In this paper, the temperature of butane flame is measured by Thin Filament Pyrometer(TFP). The luminous length of butane flame is about 80mm. The high temperature resistant material tungsten-rhenium wire is placed into the flame, the diameter of tungsten-rhenium wire is 0.1mm, 0.25mm, 0.5mm.A scientific sCMOS camera calibrated by emissivity calibration experiment was used to measure the radiance of tungsten-rhenium filament, and Planck's blackbody radiation law was used to calculate the temperature of the filament., so as to get the temperature of the butane flame. The results show that the highest temperature of the butane flame measured by the filament pyrometer is 1122K.Standard armored K-type thermocouple is used to verify the experimental accuracy, and the measurement error between the calculated value and the standard value is less than 5%. The experimental results of butane combustion show that this method can be applied to similar temperature measurement.
Laser induced breakdown spectroscopy (LIBS) is an analysis technique based on laser plasma atomic emission spectroscopy. Because of its speed, non-destructive and high sensitivity, it is widely used in various fields. In order to study the laser-induced breakdown spectra of heavy metals and non-metal elements in the soil, and solve the problem of low accuracy of LIBS quantitative analysis due to spectral baseline drift, an Adaptive Iterative Re-weighted Partial Least Squares (air-PLS) baseline correction method is proposed to improve the accuracy of LIBS quantitative analysis. In this paper, 8 kinds of standard soil samples are used, 2 grams of each were extracted and placed in a tableting mold, using a 20MPa hydraulic press to form a smooth sheet with a diameter of 30mm and a thickness of 3mm for use. The laser energy was set to 30mJ, and the pulse repetition frequency was set to 5Hz. Plasma spectral lines of metal element Mg of different samples were obtained through experiments, and linear PLS was used to model and analyze the original spectrum and the spectrum after baseline correction respectively. Experimental results show that the accuracy of LIBS quantitative analysis is greatly improved after baseline correction. After using the method described in this article for baseline correction, the coefficient of determination R2 increased from 0.9553 to 0.9858, and the root mean square error RMSEC decreased from 1.5610 to 0.8571. The accuracy of LIBS quantitative analysis has been significantly improved. The study of this technology can provide guidance for the quantitative analysis of Mg and other elements in the soil.
Because of the influence of extreme environment such as high temperature, high pressure, high speed and high impact, it is difficult to measure the transient high temperature of high temperature flame in the explosion field accurately. This kind of transient temperature measurement is often accompanied by high pressure or high speed air flow, most of which are non repeatable one-time processes. Therefore, poor measurement conditions, high technical difficulty and inaccurate temperature measurement are all problems that can not be ignored. At the same time, there are high requirements for the reliability and data acquisition rate of the system. In this paper, we use the alcohol burner to operate in the laboratory, use the infrared thermal imager to collect the temperature of the nozzle after the alcohol is fully burned, adjust the flame emissivity and collect the temperature of the flame, and export the collected flame pictures for data analysis. By using modern simulation software, combining hydrodynamics and software simulation, the turbulent k-ε model is applied to simulate the single nozzle high temperature flame through the material transfer and fluid heat transfer in the combustion process. Comparing the simulation results with the experimental data, it can be seen that the simulation results well reproduce the experimental parameters such as the velocity and pressure of the nozzle and the temperature of the exit flame, including the mass fraction of each material after combustion, which is roughly similar to the temperature field collected by the infrared thermal imager, providing an efficient and more accurate verification means for the detection and reconstruction of multiple temperature fields in the future.
The non-contact temperature measurement method has been widely used in the field of temperature measurement. Based on element energy spectrum excitation and Laser induced breakdown spectroscopy (LIBS) mechanism, through the analysis of the intrinsic physical properties of the object under test, the excitation characteristic spectrum of heated internal elements in high temperature field was explored, in order to select effective detection wavelength of non-contact detection module, and designed a narrow-band filter module to compress the detection band. The accuracy of optical detection model can be improved. By preparing and analyzing samples of various elements, K and Cu were selected as external doping elements, the characteristic wavelength of K and Cu can be used as an effective detection wavelength, the CMOS camera was used to detect the burner flame under the different wavelengths and obtained the flame image. The experimental results validate the feasibility of the method.
