全方向推进器非定常水动力性能的面元预报方法

Prediction of Variable Vector Propeller Unsteady Performance by Panel Method

研究了全方向推进器非定常水动力性能的面元预报方法,基于螺旋桨面元法建立了全方向推进器的非定常水动力性能计算的数学模型,对全方向推进器的非定常水动力性能进行了数值预报。采用了关于扰动速度势的基本积分微分方程,并采用双曲面元以消除面元间的缝隙。用Newton-Raphson迭代过程在桨叶随边满足压力Kutta条件。在计算面元的影响系数时,应用Morino导出的解析计算公式加快了数值计算的速度。为避免数值求导中的奇异性,用Yanagizawa方法求得物体表面上的速度分布。本文计算结果与日本水池模型试验结果、升力线方法计算结果及升力面方法计算结果进行了对比。

The variable vector propeller （VVP） is a new type energy-saving thruster. The blade of the variable vector propeller can rotate around its own axis while the variable vector propeller is running, thus the pitch angle of the blades will be changed periodically. Because of the reason mentioned above the lateral pressure exists. Therefore the variable vector propeller can provide three-dimensional thrust when it is installed on the fore and the end of the submarine. The structure strengthland the general arrangement as well as the maneuver of the submarine are improved as the variable vector propeller is used. The mathematical method for predicting the hydrodynamic characteristics of the variable vector propeller under unsteady condition is presented based on panel method. The mathematical models based on panel method, potential flow theory and Green theorem are also presented. The hydrodynamic characteristics are predicted numerically. To avoid gap between panels the hyperboloidal quadrilateral panels are used. The presents Kutta condition on the trailing edge of the variable vector propeller blade is satisfied by Newton-Raphson iterative procedure. The influence coefficients of panels are calculated by Morino＇s analytical formulations to improve numerical calculation speed and the method developed by Yanagizawa is used to eliminate the point singularity on derivation calculation while determining the velocities on propeller surface. To determine the shape of the trailing vortex during solving the equation, the trailing area is divided to two parts ： transition area and far-off area. Two different shapes are applied on the two areas to simulate the trailing vortex. When the velocities on propeller surface are determined, the pressures on the surface can be given by using the Bernoulli equation and the influence of the viscosity is taken into account by calculating the force friction. Finally, the experimental data by Naotica NANBA are compared with the calculation results based on lifting-line theory, the calculation results based on lifting-surface theory and the results by the method in this paper. It is concluded from the comparisons that the agreement between the results by the method presented by authors and the experimental data by Naotica NANBA is the best.