The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the ...The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.展开更多
A much better substitutional means is discussed to calculate the flametemperature field with the application of digital image processing technology. Three non-contactingtemperature measurements are used and compared. ...A much better substitutional means is discussed to calculate the flametemperature field with the application of digital image processing technology. Three non-contactingtemperature measurements are used and compared. Such as the traditional two-color temperaturemeasurement, the CCD filtering two-color temperature measurement and the monochromatic temperaturemeasurement. It is indicated that the CCD two-color temperature measurement is not a fully correctmeans because of its poor theoretical basis. The monochromatic temperature measurement acquires arelatively ideal temperature field distribution in spite of needing a reference temperature. Itshould be noted that the Abel transformation applied in the plasma diagnosis is for the first timeintroduced to solve the problem of three-dimensional flame brightness piling.展开更多
Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated wi...Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during com...展开更多
Flame detection is a research hotspot in industrial production,and it has been widely used in various fields.Based on the ignition and combustion video sequence,this paper aims to improve the accuracy and unintuitive ...Flame detection is a research hotspot in industrial production,and it has been widely used in various fields.Based on the ignition and combustion video sequence,this paper aims to improve the accuracy and unintuitive detection results of the current flame detection methods of gasifier and industrial boiler.A furnace flame detection model based on support vector machine convolutional neural network(SCNN)is proposed.This algorithm uses the advantages of neural networks in the field of image classification to process flame burning video sequences which needs detailed analysis.Firstly,the support vector machine(SVM)with better small sample classification effect is used to replace the Softmax classification layer of the convolutional neural network(CNN)network.Secondly,a Dropout layer is introduced to improve the generalization ability of the network.Subsequently,the area,frequency and other important parameters of the flame image are analyzed and processed.Eventually,the experimental results show that the flame detection model designed in this paper is more accurate than the CNN model,and the accuracy of the judgment on the flame data set collected in the gasifier furnace reaches 99.53%.After several ignition tests,the furnace flame of the gasifier can be detected in real time.展开更多
A novel approach to extract flame fronts, which is called the conditioned level-set method with block division （CLSB）, has been developed. Based on a two-phase level-set formulation, the conditioned initialization a...A novel approach to extract flame fronts, which is called the conditioned level-set method with block division （CLSB）, has been developed. Based on a two-phase level-set formulation, the conditioned initialization and region-lock optimiza-tion appear to be beneficial to improve the efficiency and accuracy of the flame contour identification. The original block- division strategy enables the approach to be unsupervised by calculating local self-adaptive threshold values autonomously before binarization. The CLSB approach has been applied to deal with a large set of experimental data involving swirl- stabilized premixed combustion in diluted regimes operating at atmospheric pressures. The OH-PLIF measurements have been carried out in this framework. The resulting images are, thus, featured by lower signal-to-noise ratios （SNRs） than the ideal image; relatively complex flame structures lead to significant non-uniformity in the OH signal intensity; and, the mag- nitude of the maximum OH gradient observed along the flame front can also vary depending on flow or local stoichiometry. Compared with other conventional edge detection operators, the CLSB method demonstrates a good ability to deal with the OH-PLIF images at low SNR and with the presence of a multiple scales of both OH intensity and OH gradient. The robustness to noise sensitivity and intensity inhomogeneity has been evaluated throughout a range of experimental images of diluted flames, as well as against a circle test as Ground Truth （GT）.展开更多
As for the high sustainable solar hydrogen production via water splitting,transition metal doping on an oxide photoanode in photoelectrochemical(PEC)cells has been recognized as an effective approach.However,conventio...As for the high sustainable solar hydrogen production via water splitting,transition metal doping on an oxide photoanode in photoelectrochemical(PEC)cells has been recognized as an effective approach.However,conventional thermal-diffusionmediated doping strategies face the challenge of resolving sluggish catalytic kinetics for oxygen evolution reaction(OER)and its practical utilization for the synthesis of photoanode films.Herein,we introduce facile ultrafast flame-boosted doping of Mo into a BiVO_(4)(FL MoBVO)film for 20 s to achieve an efficient PEC OER.Mo elements in a low-valence state(i.e.,Mo^(6−δ))and Mo^(6+)are successfully doped into the photoanode,which manipulate the energy band structure,facilitating the downward shift of band edges and promoting the surface catalytic kinetics.Consequently,the flame-boosted Mo-doping results in superior PEC performance in a mild environment with neutral electrolyte without introducing any other additives or co-catalysts,where the photocurrent density at 1.23 V_(RHE) under 1 sun illumination in pH 7 is outstandingly enhanced,over 9-fold higher than that of a pristine BiVO_(4).The flame-boosted doping induces significantly enhanced photoexcited charge transport and catalytic reaction kinetics performances simultaneously.Our report provides the effective strategy boosting both the thermodynamic and kinetic charge migration properties for sustainable materials.展开更多
基金supported by the National Natural Science Foundation of China (10902124)
文摘The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.
