Combustion chamber tester

Abstract

The application discloses a combustion chamber tester, which comprises a combustion chamber device, an air inlet pipe in fluid communication with an inlet of the combustion chamber device, and an air outlet pipe in fluid communication with an outlet of the combustion chamber device, wherein a plurality of air outlet valves are arranged in the air outlet pipe along a gas flow direction. By adjusting different opening combinations of the plurality of air outlet valves, the characteristic acoustic frequency of the combustion chamber test piece can be adjusted, and then it is verified by test that whether the combustion heat release is coupled with pressure pulsation under the condition, and further combustion oscillation phenomenon occurs, and further the relationship between the combustion oscillation pulsation amplitude and the oil-gas ratio and other state parameters can be obtained, and the safe and stable operation range of the combustion chamber is obtained.

Description

Technical Field

[0001] This invention relates to the field of aero-engine research and development and testing, and in particular to a combustion chamber test apparatus. Background Technology

[0002] Combustion oscillation is an oscillatory process occurring in the combustor of aero-engines and gas turbines, characterized by the coupling of combustion heat release pulsations and pressure pulsations. When the phase difference between the combustor heat release pulsations and the internal air pressure pulsations is less than 1 / 4 of a period, coupling occurs between them, leading to combustion oscillation. Specifically, the coupling process is as follows: the heat release pulsations within the combustor cause pulsations in the internal pressure and velocity; these pulsations cause pulsations in the airflow and fuel flow entering the combustor, which in turn cause pulsations in the air-fuel ratio within the combustor; and these pulsations further cause heat release pulsations, forming a feedback loop that continues to excite combustion oscillation.

[0003] The operating parameters (inlet air temperature, pressure, and fuel-air ratio) of the combustion chambers of aero engines and ground-based gas turbines span a wide range. Under certain operating conditions, combustion oscillations may occur. Once combustion oscillations occur, they will cause pulsations in the temperature, pressure, and fuel-air ratio within the combustion chamber. In severe cases, this can lead to backfire, overheating, or even structural failure, affecting the overall performance and safety of the engine. If the vibration frequency of components such as the flame tube and fuel nozzles is coupled with the combustion oscillation frequency, it will further cause hardware resonance, which may lead to fatigue failure of the hardware in a short period of time, with very serious consequences.

[0004] Therefore, in the development of combustion chambers, obtaining combustion oscillation characteristics through experiments plays a crucial role in identifying oscillation boundaries and reducing development risks. In existing technologies, typical combustion chamber test equipment primarily obtains the combustion chamber outlet gas through gas sampling, and then analyzes it to obtain combustion efficiency and pollution emissions, or arranges temperature and pressure measuring points along the combustion chamber to obtain temperature and pressure distributions. The acoustic boundaries of such test equipment are inherent boundaries, and the characteristic frequencies of the test system are constant values, which may differ significantly from the characteristic frequencies of the combustion chamber components. Therefore, it is impossible to determine whether combustion heat release is coupled with the air pressure pulsation frequency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defect of the existing combustion chamber tester that cannot obtain the conclusion of whether the combustion heat release is coupled with the air pressure pulsation frequency, and to provide a combustion chamber tester.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] A combustion chamber test apparatus, the combustion chamber test apparatus comprising:

[0008] Combustion chamber device;

[0009] An intake manifold, which is in fluid communication with the inlet of the combustion chamber device;

[0010] An exhaust pipe is fluidly connected to the outlet of the combustion chamber device, and multiple exhaust valves are provided inside the exhaust pipe along the gas flow direction.

[0011] In this scheme, by adjusting different combinations of opening degrees of multiple exhaust valves, the characteristic acoustic frequency of the combustion chamber test piece can be adjusted. Then, through experiments, it can be verified whether the combustion heat release under this condition is coupled with pressure pulsation, thus causing combustion oscillation. Furthermore, the relationship between the amplitude of combustion oscillation pulsation and state parameters such as the air-fuel ratio can be obtained, and the range of safe and stable operation of the combustion chamber can be obtained.

[0012] Preferably, the exhaust pipe has the same inner diameter at all points along the axial direction.

[0013] In this design, the exhaust pipe is a pipe with a uniform diameter at all points along the axial direction, which is easy to process and has a low cost.

[0014] Preferably, the combustion chamber assembly includes a casing, with the intake pipe connected to the front end of the casing and the exhaust pipe connected to the rear end of the casing.

[0015] In this design, the casing, intake pipe, and exhaust pipe form a single pipeline, which more closely resembles the actual combustion chamber environment and improves the accuracy of the test results.

[0016] Preferably, the inner diameter of the casing is the same as the inner diameter of the exhaust pipe.

