Method, apparatus, and system for testing liquid propellant flame combustion response

Abstract

The present application relates to a kind of liquid propellant flame combustion response test method, device and system, comprising obtaining target characteristic response frequency;Utilize target characteristic response frequency to calculate target combustion chamber length;Corresponding target combustion chamber is obtained with target combustion chamber length;Pulser is used to respectively in target combustion chamber ignition and after extinguishing to target combustion chamber pulse is applied;Pressure sensor is used to collect target combustion chamber ignition and after extinguishing pressure signal;According to the pressure signal of different positions in target combustion chamber ignition and after extinguishing, draw ignition and after extinguishing pressure attenuation characteristic curve;According to the attenuation coefficient of ignition and after extinguishing pressure attenuation characteristic curve of ignition pressure attenuation characteristic curve and the difference of attenuation coefficient of after extinguishing pressure attenuation characteristic curve calculated as target characteristic response frequency corresponding propellant flame combustion response.The method excitation amplitude is larger and excitation frequency variable.

Description

Technical Field

[0001] This invention relates to the field of aerospace technology, and in particular to a method, apparatus and system for testing the combustion response of liquid propellant flames. Background Technology

[0002] Combustion instability is a common physical phenomenon in power plants involving combustion processes, ranging from solid and liquid rocket engines to aircraft engines and gas turbines. This problem arises from the coupling of acoustic vibrations within the combustion chamber of different devices with the combustion process, and can potentially lead to severe damage or even destruction of the power plant.

[0003] Currently, the unsteady-state response prediction of a propulsion unit can only be obtained by applying external excitation to the unit. Existing technologies typically employ a method of directly applying acoustic excitation to the combustion chamber cavity using a loudspeaker or similar device to predict the unsteady-state response of a liquid-propelled combustion flame under acoustic excitation. For liquid-propelled propulsion units, the excitation source of this prediction method cannot provide a large-amplitude oscillation pulse, resulting in a significant difference between the predicted value and the actual unsteady-state response. Furthermore, this method can only predict the unsteady-state response at a single oscillation pulse frequency. Summary of the Invention

[0004] Therefore, it is necessary to provide a test method, apparatus, and system for the combustion response of liquid propellant flames with large excitation amplitude and variable excitation frequency to address the above-mentioned technical problems.

[0005] In a first aspect, the present invention provides a method for testing the combustion response of a liquid propellant flame, comprising the following steps:

[0006] Obtain the target feature response frequency;

[0007] The target combustion chamber length is calculated using the target characteristic response frequency; specifically, the target characteristic response frequency is input into the characteristic response frequency model or characteristic response frequency software to calculate the target combustion chamber length.

[0008] Obtain the target combustion chamber corresponding to the target combustion chamber length;

[0009] A pulse generator is used to apply pulses to the target combustion chamber during ignition and after flameout.

[0010] Pressure sensors are used to collect pressure signals in the target combustion chamber during ignition and after flameout.

[0011] Based on the pressure signals at different locations during and after ignition in the target combustion chamber, plot the pressure attenuation characteristic curves during and after ignition.

[0012] The attenuation coefficients of the pressure attenuation characteristic curve during ignition and after ignition are calculated based on the pressure attenuation characteristic curves during ignition and after ignition, respectively.

[0013] The difference between the attenuation coefficient of the pressure attenuation characteristic curve during ignition and the attenuation coefficient of the pressure attenuation characteristic curve after extinguishing is the propellant flame combustion response corresponding to the target characteristic response frequency.

[0014] In one embodiment, the target combustion chamber is either a single unit or composed of multiple sub-combustion chambers with known characteristic response frequencies and lengths.

[0015] In one embodiment, the pressure signals of the target combustion chamber during ignition and after extinguishing are collected using pressure sensors. This involves using multiple pressure sensors to collect pressure signals at different locations in the target combustion chamber during ignition and after extinguishing.

[0016] In one embodiment, the characteristic response frequency model is:

[0017]

[0018] In the formula, f is the target characteristic response frequency, l is the combustion chamber length, n is the modal order, and c is the speed of sound.

[0019] In one embodiment, the characteristic response frequency software is COMSOL or ANSYS.

