Research On Working Process Of Pasty Propellant Rocket Motor

With the modern propulsion technology development, pasty propellant rocket motor has become the hot spot area and the development direction of this field. In this paper, technical problems, existing in the pasty propellant rocket motor, and steady combustion characteristics of pasty propellant were studied. It has laid a foundation of theory and technology for the rocket motor. In this paper, the work reads as follows:(1) The extrudate swell characteristics of pasty propellant were studied, in order to supporting analysis the initial combustion surface of pasty propellant rocket motor. For the conical expansion nozzle:Extrudate swell test of pasty propellant simulacrum was carried out. Extrudate swell stability and process were analyzed. And influences of time on pasty propellant burning surface was studied. For the straight round nozzle:The non-linear regression method was used to fit the steady and dynamic shear test results of pasty propellant simulacrum. And viscoelastic parameters of PTT model constitutive relation were obtained. By integrating with continuity equation and momentum equation, two-dimensional axisymmetric isothermal extrudate swell was simulated. Influences of nozzle size and supply speed on extrudate swell ratio were analyzed.(2) Characteristics of pasty propellant flow in the high-temperature tube and air-pasty propellant pipe flow were studied, in order to provide technical support for combustion rate analysis and safety analysis. Power-law model was introduced to represent the rheology of the propellant. The temperature dependence of the viscosity was taken into account by Arrhenius equation. Pasty propellant flow in the high-temperature tube was simulated. Characteristics and thermal stability of the flow were analyzed. And also combustion rate of pasty propellant. By regarding air bubbles as incompressible particles, a gas-liquid two-phase model was established to simulate the air-pasty propellant pipe flow. Influences of bubble content on flow velocity and the pipe pressure drop were analyzed.(3) Start-up characteristics of pasty propellant supply pipeline were studied to help decide the restart time and thrust when the motor restart working. In case of dividing the transient start-up process into pressure wave transmission, compression behind wave and displacement after compression, a start-up model of pasty propellant supply pipeline was established. Herschel-Bulkley model and time dependent Herschel-Bulkley model were used to represent the rheology of displacement fluid and extrudate fluid, respectively. The model was validated by tests. Influences of the pipeline size and supply velocity on start-up time were analyzed.(4) The interior ballistic characteristics of pasty propellant rocket motor were studied. Integrated with studies on die swell, pasty propellant flow in hot pipe and start-up, burning surface equations and burning rate functions were analyzed. Burning surface equations of straight round nozzle and conical expansion nozzle under mathematical form were derived. Based on the pasty propellant rocket motor working process, an interior ballistic model of pasty propellant rocket motor was established. Finally, engine test was done to validate the model.(5) The steady combustion characteristics of pasty propellant were studied. Drawing on theoretical model of non-catalytic propellant, the burning rate formula of pasty propellant was obtained from the propellant components. Based on the colorimetric temperature measurement technology of color CCD and the low-order piecewise linear interpolation, a temperature measurement software of pasty propellant flame was coded. The software accuracy was test by bunsen burner. And the macroscopic property of pasty propellant steady combustion field was obtained. Respectively, the combustion test of continuous supply and multi-pulse supply on conical expansion nozzle and slot nozzle were carried out. The steady combustion characteristics of pasty propellant were analyzed.The study method and results have guiding significance for pasty propellant rocket motor design and working processing analysis. It will be helpful to speed up researches on this field in our country, and reduce the disparity between the foreign advanced technology and ours.