Design And Performance Of Plume Conductive Propellant

With the development of military science and technology,research on composite solid propellants has continued to deepen.Hydroxyl-terminated polybutadiene(HTPB)-based composite solid propellant has been widely used in various strategic,tactical and uncontrol rocket weapons because of its characteristics of high energy and strong anti-aging properties,and become one of the most widely used propellants in the world.In order to further expand the application of solid propellants in the fields of magnetic fluid power generation,plasma propulsion and field radiation propulsion,it is necessary to conduct related research on the electrical conductivity of its plumes.Combining the electron collision theory and the alkali metal salt ionization theory,the mathematical model of the electrical conductivity of the HTPBbased composite solid propellant was established.This paper focused on the electrical properties,mechanical properties and combustion properties of HTPB-based composite solid propellants under different alkali metal salt doping levels.The specific research content is as follows:(1)Based on the principle of plume ionization,the alkali metal salt additives were determined to be cesium nitrate and cesium perchlorate.In order to fully study the effect of different doping levels on the performance of the propellant,the additive content was determined to be 5%,10%,15% and 20%.Plume conductive propellant(PCP)formula is mainly composed of HTPB,ammonium perchlorate(AP),alkali metal salt and aluminum powder.The preparation process of PCPs was studied,and the performance of the grains was characterized.The results showed that the D50(particle size with cumulative content of 50%)of AP,cesium perchlorate,and cesium nitrate were 35.83 μm,33.65 μm and 43.30 μm,respectively.The thermal decomposition of PCP has undergone two processes of endothermic melting and exothermic gas production at 239℃～250℃ and 330℃～370℃.The apparent activation energy of HTPB-based composite solid propellant without alkali metal salt(NPCP),PCP with 10% cesium nitrate and PCP with 10% cesium perchlorate were 182 k J/mol～183.7k J/mol,149.3 k J/mol～151.8 k J/mol and 138.6 k J/mol～141.6 k J/mol,respectively.The functional group information was tested by Fourier infrared spectroscopy.The test results showed that cesium nitrate and cesium perchlorate have excellent compatibility with the main components of the HTPB-based composite solid propellant.(2)Based on the electron collision theory and alkali metal salt ionization theory,the mathematical model of the composite solid propellant plume conductivity was established.By using NASA-CEA software,the combustion temperature and specific impulse of HTPB-based composite solid propellants with different alkali metal salt doping levels were calculated.Combining with Sa Ha equation,Spitzer equation,adiabatic flame temperature and other thermodynamic parameters,the electrical conductivity of PCP plume was theoretically calculated.The conductivity of NPCP is 4.37 S/m,PCP containing 5%,10%,15% and 20%cesium nitrate is 997.00 S/m,1014.49 S/m,984.72 S/m and 912.84 S/m,respectively.PCP containing 5%,10%,15% and 20% cesium perchlorate is 1017.47 S/m,1081.19 S/m,1112.92S/m and 1123.01 S/m,respectively.(3)Under DC circuit with a power supply voltage of 200 V to 600 V,the characteristics of the ion current in the propellant plume were studied using the electrode plate method.The experimentally measured conductivity of NPCP is 3.90 S/m,PCP containing 5%,10%,15%and 20% cesium nitrate is 814.29 S/m,925.71 S/m,899.14 S /m and 737.14 S/m,respectively.PCP containing 5%,10%,15% and 20% cesium perchlorate is 902.57 S/m,1002.86 S/m,1028.57 S/m and 1037.14 S/m,respectively.The average error is about 12.73%.The error is mainly caused by the difference in the degree of ionization and the combustion temperature.The uniaxial tensile test of composite solid propellant containing alkali metal salt was carried out at room temperature.The tensile strength of PCP containing cesium nitrate was 0.28 MPa～0.68 MPa,and the elongation at break was 1.72%～5.11%.The tensile strength of cesium chlorate PCP ranges from 0.64 MPa to 0.78 MPa,and the elongation at break ranges from 4.6%to 7.2%.(4)The effects of different pressures and different alkali metal contents on the combustion process of PCP were studied.The pressure range is 0.1 MPa～2.5 MPa.The burning rate of NPCP was measured in the range of 4.62 mm/s to 5.98 mm/s,and the pressure index is 0.148.The burning rate range of PCP containing 5%,10%,15% and 20% cesium nitrate is 1.73mm/s～4.84 mm/s,the pressure index range is 0.44～0.50,PCP containing 5%,10%,15% and20% cesium perchlorate is 2.45 mm/s～6.12 mm/s,and the pressure index ranges from 0.34 to0.51.The combustion temperature of PCP was studied,and the combustion surface temperature and final combustion temperature of NPCP,PCP containing cesium perchlorate,and PCP containing cesium nitrate were measured to be 360℃ and 1200 ℃,230 ℃ and 1090 ℃,190 ℃and 1070 ℃,respectively.