Research on active balancing characteristics for axial thrust of a turbopump

A 10-ton class closed-cycle engine using liquid oxygen and kerosene is being developed as the upper stage engine for the next KSLV (Korea Space Launch Vehicle) model. This engine employs staged combustion to enhance the thrust and specific impulse. In that the turbopump pressure in a staged combustion closed-cycle engine is greatly increased, an active thrust balancing system is required to control the axial force of the turbopump. Two types of active thrust balancing systems with one axial control gap and two axial control gaps were investigated through a pressure and leakage flow analysis in an effort to enhance the axial thrust control capability. A reduced-order computational program was developed to perform the present study. As a result of the analysis, it was confirmed that the two-gap control method is capable of controlling the axial thrust in a wider area compared to the one-gap control method due to the additional control elements.