High-temperature high-pressure combustion chamber spectral characteristic transmission device based on special optical fiber probe

Abstract

The application discloses a high-temperature and high-pressure combustion chamber spectrum characteristic transmission device based on a special optical fiber probe head, which comprises an optical fiber probe head, a light guide optical fiber, a light emitting characteristic analysis device and a cooling liquid pump; the optical fiber probe head comprises high-transmittance optical glass, a metal cooling sleeve and an optical flange; the high-transmittance optical glass can transmit ultraviolet-visible light with a wavelength of 100-760 nm; the metal cooling sleeve comprises a cylindrical sleeve and a connecting cap; the cylindrical sleeve is coaxially arranged on the outer periphery of the high-transmittance optical glass and is sealingly arranged in a probe head mounting hole; the light guide optical fiber can collect the ultraviolet-visible light transmitted through the high-transmittance optical glass and is connected with the light emitting characteristic analysis device; and the cylindrical sleeve and the connecting cap are both provided with cooling channels connected with the cooling liquid pump. The application can analyze the chemical reaction light emitting characteristics in the high-temperature and high-pressure combustion chamber in real time, is especially suitable for monitoring the spontaneous radiation characteristics of OH*, CH* and C2* groups generated in the combustion process, and thus can determine the reaction region and the reaction heat release.

Description

Technical Field

[0001] This invention relates to a testing device, and more particularly to a high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe. Background Technology

[0002] The design and manufacture of high-temperature, high-pressure combustors have always been a recognized challenge. These combustors are characterized by high power density, small size, and extreme temperatures and pressures. Furthermore, most of these combustors (e.g., those in aero-engines, gas turbines, air heaters, rocket engines) are prone to unstable combustion, causing significant damage to the engine (e.g., performance degradation, vibration, ablation). Studying the combustion characteristics within the combustor is crucial for optimizing design and improving performance. However, limitations imposed by the pressure and temperature within the combustor make it difficult to perform large-area optical windowing, and even more difficult to observe the combustion characteristics. Currently, only pressure measurements are used to study the dynamic characteristics within the combustor, severely restricting the development of such combustors.

[0003] When studying the combustion characteristics of a combustion chamber, optical windowing is commonly used. While this method allows for the study of flame characteristics over a large area of ​​the combustion chamber, it is more suitable for combustion chambers with lower pressures and temperatures. When the pressure is too high, the optical windowing method has the following shortcomings, which require improvement:

[0004] 1. Optical window openings have low pressure resistance and may cause problems such as glass breakage or air leakage under high pressure and temperature.

[0005] 2. Optical windows cause significant damage to the combustion chamber structure. Under high pressure, they can easily compromise the overall strength of the combustion chamber, leading to stress concentration and even explosions. In other words, they pose a great challenge to the structural strength of high-pressure combustion chambers.

[0006] Currently, fiber optic probes are used to measure the luminescence characteristics of combustion chambers, but these primarily target atmospheric or low-pressure combustion chambers. However, the results obtained under these atmospheric and low-pressure conditions are subcritical conclusions. At higher pressures, reaching supercriticality, the physical properties change dramatically, showing significant differences from subcritical conditions. This makes it difficult to apply the conclusions drawn from low-pressure research to practical engineering applications.

[0007] During hydrocarbon fuel combustion, the primary light source originates from groups such as OH*, CH*, and C2*, whose spontaneous emission produces light at specific wavelengths (OH* 310nm, CH* 430nm, C2* 470-550nm), while other groups do not produce light at these wavelengths. Therefore, by extracting the spontaneous emission from the combustion chamber using a specialized fiber optic probe and combining it with a bandpass filter of a specific wavelength, the chemical reaction characteristics and heat release characteristics at specific locations within the combustion chamber can be analyzed. Furthermore, this enables the monitoring of chemical reactions in high-temperature, high-pressure (up to 20MPa, 3000K) combustion chambers, providing guidance for the design of high-temperature, high-pressure combustion chambers in engineering practice. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe. This high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe can analyze the chemical reaction luminescence characteristics in the combustion chamber (especially the high-temperature and high-pressure combustion chamber) in real time. It is particularly suitable for monitoring the spontaneous emission characteristics of groups such as OH*, CH*, and C2* generated during combustion, thereby determining the reaction area, reaction heat release, etc.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe includes an optical fiber probe, a light guide fiber, a luminescence characteristic analysis device, and a coolant pump.