基金This project is supported by National Natural Science Foundation of China(No.59776005)Provincial Science Foundation of Education Department of Zhejiang, China (No.20000002)
文摘A much better substitutional means is discussed to calculate the flametemperature field with the application of digital image processing technology. Three non-contactingtemperature measurements are used and compared. Such as the traditional two-color temperaturemeasurement, the CCD filtering two-color temperature measurement and the monochromatic temperaturemeasurement. It is indicated that the CCD two-color temperature measurement is not a fully correctmeans because of its poor theoretical basis. The monochromatic temperature measurement acquires arelatively ideal temperature field distribution in spite of needing a reference temperature. Itshould be noted that the Abel transformation applied in the plasma diagnosis is for the first timeintroduced to solve the problem of three-dimensional flame brightness piling.
基金supported by the Special Program for Key Basic Research of the Ministry of Science and Technology of China(No.2006CB708603)the National Natural Science Foundation of China(No.50673046)Shandong Natural Science Foundation(No.Q2008B04)
文摘Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during com...
基金Supported by Shaanxi Province Key Research and Development Project(No.2021GY-280)Shaanxi Province Natural Science Basic ResearchProgram Project(No.2021JM-459)National Natural Science Foundation of China(No.61834005,61772417,61802304,61602377,61634004)。
文摘Flame detection is a research hotspot in industrial production,and it has been widely used in various fields.Based on the ignition and combustion video sequence,this paper aims to improve the accuracy and unintuitive detection results of the current flame detection methods of gasifier and industrial boiler.A furnace flame detection model based on support vector machine convolutional neural network(SCNN)is proposed.This algorithm uses the advantages of neural networks in the field of image classification to process flame burning video sequences which needs detailed analysis.Firstly,the support vector machine(SVM)with better small sample classification effect is used to replace the Softmax classification layer of the convolutional neural network(CNN)network.Secondly,a Dropout layer is introduced to improve the generalization ability of the network.Subsequently,the area,frequency and other important parameters of the flame image are analyzed and processed.Eventually,the experimental results show that the flame detection model designed in this paper is more accurate than the CNN model,and the accuracy of the judgment on the flame data set collected in the gasifier furnace reaches 99.53%.After several ignition tests,the furnace flame of the gasifier can be detected in real time.
文摘A novel approach to extract flame fronts, which is called the conditioned level-set method with block division （CLSB）, has been developed. Based on a two-phase level-set formulation, the conditioned initialization and region-lock optimiza-tion appear to be beneficial to improve the efficiency and accuracy of the flame contour identification. The original block- division strategy enables the approach to be unsupervised by calculating local self-adaptive threshold values autonomously before binarization. The CLSB approach has been applied to deal with a large set of experimental data involving swirl- stabilized premixed combustion in diluted regimes operating at atmospheric pressures. The OH-PLIF measurements have been carried out in this framework. The resulting images are, thus, featured by lower signal-to-noise ratios （SNRs） than the ideal image; relatively complex flame structures lead to significant non-uniformity in the OH signal intensity; and, the mag- nitude of the maximum OH gradient observed along the flame front can also vary depending on flow or local stoichiometry. Compared with other conventional edge detection operators, the CLSB method demonstrates a good ability to deal with the OH-PLIF images at low SNR and with the presence of a multiple scales of both OH intensity and OH gradient. The robustness to noise sensitivity and intensity inhomogeneity has been evaluated throughout a range of experimental images of diluted flames, as well as against a circle test as Ground Truth （GT）.
基金supported by the Korea Institute for Advancement of Technology(KIAT)and the Ministry of Trade,Industry and Energy(MOTIE),Republic of Korea(Grant P0017363)by the National Research Foundation of Korea(NRF),Ministry of Science and ICT,South Korea(Grants 2022R1A2C1011559 and RS-2024-00405818)This study is the result of a research project conducted with the funds of the Open R&D program of Korea Electric Power Corporation(R23XO04).
文摘As for the high sustainable solar hydrogen production via water splitting,transition metal doping on an oxide photoanode in photoelectrochemical(PEC)cells has been recognized as an effective approach.However,conventional thermal-diffusionmediated doping strategies face the challenge of resolving sluggish catalytic kinetics for oxygen evolution reaction(OER)and its practical utilization for the synthesis of photoanode films.Herein,we introduce facile ultrafast flame-boosted doping of Mo into a BiVO_(4)(FL MoBVO)film for 20 s to achieve an efficient PEC OER.Mo elements in a low-valence state(i.e.,Mo^(6−δ))and Mo^(6+)are successfully doped into the photoanode,which manipulate the energy band structure,facilitating the downward shift of band edges and promoting the surface catalytic kinetics.Consequently,the flame-boosted Mo-doping results in superior PEC performance in a mild environment with neutral electrolyte without introducing any other additives or co-catalysts,where the photocurrent density at 1.23 V_(RHE) under 1 sun illumination in pH 7 is outstandingly enhanced,over 9-fold higher than that of a pristine BiVO_(4).The flame-boosted doping induces significantly enhanced photoexcited charge transport and catalytic reaction kinetics performances simultaneously.Our report provides the effective strategy boosting both the thermodynamic and kinetic charge migration properties for sustainable materials.
