio of the engine increases, the temperature of the combustion chamber outlet gas becomes higher and higher. The average temperature of the outlet gas of an engine with a power-to-weight ratio of 10 has reached 1850K, and the temperature of the combustion chamber outlet of an engine with a power-to-weight ratio of 15 or higher is even higher (above 2000K), which exceeds the measurement limit of conventional thermocouples. Therefore, it is no longer possible to directly use thermocouples to measure the combustion chamber outlet temperature. In addition, thermocouple technology is difficult to visualize.

[0006] (2) Gas Analysis Method

[0007] The combustion gas analysis method involves collecting high-temperature combustion gas at the combustion chamber outlet, analyzing the content ratio of various components in the combustion gas, and using the first law of thermodynamics to analyze the combustion reaction of the fuel. Usually, under adiabatic conditions, the composition of the combustion gas in the combustion chamber can directly reflect the temperature of the combustion gas. By combining parameters such as the calorific value of aviation fuel and the inlet temperature of the combustion chamber, the composition of the combustion gas can be measured, and then the temperature of the combustion chamber outlet combustion gas can be calculated.

[0008] Because gas analysis requires the extraction of sample gas for testing, including sample gas delivery, replacement, and instrument response, the response time is generally around 20-30 seconds, resulting in poor real-time performance. This makes it practically unusable during high-speed flight of aircraft. Furthermore, the visualization of combustion states through gas composition analysis of combustion conditions and temperature distribution is also quite challenging.

[0009] (3) Radiation detection

[0010] Since the direct reaction of fuel combustion is to emit light and heat, and the hysteresis of light is minimal, detecting the state of light within the combustion chamber can quickly reflect the combustion status. By detecting the light emitted during fuel combustion within the combustion chamber, it is possible to detect ignition / extinguishing and flame stability in the engine combustion chamber. However, since radiation optics detection requires a relatively stable optical path, and for aero-engine combustion chambers, flame combustion takes place in the flame tube, which is a confined space, forming the optical path is quite difficult, and related technological development still requires further research.

[0011] Because the aforementioned methods all have certain limitations, some have begun to use ECT (Extreme Capacitance Tomography) technology. ECT is a non-invasive measurement method commonly used in industrial two-phase or multiphase flow detection. In recent years, ECT imaging technology has developed rapidly, and its application scope has gradually expanded. One new application of ECT technology is flame visualization monitoring. Using ECT to detect flames not only ensures that the physical properties and thermal radiation flow field of the flame are not disturbed, but also enables real-time visual monitoring of the flame, obtaining more comprehensive combustion information. With the rapid development of computer technology and the increasing demands for detection technology, image-based flame detection methods have a very promising future.

[0012] The earliest application of ECT (Electronic Capacitance Tomography) for flame detection was by Roger C. Waterfall et al. at the University of Manchester, who used ECT to determine the flame's position and shape, as well as the equivalent dielectric constant of the flame with respect to air. In China, Liu Shi et al. used ECT to accurately display the flame's position and shape within a porous media burner and derived and verified the complex equivalent dielectric constant model of the flame, further demonstrating the feasibility of using ECT for flame detection. Cao Zhang et al. at Beijing University of Aeronautics and Astronautics designed a ring-shaped ECT sensor using a bluff body support as the internal electrode and employed an improved Calderon method to monitor the backfire flame state in a bluff body burner, providing a new method for exploring unstable combustion factors and visually monitoring flames.

[0013] Currently, research on visual monitoring of flame combustion status mainly focuses on combustion within the furnace of industrial boilers. Research applying capacitance tomography (ECT) technology to flame monitoring in the combustion chambers of civil aircraft engines is extremely rare. Furthermore, aircraft engine combustion chambers can be broadly categorized into three types: single-tube combustion chambers, annular combustion chambers, and full-annular combustion chambers. After a considerable period of development, the full-annular combustion chamber has gradually gained dominance due to its compact structure, reduced weight, high space utilization, and ability to achieve a more uniform outlet temperature. Currently, most civil aircraft engines utilize full-annular combustion chambers. This type of annular engine combustion chamber differs from ordinary chambers in that its walls are made of metal. This internal metal structure significantly affects the sensor's sensing field distribution, greatly reducing measurement accuracy. Therefore, this type of annular engine combustion chamber is no longer suitable for measurement using traditional ECT circular sensors, necessitating improvements to the traditional ECT circular sensor. Summary of the Invention

