A method, device and equipment for determining plume temperature and pressure based on OH radicals

Abstract

This invention discloses a method, apparatus, and equipment for determining the temperature and pressure of engine exhaust plumes based on OH radicals, relating to the field of engine exhaust plume testing technology. It addresses the problem of high error rates caused by interference from the exhaust plume flow field in existing contact measurement methods. The method includes: acquiring spectral data of the engine exhaust plume; preprocessing and extracting the spectral data to obtain the target rotation spectrum of OH radicals and determining the spectral line intensities of the target rotation spectrum; determining the exhaust plume temperature based on the spectral line intensities using the Boltzmann diagram method; substituting the exhaust plume temperature into an OH radical temperature broadening model to obtain temperature broadening; determining pressure broadening based on the target rotation spectrum, temperature broadening, and OH radical temperature-pressure coupling model; and determining the exhaust plume pressure based on the radical pressure broadening model. The OH radical-based exhaust plume temperature and pressure determination method provided by this invention uses a non-contact method to determine temperature and pressure, exhibiting strong anti-interference capabilities.

Description

Technical Field

[0001] This invention relates to the field of engine exhaust flame testing technology, and in particular to a method, apparatus and equipment for determining exhaust flame temperature and pressure based on OH free radicals. Background Technology

[0002] Exhaust flame temperature and pressure are crucial parameters for rocket engine operation. Exhaust flame temperature directly reflects the combustion efficiency and energy release within the combustion chamber; exhaust flame pressure distribution directly affects nozzle expansion efficiency, and pressure data can verify whether the nozzle is operating under optimal conditions. Furthermore, the erosion rate of nozzle and combustion chamber materials under high temperature and high pressure is directly related to exhaust flame temperature and pressure. Long-term monitoring of exhaust flame temperature and pressure can provide a basis for material life modeling and guide maintenance cycles. Therefore, measuring exhaust flame temperature and pressure is of great significance for optimizing the combustion process, controlling emissions, and preventing equipment failures.

[0003] Traditional temperature and pressure measurements mainly rely on contact detection methods, such as thermocouples, thermistors, and pressure sensors. However, traditional contact sensors can cause flow field interference in the supersonic flow field of the exhaust flame, resulting in local pressure measurements deviating from the true values. Summary of the Invention

[0004] The purpose of this invention is to provide a method, apparatus, and equipment for determining the temperature and pressure of the exhaust flame based on OH free radicals, in order to solve the problem that existing contact measurement methods are easily affected by the exhaust flame flow field and have high errors.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a method for determining the tail flame temperature and pressure based on OH free radicals, comprising:

[0007] Acquire spectral data of the engine exhaust flame;

[0008] The spectral data is preprocessed and extracted to obtain the target rotation spectrum of the OH radical, and the spectral line intensity of the target rotation spectrum is determined.

[0009] The tail flame temperature was determined using the Boltzmann diagram method based on the intensity of the spectral lines.

[0010] Substituting the tail flame temperature into the OH radical temperature broadening model, the temperature broadening was calculated.

[0011] Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening;

[0012] Substituting the pressure broadening into the OH radical pressure broadening model, the tail flame pressure was calculated.

[0013] Optionally, the step of preprocessing and extracting the spectral data to obtain the target rotation spectrum of the OH radical, and determining the spectral line intensity of the target rotation spectrum, includes:

[0014] The spectral data is denoised and baseline corrected to obtain spectral corrected data.

[0015] Extract the target rotational spectral line of the same vibrational band within the target wavelength from the spectral correction data;

[0016] The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line.

[0017] The integrated intensity of the target rotation spectral line is normalized to obtain the spectral line intensity of the target rotation spectral line.

[0018] Optional, use the formula:

[0019]

[0020] The linear relationship between spectral line intensity and rotational level energy is fitted to determine the slope value;

[0021] in, This is a quantity relating spectral line intensities. For the rotation quantum number The corresponding rotational energy level, For Einstein's emission coefficient, For the rotation quantum number The corresponding rotational level degeneracy, It is a constant;

[0022] The exhaust temperature is determined based on the slope value.

[0023] Optionally, substituting the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening includes:

[0024] Substitute the value of the exhaust flame temperature into the formula:

[0025]

[0026] The temperature broadening was calculated;

[0027] in, For temperature broadening, The tail flame temperature, Molecular mass Boltzmann's constant, At the speed of light, This is the transition center frequency.

