Aiming at the change in intake air flow caused by the injection of natural gas in intake manifold if one simply replaces the gasoline injector with natural gas injector with the installing position of injector in inta...Aiming at the change in intake air flow caused by the injection of natural gas in intake manifold if one simply replaces the gasoline injector with natural gas injector with the installing position of injector in intake manifold unchanged, and also the reflection of gas toward intake manifold inlet resulted from the impingement between the injected large volumetric natural gas jet and intake valve, an impulsively started natural gas jet injected from a gas injector is characterized as a three-dimensional unsteady compressible viscous turbulent flow, based on which its transient development process is numerically analyzed using general-purpose CFD codes. The predicted velocity vector maps show a vortex, which indicates the occurrence of an unsteady state jet region, is formed downstream of the jet. A schlieren apparatus is utilized to get several groups of visible schlieren photographs of natural gas jets. In the experiment, photographs of natural gas jets taken by a CCD camera are laid in a portrait processor where the shapes, tip penetration distance and injection angles of the gas jets are investigated. Comparisons between predicted results and measurements indicate an excellent agreement between simulations and experimental results.展开更多
In order to present a retrospective analysis of exposition accidents using input data from investigation processes,data from a specific accident was examined,in which we analyzed possible involved gas species（ liquef...In order to present a retrospective analysis of exposition accidents using input data from investigation processes,data from a specific accident was examined,in which we analyzed possible involved gas species（ liquefied petroleum gas; nature gas） and computed their concentrations and distributions based on the interactions between the structures and the effects of the explosion. In this study,5 scenarios were created to analyze the impact effect. Moreover,a coupling algorithm was put into practice,with a practical outflow boundary and joint strength are applied. Finally,the damage effects of each scenario were simulated. Our experimental results showed significant differences in the 5 scenarios concerning the damage effects on the building structures. The results from scenario 3 agree with the accident characteristics,demonstrating the effectiveness of our proposed modeling method. Our proposed method reflects gas properties,species and the concentration and distribution,and the simulated results validates the root cause,process,and consequences of accidental explosions. Furthermore,this method describes the evolution process of explosions in different building structures. Significantly,our model demonstrates the quantatative explosion effect of factors like gas species,gas volumes,and distributions of gases on explosion results. In this study,a feasible,effective,and quantitative method for structure safety is defined,which is helpful to accelerate the development of safer site regulations.展开更多
基金This project is supported by Provincial Natural Science Foundation of Shandong (No.Y2000F07)Scientific Research Foundation for Returned Overseas Chinese Scholars, Education Ministry of China.
文摘Aiming at the change in intake air flow caused by the injection of natural gas in intake manifold if one simply replaces the gasoline injector with natural gas injector with the installing position of injector in intake manifold unchanged, and also the reflection of gas toward intake manifold inlet resulted from the impingement between the injected large volumetric natural gas jet and intake valve, an impulsively started natural gas jet injected from a gas injector is characterized as a three-dimensional unsteady compressible viscous turbulent flow, based on which its transient development process is numerically analyzed using general-purpose CFD codes. The predicted velocity vector maps show a vortex, which indicates the occurrence of an unsteady state jet region, is formed downstream of the jet. A schlieren apparatus is utilized to get several groups of visible schlieren photographs of natural gas jets. In the experiment, photographs of natural gas jets taken by a CCD camera are laid in a portrait processor where the shapes, tip penetration distance and injection angles of the gas jets are investigated. Comparisons between predicted results and measurements indicate an excellent agreement between simulations and experimental results.
基金Supported by the National Natural Science Foundation of China(E041003)the Fundamental Research Funds for the Central Universities(FRF-TP-15-105A1)the Postdoctoral Science Foundation of China(2015M580049)
文摘In order to present a retrospective analysis of exposition accidents using input data from investigation processes,data from a specific accident was examined,in which we analyzed possible involved gas species（ liquefied petroleum gas; nature gas） and computed their concentrations and distributions based on the interactions between the structures and the effects of the explosion. In this study,5 scenarios were created to analyze the impact effect. Moreover,a coupling algorithm was put into practice,with a practical outflow boundary and joint strength are applied. Finally,the damage effects of each scenario were simulated. Our experimental results showed significant differences in the 5 scenarios concerning the damage effects on the building structures. The results from scenario 3 agree with the accident characteristics,demonstrating the effectiveness of our proposed modeling method. Our proposed method reflects gas properties,species and the concentration and distribution,and the simulated results validates the root cause,process,and consequences of accidental explosions. Furthermore,this method describes the evolution process of explosions in different building structures. Significantly,our model demonstrates the quantatative explosion effect of factors like gas species,gas volumes,and distributions of gases on explosion results. In this study,a feasible,effective,and quantitative method for structure safety is defined,which is helpful to accelerate the development of safer site regulations.