[0017] In this design, the exhaust gas from the casing can smoothly enter the exhaust pipe, and the characteristics of the combustion chamber tester are quite similar to those of an actual combustion chamber.

[0018] Preferably, the combustion chamber device includes a flame tube, the rear end of which is flush with the front end of the exhaust pipe.

[0019] In this design, the front end of the exhaust pipe is aligned with the flame tube, so the distance between the exhaust valve inside the exhaust pipe and the flame tube can be any value above 0, and the combustion chamber tester can simulate a wide range of different characteristic frequencies.

[0020] Preferably, the exhaust valve includes a solenoid valve for controlling the opening degree of the exhaust valve.

[0021] In this design, the solenoid valve can be remotely controlled. During the test, the test personnel do not need to approach the combustion chamber test apparatus to adjust the opening of the solenoid valve, thereby ensuring the safety of the test personnel.

[0022] Preferably, the intake pipe has a constriction section, the inner diameter of which gradually increases from the middle along the axis to both sides.

[0023] In this scheme, by setting a shrinkage orifice section, a clean and well-defined boundary is obtained, thereby improving the accuracy of the test results.

[0024] Preferably, a pressure pulsation sensor is provided inside the combustion chamber device.

[0025] In this scheme, the pressure pulsation sensor can obtain pulsating pressure data in the combustion chamber device to verify whether the heat release in the combustion chamber is coupled with the pulsation of air pressure. If the two are coupled, the pressure pulsation amplitude at the characteristic frequency monitored by the pulsating pressure sensor on the tester will increase significantly.

[0026] Preferably, the combustion chamber device includes a flame tube, and the pressure pulsation sensor is located on the outer wall of the flame tube.

[0027] In this scheme, the specific location and number of pressure pulsation sensors on the flame tube are determined according to the combustion chamber design.

[0028] Preferably, the flow area of ​​the exhaust valve is continuously adjustable.

[0029] In this design, the flow area is adjusted by controlling the opening degree of a solenoid valve, allowing the characteristic frequency of the combustion chamber test instrument to be continuously adjustable. The flow area of ​​each exhaust valve can be adjusted by changing the valve opening degree to obtain different opening combinations, thereby enabling the combustion chamber test instrument to obtain different characteristic frequencies.

[0030] The significant advantages of this invention are as follows: The combustion chamber test apparatus of this invention allows adjustment of the characteristic acoustic frequency of the combustion chamber test piece by varying the opening combinations of multiple exhaust valves. Then, through testing, it verifies whether combustion heat release under these conditions couples with pressure pulsations, leading to combustion oscillations. Furthermore, it allows for the determination of the relationship between the amplitude of combustion oscillation pulsations and state parameters such as the air-fuel ratio, thus establishing the safe and stable operating range of the combustion chamber. This test apparatus is simple in structure, easy to adjust, has low processing costs, is easy to design and manufacture, and has low maintenance costs. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a combustion chamber test apparatus in the prior art.

[0032] Figure 2 This is a schematic diagram of the structure of a combustion chamber test apparatus according to an embodiment of the present invention. Detailed Implementation

[0033] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0034] This embodiment provides an adjustable acoustic boundary combustion chamber tester, which can adjust the characteristic frequency of the combustion chamber cavity to simulate a certain characteristic frequency of the combustion chamber when it is working in the engine. Combustion chamber tests can be carried out on this tester to verify whether combustion oscillations exist in the combustion chamber, and then to verify measures to prevent combustion oscillations.

[0035] The combustion chamber tester obtains the characteristic frequency f. * The principle is as follows:

[0036] Assume the characteristic frequency of the combustion chamber device is known to be f. * The corresponding acoustic wavelength λ can be calculated using formulas (1) and (2) based on the temperature T under the working conditions of the combustion chamber. When the minimum throttling area downstream of the flame tube outlet is the sound velocity section, and the characteristic length L of the test piece is n times the acoustic wavelength λ (n is an integer multiple of λ / 4 to λ / 2, and the value of n depends on the acoustic characteristics of the flame tube inlet), the sound wave is reflected upstream at the outlet of the test piece. Substituting this into formula (3), L can be calculated. Furthermore, the valve opening at length L makes the gas flow velocity at this section reach the sound velocity, forming a blocking acoustic boundary. At this time, the pulsation velocity, pulsation pressure, and pulsation density at this section conform to formula (4).

[0037]

[0038] λ=V / f * Formula (2)

[0039] L=λ·n Formula (3)

[0040]

[0041] Where V is the speed of sound, λ is the wavelength, k is the adiabatic index, T is the temperature, R is the gas constant, u′ is the pulsation velocity, p′ is the pulsation pressure, and ρ′ is the pulsation density. The average speed is the time-averaged speed. Average pressure over time is the time-averaged density.