Laser induced breakdown spectroscopy(LIBS)was an analysis technique based on laser plasma atomic emission spectroscopy. Because of its fast, non-destructive and high sensitivity, it was widely used in various fields. In order to study the laser induced breakdown spectra of heavy metal element and non-metal element in the soil, A method based on traditional laser induced breakdown spectroscopy (LIBS) technology with cavity constraints was proposed to improve the plasma emission spectrum. In this paper, the cylindrical aluminum cavity with the diameter of 2mm, 3mm, 4mm, 5mm, and 6mm at the same thickness were placed on the surface of the soil sample, the laser energy was set to 30mJ, and the pulse repetition frequency was set to 5Hz. The plasma lines of heavy metal element (Ba II 455.4nm) and non-metal element (Si I 288.158nm) under different cavity constraints were obtained, and the enhancement factor and signal-to-noise ration(SNR)of these two characteristic lines under different diameter cavity constraints were studied. The experimental results show that the plasma line has a certain enhancement under the condition of cavity restriction than without cavity restriction. As the diameter of the circular cavity increases, the enhancement factor tends to increase first and then decrease, and the spectral enhancement effect is the best when the diameter is 5mm. The change trend of the signal-to-noise ratio is consistent with the enhancement factor, which reaches the maximum when the cavity diameter is 5 mm. The study of this technology can provide guidance for the qualitative analysis of Ba and Si elements in soil.
CO2 laser is a molecular laser that can excite laser beams in the far infrared range of 9~11μm. It works in both pulsed and continuous modes. Time constant is an important index to ensure thermoelectric dynamic performance. In order to verify that the dynamic performance of WRe film thermocouple is better than that of ordinary K-type thermocouple, it has a fast response and a short time constant. The tset system consists of CO2 laser, shieldingbox, elliptic mirror, thermocouple, infrared detector and acquisition circuit. A pulsed CO2 laser with a laser wavelength of 10.6 μm is used as the excitation heat source to act on the thermal junction. Time constant dynamic test was carried out on tungsten-rhenium thin film thermocouples WRe3/25 and ordinary K-type thermocouples with a thickness of micron.The time constant testing method of thermocouple can be intuitively obtained by making a tangent line at the highest point of the response curve, and the intersection point of the tangent line and the horizontal axis of the coordinate is the time constant value of the thermocouple. The experimental results show that the WRe film thermocouple has a faster response time and a smaller time constant. Therefore, the conclusion that this thin film thermocouple has better dynamic characteristics than the ordinary K type thermocouple is verified.
Based on the double line of atomic emission temperature measurement technology, combined with storage measurement technology, the photoelectric thermometer was designed by using Y-type fiber, narrow band filter, silicon photomultiplier tube (SiPM). Record the temperature value measured by the photo thermometer and the temperature value displayed on the LCDpanel of the chamber furnace, and obtain the static sensitivity coefficient K by the least squares method. The temperature indicated by the high-temperature box furnace is used as the standard temperature value. A static calibration system is built. The temperature of the heated copper sheet was measured using a statically calibrated photometric temperature measurement system and compared with the measurement results of the M5 infrared. The experimental results verify the feasibility of temperature measurement system. The research work in this paper has important reference value for the development of temperature measurement technology of atomic emission spectroscopy.
When analyzing high-luminance objects such as plasma and high-temperature fireballs, in order to enhance the image of highlight targets, a false-color-depth method, similar to the reduction of the color depth, is proposed. Multiple false-color-depth figures with low color depth were acquired by this method and then multiply these low-color-depth figures to get a final figure. The processed figures, as a result, show that the low-brightness background of the image can be effectively attenuated by this simple algorithm, and the preliminary gray-level image segmentation can be performed on the high-luminance target.
