Study On The Working Characteristics Of Soft Pulse Separation Device Of Double Pulse Motor

Dual pulse motor(DPM)with axial pulse separation device(PSD)has the characteristics of simple structure,light weight and high charge density,it is often used as the power device of large caliber rocket missile weapon system.In this paper,based on the research background of the soft axial PSD,the working characteristics of soft pulse separation device were studied.and the thermal environment of the soft PSD in the process of I pulse was analyzed.The ablation carbonization process of the soft PSD was studied by the program of the ablation calculation program.A two-way fluid structure coupling model for the soft PSD opening process of Ⅱpulse ignition transient was established,and the effects of morphology change of the soft PSD after ablation,mass flow rate of igniter,prefabricated defect shape of the soft PSD and material of the soft PSD on the opening process of the soft PSD were studied,which provides an important reference value for the design of the soft pulse separation device of dual pulse motor.(1)The internal flow field of the two-phase flow in the combustion chamber of the dual pulse motor with radial PSD during Ⅰ pulse operation,and the two-way flow thermal coupling process between the flow field and the soft PSD in the Ⅰ pulse combustor were numerically calculated,the thermal environment of the soft PSD in the working process of I pulse was analyzed.The calculation results show that,The particle concentration near the nozzle axis is large,the temperature change of particle phase lags behind that of gas phase,the temperature drop of internal flow field is small,and the velocity of particle phase lags behind relatively,resulting in the temperature near the nozzle axis is higher than that at other positions of the same section,and the Mach number is lower.The particles have a good flow following property.The particles do not enter the combustion chamber head,but move to the nozzle outlet with the flow.During the movement,some particles will collide with the wall of nozzle convergence section and rebound.The heat flux on the contact surface between the soft PSD and the flow field in the combustion chamber gradually decreases and tends to be stable with time.(2)Combined with the numerically calculated characteristic parameters of thermal environment of soft PSD under Ⅰ pulse operation,the ablation process of the soft PSD was numerically simulated by using the ablation calculation program,and the variation rules of the internal temperature,density distribution and thermal conductivity of the soft PSD material in the process of pyrolysis diffusion,pyrolysis carbonization and thermogravimetry were obtained The influence of heat flux on the ablation and carbonization process of the soft PSD was analyzed.The results show that the higher the heat flux is,the faster the temperature rising rate is,but it only affects the internal temperature distribution in a certain range.(3)The two-way fluid structure coupling computational model for the soft PSD opening process of Ⅱ pulse ignition transient was established.The mass flow rate model of Ⅱ pulse igniter,the ignition model of propellant charge and the combustion model of propellant charge were written into the fluid calculation platform by user-defined function(UDF),and the opening process of the soft PSD was simulated.The flow field characteristics,pressure impact characteristics and the mechanical properties of the soft PSD were analyzed.The results show that the ignition gas and additive gas first hit the center of the inner surface of the soft PSD,and then spread around.At 4.25 ms,the prefabricated defects on the back of the interlayer reached the tensile strength of the material,and the soft PSD cracked and opened.the equivalent stress and total deformation of the soft PSD first increase,then decrease and then increase.(4)Tthe effects of morphology change of the soft PSD after ablation,mass flow rate of igniter,prefabricated defect shape of the soft PSD and material of the soft PSD on the fluid region and solid region during the opening process of the soft PSD were studied.The results show that the thickness of the soft PSD becomes thinner and the morphology of the preformed defects changes after ablation,resulting in shorter opening time of the soft PSD and difficult control of the fracture position and shape.With the increase of mass flow rate of igniter,the first ignition time of propellant charge is shortened,the rupture time of the soft PSD is shortened,and the pressure of the fluid domain increases.The parameters of the soft PSD with different shapes of prefabricated defects will also change during the opening process.Through the comparison,it can be seen that the effect of choosing "ten" shape prefabricated defects is more ideal in practical engineering application.The change of the soft PSD material has a great influence on the rupture time and total deformation of the soft PSD,but not on the convective domain.