[0014] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, the first objective of this invention is to provide an ECT flame monitoring sensor that fits snugly within the combustion chamber of an aero-engine. The technical solution of this invention is as follows:

[0015] An ECT flame monitoring sensor for fitting into the combustion chamber of an aero-engine, wherein the combustion chamber is a full-ring combustion chamber, including an annular outer wall and an inner wall, the inner wall of which encloses a central drive shaft chamber for accommodating a drive shaft, and the ECT flame monitoring sensor is located at the outlet of the aero-engine combustion chamber, characterized in that the ECT flame monitoring sensor includes an outer shielding layer, an outer electrode, an outer shielding electrode, an inner shielding layer, an inner electrode, and an inner shielding electrode;

[0016] The outer shielding layer is located on the outer side of the outer wall of the aero-engine combustion chamber and extends in a ring along the outer circumferential direction of the aero-engine combustion chamber wall. The outer shielding layer is provided with multiple outer electrodes and an outer shielding electrode. The multiple outer electrodes are arranged along the circumferential direction of the outer shielding layer, and the outer shielding electrode is provided between any two adjacent outer electrodes.

[0017] The inner shielding layer is located on the inner side of the inner wall of the central drive shaft chamber and extends in a ring along the inner circumferential direction of the inner wall of the central drive shaft chamber. The inner shielding layer is provided with multiple inner electrodes and inner shielding electrodes. The multiple inner electrodes are arranged along the circumferential direction of the inner shielding layer, and the inner shielding electrode is provided between any two adjacent inner electrodes.

[0018] Furthermore, the plurality of external electrodes are arranged at uniform intervals along the circumference of the external shielding layer.

[0019] Furthermore, the plurality of inner electrodes are arranged at uniform intervals along the circumference of the inner shielding layer.

[0020] Furthermore, there are a total of 12 external electrodes and a total of 4 internal electrodes.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Compared with the traditional ECT circular sensor, this solution has improved the structure of the ECT circular sensor, designing it as a ring-shaped ECT sensor with multiple internal and external electrodes. The structural design of the ring-shaped ECT sensor not only has a very high degree of fit with the geometry of the full-ring combustion chamber, but the internal and external electrode design also helps to improve the sensitivity of the measurement sensitive field in the central region and improve the measurement accuracy, opening up new ideas for flame monitoring in aero-engine combustion chambers.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0025] Figure 1 This is a cross-sectional schematic diagram of an annular combustion chamber in an aero-engine in the prior art;

[0026] Figure 2 This is a schematic diagram of the present invention located at the outlet of the combustion chamber of an aircraft engine;

[0027] Figure 3 This is a reference diagram showing the usage state of the present invention.

[0028] Figure label:

[0029] 1. Outer wall of the combustion chamber; 2. Inner wall of the combustion chamber; 3. Outer wall of the flame tube; 4. Inner wall of the flame tube; 5. Nozzle; 6. Outer shielding layer; 7. Outer electrode; 8. Outer shielding electrode; 9. Inner shielding layer; 10. Inner electrode; 11. Inner shielding electrode; 12. Inner wall of the central drive shaft. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "vertical," "circumferential," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, 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, and therefore should not be construed as a limitation of the present invention.

[0032] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] like Figure 1The diagram shows a cross-sectional view of a conventional annular combustion chamber for an aero-engine. This combustion chamber is fully annular, with an annular outer combustion chamber wall 1 and an inner combustion chamber wall 2. The inner combustion chamber wall 2 encloses and defines a central drive shaft chamber 12 for housing the drive shaft. A flame tube is provided between the outer and inner walls of the combustion chamber, and a plurality of nozzles 5 are arranged at intervals along the circumference of the combustion chamber between the outer wall 3 and the inner wall 4 of the flame tube.

[0034] Depend on Figure 1 It is known that this annular engine combustion chamber differs from ordinary chambers in that its chamber walls are made of metal. This internal metal structure will seriously affect the sensor's sensing field distribution, greatly reducing the measurement accuracy. As a result, this annular engine combustion chamber is no longer suitable for measurement using traditional ECT circular sensors.

[0035] Therefore, considering the unique structure of the annular combustion chamber, the inventors improved the traditional ECT circular sensor. For example... Figure 2 As shown, the ECT flame monitoring sensor includes an outer shielding layer 6, an outer electrode 7, an outer shielding electrode 8, an inner shielding layer 9, an inner electrode 10, and an inner shielding electrode 11.