[0028] Optionally, based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening, including:

[0029] Based on the target rotation spectrum and formula:

[0030]

[0031]

[0032] Nonlinear least squares fitting is performed until the sum of squared residuals between the model fitting peak height and the characteristic peak height is less than or equal to a preset threshold, thus completing the fitting and obtaining pressure broadening; the characteristic peak height is the peak height at the characteristic peak wavelength of the target rotation spectrum.

[0033] in, To fit the peak height of the model, The height of the center peak of the target rotation spectrum. This is a temperature-pressure coupling model for OH free radicals. For baseline offset, The wavelength of the target rotation spectrum, The center wavelength, To broaden the scope of pressure, For temperature broadening, For Fadieva function, Indicates taking the real part, It is an imaginary number.

[0034] Optionally, substituting the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure includes:

[0035] Substitute the value of the pressure broadening into the formula:

[0036]

[0037] The tail flame pressure was calculated;

[0038] in, To broaden the scope of pressure, Pressure broadening at reference temperature and reference pressure, For the tail flame pressure, The tail flame temperature, For reference temperature, For reference pressure, These are empirical parameters.

[0039] Optionally, acquiring the spectral data of the engine exhaust flame includes:

[0040] A non-contact OH radical spectral testing system was constructed. The non-contact OH radical spectral testing system includes a focusing lens, an optical fiber probe, a high-resolution spectrometer, and a computer connected in sequence. The focusing lens and the optical fiber probe are installed at a preset distance from the engine exhaust flame.

[0041] The non-contact OH radical spectral testing system was activated to collect spectral data of the engine exhaust flame.

[0042] Optionally, the step of integrating the intensity of each target rotation spectral line by area to obtain the integrated intensity of the target rotation spectral line includes:

[0043] Formula used:

[0044]

[0045] The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line.

[0046] in, For integral intensity, Rotate the spectral line to the target. The wavelength of the target rotation spectrum.

[0047] Compared with existing technologies, this invention provides a method for determining exhaust flame temperature and pressure based on OH radicals, comprising: acquiring spectral data of engine exhaust flame; preprocessing and extracting the spectral data to obtain the target rotation spectrum of OH radicals and determining the spectral line intensities of the target rotation spectrum; determining the exhaust flame temperature based on the spectral line intensities using the Boltzmann diagram method, which can directly invert the temperature by measuring the spectral line intensity ratios corresponding to different energy levels, avoiding the complexity of absolute intensity calibration; substituting the exhaust flame temperature into the OH radical temperature broadening model to calculate the temperature broadening; fitting the relationship between the peak height and baseline shift of the target rotation spectrum based on the target rotation spectrum, temperature broadening, and OH radical temperature-pressure coupling model to obtain the pressure broadening; and substituting the pressure broadening into the OH radical pressure broadening model to calculate the exhaust flame pressure. This application presents a method for determining the temperature and pressure of the exhaust flame using spectral data. This method offers significant advantages, including non-contact and rapid measurement. Secondly, by selecting specific spectral lines, interference from other substances can be reduced, resulting in strong anti-interference capabilities. Thirdly, spectroscopic methods can perform multi-parameter detection, simultaneously acquiring various information such as temperature, pressure, and gas composition. OH radicals, as important intermediate products in high-temperature combustion processes, exhibit strong emission characteristics in the ultraviolet band, making their signals easy to detect and highly sensitive. Furthermore, this method eliminates the need for traditional contact sensors, avoiding interference from the supersonic flow field of the exhaust flame and damage from high temperatures that can occur with traditional contact sensors. Moreover, by constructing OH radical temperature broadening models, OH radical pressure broadening models, and OH radical temperature-pressure coupling models, temperature and pressure parameters can be simultaneously inverted based solely on the target rotation spectrum of OH radicals, overcoming the limitation of single-spectral techniques that can only invert a single parameter.

[0048] In a second aspect, the present invention also provides a device for determining the tail flame temperature and pressure based on OH radicals, comprising:

[0049] The spectral data acquisition module is used to acquire the spectral data of the engine exhaust flame;

[0050] The spectral line intensity determination module is used to preprocess and extract the spectral data to obtain the target rotation spectrum of the OH radical and determine the spectral line intensity of the target rotation spectrum.

[0051] The exhaust flame temperature determination module is used to determine the exhaust flame temperature based on the spectral line intensity using the Boltzmann diagram method.

