Experimental Research And Numerical Simulation On Working Characteristics Of Pasty Propellant Rocket Engine

Pasty rocket engines possess many advantages of solid rocket engines and liquid rocket engines, becoming one of the important types of current new developing chemical propellant rocket engines. In this dissertation, both experiment and numerical simulations are employed. The rheological properties, combustion characteristics and pipe extrusion flow characteristics of pasty propellant and the ignition performance of pasty rocket engine are investigated. The technological reference and experimental foundation of system design and performance prediction of pasty rocket engines are provided.First, rheological properties of pasty propellant are tested and analyzed with a rotational rheometer. The power law constitutive equations of the propellant are obtained by fitting the relationship curve between viscosity and the angular frequency of rheometer. The laser ignition experiments are carried out under different pressures for propellants with initial temperature of 25℃, using the CO2 laser ignition system. The phenomenon and characteristics of the ignition are observed and analyzed. The variation of burning rate with environment pressure is fitted with the index-law burning rate formulation.Second, the calculation model of pipe extrusion is established. For initial states with and without pasty propellant prefilled in pipes in advance, the extrusion processes are numerically simulated under different pipe diameters and mass flow rates. The variation of extrusion states, velocity and pressure loss are obtained for different simulation conditions. The influence of two initial states to pipe extrusion characteristics is analyzed and compared with advantages and disadvantages. It can be concluded that the prefilled condition outweighs the counterpart without pasty propellant prefilled in pipes in term of ignition. Thus, this initial state is selected and the pipe extrusion experiments are carried out under different pipe diameters and mass flow rates. The validity of the numerical simulation, the rationality of parameter setting and the reliability of the hydraulic squeezing approach are confirmed by test results.Third, according to the characteristics of the pasty propellant pipe extrusion and the working principle of the pasty rocket engine, the combustion in the combustion chamber is divided into three stages, namely, the initial combustion stage, the stabile combustion stage and the remaining propellant combustion stage. The interior ballistic differential equation is deduced and the mathematical forms of combustion surface in different stages were obtained. The zero-dimension interior ballistic model is established and the interior ballistic calculation program is compiled. The interior ballistic model is verified by the pressure-to-time curve from engine ignition tests. The results show that the established interior ballistic model has good precision, and can be used for simulation of rocket engine working process with reasonability and reliability.Finally, the pasty rocket engine test system is designed and built. The rocket engine ignition tests are successfully completed for the pasty propellant with supplying mass flow rates of 0.5kg/s,0.8kg/s,1.5kg/s and2.2 kg/s. The pressure-to-time curves are measured and the working characteristics of the pasty rocket engine under different flow rates are analyzed. The results show that the designed pasty rocket engine test system is proved to be with high feasibility and testing repeatability, and the hydraulic supplying system works with high reliability.