Calibration method of plume flame component measurement system

Abstract

The invention discloses a calibration method for a plume flame component measurement system. The calibration method comprises the following steps: step 1, preparing a light source, a CCD (Charge Coupled Device) optical fiber spectrometer, a computer host and a display screen; step 2, performing collimation and focusing adjustment on the light source to change light emitted by the light source into parallel light, and then calibrating the light source by using a high-temperature black body; a light source with a characteristic spectrum, such as a mercury lamp spectrum, is adopted as a calibration light source, the corresponding pixel point position of a characteristic spectrum line on a CCD is found, matching of CCD pixels and wavelengths is achieved through algorithms such as cubic polynomial fitting, wavelength calibration is completed, radiation of a light source calibration light source in a unit solid angle is calculated and described through a Rank formula, and the calibration accuracy is improved. The method comprises the following steps of: calculating radiation data of a light source, calculating response rates R at different wavelengths according to the calculated radiation data of the light source, thereby obtaining a response curve of the spectrograph, obtaining a wavelength response curve of the spectrograph, obtaining normalized intensity of a measured spectrum, and further carrying out various measurements and analyses related to the intensity of a spectral line.

Description

Technical Field

[0001] The invention relates to the technical field of plume component measurement, and in particular to a plume component measurement system calibration method. Background Art

[0002] Liquid rocket engines are usually made of metal. When the engine is worn, ablated, or otherwise damaged, the metal impurities that enter the plume emit sufficiently strong spectra at high temperatures in the flow field. Even when the concentration of the components is relatively low, these emission spectra can be measured. Therefore, spectral analysis technology is used to measure the plume composition. The plume spectrum measurement technology is to achieve qualitative analysis of the elements by identifying the characteristic spectra excited by the metal impurity elements in the Mach disk. Before measurement, the metal components of the main engine components are obtained, the plume composition is analyzed, and a plume spectrum measurement system is developed to obtain the characteristic spectra of the metal elements. However, the current measurement of the plume spectrum must be based on the analysis of the theoretical wavelength of the metal elements, and the radiation spectrum generated by these metal impurities is a nonlinear function of temperature, concentration, and pressure. When the engine is operating at high temperatures, the wavelength of the radiation spectrum will change, and it is impossible to accurately achieve qualitative measurement of the elements in the plume. There is a lack of wavelength calibration means for the elements at high temperatures, and there is a lack of quantitative standards for determining the concentration of the elements. There is no effective calibration method, so it is impossible to perform more accurate quantitative analysis through the test data of the plume spectrum measurement to analyze the internal health of the engine. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a method for calibrating a plume composition measurement system, which solves the problems raised by the above-mentioned background technology.

[0004] To achieve the above objectives, the present invention is implemented by the following technical solutions: A method for calibrating a plume component measurement system comprises the following steps: Step 1: Prepare the light source, CCD fiber spectrometer, computer host and display screen; Step 2: collimate and focus the light source to make the light emitted by the light source become parallel light, and then calibrate the light source using a high-temperature black body; Step 3, matching the CCD photosensitive element in the CCD fiber optic spectrometer with the light irradiated by the light source, and then connecting the CCD fiber optic spectrometer and the CCD photosensitive element through an optical fiber; Step 4: Connect the CCD fiber optic spectrometer to a computer host via a USB data cable, and connect the host to a display screen; Step 5, turn on the light source, the light emitted by the light source irradiates the CCD photosensitive element, the CCD photosensitive element transmits the received light source light to the CCD fiber optic spectrometer through the optical fiber, the CCD fiber optic spectrometer converts the light source light signal of the received light into an electrical signal, and then transmits it to the computer through the USB data cable, the computer performs data calculation and processing, and then sends it to the display for display; Step 6: Find the position of the corresponding pixel point in the CCD pixel displayed on the display screen by the spectrum line of the light source, and achieve the matching of CCD pixel and wavelength through algorithms such as cubic polynomial fitting to complete the calibration of CCD wavelength; Step 7. Use Rank's formula to calculate the radiation per unit solid angle of the light source calibration light source:

[0005] Where c is the speed of light, h is Planck's constant, k is Boltzmann's constant, T is the temperature of the black body, and the spectral line intensity of the light source measured by the spectrometer at a certain frequency is , and the radiance of the standard light source at this frequency calculated using the above formula is , then the response rate of the spectrometer is as follows:

[0006] By calculating the response rate R at different wavelengths, we can get the response curve of the spectrometer. Once we get the wavelength response curve of the spectrometer, we can get the normalized intensity of the measured spectrum, and then we can carry out various measurements and analyses related to the spectral line intensity.

