模拟自由面影响的涡格方法

Vortex lattice method for the simulation of free-surface effects

基于涡格法来计算自由面影响下的水下航行体或螺旋桨水动力性能。水下航行体、螺旋桨以及自由面均采用涡格来表达,航行体涡格布置在真实物面上,桨叶涡格布置在拱弧面上,自由面涡格布置在静水面上方合适的距离处。通过奇点系的诱导速度来模拟物体与自由面的相互作用,在物面(或螺旋桨拱弧面)上满足不可穿透条件及在静水面上满足线性自由面条件,建立关于涡强的线性方程组并联立求解。通过球体、水翼及螺旋桨等算例考察了该方法的收敛性和精度,并讨论了进速和沉深对螺旋桨水动力性能的影响。

A vortex-lattice method is proposed for simulating free-surface effects on the hydrodynamic performance of submerged moving bodies and the propeller. The bodies, the propeller, and the free surface are all modeled with vortex lattices. The vortex lattices are located on exact body surfaces for the bodies, on blade camber surfaces for the propeller, and slight above the still water surface for the free surface, respectively. The interactions between the bodies/propeller and the free surface are simulated via the velocity induced by the vortex lattices. By implementing simultaneously the non-penetration condition on the body/camber surfaces and the linearized free-surface condition on the still water surface, a set of linear algebraic equations are established for the unknown vortex-lattice strengths. Using a sphere, a hydrofoil, and a propeller respectively, the convergence property and accuracy of the present method are explored, and the effects of the advance speed and the submerged depth on propeller hydrodynamics performance are investigated.