Experimental and theoretical comparison of two swirl brake designs

Experimental and theoretical data are presented for two interchangeable swi rl brakes designed in connection with the Space Shuttle Main Engine (SSME) Alternate Turbopump Development (ATD) High-Pressure Fuel Turbopump (HPFTP) program. The experimental data includes rotordynamic data for a extensive v ariation of test variables. Comparison OS the swirl brake performance revea led that a nonaerodynamic swirl brake design proved as efficient and at tim es better than an aerodynamic design. For this reason a theoretical investi gation using computational fluid dynamics (CFD) was recently carried out. T his modeling focused on predicting the seal inlet swirl ratio which is the primary swirl brake performance parameter. The nonaerodynamic swirl brake s howed superior performance for a variety of test variable conditions. Stron g separation vortices within the swirl vanes are the main reason for this f inding.