[0042] Figure 1 The diagram shows a combustion chamber test apparatus with fixed acoustic boundaries in the prior art. It includes an intake section 110, a combustion chamber 120, and a rear measuring section 130. A flame tube 140 is disposed within the combustion chamber, with a length Lc. The distance between the exhaust contraction orifice 131 of the rear measuring section 130 and the rear end of the flame tube 140 is X0. The characteristic length of the test apparatus is Lc + X0, which is not adjustable; therefore, the characteristic frequency f is... * Not adjustable.

[0043] like Figure 2As shown, the combustion chamber test apparatus provided in this embodiment includes a combustion chamber device 220, an intake pipe 210, and an exhaust pipe 230. The intake pipe 210 is in fluid communication with the inlet of the combustion chamber device 220; the exhaust pipe 230 is in fluid communication with the outlet of the combustion chamber device 220, and a plurality of exhaust valves 231 are provided in the exhaust pipe 230 along the gas flow direction.

[0044] By adjusting different combinations of opening degrees of multiple exhaust valves 231, the characteristic acoustic frequency of the combustion chamber test piece can be adjusted. Then, through experiments, it can be verified whether the combustion heat release under this condition is coupled with pressure pulsation, thus causing combustion oscillation. Furthermore, the relationship between the amplitude of combustion oscillation pulsation and state parameters such as the air-fuel ratio can be obtained, thus obtaining the range of safe and stable operation of the combustion chamber.

[0045] In this embodiment, the exhaust pipe 230 has the same inner diameter at all points along the axial direction, that is, the exhaust pipe 230 is a pipe with a uniform diameter at all points along the axial direction, which is easy to process and has a low cost.

[0046] The combustion chamber device 220 includes a casing 223, an intake pipe 210 connected to the front end of the casing 223, and an exhaust pipe 230 connected to the rear end of the casing 223. The casing 223, the intake pipe 210, and the exhaust pipe 230 together form a pipeline, which is closer to the actual combustion chamber environment and improves the accuracy of the test results.

[0047] The inner diameter of the casing 223 is the same as the inner diameter of the exhaust pipe 230. The exhaust from the casing 223 can smoothly enter the exhaust pipe 230, which makes the characteristics of the combustion chamber tester closer to those of an actual combustion chamber, ensuring that the test results are close to the true values.

[0048] In this embodiment, the combustion chamber device 220 includes a flame tube 222, which is disposed within the casing 223. The rear end of the flame tube 222 is flush with the front end of the exhaust pipe 230. Since the front end of the exhaust pipe 230 is aligned with the flame tube 222, the distance between the exhaust valve 231 within the exhaust pipe 230 and the flame tube 222 can be any value greater than 0, allowing the combustion chamber tester to simulate a wide range of different characteristic frequencies. A nozzle 224 is connected to the front end of the flame tube 222, and the combustion chamber tester may be equipped with a flow meter for monitoring the flow rate of the nozzle 224.

[0049] A pressure pulsation sensor 221 is installed inside the combustion chamber device 220 to obtain pulsating pressure data with a frequency of 10–5000 Hz and an amplitude of 0–500 kPa. The pressure pulsation sensor 221 can obtain pulsating pressure data within the combustion chamber device 220 to verify whether the heat release in the combustion chamber is coupled with the pulsation of air pressure. If the two are coupled, the pressure pulsation amplitude at the characteristic frequency monitored by the pulsating pressure sensor 221 on the test apparatus will increase significantly.

[0050] In a preferred embodiment, the pressure pulsation sensor 221 is located on the outer wall of the flame tube. The specific location and number of pressure pulsation sensors 221 on the flame tube are determined according to the combustion chamber design.

[0051] In this embodiment, the exhaust valve 231 includes a solenoid valve for controlling the opening degree of the exhaust valve. The solenoid valve can be remotely controlled, allowing the test personnel to adjust its opening degree without approaching the combustion chamber test apparatus during the test, thus ensuring their safety. It is understood that those skilled in the art can also choose other types of remotely controllable valves to control the exhaust valve 231, and this disclosure does not limit this choice.

[0052] The flow area of ​​the exhaust valve 231 is continuously adjustable. The flow area is adjusted by controlling the opening degree of the solenoid valve, thus making the characteristic frequency of the combustion chamber test instrument continuously adjustable. The flow area of ​​each exhaust valve 231 can be adjusted by the valve opening degree to obtain different opening combinations, thereby enabling the combustion chamber test instrument to obtain different characteristic frequencies. Specifically, the exhaust valve 231 can be a butterfly valve, a round hole valve, or other valves of any shape with throttling function.

