CFD analysis of the lateral loads of a propeller in oblique flow

Abstract

Large propeller lateral loads may be generated under oblique flow condition, which is critical to the safety of stern tube bearing of a ship. In the present study, the effect of oblique flow on propeller lateral loads is numerically investigated based on URANS method, coupled with SST k-ω turbulent model and sliding mesh method. An 82, 000 DWT bulk carrier with a single right-handed screw is computed. Both open water and behind-hull conditions are simulated for a range of drift angles from −20 to 20°. The lateral loads in open water increase with the drift angle increasing in a slightly non-linear trend. However, the behind-hull results are quite different from that in open water. At behind-hull conditions, the horizontal loads monotonously, non-linearly increase as the drift angle increases, while the vertical loads peak at the −5 deg drift angle (corresponding to the transverse flow coming from the portside). In large drift angles, the behind-hull lateral loads reach a larger percentage of the axial loads compared with the open-water results. Scale effect is also investigated by simulating the behind-hull flows with three scales. It is revealed that the increase in scales causes a slight decrease on the horizontal loads independently of drift angles, while it causes a remarkable increase and decrease on the vertical components for positive and negative drift angles, respectively.