ある漁船模型の風圧力とその解析モデルについて

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Studies about wind forces acting on a ship's structures above the surface of water have been conducted by many researchers from old time, This is because wind forces cause speed loss and leeway of a ship in her navigation, difficulties in keeping her course and berthing performance during harbor maneuvering, swing motion and cutting of hawsers in her mooring, and so on. These wind forces have been analysed as a resultant force or components of longitudinal force X, lateral force Y and yaw-moment N. There is no research, however, which deals with these forces as described by a mathematical model like hydrodynamic forces during a ship's maneuvering, or composed of fluid dynamic components due to its characteristics, for example friction force, lift force and so on. This paper separates fluid force from ideal fluid force (Munk moment), lift and induced drag forces due to viscosity, and cross flow drag force. In particular, the cross flow drag coefficient C_D is assumed to be C_<D90> ∣sinβ∣ varing with drift angleβ (as mentioned in author's paper [1]) and the lift coefficient C_L is assumed to be proportional to cosβ multiplied by a coefficient which corrects for the small drift angle. As the result, longitudinal force X, lateral force Y and yaw moment N of wind forces acting on a ship are described by the following mathematical model X=X<uvv>v^2・cosβ+X_<uuuvv>(1/U)・uv^2・cos^2β+X_<u∣u∣>u∣u∣+X_<∣vv∣>・∣v∣^2 Y=Y_<uuv>・cosβ+Y_uuvvv(1/U)・v^3・cos^2β+1/2ρ∫C_<D90>∣sinβ∣・v・∣v∣・d_m・dx N=(m_x-m_y)uv+N_<uuv>・uv・cosβ+N_<uuvvv>(1/U)・v^3・cos^2β+1/2ρ∫C_<D90>∣sinβ∣・v・∣v∣・x・d_m・dx where u: Ucosβ, v: -Usinβ U: wind speed, β: wind direnction angle m_x, m_y: added mass, C_<D90>: cross flow drag coefficient atβ=90deg As a result of analysing wind forces acting on a 1/200 scale image model of a fishing boat measured by a wind tunnel test, it is indicated that the mathematical model mentioned above is very effective to describe wind forces X, Y and N and each of these forces can be subdivided into elementary components of fluid dynamic characteristics.
社団法人日本船舶海洋工学会の論文
1989-09-25

ある漁船模型の風圧力とその解析モデルについて

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