Influence of skew on the added mass and damping characteristics of marine propellers

The objective of this work is to investigate the influence of skew on the added mass and damping matrices, which govern the vibration characteristics of the propulsion system. A 3-D curved lifting line model is developed to predict the propeller performance, and the model is validated with experimental measurements of the open water performance for the classic DTMB propellers 4381-4384 with varying skew. To compute the added mass and damping matrices of skewed propellers, the 3-D curved lifting line model is coupled with 2-D unsteady thin foil theory. The added mass and damping predictions are validated with published numerical data and empirical equations for a propeller with moderate skew. The added mass and damping characteristics of DTMB propellers 4381-4384 are calculated, and the influence of skew on these characteristics is discussed. The results show that skew affects the coupled motions with the sway, heave, pitch, and yaw components of the added mass and damping matrices, while the influence on the surge and roll components is negligible.