Launch safety of explosive charges has become an urgent problem to be solved by all countries in the world aslaunch situation of ammunition becomes consistentlyworse.However, the existing numericalmodels have differen...Launch safety of explosive charges has become an urgent problem to be solved by all countries in the world aslaunch situation of ammunition becomes consistentlyworse.However, the existing numericalmodels have differentdefects. This paper formulates an efficient computational model of the combustion of an explosive charge affectedby a bottom gap in the launch environment in the context of the material point method. The current temperatureis computed accurately from the heat balance equation, and different physical states of the explosive charges areconsidered through various equations of state. Microcracks in the explosive charges are described with respectto the viscoelastic statistical crackmechanics (Visco–SCRAM) model. Themethod for calculating the temperatureat the bottomof the explosive charge with respect to the bottomgap is described. Based on this combustionmodel,the temperature history of a Composition B (COMB) explosive charge in the presence of a bottom gap is obtainedduring the launch process of a 155-mm artillery. The simulation results show that the bottom gap thickness shouldbe no greater than 0.039 cm to ensure the safety of the COM B explosive charge in the launch environment. Thisconclusion is consistent with previous results and verifies the correctness of the proposed model. Ultimately, thispaper derives amathematical expression for themaximumtemperature of the COMB explosive chargewith respectto the bottomgap thickness (over the range of 0.00–0.039 cm), and establishes a quantitative evaluationmethod forthe launch safety of explosive charges.The research results provide some guidance for the assessment and detectionof explosive charge safety in complex launch environments.展开更多
This paper presents the concept of a passive electrochemical hydrogen recombiner(PEHR).The reaction energy of the recombination of hydrogen and oxygen is used as a source of electrical energy according to the operatin...This paper presents the concept of a passive electrochemical hydrogen recombiner(PEHR).The reaction energy of the recombination of hydrogen and oxygen is used as a source of electrical energy according to the operating principle for hydrogen fuel cells to establish forced circulation of the hydrogen mixture as an alternative to natural circulation(as is not utilized in conventional passive autocatalytic hydrogen recombiners currently used in nuclear power plants(NPPs)).The proposed concept of applying the physical operation principles of a PEHR based on a fuel cell simultaneously increases both productivity in terms of recombined hydrogen and the concentration threshold of flameless operation(the‘ignition’limit).Thus,it is possible to reliably ensure the hydrogen explosion safety of NPPs under all conditions,including beyond-design accidents.An experimental setup was assembled to test a laboratory sample of a membrane electrode assembly(MEA)at various hydrogen concentrations near the catalytic surfaces of the electrodes,and the corresponding current–voltage characteristics were recorded.The simplest MEA based on the Advent P1100W PBI membrane demonstrated stable performance(delivery of electrical power)over a wide range of hydrogen concentrations.展开更多
基金the Natural Science Foundation of Heilongjiang Province,China(LH2019A008).
文摘Launch safety of explosive charges has become an urgent problem to be solved by all countries in the world aslaunch situation of ammunition becomes consistentlyworse.However, the existing numericalmodels have differentdefects. This paper formulates an efficient computational model of the combustion of an explosive charge affectedby a bottom gap in the launch environment in the context of the material point method. The current temperatureis computed accurately from the heat balance equation, and different physical states of the explosive charges areconsidered through various equations of state. Microcracks in the explosive charges are described with respectto the viscoelastic statistical crackmechanics (Visco–SCRAM) model. Themethod for calculating the temperatureat the bottomof the explosive charge with respect to the bottomgap is described. Based on this combustionmodel,the temperature history of a Composition B (COMB) explosive charge in the presence of a bottom gap is obtainedduring the launch process of a 155-mm artillery. The simulation results show that the bottom gap thickness shouldbe no greater than 0.039 cm to ensure the safety of the COM B explosive charge in the launch environment. Thisconclusion is consistent with previous results and verifies the correctness of the proposed model. Ultimately, thispaper derives amathematical expression for themaximumtemperature of the COMB explosive chargewith respectto the bottomgap thickness (over the range of 0.00–0.039 cm), and establishes a quantitative evaluationmethod forthe launch safety of explosive charges.The research results provide some guidance for the assessment and detectionof explosive charge safety in complex launch environments.
基金Open access funding provided by North-West University
文摘This paper presents the concept of a passive electrochemical hydrogen recombiner(PEHR).The reaction energy of the recombination of hydrogen and oxygen is used as a source of electrical energy according to the operating principle for hydrogen fuel cells to establish forced circulation of the hydrogen mixture as an alternative to natural circulation(as is not utilized in conventional passive autocatalytic hydrogen recombiners currently used in nuclear power plants(NPPs)).The proposed concept of applying the physical operation principles of a PEHR based on a fuel cell simultaneously increases both productivity in terms of recombined hydrogen and the concentration threshold of flameless operation(the‘ignition’limit).Thus,it is possible to reliably ensure the hydrogen explosion safety of NPPs under all conditions,including beyond-design accidents.An experimental setup was assembled to test a laboratory sample of a membrane electrode assembly(MEA)at various hydrogen concentrations near the catalytic surfaces of the electrodes,and the corresponding current–voltage characteristics were recorded.The simplest MEA based on the Advent P1100W PBI membrane demonstrated stable performance(delivery of electrical power)over a wide range of hydrogen concentrations.