Research Of Morphing Fin Stabilizer And Its Application In Underwater Vehicles

Since fin stabilizer came into use in 1889, It has enjoyed increasing reputation in ameliorating both ships and submarines roll motions. It's highly significant to establish the lift model of those deformable fin stabilizers with great increase in lift only by surface modification. Motivated by the progress of deformable fin stabilizers, The present paper is going to focus on three kinds of fin stabilizer models:fin stabilizer with bumpy surface, fin stabilizer with change in camber, fin stabilizer with deflected flap.The basis of introducing bumps to fin surface stems from the design of an inflatable -rigid wing for the University of Kentucky Big Blue student project. The proposed method here is to increase lift and delay stall by keeping the flow tripped at all times along the surface. The hydrodynamic software called FLUENT was introduced here to simulate the flow field of Fin Stabilizer with bumpy surface in 3 dimensional. It was found that the extent of separation was lesser for the fin stabilizer with bumpy surface when compared to the experiment result of standard NACA0015 with the same aspect ratio, span and chord length. Based on the comparison, the mechanism of lift increase was briefly discussed here.Inspired by reducing roll motions in an economical way, a promising methods was employed here with camber optimized fin stabilizer. Based on the mathematical model of fin stabilizer with change in camber operating at zero speed stream promoted by Harbin Engineering University, lift in random sea states was expressed by measureless operation of the largest fin angle to the amplitude of random wave. Target function was established with the purpose to produce the highest lift at the lowest cost of energy. The optimum camber was obtained by PSO(Particle Swarm Optimization) algorithm and the fin stabilizer system with the optimal camber was applied to underwater vehicles.However the fin stabilizer with optimized camber is not practical, which couldn't be actually implemented to ships or submarines. Referring to the deflected flap with high research attractions in aviation and the theoretical fin stabilizer with flap promoted by Harbin Engineering University, The objective of this study is to critically introduce deflected flap into fin stabilizer operated at zero free stream velocity by numerical simulation. A preliminary 2D CFD study to explore hydrodynamics of standard NACA 0015 fin and fin with flap at zero free stream velocity has been carried out. The effects of critical parameters like the ratio of flap chord to section chord (M/F), flap deformation angle(B), amplitude of pitching(A) and the increased frequency(k)on fin with flap has been critically investigated. The results indicate that an obvious enhancement hydrodynamics is observed for a fin with M/F of 0.1. It is also found that hydrodynamics of fin with flap is sensitive to flap deformation angle, amplitude and frequency of pitching. The greater the amplitude and frequency, the greater the lift becomes. Finally, after comparison of lift on fin with deflected flap and XTTM extendable fin stabilizer, we conclude that at zero free stream velocity obvious lift increase is found on fin with deflected flap oscillating at high speed; while XTTM extendable fin stabilizer is more efficient than fin with deflected flap oscillating at low speed.