[0052] The temperature broadening determination module is used to substitute the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening;

[0053] The pressure broadening determination module is used to fit the relationship between the peak height and baseline shift of the target rotation spectrum based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model to obtain the pressure broadening;

[0054] The tail flame pressure calculation module is used to substitute the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure.

[0055] Thirdly, the present invention also provides a device for determining the tail flame temperature and pressure based on OH radicals, comprising:

[0056] Communication unit / communication interface, used to acquire spectral data of engine exhaust flame;

[0057] A processing unit / processor is used to preprocess and extract the spectral data to obtain the target rotation spectrum of OH radicals and determine the spectral line intensity of the target rotation spectrum;

[0058] The tail flame temperature was determined using the Boltzmann diagram method based on the intensity of the spectral lines.

[0059] Substituting the tail flame temperature into the OH radical temperature broadening model, the temperature broadening was calculated.

[0060] Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening;

[0061] Substituting the pressure broadening into the OH radical pressure broadening model, the tail flame pressure was calculated.

[0062] Compared with the prior art, the beneficial effects of the second aspect device solution and the third aspect equipment solution provided by the present invention are the same as the beneficial effects of the method for determining the tail flame temperature and pressure based on OH free radicals described in the above technical solutions, and will not be repeated here. Attached Figure Description

[0063] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0064] Figure 1 A flowchart of the method for determining the tail flame temperature and pressure based on OH free radicals provided by the present invention;

[0065] Figure 2 This is a schematic diagram of the non-contact OH radical spectroscopy testing system provided by the present invention;

[0066] Figure 3A schematic diagram of the structure of the device for determining the tail flame temperature and pressure based on OH free radicals provided by the present invention;

[0067] Figure 4 A schematic diagram of the structure of the device for determining the tail flame temperature and pressure based on OH free radicals provided by the present invention.

[0068] Figure label:

[0069] 1-Focusing lens, 2-Fiber optic probe, 3-High-resolution spectrometer, 4-Computer, 5-Nozzle. Detailed Implementation

[0070] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0071] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0072] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0073] Before introducing the embodiments of the present invention, the relevant terms involved in the embodiments of the present invention are first defined as follows:

[0074] The Voigt function is an important mathematical function used in molecular spectroscopy, atomic physics, and spectral analysis to describe the profile of spectral lines. It is the convolution of a Gaussian function and a Lorentz function, and is used to simulate the shape of spectral lines that are simultaneously affected by Doppler broadening and natural or collisional broadening.

[0075] The Faddeeva function is a special type of complex function and a core tool for describing phenomena such as spectral line broadening and diffusion processes.

[0076] Traditional contact sensors are easily affected by flow field interference when testing pressure and temperature, causing the measured values ​​to deviate from the true values, and the sensors are easily damaged during exhaust flame measurement.

[0077] To address the aforementioned problems, this invention provides a method, apparatus, and equipment for determining exhaust flame temperature and pressure based on OH radicals. Utilizing high-precision spectroscopic detection technology, it overcomes the shortcomings of traditional methods, enabling the determination of exhaust flame temperature and pressure in complex environments. This provides measured boundary conditions for computational fluid dynamics simulation models and data support for engine health monitoring. The following description, in conjunction with the accompanying drawings, further clarifies these points.

[0078] See Figure 1 The method for determining the tail flame temperature and pressure based on OH free radicals provided by this invention includes the following steps:

[0079] Step 100: Obtain spectral data of the engine exhaust flame;

[0080] Traditional contact sensors' platinum-based electrode materials are prone to oxidation and ablation in oxygen-rich environments, making continuous temperature measurement difficult. To address this issue, this invention employs a non-contact OH free radical spectroscopy testing system to acquire spectral data of engine exhaust plumes. Figure 2As shown, the non-contact OH radical spectroscopy testing system includes a focusing lens 1, a fiber optic probe 2, a high-resolution spectrometer 3, and a computer 4 connected in sequence. The focusing lens 1 and the fiber optic probe 2 are installed at a preset distance from the exhaust plume emitted by the nozzle 5. The focusing lens 1 and the fiber optic probe 2 are fixed by bolts or other connecting components. The focusing lens efficiently collects and focuses the light signal emitted from the acquisition area onto the fiber optic probe 2. The fiber optic probe efficiently and with low loss transmits the focused light signal to the high-resolution spectrometer. The high-resolution spectrometer transmits the light signal to the computer over a long distance via photoelectric conversion, thereby obtaining the spectral data of the engine exhaust plume. The preset distance can be greater than or equal to 8 meters, ensuring a safe distance between the fiber optic probe and the focusing lens and the liquid rocket engine. This avoids interference from the supersonic flow field of the exhaust plume and damage from high temperatures, thereby improving the accuracy of the acquired data, extending the service life of the fiber optic probe and the focusing lens, and enhancing long-term working capability. Multiple sets of focusing lenses, fiber optic probes, and high-resolution spectrometers can be set up to collect spectral data from different locations of the exhaust plume.