[0007] Preferably, the light source is a mercury lamp.

[0008] Preferably, the light source and the CCD photosensitive element are packaged together using a sealed shell.

[0009] Preferably, the method of USB data line transmission in step 4 is the following steps: Step 41: Set at least four USB interrupt endpoints. Step 42, define a first global variable M and assign an initial value of 0, or other values ​​as agreed with the receiving party; define an update formula S: M=M+1, as agreed with the receiving party; define a split mark length and number data, wherein the split mark length is used to mark the starting position of the target data to be split; Step 43, split the target data from the front to the back according to the split mark length to obtain a section of valid data, wherein the length of the valid data does not exceed the difference between the length of the interrupt endpoint and the length of the numbered data; and fill M into the numbered data; Step 44, initiating a USB IN request to the USB interrupt endpoint, each USB interrupt endpoint receives a data packet, the data packet including valid data and serial number data; after each data packet is received, initiating a USB IN request again to the USB interrupt endpoint that received the data packet; Step 45: define a storage area, and store all data packets received by the USB interrupt endpoint in the storage area in order according to the serial number data. Step 46: The application layer reads valid data from the storage area in the order of the numbered data.

[0010] Beneficial Effects The present invention provides a method for calibrating a plume composition measurement system. Compared with the prior art, it has the following beneficial effects: 1. The plume composition measurement system calibration method adopts a light source with a characteristic spectrum (such as a mercury lamp spectrum) as a calibration light source, finds the pixel position corresponding to the characteristic spectrum line on the CCD, and realizes the matching of CCD pixels and wavelengths through algorithms such as cubic polynomial fitting, completes the calibration of the wavelength, and uses the Rank formula to calculate and describe the radiation of the calibration light source within a unit solid angle. Then, the response rate R at different wavelengths is calculated through the calculated light source radiation data, and the response curve of the spectrometer can be obtained. After obtaining the wavelength response curve of the spectrometer, the normalized intensity of the measured spectrum can be obtained, and various measurements and analyses related to the spectral line intensity can be carried out.

[0011] 2. The plume component measurement system calibration method is to split the USB transmission data into multiple valid data segments from the front to the back according to the split mark length, and the length of each valid data segment does not exceed the difference between the length of the interrupt endpoint and the length of the numbered data, and M is filled in the numbered data, so that it is convenient to find the position where the splitting needs to start each time the data packet is split, without re-splitting or missing, and each USB interrupt endpoint receives a data packet, and the data packet includes valid data and numbered data; after each data packet is received, a USB IN request is initiated again to the USB interrupt endpoint that receives the data packet, and the received data packet is sequentially stored in the storage area according to the numbered data, and the application layer reads the valid data from the storage area according to the order of the numbered data, so that the errors of data transmission are reduced and the accuracy of the data is improved. Thereby improving the accuracy of calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the work flow chart of the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] See also Figure 1 The present invention provides a technical solution: a method for calibrating a plume component measurement system, comprising the following steps: Step 1: Prepare the light source, CCD fiber spectrometer, computer host and display screen; Step 2: collimate and focus the light source to make the light emitted by the light source become parallel light, and then calibrate the light source using a high-temperature black body; Step 3, matching the CCD photosensitive element in the CCD fiber optic spectrometer with the light irradiated by the light source, and then connecting the CCD fiber optic spectrometer and the CCD photosensitive element through an optical fiber; Step 4: Connect the CCD fiber optic spectrometer to a computer host via a USB data cable, and connect the host to a display screen; Step 5, turn on the light source, the light emitted by the light source irradiates the CCD photosensitive element, the CCD photosensitive element transmits the received light source light to the CCD fiber optic spectrometer through the optical fiber, the CCD fiber optic spectrometer converts the light source light signal of the received light into an electrical signal, and then transmits it to the computer through the USB data cable, the computer performs data calculation and processing, and then sends it to the display for display; Step 6: Find the position of the corresponding pixel point in the CCD pixel displayed on the display screen by the spectrum line of the light source, and achieve the matching of CCD pixel and wavelength through algorithms such as cubic polynomial fitting to complete the calibration of CCD wavelength; Step 7. Use Rank's formula to calculate the radiation per unit solid angle of the light source calibration light source:

[0015] Where c is the speed of light, h is Planck's constant, k is Boltzmann's constant, T is the temperature of the black body, and the spectral line intensity of the light source measured by the spectrometer at a certain frequency is , and the radiance of the standard light source at this frequency calculated using the above formula is , then the response rate of the spectrometer is as follows:

[0016] By calculating the response rate R at different wavelengths, the response curve of the spectrometer can be obtained. By obtaining the wavelength response curve of the spectrometer, the normalized intensity of the measured spectrum can be obtained, and then various measurements and analyses related to the spectral line intensity can be carried out. The light source is a mercury lamp, which has strong spectral lines in the near-ultraviolet region, and the spectral lines related to the metal elements studied are located near the near-ultraviolet region. The light source and the CCD photosensitive element are packaged together using a sealed shell to reduce the influence of external light on calibration; A light source with a characteristic spectrum (such as a mercury lamp spectrum) is used as the calibration light source, and the corresponding pixel position of the characteristic spectral line on the CCD is found. The matching of CCD pixels and wavelengths is achieved through algorithms such as cubic polynomial fitting, and the wavelength calibration is completed. The Rank formula is used to calculate and describe the radiation of the calibration light source within a unit solid angle. The response rate R at different wavelengths is calculated using the calculated light source radiation data, and the response curve of the spectrometer can be obtained. Once the wavelength response curve of the spectrometer is obtained, the normalized intensity of the measured spectrum can be obtained, and various measurements and analyses related to the spectral line intensity can be carried out.

[0017] Furthermore, the method of USB data line transmission in step 4 is as follows: Step 41: Set at least four USB interrupt endpoints. Step 42, define a first global variable M and assign an initial value of 0, or other values ​​as agreed with the receiving party; define an update formula S: M=M+1, as agreed with the receiving party; define a split mark length and number data, wherein the split mark length is used to mark the starting position of the target data to be split; Step 43, split the target data from the front to the back according to the split mark length to obtain a section of valid data, wherein the length of the valid data does not exceed the difference between the length of the interrupt endpoint and the length of the numbered data; and fill M into the numbered data; The purpose of defining the split marker length is to facilitate finding the position where the splitting needs to start each time the valid data is split, without re-splitting or missing splits; Step 44, initiating a USB IN request to the USB interrupt endpoint, each USB interrupt endpoint receives a data packet, the data packet including valid data and serial number data; after each data packet is received, initiating a USB IN request again to the USB interrupt endpoint that received the data packet; Step 45, defining a storage area, and storing all data packets received by the USB interrupt endpoints in the storage area in order according to the serial number data; Because the numbered data corresponding to the split valid data is sorted from small to large when the sender sends data, it is also saved in this order to ensure that the first data packet in the storage area is the data packet with the smallest numbered data in the current storage area, which is convenient for the application layer to determine whether to read valid data each time. It should be noted that the storage area only requires the numbered data to be in order from small to large, and does not require continuous and uninterrupted sorting. Similarly, if the numbered data corresponding to the valid data is arranged from large to small when the sender sends data, that is, M decreases, the receiving end needs to arrange it in the order of the data packets in the current storage area from large to small when saving the data packets; Step 46, the application layer reads valid data from the storage area in the order of the numbered data; The USB transmission data is split into multiple valid data segments from the front to the back according to the split mark length, and the length of each valid data segment does not exceed the difference between the length of the interrupt endpoint and the length of the numbered data. M is filled in the numbered data, so that it is convenient to find the position where the splitting needs to start each time the data packet is split, without re-splitting or missing. Each USB interrupt endpoint receives a data packet, and the data packet includes valid data and numbered data; after each data packet is received, a USB IN request is initiated again to the USB interrupt endpoint that receives the data packet, and the received data packet is sequentially stored in the storage area according to the numbered data. The application layer reads the valid data from the storage area according to the order of the numbered data, so as to avoid errors in data transmission and improve the accuracy of the data. Thus, the accuracy of calibration is improved.

