Effects of Inflow through Inner Seal on TOBI Pre-swirl System

To improve the performance of aircraft gas turbines, turbine inlet temperature have been continuously increasing. Accordingly, the application of high-temperature materials and sophisticated secondary air system designs have become essential to ensure stable operation under high-temperature conditions. In particular, the pre-swirl system, which transports cooling air with minimal loss, is a critical component for cooling parts exposed to high temperature. In this study, the influence of inflow entering through the cavity of the pre-swirl system on the overall system was numerically analyzed. By comparing the changes in swirl ratio and total temperature drop effectiveness under various inflow mass flow rates, the effect of inflow on the relative total temperature of cooling air at the receiver holes was evaluated. The results showed that inflow with a relatively low swirl ratio reduces the swirl of the cooling air passing through the pre-swirler, thereby increasing the relative total temperature at the receiver holes. Based on these findings, design criteria for allowable inflow and considerations for pre-swirler design are proposed.