[0081] Step 200: Preprocess and extract the spectral data to obtain the target rotation spectrum of the OH radical, and determine the spectral line intensity of the target rotation spectrum;

[0082] Specifically, step 200 can be implemented based on the following steps:

[0083] Step 210: Perform denoising and baseline correction on the spectral data to obtain spectral correction data;

[0084] Denoising and baseline correction mainly involve removing background noise.

[0085] Step 220: Extract the target rotation spectral line of the same vibration band within the target wavelength from the spectral correction data;

[0086] OH radicals are reactive oxygen species formed by the loss of electrons from hydroxyl radicals. They are important intermediate products in high-temperature combustion processes and exhibit strong emission characteristics in the ultraviolet band, making their signals easy to detect and highly sensitive. Under specific conditions, OH radicals undergo electronic transitions and release photons. The emission spectrum generated by this transition is concentrated in the near-outer light to visible light region, with the main wavelength range being 306-325 nm. Therefore, the center wavelength of the target wavelength can be any value within 306-325 nm, such as 306 nm and 307 nm, and the range can be set as needed, for example, within ±1 nm. The same vibrational band refers to a set of spectral lines in which the vibrational energy number changes in the same way during the electronic transition of the molecule. For example, multiple target rotational spectral lines of the same vibrational band of OH radicals near 306 nm can be selected, such as the rotational quantum numbers J=5, 6, 7, 8, 9 of the Q1 branch and the rotational quantum numbers J=8, 9 of the R1 branch. Selecting a reference for rotating spectral lines: Choose isolated curves to avoid curve overlap; cover a wide range of J values, such as J=5-15, to provide fitting accuracy.

[0087] Step 230: Integrate the intensity of each target rotation spectral line by area to obtain the integrated intensity of the target rotation spectral line;

[0088] Specifically, formula (1) is used:

[0089] (1)

[0090] The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line.

[0091] in, For integral intensity, Rotate the spectral line to the target. The wavelength of the target rotation spectrum.

[0092] Step 240: Normalize the integrated intensity of the target rotation spectral line to obtain the spectral intensity of the target rotation spectral line.

[0093] Step 300: Determine the tail flame temperature based on the spectral line intensities using the Boltzmann diagram method;

[0094] Within the same vibrational band, the line intensities of different rotational quantum numbers J follow a Boltzmann distribution. Therefore, spectral lines of different rotational quantum numbers within the same vibrational band can be selected, and the temperature effect can be decoupled by utilizing the dependence of their line intensity on temperature. Based on the Boltzmann distribution law of molecular rotational energy levels, the temperature T can be inverted by determining the ratio of spectral line intensities of different rotational quantum numbers J within the same vibrational band.

[0095] Step 400: Substitute the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening;

[0096] The OH radical temperature broadening model is constructed based on Gaussian linearity and is used to calculate the full width at half maximum (FWHM) of the temperature broadening.

[0097] Step 500: Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, fit the relationship between the peak height and baseline shift of the target rotation spectrum to obtain the pressure broadening;

[0098] The OH radical temperature-pressure coupling model is constructed based on the OH radical temperature broadening model, the OH radical pressure broadening model, the convolution theorem, and the Faddeeva function. The OH radical temperature-pressure coupling model is a voigt function.

[0099] Step 600: Substitute the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure.

[0100] The OH radical pressure broadening model is based on the Lorentz linear model and is used to calculate the full width at half maximum (FWHM) of the pressure broadening.

