波によるHeavingおよびPitchingの強制力をうけない船型について

概要

論文の詳細を見る
It has been shown by Ursell [1]that there are prisms of certain sections which do not create waves when they roll in a still water surface. This problem has been extended by Bessio [3] in motion of six degree of freedom. On the other hand, Newman [4] has shown making use of Haskind relation that damping coefficient for any motion of a body is directly related to the exciting force acting on the same body in waves.These results indicate that there must be bodies which will not be acted by any exciting force by waves.In this paper, the Authors delt with this problem restricting it to the case of heaving and pitching motion. It has been shown by Motora [5] that heaving force acting on a body in waves is approximately expressed in the following from : F_<ZW>=γ_1K_ZρVZ_W+γ_2N_ZZ_W+γ_3ρgAZ_W where γ_1,γ_2 and γ_3 are correction factors which are the functions of wave number K=ω^2/g K_Z is the added mass coefficient of the body for heaving V is the volum of the body Z_W is the surface elevation of waves N_Z is the damping coefficient ρ is the density of water g is the accerelation of gravity A is the water plane area of the body The first term shows the body wave interaction and the third term shows the Froude Krylov force with Smith Correction. Since Z_W=-ω^2Z_W, it is clear that the first term of the right hand side of the equation is reverse in sign compared to the third term. In the case of usual ship forms however, in significant frequency range, the first term is not so large compared with the third term.However, if a section form of a ship is designed so that the first term is comparable with the third term at significant frequency of waves, those two term will cancel each other and only the second term-the damping term-will remain.On the other hand, Newman's relation shows that the damping coefficient is proportional to the square of heaving force which is now very small. Therefore, it is possible to make the heaving excitation practically zero at specified frequency of waves.In this paper, the Authors showed some examples of such forms and the measured heaving exciting force. Though only results in two dimensional problem were shown, this problem can be extended into three dimensional problems.
社団法人日本船舶海洋工学会の論文

波によるHeavingおよびPitchingの強制力をうけない船型について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク