不同航速下某浅吃水船耐波性分析

Seakeeping Analysis of Shallow Draft Vessel at Various Speeds

采用Hydro Star软件,系统分析某浅吃水船在不同航速时的耐波性能。研究结果表明:零航速、设计吃水工况下,横浪时垂荡和横摇运动最为显著。随着波浪偏移至艏/艉附近(±30°),横摇响应幅值算子(RAO)迅速减小;对于左舷处的监测点,纵向、垂向加速度RAO曲线关于左右舷浪向呈不对称分布,差异在横浪附近表现得尤为明显,横向运动的对称性则与此无关;横浪下1阶波浪力矩表现为双峰构型,相较于斜浪更大,导致横摇运动加剧;而斜浪下,低频波浪力矩对横摇起主要作用,且更高的航速对应了更大的等效黏性阻尼,从而一定程度上抑制了横摇响应;根据4级海况的短期预报结果,垂向加速度沿船长不同位置分布不均,随浪向、航速的变化规律也各不相同,在实际营运中应予以综合考虑,以避免不利因素的影响。

The seakeeping performance of a shallow draft vessel at various speeds by HydroStar is comprehensively investigated.The numerical results prove that beam seas induce the most remarkable heave and roll motions under designed draft and zero speed conditions.Accompanied by wave directions shifted close to stern and bow(±30°),roll response amplitude operators(RAO)are rapidly reduced.For monitoring points located at portside,longitudinal and vertical acceleration RAOs are asymmetrical about wave from portside and starboard,the differences are especially obvious near beam seas,however,transversal motions are exceptional.Further analysis indicates that first order wave moments behave bimodal configurations at beam seas and are greater compared to quartering seas,causing corresponding to the intensified roll motion.In comparison,at quartering seas,wave moments at low-frequency ranges play dominant roles in roll motion,the elevated speed is corresponding to higher equivalent viscous damping,inhibiting roll response to a certain extent.According to the short-term prediction results for sea state 4,vertical accelerations are non-uniformly distributed along vessel length and randomly varies with speed and wave direction,overall considerations should be paid in order to avoid unfavorable situations during actual operations.