Analysis Of Tandem Propellers Interference With A Hybrid Eulerian-Lagrangian Method

Abstract

A hybrid Eulerian-Lagrangian solver is applied to investigate aerodynamic interference in a tandem propeller configuration. The solver couples ROSITA with DUST to capture near-field loads and far-field wake structures efficiently. Grid convergence on a single three-blade propeller at advance ratio J=0.8 yields thrust and power coefficients within 1% and 3% of wind-tunnel measurements. For a tandem arrangement with axial spacing La/R = 5 and radial offset Lr/R = 1, the effects of phase offset and co/counter-rotation on the downstream propeller are quantified. In the baseline co-rotating case, the rear propeller incurs 7.4% thrust and 4.5% power losses and two-order-of-magnitude increases in unsteady fluctuations. Under the same rotational condition, a 30? phase offset magnify these losses and fluctuations, while 90? phase offset performs the opposite. Counter-rotation reduces oscillations by over 70% despite larger mean performance penalties. Blade-vortex interaction analysis reveals that phase control and rotation direction alter the alignment of tip vortices with the rear blade and thereby modify the induced velocities, governing loss and fluctuation characteristics.