[0020] In a second aspect, the present invention provides a test device for the combustion response of a liquid propellant flame, and a test method for the combustion response of a liquid propellant flame, comprising a tubular combustion chamber, a nozzle cap and an end cap located on both sides of the combustion chamber to seal the combustion chamber, and an air inlet connector, wherein the nozzle cap and the end cap are fixedly connected to the combustion chamber, the air inlet connector is fixedly installed on the end cap, and the air inlet connector is connected to the combustion chamber.

[0021] The outer side wall of the combustion chamber is provided with a pulse generator connector for connecting the pulse generator, at least one sensor pressure measuring base for placing a sensor, and an ignition connector. The pulse generator connector, sensor pressure measuring base, and ignition connector are all fixedly connected to the combustion chamber.

[0022] In one embodiment, the combustion chamber includes at least one pipe section.

[0023] In one embodiment, the combustion chamber includes multiple sub-combustion chambers with known characteristic response frequencies and lengths, and each sub-combustion chamber has an pulse generator connector and a sensor pressure measuring seat on its outer side wall;

[0024] Any two adjacent sub-combustion chambers are fixedly connected by a connecting flange.

[0025] Thirdly, the present invention provides a testing system for the combustion response of a liquid propellant flame, and a testing method for controlling the testing device for the combustion response of a liquid propellant flame to realize the combustion response of a liquid propellant flame, comprising:

[0026] Pulse generator module, which is used to generate pulse excitation, includes multiple pulse generators;

[0027] A sensor module is used to measure the pressure signal in the combustion chamber. The sensor module includes at least one sensor.

[0028] The control module is used to control the ignition of the combustion chamber and the pulse generator.

[0029] The data acquisition module is used to acquire the pressure signal of the combustion chamber measured by the sensor module, process the pressure signal, and calculate the propellant flame combustion response.

[0030] The beneficial effects of this invention are:

[0031] (1) The present invention uses a pulse generator to provide pulse excitation to the target combustion chamber where the liquid propellant is located, which can provide a large amplitude pulse oscillation to realize the response characteristics test of the liquid propellant combustion flame. Moreover, the large amplitude oscillation will produce obvious nonlinear effects, which is more conducive to the response characteristics test of the combustion flame.

[0032] (2) The length of the combustion chamber used in this invention corresponds to the target response frequency, enabling testing at different frequencies.

[0033] (3) The combustion chamber of the present invention can be constructed by splicing together multiple sub-combustion chambers with known characteristic response frequencies and lengths. In order to achieve the response characteristics test of liquid propellant combustion flame at different frequencies, multiple sub-combustion chambers with known characteristic response frequencies and lengths can be used to construct a combustion chamber of the required length. Therefore, the method of the present invention also has the characteristic of saving consumables. Attached Figure Description

[0034] Figure 1 One of the flowcharts for a test method of liquid propellant flame combustion response provided in an embodiment of the present invention;

[0035] Figure 2 It is the pressure attenuation characteristic curve;

[0036] Figure 3 This is a schematic diagram of the pressure time series during the descent phase provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the descending segment FFT curve provided in an embodiment of the present invention;

[0038] Figure 5This is a schematic diagram of attenuation coefficient calculation provided in an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the structure of the test device for the combustion response of liquid propellant flame in an embodiment of the present invention;

[0040] Figure 7 This is another schematic diagram of the test device for the combustion response of liquid propellant flame in an embodiment of the present invention.

[0041] Explanation of reference numerals in the attached drawings: 100, Combustion chamber; 200, Nozzle cap; 300, End cap; 400, Air inlet connector; 500, Pulse generator connector; 600, Sensor pressure gauge; 700, Ignition connector; 800, Sub-combustion chamber; 900, Connecting flange. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] In one embodiment, such as Figure 1 As shown, Figure 1 This is one of the flowcharts illustrating a method for testing the combustion response of a liquid propellant flame provided in an embodiment of the present invention. The method for testing the combustion response of a liquid propellant flame includes the following steps:

[0044] S101. Obtain the target feature response frequency;

[0045] S102. Calculate the target combustion chamber length using the target characteristic response frequency; specifically, input the target characteristic response frequency into the characteristic response frequency model or characteristic response frequency software to calculate the target combustion chamber length.

