非线性涡格法预报桨后舵附推力鳍水动力性能

Study of the rudder with additional thrust fins used by non-linear vortex lattice method

对螺旋桨与舵附推力鳍分别采用升力面法和非线性涡格法计算.螺旋桨、舵附推力鳍两者之间的相互干扰采用迭代计算.数值计算过程中考虑了推力鳍端部分离涡的影响,提高了理论预报的准确性.螺旋桨尾流区分为过渡区和远尾流区.过渡区长度取3.0D,以使舵附推力鳍完全处于螺旋桨尾流的过渡区内,过渡区采用圆锥螺旋面来模拟涡片的变形现象.对影响推力鳍助推效率的几个主要参数进行了变尺度研究.并将结果与前人的计算结果进行了对比,计算结果显示螺旋桨后的舵附推力鳍助推效率随着安装角的改变而显著变化.存在最佳安装角,大约为5°,离开这个最佳安装角,推力鳍的助推效率将下降;推力鳍的展长与螺旋桨半径之比在0.9左右时推力鳍的助推效率最高;螺旋桨进速系数越小,推力鳍的助推效率越大.

Lifting surface method and non-linear vortex lattice method were used for the calculation of propeller and rudder with additional thrust fins respectively. Hydrodynamic interaction between them was achieved by interactive calculation. The free vortices at tips of the additional thrust fins were considered to enhance the precision of calculation. The wake of propeller was composed of transition and remoteness domains. The length of transition domain was about three time of diameter of propeller to comprise the rudder with additional thrust fins totally. The transition domain was simulated by taper helix surface. Through changing dimensions, this paper studied the principal parameters that affected additional thrust efficiency of the thrust fins. The comparison between theoretical result and other resuits showed that the present method was effective and useful. The results revealed that the efficiency of fins was sensitive to the angle. An optimal angle of fins existedwas about 5°. Away from the optimal angle, the efficiency of fins would descend observably. The wingspan of fins should be about 0.9 time of propeller radius. Along with the diminution of advance coefficient, the efficiency of fins would increase.