[0101] As demonstrated by the above steps, the method for determining the temperature and pressure of the exhaust flame using spectral data in this application has significant advantages such as non-contact and rapid measurement. Secondly, by selecting specific spectral lines, interference from other substances on the measurement results can be reduced, resulting in strong anti-interference capabilities. Thirdly, the spectroscopic method can perform multi-parameter detection, simultaneously acquiring various information such as temperature, pressure, and gas composition. OH radicals, as important intermediate products in high-temperature combustion processes, exhibit strong emission characteristics in the ultraviolet band, making their signals easy to detect and highly sensitive. Furthermore, this method does not require traditional contact sensors, avoiding the interference from the supersonic flow field of the exhaust flame and the damage caused by high temperatures that occur with traditional contact sensors. Furthermore, by constructing an OH radical temperature broadening model, an OH radical pressure broadening model, and an OH radical temperature-pressure coupling model, temperature and pressure parameters can be simultaneously inverted based solely on the target rotation spectrum of the OH radical. This overcomes the limitation of single-spectral techniques, which can only invert a single parameter. In addition, in atomic absorption spectroscopy, spectral line broadening is often caused by both the Doppler effect and the pressure effect. The OH radical temperature-pressure coupling model in this application uses the VOOIT function, which provides high fitting accuracy for such spectra and results in high accuracy of the final calculated pressure.

[0102] based on Figure 1 In addition to the method described herein, this specification also provides some specific implementation methods of this method, which will be described below.

[0103] As an optional approach, step 300 can be implemented based on the following steps:

[0104] Step 310: Use formula (2):

[0105] (2)

[0106] The linear relationship between spectral line intensity and rotational level energy is fitted to determine the slope value;

[0107] in, This is a quantity relating spectral line intensities. For the rotation quantum number The corresponding rotational energy level, For Einstein's emission coefficient, For the rotation quantum number The corresponding rotational level degeneracy, It is a constant; , as well as It can be obtained through standard databases such as NIST, LIFBASE, and HITRAN. Formula (5) is an approximate expression for the spectral line intensity following the Bolman distribution.

[0108] Step 320: Determine the tail flame temperature based on the slope value.

[0109] For example, OH radicals are obtained from the LIFBASE database. Rotational spectral line energy level parameters , as well as The value is used to calculate the corresponding value for each spectral line. and The results are shown in Table 1:

[0110] surface Table of parameters corresponding to -OH free radical

[0111]

[0112] Fit the data based on Table 1 and The linear relationship is: Obtain the slope Thus, the tail flame temperature was calculated to be 2900K.

[0113] As an alternative approach, specifically, step 400 may include the following steps:

[0114] Substitute the value of the tail flame temperature into formula (3):

[0115] (3)

[0116] The temperature broadening was calculated;

[0117] in, For temperature broadening, This refers to the exhaust flame temperature, expressed in Kelvin (K). Molecular mass, unit: kg Boltzmann's constant, , Given the speed of light, c = 3 × 10⁸ m / s, This is the transition center frequency.

[0118] For example, given T=2900K, the molecular weight of OH is... Select the center wavelength If it is 306.4nm, then Calculations yielded .

[0119] As an optional approach, step 500 can be implemented based on the following steps:

[0120] Step 510: Based on the target rotation spectrum and formula (4):

[0121] (4)

[0122] Nonlinear least squares fitting is performed until the sum of squared residuals between the model fitting peak height and the characteristic peak height is less than or equal to a preset threshold, thus completing the fitting and obtaining pressure broadening; the characteristic peak height is the peak height at the characteristic peak wavelength of the target rotation spectrum.

[0123] The temperature-pressure coupling model for OH radicals is shown in equation (5):

[0124] (5)

[0125] The objective function for nonlinear least squares fitting is shown in equation (6):

[0126] (6)

[0127] in, To fit the peak height of the model, The height of the center peak of the target rotation spectrum. For the k-th wavelength The characteristic peak height, k>0, and N is the total number of wavelengths in the target rotation spectrum. For baseline offset, The wavelength of the target rotation spectrum, To transition the center frequency, To broaden the scope of pressure, For temperature broadening, The Fadieva function, whose real part corresponds to the Voigt function, Indicates taking the real part, This is the normalization factor.

[0128] For example, the fitting algorithm can employ typical algorithms such as the Levenberg-Marquard algorithm, and the pressure broadening obtained through fitting is achieved. It is 0.75cm -1 , The wavelength is 306.4 nm, and the center peak height is... 250 counts.

[0129] As an optional approach, step 600 may specifically include the following steps:

[0130] Substitute the value of pressure broadening into formula (3):

[0131] (3)

[0132] The tail flame pressure was calculated;

[0133] in, To broaden the scope of pressure, Pressure broadening at reference temperature and reference pressure, For the tail flame pressure, The tail flame temperature, For reference temperature, For reference pressure, These are empirical parameters.

