A computational study of the flow in a tandem inducer/impeller rocket pump has been performed using a 3D elliptic flow program including viscous effects. The axial inducer has four blades and the centrifugal impeller has eight main blades and sixteen splitter blades. The purpose of this thesis is to investigate the flow in the turbopump, and check its proper design. A literature review discusses both elements of the pump, and then analyzes the possible matching configurations. More details are given for the geometry of interest. The generation of a single zone 3D grid for the tandem combination is then presented in detail, after which simpler grids are derived for the inducer alone. The results of the 3D tandem inducer/impeller calculation are presented extensively to provide good knowledge of the flow inside this little investigated configuration. Velocity vectors, static pressure and rotary stagnation pressure are shown in meridional and blade-to-blade views. A balanced flow split is achieved in the impeller main-blade passages. Cavitation inception is also discussed. Additional 3D calculations are performed for the inducer alone, with varying exit geometry (axial or radial). Comparisons of geometry influence on the inducer flow are carefully investigated, as well as the influence of the impeller. The impeller slightly modifies the inducer exit flow but not its overall performance. As a consequence, it is found that separate design calculations could be performed for the inducer and the impeller. The latter would use the inducer circumferentially averaged exit flow as its inlet conditions. It is suggested that impeller suction performance be optimized using tandem inducer/impeller calculations. / Master of Science