[0046] S103. Obtain the target combustion chamber 100 corresponding to the length of the target combustion chamber.

[0047] Specifically, the target combustion chamber 100 has two functions: first, to provide a confined space environment for the propellant combustion flame, generating higher temperatures and pressures; and second, to construct a basic acoustic environment, generating the required acoustic frequency after the introduction of pulse oscillations.

[0048] S104. Apply pulses to the target combustion chamber 100 during ignition and after extinguishing using a pulse generator.

[0049] The pulse generator in this embodiment can be, but is not limited to, a high-pressure external pulse actuator for a T-type burner. Since the pulse generator only begins operation some time after ignition in the combustion chamber 100, its sealing and heat insulation are crucial. High-temperature, high-pressure gas entering the pulse generator from the combustion chamber 100 may ignite the propellant, causing the pulse generator to malfunction. Therefore, a high-pressure external pulse actuator for a T-type burner is preferred, featuring structures such as plugs and baffles to isolate the combustion chamber 100 environment from the pulse generator combustion chamber 100. When in use, a high-pressure external pulse actuator for a T-type burner with a propellant charge of 2–15 g can generate a pressure pulse of 20–50 MPa, reaching its peak pressure within 2–10 ms.

[0050] The working principle of the high-pressure external pulse exciter used in the T-type burner is as follows: In the combustion chamber 100, the igniter ignites a given mass of gunpowder, which generates gas with a certain pressure and temperature, pushes open the sealing plug, and enters the engine thrust chamber through the nozzle, thereby generating the required disturbance.

[0051] It should be noted that the excitation frequency of the pulse generator is controlled by the length of the combustion chamber 100. Different combustion chamber 100 lengths will produce different frequencies under the excitation of the same pulse generator.

[0052] S105. Use a pressure sensor to collect the pressure signal of the target combustion chamber 100 during ignition and after flameout.

[0053] S106. Based on the pressure signals at different locations during and after ignition in the target combustion chamber 100, plot the pressure attenuation characteristic curves during and after ignition. For example... Figure 2 As shown, Figure 2 This is the pressure decay characteristic curve. In the figure, P represents the combustion chamber pressure of 100, t is time, and τ is... d This is the decay period.

[0054] S107. Calculate the attenuation coefficient of the pressure attenuation characteristic curve during ignition and the attenuation coefficient of the pressure attenuation characteristic curve after ignition based on the pressure attenuation characteristic curves during ignition and after extinguishing, respectively.

[0055] Specifically, the formula for calculating the attenuation coefficient is:

[0056]

[0057] In the formula, and are two adjacent pressure extremes in the pressure attenuation characteristic curve, respectively.

[0058] S108. The difference between the attenuation coefficient of the pressure attenuation characteristic curve during ignition and the attenuation coefficient of the pressure attenuation characteristic curve after extinguishing is the propellant flame combustion response corresponding to the target characteristic response frequency.

[0059] In this embodiment, the attenuation coefficients of the pressure attenuation characteristic curve during ignition and the pressure attenuation characteristic curve after extinguishing are defined as and , respectively. The difference between the two is the combustion gain of the propellant combustion flame at this oscillation frequency.

[0060] In one embodiment, the target combustion chamber 100 is either a single unit or composed of multiple sub-combustion chambers 800 with known characteristic response frequencies and lengths.

[0061] In one embodiment, the pressure signals of the target combustion chamber 100 during ignition and after extinguishing are collected using pressure sensors. This involves using multiple pressure sensors to collect pressure signals at different locations within the target combustion chamber 100 during ignition and after extinguishing. Multiple pressure sensors can provide more comprehensive information on pressure oscillations, such as measurements of the pressure vibration modes in the combustion chamber 100.

[0062] In one embodiment, the characteristic response frequency model is:

[0063]

[0064] In the formula, f is the target characteristic response frequency, l is the length of the combustion chamber (100), n is the modal order, and c is the speed of sound.

[0065] In one embodiment, the characteristic response frequency software is COMSOL or ANSYS.

