The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with ...The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.展开更多
Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base prop...Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.展开更多
文摘The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.
文摘Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.