In order to enhance the emission spectrum of plasma in laser induced breakdown spectroscopy (LIBS), magnetic fields with different intensities were applied around the plasma to investigate its enhancement. Adjust the laser energy to 60mJ, change the magnetic field strength, use the traditional LIBS, magnetic field enhanced LIBS (MF-LIBS) for laser-induced breakdown of pure copper samples, to obtain the spectral comparison of characteristic line of trace elements (Bi I 206.16 nm) under different constraints and analysis of its enhancement mechanism. The experimental results show that the magnetic field of 153mT will reduce the spectral intensity, the 20mT, 50mT, and 90mT magnetic fields will enhance the spectral intensity. The stronger the magnetic field, the better the spectral enhancement effect, but the enhancement effect of 20mt is not obvious. The Lorenz fitting coefficient of the line is the lowest when magnetic field is not applied, the fitting coefficient gradually increases at 153mT, 20mT, 50mT and 90mT magnetic fields, indicating that the line shape is closer to the Lorentz type. And the spectral line width are also larger and reaches the largest when the 90 mT magnetic field is applied.
Laser induced breakdown spectroscopy (LIBS) is an analytical technique that has received increasing attention due to many applications. A continuous background will cause baseline drift, which significantly affects spectral analysis. In this paper, an automated baseline correction method based on iterative morphological operations and weighted penalized least squares method is used for LIBS spectral baseline correction. This method can correct the estimated baseline. Experiments on simulated spectra and actual laser-induced breakdown of stainless steel sample LIBS data show that this method is accurate and flexible when used for LIBS spectral baseline correction.
Aimed to the testing requirement of the transient high temperature in the bore of barrel weapon, which has the problems of high temperature, high pressure, high overload and narrow adverse environment, the photoelectric pyrometer was researched based on the temperature measurement technology of double line of atomic emission spectrum and storage measurement technology, which used silicon photomultiplier. Al I 690.6nm and 708.5nm were selected as the temperature measurement element spectral lines, spectral line intensity was converted into a voltage value by silicon photomultiplier, the temperature was obtained through the ratio of two spectrum lines. The temperature is measured by the photoelectric thermometer and the infrared thermometer when heating aluminum by oxyhydrogen flame, and the relative error was 1.75%. Results show the temperature dependence of the two methods is better, and prove the feasibility of the method.
KEYWORDS: Aluminum, Temperature metrology, Combustion, Spectroscopy, Chemical species, Oxygen, Thermodynamics, Data acquisition, Databases, Thermometry
In the case of conventional contact temperature measurement, there is a delay phenomenon and high temperature resistant materials limitation. By using the faster response speed and theoretically no upper limit of the non-contact temperature method, the measurement system based on the principle of double line atomic emission spectroscopy temperature measurement is put forward, the structure and theory of temperature measuring device are introduced. According to the atomic spectrum database (ASD), Aluminum(Al) I 690.6 nm and Al I 708.5 nm are selected as the two lines in the temperature measurement. The intensity ratio of the two emission lines was measured by a spectrometer to obtain the temperature of Al burning in pure oxygen, and the result compared to the temperature measured by the thermocouple. It turns out that the temperature correlation between the two methods is good, and it proves the feasibility of the method.
KEYWORDS: Temperature metrology, Spectroscopy, Sodium, Combustion, Potassium, Chemical species, Fiber lasers, Standards development, Weapons, Chemical elements
Aimed at the testing requirement of the transient high temperature in explosion field and the bore of barrel weapon, the temperature measurement system of double line of atomic emission spectrum was designed, the method of flame spectrum testing system were used for experimental analysis. The experimental study of wood burning spectra was done with flame spectrum testing system. The measured spectra contained atomic emission spectra of the elements K, Na, and the excitation ease of two kinds atomic emission spectra was analyzed. The temperature was calculated with two spectral lines of K I 766.5nm and 769.9nm. The results show that, compared with Na, the excitation temperature of K atomic emission spectra is lower. By double line method, the temperature of wood burning is 1040K, and error is 3.7%.
Thermal inertia and finite heat conduction make the acquired temperature from temperature sensor be not reliable
enough. So, it is necessary to make a dynamic calibration to the sensor. The frequency-response characteristics of high
speed radiation thermometer surpass that of the temperature sensor; therefore it can be used as the reference value to
calibrate the latter and let system error is corrected. The traceable dynamic calibration method is used to calibrate
CHAL-010 thermocouple (manufactured by OMEGA Company). The thermocouple's time constant as well as error
correction value of dynamic temperature measurement is obtained from it. The traceability is accomplished successfully
through unbroken chain of comparisons with appropriate standard at the system.
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