[0134] For example, n=0.5, pressure broadening It is 0.75cm -1 If the reference pressure is standard atmospheric pressure, then =1 atm, =296K, pressure broadening at reference temperature and reference pressure It is 0.08cm -1 The inversion yielded a tail flame pressure P of 29.3 atm, or 2.9 MPa.

[0135] The embodiments of the present invention can divide functional modules according to the above method examples. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in the embodiments of the present invention is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0136] When dividing each function into modules according to its corresponding function. Figure 3 A schematic diagram of the device for determining the tail flame temperature and pressure based on OH free radicals provided by this invention is shown. Figure 3 As shown, the device includes:

[0137] The spectral data acquisition module 301 is used to acquire the spectral data of the engine exhaust flame;

[0138] The spectral line intensity determination module 302 is used to preprocess and extract the spectral data to obtain the target rotation spectrum of the OH radical and determine the spectral line intensity of the target rotation spectrum.

[0139] The tail flame temperature determination module 303 is used to determine the tail flame temperature based on the spectral line intensity using the Boltzmann diagram method.

[0140] Temperature broadening determination module 304 is used to substitute the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening;

[0141] The pressure broadening determination module 305 is used to fit the relationship between the peak height and baseline shift of the target rotation spectrum based on the target rotation spectrum, the temperature broadening and the OH radical temperature-pressure coupling model to obtain the pressure broadening;

[0142] The tail flame pressure calculation module 306 is used to substitute the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure.

[0143] Optionally, the spectral line intensity determination module 302 may specifically include:

[0144] The correction unit is used to perform noise reduction and baseline correction processing on the spectral data to obtain spectral correction data.

[0145] The spectral line extraction unit is used to extract the target rotational spectral line of the same vibrational band within the target wavelength from the spectral correction data.

[0146] An integration calculation unit is used to perform area integration on the intensity of each target rotation spectral line to obtain the integrated intensity of the target rotation spectral line.

[0147] The normalization unit is used to normalize the integral intensity of the target rotation spectral line to obtain the spectral line intensity of the target rotation spectral line.

[0148] Optionally, the exhaust flame temperature determination module 303 can be specifically used for:

[0149] Formula used:

[0150]

[0151] The linear relationship between spectral line intensity and rotational level energy is fitted to determine the slope value;

[0152] in, This is a quantity relating spectral line intensities. For the rotation quantum number The corresponding rotational energy level, For Einstein's emission coefficient, For the rotation quantum number The corresponding rotational level degeneracy, It is a constant;

[0153] The exhaust temperature is determined based on the slope value.

[0154] Optionally, the temperature broadening determination module 304 can be specifically used for:

[0155] Substitute the value of the exhaust flame temperature into the formula:

[0156]

[0157] The temperature broadening was calculated;

[0158] in, For temperature broadening, The tail flame temperature, Molecular mass Boltzmann's constant, At the speed of light, This is the transition center frequency.

[0159] Optionally, the pressure broadening determination module 305 can be specifically used for:

[0160] Based on the target rotation spectrum and formula:

[0161]

[0162]

[0163] Nonlinear least squares fitting is performed until the sum of squared residuals between the model fitting peak height and the characteristic peak height is less than or equal to a preset threshold, thus completing the fitting and obtaining pressure broadening; the characteristic peak height is the peak height at the characteristic peak wavelength of the target rotation spectrum.

[0164] in, To fit the peak height of the model, The height of the center peak of the target rotation spectrum. This is a temperature-pressure coupling model for OH free radicals. For baseline offset, The wavelength of the target rotation spectrum, The center wavelength, To broaden the scope of pressure, For temperature broadening, For Fadieva function, Indicates taking the real part, It is an imaginary number.

[0165] Optionally, the exhaust pressure calculation module 306 can be specifically used for:

[0166] Substitute the value of the pressure broadening into the formula:

[0167]

[0168] The tail flame pressure was calculated;

[0169] in, To broaden the scope of pressure, Pressure broadening at reference temperature and reference pressure, For the tail flame pressure, The tail flame temperature, For reference temperature, For reference pressure, These are empirical parameters.

[0170] Optionally, the spectral data acquisition module 301 may specifically include:

[0171] A non-contact OH radical spectroscopy testing system construction unit is used to construct a non-contact OH radical spectroscopy testing system. The non-contact OH radical spectroscopy testing system includes a focusing lens, an optical fiber probe, a high-resolution spectrometer, and a computer connected in sequence. The focusing lens and the optical fiber probe are installed at a preset distance from the engine exhaust flame.

[0172] The acquisition unit is used to start the non-contact OH radical spectral testing system to acquire spectral data of the engine exhaust flame.

[0173] Optionally, the integration calculation unit can be specifically used for:

[0174] Formula used:

[0175]

[0176] The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line.

[0177] in, For integral intensity, Rotate the spectral line to the target. The wavelength of the target rotation spectrum.

[0178] The above mainly describes the solutions provided by the embodiments of the present invention from the perspective of the interaction between various modules. It is understood that, in order to achieve the above functions, it includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, the present invention can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0179] When using the corresponding integrated unit Figure 4 A schematic diagram of the device for determining the tail flame temperature and pressure based on OH free radicals provided by this invention is shown. Figure 4 As shown, the device includes:

[0180] Communication unit / communication interface, used to acquire spectral data of engine exhaust flame;

[0181] A processing unit / processor is used to preprocess and extract the spectral data to obtain the target rotation spectrum of OH radicals and determine the spectral line intensity of the target rotation spectrum;

[0182] The tail flame temperature was determined using the Boltzmann diagram method based on the intensity of the spectral lines.

[0183] Substituting the tail flame temperature into the OH radical temperature broadening model, the temperature broadening was calculated.

[0184] Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening;

[0185] Substituting the pressure broadening into the OH radical pressure broadening model, the tail flame pressure was calculated.

[0186] like Figure 4 As shown, the processor described above can be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits used to control the execution of the program of the present invention. The communication interface described above can be one or more. The communication interface can use any transceiver-like device for communicating with other devices or communication networks.

[0187] like Figure 4 As shown, the terminal device described above may also include a communication line. The communication line may include a path for transmitting information between the components described above.

[0188] Optional, such as Figure 4 As shown, the terminal device may further include a memory. The memory stores computer execution instructions for implementing the present invention, and the execution is controlled by a processor. The processor executes the computer execution instructions stored in the memory, thereby implementing the method provided in the embodiments of the present invention.

[0189] like Figure 4 As shown, the memory can be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited to these. The memory can exist independently and be connected to the processor via communication lines. The memory can also be integrated with the processor.

[0190] Optionally, the computer execution instructions in the embodiments of the present invention may also be referred to as application code, and the embodiments of the present invention do not specifically limit this.

[0191] In a specific implementation, as one example, such as Figure 4 As shown, a processor may include one or more CPUs, such as Figure 4 CPU0 and CPU1 in the CPU.

[0192] In a specific implementation, as one example, such as Figure 4 As shown, the terminal device may include multiple processors, such as Figure 4 The processors in the system. Each of these processors can be a single-core processor or a multi-core processor.

[0193] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a terminal, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); or it can be a semiconductor medium, such as a solid-state drive (SSD).

[0194] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0195] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for determining the temperature and pressure of an OH radical based plume, characterized in that, include: Acquire spectral data of the engine exhaust flame; The spectral data is preprocessed and extracted to obtain the target rotation spectrum of the OH radical, and the spectral line intensity of the target rotation spectrum is determined. The tail flame temperature was determined using the Boltzmann diagram method based on the intensity of the spectral lines. Substituting the tail flame temperature into the OH radical temperature broadening model, the temperature broadening was calculated. Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening; Substituting the pressure broadening into the OH radical pressure broadening model, the tail flame pressure was calculated.

2. The method of claim 1, wherein the OH-radical-based afterflame temperature and pressure determination method is characterized by, The preprocessing and extraction of the spectral data to obtain the target rotation spectrum of the OH radical, and the determination of the spectral line intensity of the target rotation spectrum, include: The spectral data is denoised and baseline corrected to obtain spectral corrected data. Extract the target rotational spectral line of the same vibrational band within the target wavelength from the spectral correction data; The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line. The integrated intensity of the target rotation spectral line is normalized to obtain the spectral line intensity of the target rotation spectral line.

3. The method of claim 1, wherein the OH-radical-based afterflame temperature and pressure determination method is characterized by, The method of determining the exhaust flame temperature based on the spectral line intensity using the Boltzmann diagram includes: Formula used: ； The linear relationship between spectral line intensity and rotational level energy is fitted to determine the slope value; wherein is the spectral line intensity relation, is the rotational quantum number is the corresponding rotational energy level energy, is the Einstein emission coefficient, is the rotational quantum number is the corresponding rotational energy level degeneracy, is a constant; is the plume temperature, is the Boltzmann constant; The exhaust temperature is determined based on the slope value.