[0036] The outer shielding layer 6 is located on the outer side of the outer wall 1 of the aero-engine combustion chamber and extends in a ring along the outer periphery of the aero-engine combustion chamber wall. The outer shielding layer 6 is provided with multiple outer electrodes 7 and outer shielding electrodes 8. The multiple outer electrodes 7 are evenly spaced along the circumference of the outer shielding layer 6, and an outer shielding electrode 8 is provided between any two adjacent outer electrodes 7.

[0037] The inner shielding layer 9 is located on the inner side of the inner wall 12 of the central drive shaft chamber of the aero-engine and extends in a ring along the inner circumferential direction of the inner wall 12 of the central drive shaft chamber of the aero-engine. The inner shielding layer 9 is provided with a plurality of inner electrodes 10 and inner shielding electrodes 11. The plurality of inner electrodes 10 are evenly spaced along the circumference of the inner shielding layer 9, and an inner shielding electrode 11 is provided between any two adjacent inner electrodes 10.

[0038] There are 12 external electrodes 7 and 4 internal electrodes 10.

[0039] like Figure 3 As shown, the ECT flame monitoring sensor in this scheme needs to be installed at the outlet of the combustion chamber of the aircraft engine during use. This way, the flame in the combustion chamber can flow through the inner and outer electrodes 7 of the ECT flame monitoring sensor after it is ejected from the outlet, causing a change in the capacitance value between the inner and outer electrodes 7, which can then be detected by the ECT flame monitoring sensor, and then relevant data processing can be performed.

[0040] Compared with the traditional ECT circular sensor, this solution has improved the structure of the ECT circular sensor, designing it as a ring-shaped ECT sensor with multiple internal and external electrodes. The structural design of the ring-shaped ECT sensor not only has a very high degree of fit with the geometry of the full-ring combustion chamber, but the internal and external electrode design also helps to improve the sensitivity of the measurement sensitive field in the central region and improve the measurement accuracy, opening up new ideas for flame monitoring in aero-engine combustion chambers.

[0041] This invention enables the visualization and monitoring of the flame state in the combustion chamber of an aero-engine and the establishment of the temperature field, which helps to solve problems such as fatigue damage and reduced reliability and lifespan caused by unstable combustion or deterioration of the outlet temperature field in the engine combustion chamber.

[0042] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An ECT flame monitoring sensor fitted to an aero-engine combustion chamber, wherein the aero-engine combustion chamber is a full-annular combustion chamber, comprising an annular outer combustion chamber wall and an inner combustion chamber wall, the inner combustion chamber wall enclosing a central drive shaft chamber for accommodating a drive shaft, and the ECT flame monitoring sensor is located at the outlet of the aero-engine combustion chamber, characterized in that, The ECT flame monitoring sensor includes an outer shielding layer, an outer electrode, an outer shielding electrode, an inner shielding layer, an inner electrode, and an inner shielding electrode. The outer shielding layer is located on the outer side of the outer wall of the aircraft engine combustion chamber and extends in a ring along the outer circumferential direction of the outer wall of the aircraft engine combustion chamber. The outer shielding layer is provided with multiple outer electrodes and an outer shielding electrode. The multiple outer electrodes are arranged along the circumferential direction of the outer shielding layer, and the outer shielding electrode is provided between any two adjacent outer electrodes. The inner shielding layer is located on the inner side of the inner wall of the central drive shaft chamber and extends in a ring along the inner circumferential direction of the inner wall of the central drive shaft chamber. The inner shielding layer is provided with multiple inner electrodes and inner shielding electrodes. The multiple inner electrodes are arranged along the circumferential direction of the inner shielding layer, and the inner shielding electrode is provided between any two adjacent inner electrodes.

2. The ECT flame monitoring sensor conforming to the combustion chamber of an aero-engine according to claim 1, characterized in that, The multiple external electrodes are arranged at uniform intervals along the circumference of the outer shielding layer.

3. The ECT flame monitoring sensor conforming to the combustion chamber of an aero-engine according to claim 1, characterized in that, The multiple inner electrodes are arranged at uniform intervals along the circumference of the inner shielding layer.

4. The ECT flame monitoring sensor conforming to the combustion chamber of an aero-engine according to claim 1, characterized in that, There are 12 external electrodes and 4 internal electrodes.

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