[0011] A through-hole for mounting a probe is provided at the center of the wall of one of the combustion chambers in the high-temperature and high-pressure combustion chamber.

[0012] The fiber optic probe consists of high-transparency optical glass, a metal cooling jacket, and an optical flange.

[0013] High-transmittance optical glass allows ultraviolet-visible light with wavelengths of 100–760 nm to pass through.

[0014] The metal cooling jacket consists of an integrally formed cylindrical sleeve and a connecting cap.

[0015] The cylindrical sleeve is coaxially sealed around the outer periphery of the high-transmittance optical glass, and the cylindrical sleeve seal is installed inside the probe mounting hole.

[0016] The diameter of the connecting cap is larger than the diameter of the cylindrical sleeve, and the optical flange is provided inside the connecting cap.

[0017] One end of the optical fiber is installed in the optical flange and located on the axis of the high-transparency optical glass, which can collect ultraviolet-visible light transmitted through the high-transparency optical glass; the other end of the optical fiber is connected to the luminescence characteristic analysis device.

[0018] Both the cylindrical sleeve and the connecting cap are equipped with cooling channels, which are connected to the coolant pump via cooling pipes.

[0019] The high-transparency optical glass includes a large cylindrical optical glass and a small cylindrical optical glass integrally formed; the diameter of the small cylindrical optical glass is no more than half the diameter of the large cylindrical optical glass, and the diameter of the large cylindrical optical glass is not less than 1 mm. The axial length of the large cylindrical optical glass is equal to the thickness of the combustion chamber wall with the probe mounting hole.

[0020] The cylindrical sleeve is welded to the probe mounting hole for sealing.

[0021] The outer wall of the cylindrical sleeve is provided with external threads, and a sealing ring groove is provided at the junction of the cylindrical sleeve and the connecting cap. A sealing gasket is placed in the sealing ring groove. The cylindrical sleeve achieves a threaded sealing connection with the probe mounting hole through the sealing gasket and the external threads.

[0022] The sealing gasket is a high-temperature resistant graphite gasket.

[0023] An annular clearance groove is coaxially provided on the outer edge of the contact surface between the connecting cap and the combustion chamber wall, and the contact surface of the connecting cap located inside the clearance groove forms a limiting and blocking surface.

[0024] The connector cap is equipped with a standard fiber optic flange interface, and the optical flange thread is installed on the outer periphery of the standard fiber optic flange interface.

[0025] High-transparency optical glass can withstand high temperatures of 3000K and high pressures of 20MPa.

[0026] The propellant used in the high-temperature and high-pressure combustion chamber is methane and oxygen; the luminescence characteristic analysis device is a photomultiplier tube, and a 430nm bandpass filter is set at one end of the photomultiplier tube connected to the optical fiber.

[0027] The present invention has the following beneficial effects:

[0028] (1) It adopts a compact design, the entire special fiber optic probe is small in size, which can be easily installed, with little damage to the combustion chamber structure, and can protect the original structural strength of the combustion chamber to the maximum extent.

[0029] (2) It adopts a high-temperature water-cooling design, which can withstand high temperatures of 3000K for short periods of time. It is connected to the combustion chamber by long threads or welding, and has high pressure resistance up to 20MPa. When using long thread connection, combined with high-temperature graphite gaskets, reliable sealing can be achieved.

[0030] (3) It is highly adaptable and can also be used under low pressure conditions. Cooling is not required when the temperature is low.

[0031] (4) Using common materials, the processing technology is simpler and the implementation is more convenient and faster than optical windowing, enabling rapid diagnosis of the combustion chamber's luminescence characteristics. Attached Figure Description

[0032] Figure 1 The diagram shows the structure of the high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to the present invention.

[0033] Figure 2 An enlarged structural diagram of the fiber optic probe in this invention is shown.

[0034] Figure 3 A three-dimensional view of the fiber optic probe of this invention is shown.

[0035] Figure 4 The diagram shows the test voltage signal of the photomultiplier tube in this embodiment.

[0036] Among them are:

[0037] 10. Fiber optic probe;

[0038] 11. Metal cooling jacket;

[0039] 111. Cylindrical sleeve; 111a. Sealing ring groove;

[0040] 112. Connecting cap; 112a. Limiting and blocking surface; 112b. Circumvention groove; 112c. Flange groove;

[0041] 113. Cooling passage; 114. Coolant inlet; 115. Coolant outlet;

[0042] 12. Bolts; 13. Optical flanges; 14. High-transparency optical glass;

[0043] 20. Combustion chamber wall; 30. Optical fiber; 40. Luminescence characteristic analysis device; 50. Coolant pump; 60. Cooling pipe. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0045] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., 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 this 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. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0046] like Figure 1 As shown, a high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe includes an optical fiber probe 10, a light guide fiber 30, a luminescence characteristic analysis device 40, and a coolant pump 50.

[0047] A through-hole probe mounting hole is provided at the center of one of the combustion chamber walls of the high-temperature and high-pressure combustion chamber. The probe mounting hole diameter is as small as 8mm, which minimizes damage to the combustion chamber structure and can basically maintain the original structural strength of the combustion chamber.

[0048] like Figure 2 and Figure 3 As shown, the fiber optic probe includes a high-transmittance optical glass 14, a metal cooling jacket 11, and an optical flange 13.

[0049] High-transmittance optical glass allows ultraviolet-visible light with wavelengths of 100–760 nm to pass through, thereby enabling the capture of chemical reaction light emission (100–760 nm) in multiple wavelength bands in the combustion chamber.

[0050] The aforementioned high-transparency optical glass includes a large cylindrical optical glass 141 and a small cylindrical optical glass 142 integrally formed. The diameter of the small cylindrical optical glass is no more than half the diameter of the large cylindrical optical glass, and the diameter of the large cylindrical optical glass is not less than 1 mm. The axial length of the large cylindrical optical glass is equal to the thickness of the combustion chamber wall with the probe mounting hole. The inner end face of the large cylindrical optical glass can directly contact the combustion chamber flame, resulting in more accurate measurements.

[0051] The metal cooling jacket includes an integrally formed cylindrical sleeve 111 and a connecting cap 112, preferably manufactured by 3D printing using a high-temperature resistant alloy.

[0052] The cylindrical sleeve is coaxially sealed around the outer periphery of the high-transmittance optical glass, and the cylindrical sleeve seal is installed inside the probe mounting hole.

[0053] The cylindrical sleeve and the high-transmittance optical glass are preferably bonded with high-temperature resistant (1520℃) inorganic adhesive, which, combined with cooling, can fully ensure the normal operation of the fiber optic probe.

[0054] The preferred installation methods for the cylindrical sleeve and the probe mounting hole are as follows:

[0055] 1. Sealed welding, the weld is firm and can withstand high pressure of 20MPa.

[0056] 2. Threaded Connection: The outer wall of the cylindrical sleeve is provided with external threads. A sealing ring groove 111a is provided at the junction of the cylindrical sleeve and the connecting cap, and a sealing gasket (preferably a high-temperature resistant graphite gasket) is placed in the sealing ring groove. The cylindrical sleeve achieves a threaded sealing connection with the probe mounting hole through the sealing gasket and the external threads. In addition, the axial length of the external threads is basically equal to the thickness of the combustion chamber wall, which is a long thread. Therefore, the threaded connection is firm and can withstand a high pressure of 20MPa.

[0057] The diameter of the aforementioned connecting cap is larger than the diameter of the cylindrical sleeve. A flange groove 112c is provided inside the connecting cap, and a standard fiber optic flange interface (such as FC, SMA, etc.) is provided inside the flange groove. The optical flange is preferably installed on the outer periphery of the standard fiber optic flange interface using bolts with 12 threads.

[0058] One end of the optical fiber is installed in the optical flange and located on the axis of the high-transparency optical glass, which can collect ultraviolet-visible light transmitted through the high-transparency optical glass; the other end of the optical fiber is connected to the luminescence characteristic analysis device.

[0059] Both the cylindrical sleeve and the connecting cap are equipped with cooling channels 113, each with a coolant inlet 114 and a coolant outlet 115. The coolant inlet 114 and outlet 115 are connected to a coolant pump via cooling pipes to form a circulating cooling system. The coolant is preferably an anti-boiling fluid, but water can also be used. During cooling operation, the coolant flows through the cooling channels into the metal cooling jacket 11, cooling the fiber optic probe and enabling the high-transmittance optical glass to withstand high temperatures of 3000K for short periods.

