海洋污损对船体摩擦阻力影响的预测方法

海洋污损对船体阻力具有严重的不利影响.文章将海洋污损归类到船体粗糙度的范畴内,基于边界层积分法研究了污损对船体摩擦阻力影响的预测方法.通过对光滑平板摩擦阻力系数的计算验证了积分法的准确性.然后采用积分法对美军FFG-7舰在3种钙质污损状况下的摩擦阻力系数进行了计算,计算结果与国外学者的研究结论吻合得较好,说明了积分法预测污损对船体摩擦阻力的影响具有可行性,且准确性较高.最后将积分法在FFG-7舰的计算结果与1957-ITTC公式及其粗糙度补贴系数ΔCf进行了对比,结果表明ITTC提出的ΔCf公式不适于表征污损对船体阻力的影响.

Method of Estimating the Effect of Marine Fouling on Frictional Resistance of Ships

Marine fouling has a severe adverse effect on the hydrodynamics of a ship's hull. In this paper, the marine fouling was approached as a type of hull roughness, and the use of the integral method in estimating its effect on the frictional resistance of ships was studied. Through the calcula-tion of the friction factor of a smooth surface, the accuracy of the integral method was verified and confirmed. The integral method was then adopted to calculate the friction factor of a U.S. Navy FFG-7 class ship under three different calcareous fouling conditions, which gave a result consistent with that from other researchers, indicating the feasibility and accuracy of the integral method in estimat-ing the effect of marine fouling on hull resistance. The result using the integral method for a FFG-7 ship was compared with result from the 1957-ITTC equation and its roughness allowance ΔCf . The result shows that the ΔCf equation proposed by ITTC is not applicable to characterize the impact of fouling on hull resistance.