[0018] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0019] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by ... does not exclude the existence of other identical elements in the process, method, article or device including the element".

[0020] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calibrating a plume composition measurement system, characterized in that: The following steps are involved: Step 1: Prepare the light source, CCD fiber spectrometer, computer host and display screen; Step 2: collimate and focus the light source to make the light emitted by the light source become parallel light, and then calibrate the light source using a high-temperature black body; Step 3, matching the CCD photosensitive element in the CCD fiber optic spectrometer with the light irradiated by the light source, and then connecting the CCD fiber optic spectrometer and the CCD photosensitive element through an optical fiber; Step 4: Connect the CCD fiber optic spectrometer to a computer host via a USB data cable, and connect the host to a display screen; Step 5, turn on the light source, the light emitted by the light source irradiates the CCD photosensitive element, the CCD photosensitive element transmits the received light source light to the CCD fiber optic spectrometer through the optical fiber, the CCD fiber optic spectrometer converts the light source light signal of the received light into an electrical signal, and then transmits it to the computer through the USB data cable, the computer performs data calculation and processing, and then sends it to the display for display; Step 6: Find the position of the corresponding pixel point in the CCD pixel displayed on the display screen by the spectrum line of the light source, and achieve the matching of CCD pixel and wavelength through algorithms such as cubic polynomial fitting to complete the calibration of CCD wavelength; Step 7. Use Rank's formula to calculate the radiation per unit solid angle of the light source calibration light source: Where c is the speed of light, h is Planck's constant, k is Boltzmann's constant, T is the temperature of the black body, and the spectral line intensity of the light source measured by the spectrometer at a certain frequency is , and the radiance of the standard light source at this frequency calculated using the above formula is , then the response rate of the spectrometer is as follows: By calculating the response rate R at different wavelengths, we can get the response curve of the spectrometer. Once we get the wavelength response curve of the spectrometer, we can get the normalized intensity of the measured spectrum, and then we can carry out various measurements and analyses related to the spectral line intensity.

2. A plume composition measurement system calibration method according to claim 1, characterized in that: The light source is a mercury lamp.

3. A plume composition measurement system calibration method according to claim 2, characterized in that: The light source and the CCD photosensitive element are packaged together using a sealed shell.

4. A plume composition measurement system calibration method according to claim 3, characterized in that: The method for USB data line transmission in step 4 is as follows: Step 41: Set at least four USB interrupt endpoints. Step 42, define a first global variable M and assign an initial value of 0, or other values ​​as agreed with the receiving party; define an update formula S: M=M+1, as agreed with the receiving party; define a split mark length and number data, wherein the split mark length is used to mark the starting position of the target data to be split; Step 43, split the target data from the front to the back according to the split mark length to obtain a section of valid data, wherein the length of the valid data does not exceed the difference between the length of the interrupt endpoint and the length of the numbered data; and fill M into the numbered data; Step 44, initiating a USB IN request to the USB interrupt endpoint, each USB interrupt endpoint receives a data packet, the data packet including valid data and serial number data; after each data packet is received, initiating a USB IN request again to the USB interrupt endpoint that received the data packet; Step 45: define a storage area, and store all data packets received by the USB interrupt endpoint in the storage area in order according to the serial number data. Step 46: The application layer reads valid data from the storage area in the order of the numbered data.

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