We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as t...We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as the metrics to identify the combustion mode, with the Burke-Schumann solution as a reference. A priori validation of the flame index is conducted with a series of constructed turbulent partially premixed reactors. It indicates that the proposed flame index is able to identify the combustion mode based on the subgrid mixing information. The flame index is then applied the large eddy simulation/PDF datasets of turbulent partially premixed jet flames. Results show that the flame index separate different combustion modes and extinction correctly. The proposed flame index provides a promising tool to analyze and model the partially premixed flames adaptively.展开更多
Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting o...Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting oxygen index and the wetting angle measurements. The results show that the mean particle size of the magnesium hydroxide is about 230 nm with a platelet shape and the specific surface area is about 48 m2/g when the temperature is 55 ℃ , and the ammonia and bittern are instilled simultaneously during the reaction process. After the modification, the limiting oxygen index and physical chemistry performance of the magnesium hydroxide were examined. The results show that the contact angle of magnesium hydroxide is 132.5? and the limiting oxygen index is 31.5 %, indicating that the modified magnesium hydroxide is an effective flame retardant and can be applied as flame retardant additives of the macromolecule compounds such as plastic, synthetic rubber and synthetic fibre.展开更多
Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, ...Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame- retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained ; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel patement.展开更多
The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder esc...The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.展开更多
基金sponsored by King Abdullah University of Science and Technology(KAUST)the National Natural Science Foundation of China(Grant No.91841302)。
文摘We propose a new flame index for the transported probability density function(PDF) method. The flame index uses mixing flux projections of Lagrangian particles on mixture fraction and progress variable directions as the metrics to identify the combustion mode, with the Burke-Schumann solution as a reference. A priori validation of the flame index is conducted with a series of constructed turbulent partially premixed reactors. It indicates that the proposed flame index is able to identify the combustion mode based on the subgrid mixing information. The flame index is then applied the large eddy simulation/PDF datasets of turbulent partially premixed jet flames. Results show that the flame index separate different combustion modes and extinction correctly. The proposed flame index provides a promising tool to analyze and model the partially premixed flames adaptively.
基金Project(2002-G-101) supported by the Key Program of Science and Technology of Qinghai Province, China
文摘Preparation of superfine magnesium hydroxide with the bittern and ammonia was studied. The properties of the products were analyzed by laser granularity, X-ray diffraction, scanning electron microscope, the limiting oxygen index and the wetting angle measurements. The results show that the mean particle size of the magnesium hydroxide is about 230 nm with a platelet shape and the specific surface area is about 48 m2/g when the temperature is 55 ℃ , and the ammonia and bittern are instilled simultaneously during the reaction process. After the modification, the limiting oxygen index and physical chemistry performance of the magnesium hydroxide were examined. The results show that the contact angle of magnesium hydroxide is 132.5? and the limiting oxygen index is 31.5 %, indicating that the modified magnesium hydroxide is an effective flame retardant and can be applied as flame retardant additives of the macromolecule compounds such as plastic, synthetic rubber and synthetic fibre.
文摘Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame- retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained ; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel patement.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 50078057)Program for New Century Excellent Talents in University(Grant No. NCET-06-0340)
文摘The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.
