螺旋桨诱导的船尾脉动压力的数值模拟

Numerical simulation of propeller-induced vibrating pressure on stern

利用奇点分布的方法计算船尾脉动压力.在用面元法计算螺旋非定常水动力性能的基础上,在船舶尾部分面元并分布奇点,通过迭代求解船尾和螺旋桨的相互影响,在此计算过程中,采用较为简捷的关于扰动速度势的基本积分微分方程,并采用双面曲形状的面元以消除面元间的间隙.Newton_laphson迭代过程被用来在桨叶随边满足压力Kutta条件,使桨叶上下表面的压力在随边有良好的一致性,在计算面元的影响系数时,应用了Morino导出的解析计算公式,加快了数值计算的速度.从面元法的基本积分方程得到的偶极强度和源汇强度,直接求得流场中的速度分布,并以此计算船尾和螺旋桨的相互影响.得到稳定的流场以后,通过伯努里方程计算船尾压力分布,并通过傅里叶变换得到各个阶脉动压力.最后将计算结果和试验结果作了比较分析.

Vibrating pressure on the stern was calculated by simulating source distribution. The Panel method was used to calculate the unsteady hydrodynamic performance of a propeller. Then source was used to get a simulating model of the stern. Hydrodynamic interaction between propeller and hull was achieved by an iterative calculation. In the process, the hyperboloidal quadrilateral panels were employed to avoid gaps between the panels. The influence coefficients of the panels were determined by Morino's analytical formulations for increasing numerically calculating speed. The pressure Kutta condition was satisfied on the trailing edge of the propeller blade by Netwon-Raphson iterative procedure. Therefore the pressure coefficients of the suction and pressure faces of blade are equal on trailing edge. By solving the fundamental integral equation in panel surface method, the intensities of doublets and sources on the surface of the marine propeller can be obtained. With these doublets and sources the velocity distribution in flow field was achieved to calculate the interaction between the stern and propeller. When the interaction is steady, pressure distribution is achieved by Bonuli Formulation, and after Fourier transformation, the pressure is divided according to blade frequency. The comparison between theoretical result and experimental one shows that the method is effective and useful.