[0060] An annular clearance groove 112b is coaxially provided on the outer edge of the contact surface between the connecting cap and the combustion chamber wall. The contact surface of the connecting cap located inside the clearance groove forms a limiting and blocking surface 112a. The limiting and blocking surface can limit the insertion depth of the cylindrical sleeve and further seal it. The clearance groove reduces the contact area between the connecting cap and the combustion chamber wall, resulting in rapid cooling.

[0061] In this embodiment, tests were conducted in a model rocket engine using a methane / oxygen propellant combination at temperatures reaching 3000K. The luminescence characteristic analysis device employed a photomultiplier tube with a pre-filter of 430nm, successfully capturing the spontaneous emission characteristics of CH* in the combustion chamber, thus enabling the analysis of the heat release characteristics in the model rocket engine. A high acquisition frequency of up to 100,000Hz successfully captured the pulsating heat release characteristics in the combustion chamber, such as... Figure 4 As shown.

[0062] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe, characterized in that: Includes fiber optic probes, optical fibers, luminescence characteristic analysis devices, and coolant pumps; A through-hole for mounting a probe is provided at the center of the wall of one of the combustion chambers in the high-temperature and high-pressure combustion chamber; the propellant used for combustion in the high-temperature and high-pressure combustion chamber is methane and oxygen; The fiber optic probe consists of high-transparency optical glass, a metal cooling jacket, and an optical flange; High-transmittance optical glass allows ultraviolet-visible light with wavelengths of 100~760nm to pass through, and can withstand high temperatures of 3000K and high pressures of 20MPa; The high-transparency optical glass includes a large cylindrical optical glass and a small cylindrical optical glass integrally formed; the diameter of the small cylindrical optical glass is no more than half the diameter of the large cylindrical optical glass, and the diameter of the large cylindrical optical glass is not less than 1 mm. The axial length of the large cylindrical optical glass is equal to the thickness of the combustion chamber wall with the probe mounting hole. The metal cooling jacket includes an integrally formed cylindrical sleeve and a connecting cap; The cylindrical sleeve is coaxially sealed around the outer periphery of the high-transmittance optical glass, and the cylindrical sleeve seal is installed inside the probe mounting hole. The diameter of the connecting cap is larger than the diameter of the cylindrical sleeve, and the optical flange is provided inside the connecting cap; One end of the optical fiber is installed in the optical flange and located on the axis of the high-transparency optical glass, which can collect ultraviolet-visible light transmitted through the high-transparency optical glass; The other end of the optical fiber is connected to the luminescence characteristic analysis device; Cooling channels are provided in both the cylindrical sleeve and the connecting cap, and the cooling channels are connected to the coolant pump through cooling pipes; The luminescence characteristic analysis device is a photomultiplier tube, and a 430nm bandpass filter is set at one end of the photomultiplier tube connected to the optical fiber. The bandpass filter can successfully capture the spontaneous emission characteristics of CH* in the combustion chamber, and realize the analysis of the heat release characteristics in the model rocket engine.

2. The high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to claim 1, characterized in that: The cylindrical sleeve is welded to the probe mounting hole for sealing.

3. The high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to claim 1, characterized in that: The outer wall of the cylindrical sleeve is provided with external threads, and a sealing ring groove is provided at the junction of the cylindrical sleeve and the connecting cap. A sealing gasket is placed in the sealing ring groove. The cylindrical sleeve achieves a threaded sealing connection with the probe mounting hole through the sealing gasket and the external threads.

4. The high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to claim 3, characterized in that: The sealing gasket is a high-temperature resistant graphite gasket.

5. The high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to claim 1, characterized in that: An annular clearance groove is coaxially provided on the outer edge of the contact surface between the connecting cap and the combustion chamber wall, and the contact surface of the connecting cap located inside the clearance groove forms a limiting and blocking surface.

6. The high-temperature and high-pressure combustion chamber spectral characteristic transmission device based on a special optical fiber probe according to claim 1, characterized in that: The connector cap is equipped with a standard fiber optic flange interface, and the optical flange thread is installed on the outer periphery of the standard fiber optic flange interface.

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