4. The method for determining the tail flame temperature and pressure based on OH free radicals according to claim 1, characterized in that, The step of substituting the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening includes: Substitute the value of the exhaust flame temperature into the formula: ； The temperature broadening was calculated; in, For temperature broadening, The tail flame temperature, Molecular mass Boltzmann's constant, At the speed of light, This is the transition center frequency.

5. The method for determining the tail flame temperature and pressure based on OH free radicals according to claim 1, characterized in that, Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening, including: Based on the target rotation spectrum and formula: ； ； Nonlinear least squares fitting is performed until the sum of squared residuals between the model fitting peak height and the characteristic peak height is less than or equal to a preset threshold, thus completing the fitting and obtaining pressure broadening; the characteristic peak height is the peak height at the characteristic peak wavelength of the target rotation spectrum. in, To fit the peak height of the model, The height of the center peak of the target rotation spectrum. This is a temperature-pressure coupling model for OH free radicals. For baseline offset, The wavelength of the target rotation spectrum, The center wavelength, To broaden the scope of pressure, For temperature broadening, For Fadieva function, Indicates taking the real part, It is an imaginary number.

6. The method for determining the tail flame temperature and pressure based on OH free radicals according to claim 1, characterized in that, The step of substituting the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure includes: Substitute the value of the pressure broadening into the formula: ； The tail flame pressure was calculated; in, To broaden the scope of pressure, Pressure broadening at reference temperature and reference pressure, For the tail flame pressure, The tail flame temperature, For reference temperature, For reference pressure, These are empirical parameters.

7. The method for determining the tail flame temperature and pressure based on OH free radicals according to claim 1, characterized in that, The acquisition of spectral data of the engine exhaust flame includes: A non-contact OH radical spectral testing system was constructed. The non-contact OH radical spectral testing system includes a focusing lens, an optical fiber probe, a high-resolution spectrometer, and a computer connected in sequence. The focusing lens and the optical fiber probe are installed at a preset distance from the engine exhaust flame. The non-contact OH radical spectral testing system was activated to collect spectral data of the engine exhaust flame.

8. The method for determining the tail flame temperature and pressure based on OH free radicals according to claim 2, characterized in that, The step of integrating the intensity of each target rotation spectral line by area to obtain the integrated intensity of the target rotation spectral line includes: Formula used: ； The intensity of each target rotation spectral line is integrated by area integration to obtain the integrated intensity of the target rotation spectral line. in, For integral intensity, Rotate the spectral line to the target. The wavelength of the target rotation spectrum.

9. A device for determining the temperature and pressure of a tail flame based on OH free radicals, characterized in that, include: The spectral data acquisition module is used to acquire the spectral data of the engine exhaust flame; The spectral line intensity determination module is used to preprocess and extract the spectral data to obtain the target rotation spectrum of the OH radical and determine the spectral line intensity of the target rotation spectrum. The exhaust flame temperature determination module is used to determine the exhaust flame temperature based on the spectral line intensity using the Boltzmann diagram method. The temperature broadening determination module is used to substitute the tail flame temperature into the OH radical temperature broadening model to calculate the temperature broadening; The pressure broadening determination module is used to fit the relationship between the peak height and baseline shift of the target rotation spectrum based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model to obtain the pressure broadening; The tail flame pressure calculation module is used to substitute the pressure broadening into the OH radical pressure broadening model to calculate the tail flame pressure.

10. A device for determining the temperature and pressure of a tail flame based on OH free radicals, characterized in that, include: Communication unit / communication interface, used to acquire spectral data of engine exhaust flame; A processing unit / processor is used to preprocess and extract the spectral data to obtain the target rotation spectrum of OH radicals and determine the spectral line intensity of the target rotation spectrum; The tail flame temperature was determined using the Boltzmann diagram method based on the intensity of the spectral lines. Substituting the tail flame temperature into the OH radical temperature broadening model, the temperature broadening was calculated. Based on the target rotation spectrum, the temperature broadening, and the OH radical temperature-pressure coupling model, the relationship between the peak height and baseline shift of the target rotation spectrum is fitted to obtain the pressure broadening; Substituting the pressure broadening into the OH radical pressure broadening model, the tail flame pressure was calculated.

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