Experimental and numerical investigations on the unsteady thrust of a propeller in presence of an upstream rudder

Abstract

The unsteady thrust of a propeller in presence of an asymmetric upstream rudder is experimentally and numerically studied. First, a high-resolution dynamometer is utilized to measure the unsteady thrust of the propeller downstream of a rudder in the water tunnel. Second, by means of the large eddy simulation, a CFD model including both rudder and propeller is established to predict the flow field and the unsteady thrust of the propeller. After verifying the accuracy of the numerical method, the influences of rudder angle on the unsteady thrust of propeller are numerically studied. It is shown that for the flow field, the separation location of vortices moves upstream on the rudder surface with the increase of rudder angle. For the tonal forces, the tonal thrust increases with the rudder angle, and the transverse tonal force increases rapidly due to the increased asymmetry of the flow field. For the broadband forces, the force spectrum in the low-frequency range increases and humps appear at the blade passing frequencies.