EFFECTS OF TEMPERATURE AND INJECTOR STRUCTURE ON ATOMIZATION CHARACTERISTICS OF BIPROPELLANT: EXPERIMENTAL STUDY

In order to provide an efficient and reliable propellant injection system at a low-temperature environment for a bipropellant rocket engine, a liquid/liquid coaxial swirl jet spray experimental system was developed. The influence of different working medium temperatures on swirling atomization was studied. As the temperature of the working medium decreases, the spray cone angle and spray droplet size uniformity index decrease, and the Sauter mean diameter (SMD) and breaking length of the liquid film increase, indicating that low temperature is not conducive to the atomization of the working medium. This is because low temperature increases the viscosity of the working medium, thereby increasing flow resistance and resulting in a decrease in flow rate. The effects of different injector structures on atomization were studied. When the coaxial spray reaches the boundary mixing state, the two liquid films impinge at the outlet of the outer injector; atomization quality is better at this condition. Tangential orifices number of the outer injector and outer injector swirl chamber length-diameter ratio have a complex influence on atomization. Influences of structural parameters on atomization are essentially caused by the interaction between the inner and outer liquid films. When designing the injector structure, it is necessary to comprehensively consider various influencing factors and balance the spray cone angle, liquid film breaking length, SMD, and spray droplet size uniformity.