通气管直径对半浸式螺旋桨水动力影响

Influence of diameter of vent pipe on hydrodynamic characteristics of surface piercing propeller

为了研究通气管在不同直径大小的情况下对半浸桨的水动力性能的影响,以一已在实船应用的半浸桨为研究对象,利用VOF方法与滑移网格技术相结合开展了系统的数值计算。采用841-B型半浸桨进行验证数值计算的可行性,在设计点附近,二者误差均小于5%,这说明采用CFD方法研究半浸桨的水动力特性是可行的。研究结果表明:在低航速下,随着通气量增加,使半浸桨更容易进入全通气状态,使推力系数Kt、扭矩系数10Kq都大幅下降,但效率有所提高,让主机转速迅速提高,让半浸桨更快进入工作段;在高航速下,随着通气量增加,空气腔厚度增加,叶栅效应更加强烈,水动力性能大幅下降,此时应把通气管收起。

To analyze the effect of diameter of a vent pipe on the hydrodynamic performance of a surface piercing propeller,this study conducts numerical calculation through the volume-of-fluid method and the sliding mesh technique,taking a surface piercing propeller in a real ship as the research object.The feasibility of numerical calculation was validated using a 841-B surface piercing propeller,proving that the error was less than 5%near the design point,which indicates that studying the hydrodynamic characteristics of the surface piercing propeller is feasible.The results show that at low velocity and with an increase in ventilation,the surface piercing propeller is more likely to enter the fully-ventilated zone state so that the thrust coefficient K t and the torque coefficient of 10 K q are all greatly reduced.Efficiency is improved so that the speed of the host increases rapidly,thereby enabling the surface piercing propeller to enter into the work section faster.At a high speed and with increased ventilation,the air cavity thickness increases and the cascade effect intensifies,thereby greatly reducing the hydrodynamic performance.At this point,the vent pipe should be put away.