[0066] In one specific embodiment, a cold flow triggering experiment was performed on 100 segments of a 150mm long combustion chamber. The pulser charge consisted of 5g of black powder. A pressure sensor with a pressure range of 0–5MPa and a sampling frequency of 10kHz was selected. The resulting pressure-time series and FFT curve for the descending segment (3.91s–3.94s) are shown below. Figure 3 and Figure 4 As shown, by Figure 3 and Figure 4 It can be seen that the pressure inside the combustion chamber 100 decreases exponentially during the descent phase, with a characteristic frequency of 1422Hz.

[0067] like Figure 5 As shown, Figure 5 This is a schematic diagram for calculating the attenuation coefficient. The attenuation coefficient can be calculated based on the descending envelope, and is derived from... Figure 5 It can be seen that the sound wave enters the linear decay region at approximately 4.78 seconds. Therefore, the method in this embodiment can be used to test the response characteristics of liquid propellant combustion flames.

[0068] Based on the same inventive concept, this invention provides a testing apparatus for the combustion response of a liquid propellant flame, and a method for testing the combustion response of a liquid propellant flame. In one embodiment, such as... Figure 6 As shown, Figure 6 This is a schematic diagram of the structure of the test device for the combustion response of liquid propellant flame in an embodiment of the present invention. The test device for the combustion response of liquid propellant flame includes a tubular combustion chamber 100, a nozzle cap 200 and an end cap 300 located on both sides of the combustion chamber 100 to seal the combustion chamber 100, and an air inlet connector 400. The nozzle cap 200 and the end cap 300 are fixedly connected to the combustion chamber 100, and the air inlet connector 400 is fixedly installed on the end cap 300 and communicates with the combustion chamber 100.

[0069] The outer wall of the combustion chamber 100 is provided with a pulse generator connector 500 for connecting a pulse generator, at least one sensor pressure measuring seat 600 for placing a sensor, and an ignition connector 700. The pulse generator connector 500, the sensor pressure measuring seat 600, and the ignition connector 700 are all fixedly connected to the combustion chamber 100.

[0070] It should be noted that in this embodiment, only one pulse generator connector 500 and one sensor pressure measuring seat 600 are specifically provided on the outer wall of the combustion chamber 100. In actual use, the number can be set according to the specific situation.

[0071] It should also be noted that the positions and installation angles of the pulse generator connector 500, sensor pressure measuring base 600, and ignition connector 700 on the outer side wall can be specifically set according to actual needs.

[0072] In one embodiment, the combustion chamber 100 includes at least one pipe segment. In this embodiment, the combustion chamber 100 is a single unit and can be specifically fabricated after its length has been calculated.

[0073] In a preferred embodiment, such as Figure 7 As shown, Figure 7 This is another structural schematic diagram of the test device for the combustion response of liquid propellant flame in an embodiment of the present invention. The combustion chamber 100 includes multiple sub-combustion chambers 800 with known characteristic response frequencies and lengths. Each sub-combustion chamber 800 is provided with a pulser connector 500 and a sensor pressure measuring seat 600 on its outer side wall. Any two adjacent sub-combustion chambers 800 are fixedly connected by a connecting flange 900.

[0074] By assembling multiple sub-combustion chambers 800 with known characteristic response frequencies and lengths to form the required combustion chamber 100, it is possible to fabricate a combustion chamber 100 with an unknown characteristic response frequency, saving materials and allowing the excitation frequency to be adjusted by the number of assemblies. Furthermore, a multi-pulse generator can achieve multiple pulse excitation measurements during a single ignition.

[0075] This invention also provides a testing system for the combustion response of a liquid propellant flame, and a testing method for controlling the testing device for the combustion response of a liquid propellant flame, comprising:

[0076] The pulse generator module is used to generate pulse excitation and includes multiple pulse generators.

[0077] The sensor module is used to measure the pressure signal of the combustion chamber 100, and the sensor module includes at least one sensor.

[0078] The control module is used to control the ignition of the combustion chamber 100 and the ignition pulser. Specifically, the control module consists of a timing control program (software) and an ignition timing control system (hardware).

[0079] The data acquisition module is used to acquire the pressure signal of the combustion chamber 100 measured by the sensor module, process the pressure signal, and calculate the propellant flame combustion response. Specifically, the data acquisition module includes a strain amplifier, a data acquisition channel module (hardware), and data acquisition software.

