冰载荷冲击下的船舶推进轴系瞬态扭转振动响应分析

Transient torsional vibration analysis for ice impact of ship propulsion shaft

传统的推进轴系扭转振动响应计算聚焦于稳态响应,而传递矩阵法、系统矩阵法,可以取得满意的稳态计算结果,但无法处理冰区船舶、海洋工程船舶所遇到的变载荷、变惯量等瞬态工况。为了克服频域扭振计算方法在处理瞬态条件扭振问题的局限性,使用Newmark法从时域求解轴系扭转振动微分方程组,基于该算法对某船推进轴系在冰载荷作用下的瞬态响应做了数值计算。其结果表明,在冰载荷冲击下,轴系瞬态扭矩比稳态扭矩大;通过时频分析,在冰载荷作用期间,出现了明显的螺旋桨叶频激励,因此须避免冰载荷激励产生轴系扭转振动的叶次共振。Newmark法扭振计算结果与实船测试结果对比表明,该方法在稳态响应计算和时域曲线上都与实际测量结果基本一致,具有工程实用性。

The conventional torsional vibration calculation for ship propulsion system concentrates on the response of steady state. And the transfer matrix method and system matrix method, could get a good result of steady response. But these methods can not solve the momentary problem for ship navigation in ice and engineering ship. By employing the Newmark method to solve the torsional vibration equation in time do-main, the result was gotten for the propulsion shaft with ice impact torque on propeller. During the ice im-pact, the transient torque is bigger than steady torque and the blade frequency exciting component was found by time-frequency analysis. Avoiding blade number order resonance of ice impact is necessary. The com-parison between Newmark method result and measurement shows that Newmark method is practicable for the response of steady state and time domain curve, which results are basically the same as the measure-ment result.