J. Ahn - School of Mechanical Engineering, Chungbok National University, Chungbuk, ۲۸۶۴۴, Republic of Korea
K. Ahn - School of Mechanical Engineering, Chungbok National University, Chungbuk, ۲۸۶۴۴, Republic of Korea
H. Y. Lim - Launcher Propulsion Control Team, Korea Aerospace Research Institute, Daejean, ۳۴۱۳۳, Republic of Korea

The application of three-dimensional (۳D) printing technology in rocket engine development has numerous benefits considering cost and time. Among the various techniques of ۳D printing, the selective laser melting method has the advantage of being able to manufacture complex structures and process multiple materials. In this study, five types of coaxial injectors with different internal configurations were manufactured using metal ۳D printing. To confirm the atomization and mixing performance according to the structure of each injector's oxidizer and fuel post, a cold flow test using water and air was performed under a wide range of experimental conditions. As a result of analyzing the injection pressure drop, discharge coefficient, spray pattern, breakup length, and spray angle, the shape of the oxidizer post had a significant influence on the performance of the injector. In comparison, the effect of the fuel post structure was relatively small; however, there was a meaningful difference in the breakup length and spray angle depending on the direction of rotation.

۳D printing, Cold flow test, Shear coaxial injector, swirl coaxial injector, spray characteristics