[0053] See Figure 2 As shown, N exhaust valves 231 are arranged at different axial positions on the exhaust pipe 230. The flow area of ​​each exhaust valve 231 can be adjusted by the valve opening. The opening of each exhaust valve 231 can be remotely controlled individually. The axial positions of the exhaust valves 231 from the outlet of the flame tube 222 are X0, X1...X... N When the opening of each exhaust valve 231 is adjusted so that exhaust valve #1 231 is the downstream acoustic boundary, the characteristic length of the test piece is Lc + X1; similarly, when the opening of each exhaust valve 231 is adjusted so that exhaust valve #N 231 is the downstream acoustic boundary, the characteristic length of the test piece is Lc + X1. N Thus, the characteristic frequency f1 is obtained. * f2 * ...fN * The above operations can change the position of the 230 throttling surface of the exhaust pipe, thereby changing the characteristic length of the tester and obtaining different characteristic frequencies of the tester. Under this test environment, it can be verified whether the combustion heat release in the combustion chamber is coupled with the air pressure pulsation. If the two are coupled, the pressure pulsation amplitude at the characteristic frequency monitored by the pulsation pressure sensor on the tester will increase significantly (e.g., above 20 kPa).

[0054] The intake pipe 210 has a constriction section 211, the inner diameter of which gradually increases from the center along the axis to both sides. By setting the constriction section 211, a clean and well-defined boundary is obtained, thereby improving the accuracy of the test results. The intake pipe 210 can rectify the intake airflow. Simultaneously, at least one of the following sensors can be arranged within the intake pipe 210: a temperature sensor, a pressure sensor, and an air mass flow sensor, to obtain different operating parameters (temperature, pressure, flow rate, air-fuel ratio, etc.).

[0055] When conducting tests on the combustion chamber test apparatus of this embodiment, the acoustic boundary of the test piece can be changed by adjusting the flow area of ​​the exhaust valves 231 at different axial positions on the exhaust pipe 230 of the test apparatus, thereby adjusting the characteristic frequency inside the combustion chamber test piece to a specific value. This test apparatus can be used to conduct combustion oscillation tests to verify whether the heat release from the combustion chamber is coupled with the pulsation of air pressure.

[0056] This test apparatus can be used to conduct combustion oscillation boundary tests to obtain the influence of different operating parameters (temperature, pressure, flow rate, oil-air ratio, etc.) on the combustion oscillation amplitude, thereby obtaining the range of stable and safe operation of the combustion chamber.

[0057] The test apparatus has a simple structure, is easy to adjust, has low processing cost, is easy to design and manufacture, and has low maintenance cost.

[0058] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A combustion chamber test apparatus, characterized in that, The combustion chamber test apparatus includes: Combustion chamber device; An intake manifold, which is in fluid communication with the inlet of the combustion chamber device; An exhaust pipe is fluidly connected to the outlet of the combustion chamber device, and multiple exhaust valves are provided inside the exhaust pipe along the gas flow direction; The flow area of ​​each exhaust valve can be adjusted by the valve opening, and the opening of each exhaust valve can be controlled individually. When the opening of the exhaust valve is adjusted so that a certain exhaust valve is the downstream acoustic boundary, the characteristic length of the tester is changed, and different characteristic frequencies of the tester are obtained. The exhaust valve is a butterfly valve or a round hole valve.

2. The combustion chamber test apparatus as described in claim 1, characterized in that, The exhaust pipe has the same inner diameter at all points along the axial direction.

3. The combustion chamber test apparatus as described in claim 1, characterized in that, The combustion chamber assembly includes a casing, with the intake pipe connected to the front end of the casing and the exhaust pipe connected to the rear end of the casing.

4. The combustion chamber test apparatus as described in claim 3, characterized in that, The inner diameter of the casing is the same as the inner diameter of the exhaust pipe.

5. The combustion chamber test apparatus as described in claim 1, characterized in that, The combustion chamber device includes a flame tube, the rear end of which is flush with the front end of the exhaust pipe.

6. The combustion chamber test apparatus as described in claim 1, characterized in that, The exhaust valve includes a solenoid valve, which is used to control the opening degree of the exhaust valve.

7. The combustion chamber test apparatus as described in claim 1, characterized in that, The intake pipe has a constriction section, the inner diameter of which gradually increases from the middle along the axis to both sides.

8. The combustion chamber test apparatus as described in claim 1, characterized in that, The combustion chamber device is equipped with a pressure pulsation sensor.

9. The combustion chamber test apparatus as described in claim 8, characterized in that, The combustion chamber device includes a flame tube, and the pressure pulsation sensor is located on the outer wall of the flame tube.

10. The combustion chamber test apparatus as described in claim 1, characterized in that, The flow area of ​​the exhaust valve is continuously adjustable.

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