某调距导管桨系泊工况水力性能和流激直发声预报

采用经验证的计算流体力学方法,对某艏辅推调距导管桨设计螺距和系泊工况螺距的水动力性能进行了有效预报,并对系泊工况装船桨流激噪声进行了分析。系泊工况下,由于导管桨的抽吸作用在导管外壁近壁面区域存在与导管内部流动方向相反的逆向流动,且导管桨尾流场速度梯度分布不均匀、流动紊乱,此时桨叶与导管的推力之比约为1.2∶1。系泊工况船+桨的瞬态流场脉动信息表明,导管桨各部件噪声源强度均表现出从1倍到4倍叶频依次下降的规律,最强幅值集中在桨叶导边和导管内壁;在远场声源级频谱曲线中轴向测点线谱较高峰值位置体现出导管桨进流流场的流动特性。对比分析该艏辅推整体和各部件宽带声源级指向性,可知旋转部件(桨叶、桨榖)对总噪声级的贡献较大,静止部件是径向测点噪声的主要贡献源。

Prediction of hydrodynamic characteristics and flow noise of ducted controllable pitch propeller in bollard condition

Hydrodynamic characteristics of a ducted propeller under designed pitch and bollard pitch were predicted by validated computational fluid dynamic method.Flow noise of the ducted propeller mounted on a ship in bollard condition was also analyzed. Due to the pump suction effect,there was inverse flow around the outside of the duct in bollard condition,and the wake field was turbulent and the proportion of propeller''s thrust and duct''s was 1.2:1. The results showed that acoustic source intensity of different ducted propeller parts decreased from blade passing frequency (BPF) to 4BPF,and the highest amplitude occurred on blade leading edge and duct inner side; the far field acoustic source intensity line in frequency of axial test point reflected the ducted propeller inflow field characteristics.Analyzing the directivity of wideband sound source level (SSL) of ducted propeller and its components,it was discovered the rotary parts which contained blades and hub made large contribution to the total SSL,while the other stationary parts contributed to radial test point SSL.