[0080] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0081] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method of testing a liquid propellant flame combustion response, characterized by, Includes the following steps: Obtain the target feature response frequency; Calculate the target combustion chamber length using the target's characteristic response frequency; Specifically, the target characteristic response frequency is input into the characteristic response frequency model or characteristic response frequency software to calculate the target combustion chamber length; Obtain the target combustion chamber (100) corresponding to the target combustion chamber length; A pulse generator is used to apply pulses to the target combustion chamber (100) during ignition and after extinguishing. The pulse generator is a high-pressure external pulse exciter for a T-type burner, and is connected to the combustion chamber (100) through a pulse generator connector (500) on the outer wall of the combustion chamber (100). The pressure signal of the target combustion chamber (100) after ignition and after flameout is collected using a pressure sensor; Based on the pressure signals at different locations during and after ignition of the target combustion chamber (100), the pressure attenuation characteristic curves after ignition and extinguishing are plotted. The attenuation coefficients of the pressure attenuation characteristic curve during ignition and after ignition are calculated based on the pressure attenuation characteristic curves during ignition and after ignition, respectively. The difference between the attenuation coefficient of the pressure attenuation characteristic curve during ignition and the attenuation coefficient of the pressure attenuation characteristic curve after extinguishing is the propellant flame combustion response corresponding to the target characteristic response frequency.

2. The test method for liquid propellant flame combustion response according to claim 1, characterized in that, The target combustion chamber (100) is either a single unit or composed of multiple sub-combustion chambers (800) with known characteristic response frequencies and lengths.

3. The test method for liquid propellant flame combustion response according to claim 2, wherein, Pressure signals of the target combustion chamber (100) during ignition and after extinguishing are collected using pressure sensors. Multiple pressure sensors are used to collect pressure signals at different locations of the target combustion chamber (100) during ignition and after extinguishing.

4. The test method for liquid propellant flame combustion response according to claim 3, wherein The characteristic response frequency model is as follows: （1） wherein f is the target characteristic response frequency, l is the combustion chamber (100) length, n is the modal order, c is the speed of sound.

5. The test method for liquid propellant flame combustion response according to claim 3, wherein The characteristic response frequency software is COMSOL or ANSYS.

6. A test apparatus for liquid propellant flame response for carrying out the test method for liquid propellant flame response according to any one of claims 1 to 5, characterized in that It includes a tubular combustion chamber (100), a nozzle cap (200) and an end cap (300) located on both sides of the combustion chamber (100) to seal the combustion chamber (100), and an air inlet connector (400). The nozzle cap (200) and the end cap (300) are fixedly connected to the combustion chamber (100), and the air inlet connector (400) is fixedly installed on the end cap (300) and communicates with the combustion chamber (100). The outer wall of the combustion chamber (100) is provided with a pulse generator connector (500) for connecting a pulse generator, at least one sensor pressure measuring base (600) for placing a sensor, and an ignition connector (700). The pulse generator connector (500), the sensor pressure measuring base (600), and the ignition connector (700) are all fixedly connected to the combustion chamber (100).

7. A liquid propellant flame test apparatus according to claim 6, wherein The combustion chamber (100) includes at least one pipe section.

8. The liquid propellant flame test apparatus of claim 7, wherein, The combustion chamber (100) includes multiple sub-combustion chambers (800) with known characteristic response frequencies and lengths. Each sub-combustion chamber (800) has a pulse generator connector (500) and a sensor pressure measuring seat (600) on its outer side wall. Any two adjacent sub-combustion chambers (800) are fixedly connected by a connecting flange (900).

9. A testing system for the combustion response of a liquid propellant flame, used to control the testing apparatus for the combustion response of a liquid propellant flame as described in any one of claims 6 to 8 to implement the testing method for the combustion response of a liquid propellant flame as described in any one of claims 1 to 5, characterized in that, include: A pulse generator module, which generates pulse excitation, includes multiple pulse generators. A sensor module for measuring the pressure signal of the combustion chamber (100), the sensor module including at least one sensor; A control module for ignition control of the combustion chamber (100) and the pulse generator; The data acquisition module is used to acquire the pressure signal of the combustion chamber (100) measured by the sensor module and to process the pressure signal to calculate the propellant flame combustion response.

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